Biopharmconsortium Blog

Expert commentary from Haberman Associates biotechnology and pharmaceutical consulting.

Posts filed under: Translational medicine

Can adoptive cellular immunotherapy successfully treat metastatic gastrointestinal cancers?

 

Dr. Steven Rosenberg

Dr. Steven Rosenberg

On September 6, 2014, we published an article on this blog announcing the publication of our book-length report, Cancer Immunotherapy: Immune Checkpoint Inhibitors, Cancer Vaccines, and Adoptive T-cell Therapies, by Cambridge Healthtech Institute (CHI).

In that article, we cited the example of the case of a woman with metastatic cholangiocarcinoma (bile-duct cancer), which typically kills the patient in a matter of months. The patient, Melinda Bachini, was treated via adoptive immunotherapy with autologous tumor-infiltrating T cells (TILs) resulting in survival over a period of several years, with a good quality of life.

Our report includes a full discussion of that case, as of the date of the May 2014 publication of a report in Science by Steven A. Rosenberg, M.D., Ph.D. and his colleagues at the National Cancer Institute (NCI). Ms. Bachini’s story was also covered in a May 2014 New York Times article.

Now comes the publication, in Science on December 2015, of an update from the Rosenberg group on their clinical studies of TIL-based immunotherapy of metastatic gastrointestinal cancers. This article discusses the results of TIL treatment of ten patients with a variety of gastrointestinal cancers, including cancers of the bile duct, the colon or rectum, the esophagus, and the pancreas. The case of Ms. Bachini (“patient number 3737”) was included.

Ms. Bachini, a paramedic and a married mother of six children, and a volunteer with the Cholangiocarcinoma Foundation, was 41 years old when first diagnosed with cancer. She remains alive today—a five-year survivor—at age 46.

The Foundation produced a video, dated March 13, 2015, in which Ms. Bachini gives her “patient perspective”. This video includes her story “from the beginning”—from diagnosis through surgery and chemotherapy, and continuing with adoptive immunotherapy at the NCI under Dr. Rosenberg. Although her tumors continue to shrink and she remains alive, she still is considered to have “Stage 4” (metastatic) cancer. Ms. Bachini is a remarkable woman.

The Cholangiocarcinoma Foundation has also produced an on-demand webinar (dated October 21, 2014) on the adoptive cellular therapy trial in patients with various types of metastatic gastrointestinal cancers, led by Drs. Eric Tran and Steven Rosenberg. Ms. Bachini is also a presenter on that webinar. The December 2015 Science article is an updated version of the results of this trial.

The trial, a Phase 2 clinical study (NCT01174121) remains ongoing, and is recruiting new patients.

The particular focus of Dr. Tran’s and Dr. Rosenberg’s study in TIL treatment of gastrointestinal cancers is whether TILs derived from these tumors include T-cell subpopulations that target specific somatic mutations expressed by the cancers, and whether these subpopulations might be harnessed to successfully treat patients with these cancers. Of the ten patients who were the focus of the December 2015 publication, only Ms. Bachini had a successful treatment. In the case of Ms. Bachini, she received a second infusion of TILs that were enriched for CD4+ T cells that targeted a unique mutation in a protein known as ERBB2IP. It was this second treatment that resulted in the successful knockdown of her tumors, which continues to this day.

Despite the lack of similar successes in the treatment of the other nine patients, the researchers found that TILs from eight of these patients contained CD4+ and/or CD8+ T cells that recognized one to three somatic mutations in the patient’s own tumors. Notably, CD8+ TILs isolated from a colon cancer tumor of one patient (patient number 3995) recognized a mutation in KRAS known as KRAS G12D. This mutation results in an amino acid substitution at position 12 in KRAS, from glycine (G) to aspartic acid (D). KRAS G12D is a driver mutation that is involved in causation of many human cancers.

Although two other patients (numbers 4032 and 4069, with colon and pancreatic cancer, respectively) had tumors that expressed KRAS G12D, the researchers did not detect TILs that recognized the KRAS mutation in these patients. The researchers concluded that KRAS G12D was not immunogenic in these patients. The TILs from patient 3995 were CD8+ T cells that recognized KRAS G12D in the context of the human leukocyte antigen (HLA) allele HLA-C*08:02. [As with all T cells, TILs express T-cell receptors (TCRs) that recognize a specific antigenic peptide bound to a particular major histocompatibility complex (MHC) molecule—this is referred to as “MHC restriction”.] The two patients for whom KRAS G12D was not immunogenic did not express the HLA-C*08:02 allele.

The results seen with KRAS G12D-expressing tumor suggest the possibility of constructing genetically-engineered CD8+ T cells that express a TCR that is reactive with the KRAS mutation in the context of the HLA-C*08:02 allele. The KRAS G12D driver mutation is expressed in about 45% of pancreatic adenocarcinomas, 13% of colorectal cancers, and at lower frequencies in other cancers, and the HLA-C*08:02 allele is expressed by approximately 8% and 11% of white and black people, respectively, in the U.S. Thus, in the U.S. alone, thousands of patients per year with metastatic gastrointestinal cancers would potentially be eligible for immunotherapy with this KRASG12D-reactive T cell.

Although only Ms. Bachini (“patient number 3737”) was a long-term survivor, the researchers were able to treat three other patients with enriched populations of TILs targeting predominantly one mutated tumor antigen. Patient 4069 experienced a transient regression of multiple lung metastases of his pancreatic adenocarcinoma, but patients 4007 and 4032 had no objective response. Whereas 23% of circulating T cells at one month after treatment were adoptively transferred mutation-specific TILs in the case of Ms. Bachini, the other three patients treated with enriched populations of mutation-specific TILs showed no or minimal persistence. The researchers concluded that they will need to develop strategies designed to enhance the potency and persistence of adoptively transferred mutation-specific TILs. Nevertheless, the researchers concluded that nearly all patients with advanced gastrointestinal cancers harbor tumor mutation-specific TILs. This finding may serve as the basis for developing personalized adoptive cellular therapies and/or vaccines that can effectively target common epithelial cancers.

Conclusions

Dr. Rosenberg pioneered the study and development of adoptive cellular immunotherapy, beginning in the 1980s. Most studies with TIL-based adoptive immunotherapy have been in advanced melanoma. Adoptive cellular immunotherapy is the most effective approach to inducing complete durable regressions in patients with metastatic melanoma.

As we discussed in our cancer immunotherapy report, melanoma tumors have many more somatic mutations (about 200 nonsynonymous mutations per tumor) than most types of cancer. This appears to be due to the role of a potent immunogen—ultraviolet light—in the pathogenesis of melanoma. The large number of somatic mutations in melanomas results in the infiltration of these tumors by TILs that target the mutations. As discussed in our report, Dr. Rosenberg and his colleagues cultured TIL cell lines that addressed specific immunodominant mutations in patients’ melanomas. Treatment with these cell lines in several cases resulted in durable complete remissions of the patients’ cancers.

Dr. Rosenberg and his colleagues used the same strategy employed in identification of TIL cell lines that targeted specific mutations in melanomas to carry out the study in gastrointestinal cancers, as discussed in our report. However, the small number of somatic mutations and of endogenous TILs in gastrointestinal cancers and in most other epithelial cancers has made studies in these cancers more difficult than studies in melanoma.

in addition, the susceptibility of melanoma to treatment with checkpoint inhibitors such as the PD-1 blockers pembrolizumab (Merck’s Keytruda) and nivolumab (Bristol-Myers Squibb’s Opdivo) correlates with the large number of somatic mutations in this type of cancer. As we discussed in our December 15, 2014 article on this blog, immune checkpoint inhibitors work by reactivating endogenous tumor-infiltrating T cells (TILs). In the case of melanoma, these endogenous TILs target the numerous somatic mutations found in these cancers, and—as suggested by Dr. Rosenberg’s studies with cultured TIL cell lines—those endogenous TILs that target immunodominant mutations can induce durable compete remissions. As discussed in our December 15, 2014 blog article, the three major types of immuno-oncology treatments—immune checkpoint inhibitors, cancer vaccines, and adoptive T-cell therapies, work via related mechanisms.

In 2015, researchers showed that other types of cancers that have numerous somatic mutations are especially susceptible to checkpoint inhibitor treatment. These include, for example, non-small cell lung cancers (NSCLCs) that have mutational signatures that indicate that the cancers were caused by smoking, and cancers that have mutations in genes involved in DNA repair. (Mutations in genes involved in DNA repair pathways result in the generation of numerous additional mutations.)

Moreover, as discussed in our December 15, 2014 blog article, cancer immunotherapy researchers have been expanding the types of tumors that can be treated with checkpoint inhibitors. Genentech/Roche’s PD-L1 inhibitor that was discussed in that article, MPDL3280A, is now called atezolizumab. The clinical trials of atezolizumab discussed in that article and in our report have continued to progress. In a pivotal Phase 2 study in locally advanced or metastatic urothelial bladder cancer (UBC), atezolizumab shrank tumors in 27 percent of people whose disease had medium and high levels of PD-L1 expression and had worsened after initial treatment with platinum chemotherapy. These responses were found to be durable. According to Genentech, these results may represent the first major treatment advance in advanced UBC in nearly 30 years. Atezolizumab also gave positive results in Phase 2 clinical trials in patients with NSCLC that expresses medium to high levels of PD-L1.

Meanwhile, NewLink Genetics (Ames, IA) has entered Phase 3 clinical trials in pancreatic cancer with its HyperAcute cellular immunotherapy vaccine therapy. A Phase 2 trial of the company’s HyperAcute cellular immunotherapy algenpantucel-L in combination with chemotherapy and chemoradiotherapy in resected pancreatic cancer (clinical trial number NCT00569387) appears to be promising.

Dr. Rosenberg’s studies of TIL therapies of gastrointestinal cancers represent another approach to moving immuno-oncology treatments beyond melanoma, based on mutation-specific targeting. The types of cancers that form the focus of these studies—gastrointestinal epithelial cancers—have proven difficult to treat. Moreover, several of them are among the most common of cancers. The researchers and patients involved in these and other immuno-oncology studies are heroes, and oncologists appear to be making measured progress against cancers that have been until recently considered untreatable.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to your company, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Our New Year’s 2015 article: Notable researchers and breakthrough research of 2014

 

Pre-1917 Russian Happy Christmas and Happy New Year card

Pre-1917 Russian Happy Christmas and Happy New Year card

As is their customary practice, both Nature and Science ran end-of-year specials. The Nature special (in their 18 December issue) is entitled “365 days: Nature’s 10. Ten people who mattered this year.” The Science special (in their 19 December issue) is entitled, as usual “2014 Breakthrough of the Year.” As is also usual, there is a section for “Runners Up” to the year’s “Breakthrough”.

From the point of view of a consulting group—and a blog—that focuses on effective drug discovery and development strategies, we were disappointed with both end-of-year specials. Most of the material in these articles was irrelevant to our concerns.

Science chose the Rosetta/Philae comet-chasing mission as the “Breakthrough of the Year”, and its “runners up” included several robotics and space-technology items, as well as new “letters” to the DNA “alphabet” that don’t code for anything.

Nature also focused on comet chasers, robot makers, and space technologists, as well as cosmologist and mathematicians, and a fundraising gimmick—“the ice-bucket challenge”. Moreover, Nature was much too restrictive in titling its article “Ten people who mattered”. Every human being matters!

Nevertheless, these two special sections do contain a few gems that are both relevant to effective drug discovery and development, and are worthy of highlighting as “notable researchers of 2014” and “breakthrough research of 2014”. We discuss these in the remainder of this article.

Suzanne Topalian, M.D.

Suzanne Topalian is one of the researchers profiled in “Nature’s 10”. She is a long-time cancer immunotherapy clinical researcher who began her career in 1985 in the laboratory of cancer immunotherapy pioneer Steven Rosenberg at the National Cancer Institute (Bethesda MD). In the early days of the field, when cancer immunotherapy was scientifically premature, there was a great deal of skepticism that these types of treatments would even work. However, both Dr. Rosenberg and Dr. Topalian persevered in their research.

In 2006, Dr. Topalian moved to Johns Hopkins University (Baltimore, MD) to help launch clinical trials of Medarex/Bristol-Myers Squibb/Ono’s nivolumab, a PD-1 inhibitor. As noted in the Nature article, her work “led to a landmark publication in 2012 showing that nivolumab produced dramatic responses not only in some people with advanced melanoma but also in those with lung cancer [specifically, non–small-cell lung cancer, NSCLC].” We also discussed that publication on the Biopharmconsortium Blog, and in our recently published book-length Insight Pharma Report, Cancer Immunotherapy: immune checkpoint inhibitors, cancer vaccines, and adoptive T-cell therapies. Our report also includes discussions of Dr. Rosenberg’s more recent work in cellular immunotherapy.

As discussed in our report, nivolumab was approved in Japan as Ono’s Opdivo in July 2014 for treatment of unresectable melanoma, and a competitive PD-1 inhibitor, pembrolizumab (Merck’s Keytruda) was approved in the United States for advanced melanoma on September 5, 2014. More recently, on December 22, 2014, the FDA also approved nivolumab (BMS’ Opdivo) for advanced melanoma in the U.S. There are thus now two FDA-approved PD-1 inhibitors [in addition to the CTLA-4 inhibitor ipilimumab (BMS’ Yervoy)] available for treatment of advanced melanoma in the U.S.

Meanwhile, researchers continue to test both nivolumab and pembrolizumab for treatment of NSCLC and other cancers. And some analysts project that both of these agents are likely to be approved by the FDA for treatment of various populations of patients with NSCLC before the middle of 2015. Researchers are also testing combination therapies that include nivolumab or pembrolizumab in various cancers. And clinical trials of Genentech/Roche’s PD-L1 blocking agent MPDL3280A are also in progress.

Science’s 2013 Breakthrough of the Year was cancer immunotherapy, as we highlighted in our New Year’s 2014 blog article. Science could not make cancer immunotherapy the Breakthrough of the Year for 2014, too. Thus it chose to give physical scientists a turn in the limelight by highlighting the comet-chasing mission instead. Nevertheless, 2014 was the year in which cancer immunotherapy demonstrated its maturity by the regulatory approval of the two most advanced checkpoint inhibitor agents, pembrolizumab and nivolumab.

Implications for patients with terminal cancers

The clinically-promising results of cancer immunotherapy in a wide variety of cancers, coupled with the very large numbers of clinical trials in progress in this area, has also changed the situation for patients who have terminal cancers. Researchers who are conducting clinical trials of immunotherapies for these cancers are actively recruiting patients, of whom there are limited numbers at any one time. For example, there are now numerous clinical trials—mainly of immunotherapies—in pancreatic cancer, and most of these trials are recruiting patients. There are also active clinical trials of promising immunotherapies in the brain tumor glioblastoma. These are only two of many examples.

Recently, a 29-year-old woman with terminal glioblastoma ended her life using Oregon’s physician-assisted suicide law. Prior to her suicide, she became an advocate for “terminally ill patients who want to end their own lives”. We, however, are advocating that patients with glioblastoma and other types of terminal cancer for which there are promising immunotherapies seek out clinical trials that are actively recruiting patients. There is the possibility that some of these patients will receive treatments that will result in regression of their tumors or long-term remissions. (See, for example, the case highlighted in our September 16, 2014 blog article. There are many other such cases.) And it is highly likely that patients who participate in these trials will help researchers to learn how to better treat cancers that are now considered “incurable” or “terminal”, and thus help patients who contract these diseases in the future. From our point of view, that is a lot better than taking one’s own life via assisted suicide, and/or becoming an euthanasia advocate.

Masayo Takahashi, M.D., Ph.D.

Another researcher profiled in “Nature’s 10” is Masayo Takahashi, an ophthalmologist at the RIKEN Center for Developmental Biology (CDB) in Kobe, Japan who has been carrying out pioneering human stem cell clinical studies. We also discussed Dr. Takahashi’s research in our March 14, 2013 article on this blog.

At the time of our article, Dr. Takahashi and her colleagues planned to submit an application to the Japanese health ministry for a clinical study of induced pluripotent stem cell (iPS)-derived cells, which would constitute the first human study of such cells. They planned to treat approximately six people with severe age-related macular degeneration (AMD). The researchers planned to take an upper arm skin sample the size of a peppercorn, and transform the cells from this sample into iPS cells by using specific proteins. They were then to add other factors to induce differentiation of the iPS cells into retinal cells. Then a small sheet of these retinal cells were to be placed under the damaged area of the retina, where they were expected to grow and repair the damaged retinal pigment epithelium (RPE). Although the researchers would like to demonstrate efficacy of this treatment, the main focus of the initial studies was to be on safety.

According to the “Nature’s 10” article, such an autologous iPS-derived implant was transplanted into the back of a the damaged retina of one patient in September 2014. This patient, a woman in her 70s, had already lost most of her vision, and the treatment is unlikely to restore it. However, Dr. Takahashi and her colleagues are determining whether the transplant is safe and prevents further retinal deterioration. So far, everything has gone smoothly, and the transplant appears to have retained its integrity. However, the researchers will not reveal whether the study has been a success until a year after the transplantation.

The “Nature’s 10” article discusses how this technology might be moved forward into clinical use if the initial study is successful. It also discusses how Dr. Takahashi has been carrying her research forward in the face of a major setback that has plagued stem cell research at the CDB in 2014, as the result of the withdrawal of two once highly-regarded papers and the suicide of one of their authors.

Generation of insulin-producing human pancreatic β cells from embryonic stem (ES) cells or iPS

Another stem cell-related item, which was covered in Science’s end-of-2014 “Runners Up” article, concerned the in vitro generation of human pancreatic β cells from embryonic stem (ES) cells or iPS. For over a decade, researchers have been attempting to accomplish this feat, in order to have access to autologous β cells to treat type 1 diabetes, in which an autoimmune attack destroys a patient’s own β cells. In vitro generated β cells might also be used to screen for drugs that can improve β cell function, survival, and/or proliferation in patients with type 2 diabetes.

As reported in the Science article, two research groups—one led by Douglas A. Melton, Ph.D. (Harvard Stem Cell Institute, Cambridge, MA), and the other by Alireza Rezania, Ph.D. at BetaLogics Venture, a division of Janssen Research & Development, LLC.–developed protocols to produce unlimited quantities of β cells, in the first case from IPS cells, and in the other from ES cells.

However, in order to use the β cells to treat type 1 diabetes patients, researchers need to develop means (for example, some type of encapsulation) to protect the cells from the autoimmune reaction that killed patients’ own natural β cells in the first place. For example, Dr. Melton is collaborating with the laboratory of Daniel Anderson, Ph.D. (MIT Koch Institute for Integrative Cancer Research). Dr. Anderson and his colleagues have developed a chemically modified alginate that can be used to coat and protects clusters of β cells, thus forming artificial islets. Dr. Melton estimates that such implants would be about the size of a credit card.

The 2014 Boston biotech IPO boom

Meanwhile, the Boston area biotechnology community has seen a boom in young companies holding their initial public offerings (IPOs). 17 such companies were listed in a December 24 article in the Boston Business Journal. Among these companies are three that have been covered in the Biopharmconsortium Blog—Zafgen, Dicerna, and Sage Therapeutics.

We hope that 2015 will see at least the level of key discoveries, drug approvals, and financings seen in 2014.


As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to your company, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Late-breaking cancer immunotherapy news

Source: Medical Progress Today 12/14/12 http://bit.ly/1sPO1WU

Source: Medical Progress Today 12/14/12
http://bit.ly/1sPO1WU

In our September 16, 2014 article on this blog, we announced the publication by Cambridge Healthtech Institute’s (CHI’s) Insight Pharma Reports of a new book-length report, Cancer Immunotherapy: Immune Checkpoint Inhibitors, Cancer Vaccines, and Adoptive T-cell Therapies, by Allan B. Haberman, Ph.D.

As we said in that blog article, “cancer immunotherapy is a ‘hot’, fast-moving field”. Thus—inevitably—in the short time since the publication of our report, a great deal of late-breaking news has come in.

This article is a discussion of several key late-breaking news items, which were not published in the report.

Pricing of checkpoint inhibitor agents

As discussed in the report, two PD-1 inhibitors have been recently approved. Bristol-Myers Squibb (BMS)/Ono’s nivolumab was approved in Japan (where it is know by the brand name Opdivo) in July 2014 for treatment of unresectable melanoma. Pembrolizumab (Merck’s Keytruda) was approved in the U.S. for treatment of advanced melanoma on September 5, 2014. The very first checkpoint inhibitor to reach the market, the CTLA-4 inhibitor ipilimumab (Medarex/BMS’s Yervoy), was approved in the U.S. in 2011.

At the same time as the news of the approval of the PD-1 inhibitors nivolumab and pembrolizumab came out, information on the pricing of these agents also became available. However, because of the need to complete the report for publication, there was no time to discuss the issue of pricing adequately.

As discussed in a September 4, 2014 article in FiercePharma, the cost of nivolumab in Japan (according to the Wall Street Journal) is $143,000. According to the FierceBiotech article, this was greater than the introductory price for any other cancer drug, especially in Japan, where prices tend to be somewhat lower than in the U.S.

Meanwhile, as reported in a September 4, 2014 article in FierceBiotech, the cost of pembrolizumab in the U.S. will be $12,500 a month, or $150,000 a year.

For comparison, the launch price of BMS’ ipilimumab was $120,000. As we discussed in the report, the PD-1 inhibitors nivolumab and pembrolizumab—as seen in early clinical trials—appear to be more efficacious and have fewer adverse effects in treatment of melanoma.

As discussed in our report, checkpoint inhibitors such as ipilimumab, nivolumab and pembrolizumab are eventually likely to be used in combination with other drugs, including other immuno-oncology drugs, targeted therapies, and others. The price per month or per year of these potentially life-saving and at least in some cases curative combination therapies may thus be expected to go still higher. However, if cancers are pushed into long-term remission or even cure, then it might be possible to discontinue treatment with these expensive drug combinations. In such cases, the cost of treatment may even be less than current therapeutic regimens.

There are no analyses of the costs of specific immunotherapy drugs or cellular therapies in our report. However, we do discuss the issue of drug costs in the survey and interviews that are part of the report.

The issue of the costs of expensive drugs for life-threatening cancers is under discussion in the cancer community. For example, the American Society of Clinical Oncology (ASCO) has initiated an effort to rate oncology drugs not only on their efficacy and adverse effects, but also on their prices. ASCO’s concern is that pricing be related to the therapeutic value of drugs. And commentators such as Peter Bach, MD, MAPP (the Director of the Memorial Sloan Kettering Cancer Center’s Center for Health Policy and Outcomes) have been weighing in with their analyses. As additional immunotherapy drugs and cellular therapies reach the market, these discussions will certainly continue.

The Bristol-Myers Squibb-Merck lawsuit over PD-1 inhibitors

Another late-breaking news item that came out at the time of the publication of our report is the lawsuit between BMS and Merck over PD-1 inhibitors. Specifically, as soon as Merck gained FDA approval for pembrolizumab, BMS and its Japanese partner Ono sued Merck for patent infringement.

The patent in question is U.S. patent number 8,728,474. It was filed on December 2, 2010, granted to Ono on May 20, 2014, and licensed to BMS. The patent covers the use of anti-PD-1 antibodies to treat cancer. According to BMS and Ono’s claims, Merck started developing pembrolizumab after BMS and Ono had already filed their patent and were putting it into practice by developing their own PD-1 inhibitor, nivolumab.

The lawsuit asks for damages, and for a ruling that Merck is infringing the BMS/Ono PD-1 patent. Such a ruling may mean that BMS and Ono are owed royalties on sales of all rival PD-1 drugs, not just Merck’s. BMS/Ono and Merck are involved in parallel litigation in Europe.

Merck acknowledges Ono’s method patent, but says that it is invalid. Merck also said the lawsuit will not interfere with the U.S. launch of pembrolizumab.

We shall have to watch the proceedings in the U.S. District Court for the District of Delaware to see the outcome of this case. Although this lawsuit was not discussed in our report, the report does include a discussion of the fierce race between PD-1 inhibitor developers Merck and BMS to be the first to market, and to gain the largest market share. The lawsuit is clearly one element in this race.

Merck Serono discontinues development of the cancer vaccine tecemotide

On September 18, 2014, Merck KGaA (Darmstadt, Germany; also known as Merck Serono and EMD Serono) announced that it has discontinued development of the cancer vaccine tecemotide. Tecemotide is a peptide vaccine that was formerly known as Stimuvax. It was originally developed by Oncothyreon (Seattle, WA) and licensed to Merck Serono in 2007.

We covered tecemotide in our report, both as an example of a cancer vaccine that had failed in Phase 3 clinical trials, and as an example of a vaccine that was nevertheless still under development. As discussed in our report, in a Phase 3 trial known as START in non-small cell lung cancer (NSCLC) patients, researchers found no significant difference in overall survival between administration of tecemotide or placebo. However, a subsequent analysis suggested that there was a statistically significant survival advantage for tecemotide compared with placebo in a pre-defined subset of patients. Based on these results, Merck Serono began a second Phase 3 trial in that subset.

However, as the result of a failure in a Phase 3 trial in Japan sponsored by Oncothyreon (reported on August 19, 2014), Merck Serono decided to discontinue development.

As stated by Merck Serono’s Executive Vice President and Global Head of R&D Luciano Rossetti, “While the data from the exploratory subgroup analysis in the START trial generated a reasonable hypothesis to warrant additional study, the results of the recent trial in Japanese patients decreased the probability of current studies to reach their goals.”

As we discussed in our report, the cancer vaccine field has been rife with clinical failures—from its beginnings in the 1990s to the present day. This has especially included late-stage failures, not only that of Merck Serono’s tecemotide, but also, for example, GlaxoSmithKline’s (GSKs) MAGE-A3 vaccine. Only one anticancer vaccine—sipuleucel-T (Dendreon’s Provenge) for treatment of metastatic castration-resistant prostate cancer—has ever reached the market, and its therapeutic effects appear to be minimal.

Despite these poor results, researchers and companies persist in their efforts to develop cancer vaccines. Our report discusses why cancer vaccine R&D continues despite the overwhelming history of failure, the hypothesized reasons for these failures, and what researchers and companies can do and are doing to attempt to obtain better results.

Conclusions

As a fast-moving, important field, cancer immunotherapy will continue to generate scientific, medical, and market news. There will continue to be periodic meetings, such as the 2014 European Society for Medical Oncology (EMSO) meeting (September 26-30, Madrid, Spain), in which positive results of small, early-stage trials of several checkpoint inhibitors were presented. Our report—an in-depth discussion of cancer immunotherapy—can enable you to understand such future developments, as well as current ones. It is also designed to inform the decisions of leaders in companies and in academia that are involved in cancer R&D and treatment.

For more information on Cancer Immunotherapy: Immune Checkpoint Inhibitors, Cancer Vaccines, and Adoptive T-cell Therapies, or to order it, see the Insight Pharma Reports website.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to your company, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Cancer Immunotherapy Report Published By CHI Insight Pharma Reports

T cells attached to tumor cell. Source: MSKCC. http://bit.ly/1uPr5nl

T cells attached to tumor cell. Source: MSKCC. http://bit.ly/1uPr5nl

 

On September 9, 2014, Cambridge Healthtech Institute’s (CHI’s) Insight Pharma Reports announced the publication of a new book-length report, Cancer Immunotherapy: Immune Checkpoint Inhibitors, Cancer Vaccines, and Adoptive T-cell Therapies, by Allan B. Haberman, Ph.D.

As attested by the torrent of recent news, cancer immunotherapy is a “hot”, fast-moving field. For example:

  • On September 5, 2014, the FDA granted accelerated approval to the PD-1 inhibitor pembrolizumab (Merck’s Keytruda, also known as MK-3475) for treatment of advanced melanoma. This approval was granted nearly two months ahead of the agency’s own deadline. Pembrolizumab is the first PD-1 inhibitor to reach the U.S. market.
  • On May 8, 2014, the New York Times published an article about a woman in her 40’s who was treated with adoptive immunotherapy with autologous T cells to treat her cancer, metastatic cholangiocarcinoma (bile-duct cancer). This deadly cancer typically kills the patient in a matter of months. However, as a result of this treatment, the patient lived for over 2 years, with good quality of life, and is still alive today.

These and other recent news articles and scientific publications attest to the rapid progress of cancer immunotherapy, a field that only a few years ago was considered to be impracticable.

Our report focuses on the three principal types of therapeutics that have become the major focuses of research and development in immuno-oncology in recent years:

  • Checkpoint inhibitors
  • Therapeutic anticancer vaccines
  • Adoptive cellular immunotherapy

The discussions of these three types of therapeutics are coupled with an in-depth introduction and history as well as data for market outlook.

Also featured in this report are exclusive interviews with the following leaders in cancer immunotherapy:

  • Adil Daud, MD, Clinical Professor, Department of Medicine (Hematology/Oncology), University of California at San Francisco (UCSF); Director, Melanoma Clinical Research, UCSF Helen Diller Family Comprehensive Cancer Center.
  • Matthew Lehman, Chief Executive Officer, Prima BioMed (a therapeutic cancer vaccine company with headquarters in Sydney, Australia).
  • Marcela Maus, MD, PhD, Director of Translational Medicine and Early Clinical Development, Translational Research Program, Abramson Cancer Center, University of Pennsylvania in Philadelphia.

The report also includes the results and an analysis of a survey of individuals working in immuno-oncology R&D, conducted by Insight Pharma Reports in conjunction with this report. The survey focuses on market outlook, and portrays industry opinions and perspectives.

Our report is an in-depth discussion of cancer immunotherapy, an important new modality of cancer treatment that may be used to treat as many as 60% of cases of advanced cancer by the late 2010s/early 2020s. It includes updated information from the 2014 ASCO (American Society of Clinical Oncology) and AACR (American Association for Cancer Research) meetings. The report is designed to enable you to understand current and future developments in immuno-oncology. It is also designed to inform the decisions of leaders in companies and in academic groups that are working in areas that relate to cancer R&D and treatment.

For more information on Cancer Immunotherapy: Immune Checkpoint Inhibitors, Cancer Vaccines, and Adoptive T-cell Therapies, or to order it, see the Insight Pharma Reports website.

_____________________________________________________________________

As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to your company, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Breakthrough of the year 2013–Cancer Immunotherapy

Happy New Year! Source: Roblespepe. http://bit.ly/1cpkyHX

Happy New Year! Source: Roblespepe. http://bit.ly/1cpkyHX

As it does every year, Science published its “Breakthrough of the Year” for 2013 in the 20 December 2013 issue of the journal.

Science chose cancer immunotherapy as its Breakthrough of the Year 2013.

In its 20 December 2013 issue, Science published an editorial by its Editor-in-Chief, Marcia McNutt, Ph.D., entitled “Cancer Immunotherapy”. The same issue has a news article  by staff writer Jennifer Couzin-Frankel, also entitled “Cancer Immunotherapy”.

As usual, the 20 December 2013 issue of Science contains a Breakthrough of the Year 2013 news section, which in addition to the Breakthrough of the Year itself, also contains articles about several interesting runners-up, ranging from genetic microsurgery using CRISPR (clustered regularly interspaced short palindromic repeat) technology to mini-organs to human cloning to vaccine design.

In the Science editorial and news article, the authors focus on the development and initial successes of two types of immunotherapy:

  • Monoclonal antibody (MAb) drugs that target T-cell regulatory molecules, including the approved CTLA4-targeting MAb ipilimumab (Bristol-Myers Squibb’s Yervoy), and the clinical-stage anti-PD-1 agents nivolumab (Bristol-Myers Squibb) and lambrolizumab (Merck).
  • Therapy with genetically engineered autologous T cells, known as chimeric antigen receptor (CAR) therapy, such as that being developed by a collaboration between the University of Pennsylvania and Novartis.

The rationale for Science’s selection of cancer immunotherapy as the breakthrough of the year is that after a decades-long process of basic biological research on T cells, immunotherapy products have emerged and–as of this year–have achieved impressive results in clinical trials. And–as pointed out by Dr. McNutt–immunotherapy would constitute a new, fourth modality for cancer treatment, together with the traditional surgery, radiation, and chemotherapy.

However, as pointed out by Dr. McNutt and Ms. Couzin-Frankel, these are still early days for cancer immunotherapy. Key needs include the discovery of biomarkers that can help predict who can benefit from a particular immunotherapy, development of combination therapies that are more potent than single-agent therapies, and that might help more patients, and means for mitigating adverse effects.

Moreover, it will take some time to determine how durable any remissions are, especially whether anti-PD1 agents give durable long-term survival. Finally, although several MAb-based immunotherapies are either approved (in the case of  ipilimumab) or well along in clinical trials, CAR T-cell therapies and other adoptive immunotherapies remain experimental.

In addition to the special Science “Breakthrough 2013” section, Nature published a Supplement on cancer immunotherapy in its 19/26 December 2013 issue. This further highlights the growing importance of this field.

Cancer immunotherapy on the Biopharmconsortium Blog

Readers of our Biopharmconsortium Blog are no strangers to recent breakthroughs in cancer immunotherapy. In the case of MAb-based immunotherapies, we have published two summary articles, one in 2012 and the other in 2013. These articles noted that cancer immunotherapy was the “star” of the American Society of Clinical Oncology (ASCO) annual meeting in both years.

Our blog also contains articles about CAR therapy, as being developed by the University of Pennsylvania and Novartis and by bluebird bio and Celgene. Moreover, the Biopharmconsortium Blog contains articles on other types of cancer immunotherapies not covered by the Science articles, such as cancer vaccines.

We look forward to further progress in the field of cancer immunotherapy, and to the improved treatments and even cures of cancer patients that may be made possible by these developments.
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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to  your company, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Leukemia–going for the cure!

Chronic Myeloid Leukemia. Source: Paulo Mourao. http://bit.ly/14ZLZqA

Chronic Myeloid Leukemia. Source: Paulo Mourao. http://bit.ly/14ZLZqA

Both the 28 June 2013 issue of Science and the 27 June 2013 issue of Nature have articles or sections that feature discussions of new ways to treat or even cure various types of leukemia.

The human interest story about T-cell immunotherapy researchers in Science

The 28 June 2013 issue of Science contains an article by Science staff writer Jennifer Couzin-Frankel entitled “The Dizzying Journey to a New Cancer Arsenal”. It focuses on researchers who have been working in the engineered T cell adoptive immunotherapy project at the Perelman School of Medicine of the University of Pennsylvania. We featured a discussion of this project, which since August 6, 2012 has involved a collaboration with Novartis, in our September 12, 2012 article on this blog.

Ms. Couzin-Frankel’s article is a human interest story which especially focuses on Carl June, MD, and how he came to work on T-cell immunotherapy. This included how cancer had touched his own life, with the death of his first wife, Cynthia, in 2001. The article also focused on patients who were successfully treated with the therapy, including biotech company scientist Douglas Olson, and Emily Whitehead, who is now eight years old and achieved remission from what had been end-stage leukemia over a year ago.

As we discussed in our September 2012 article, the Penn group has been developing adoptive immunotherapy based on autologous T cells engineered with chimeric antigen receptors (CARs). Specifically, this involved a CAR with specificity for the B-cell antigen CD19, coupled with the T cell costimulatory receptor CD137 and CD3-zeta (a signal-transduction component of the T-cell antigen receptor) signaling domains. (In the Science article, CD19 is referred to by its alternative name, 4-1BB.) These engineered T cells are designed for the treatment of B-cell leukemias, such as B-cell chronic lymphocytic leukemia (CLL). As discussed both in our 2012 blog article and in the 2013 Science article, Novartis has been collaborating with the Penn group in order to industrialize production of the autologous engineered T cells and their use in treatment of patients. Via the ability of Penn to patent and license its technology, the Novartis collaboration also provides a potential means to conduct clinical trials under FDA regulation, and thus to commercialize a form of adoptive cellular immunotherapy for the first time.

Nature’s special supplement on leukemia

The 27 June 2013 issue of Nature includes an entire Nature Outlook supplement on “Leukaemia”. The supplement–or at least the portion of it that consists of articles produced under Nature’s “full responsibility for all editorial content” is available free online to all.

The general theme of the special supplement is stated in the introductory article by science writer and editor Apoorva Mandavilli “While survival rates for some types of leukaemia have improved dramatically, this family of blood cancers remains a potentially fatal disease. Research in epigenetics, immunotherapy, and cell transplants offers hope. And leukaemia is proving a testing ground for the theory of cancer stem cells — leading to knowledge that could advance cancer research overall.”

The Nature Perspective on adoptive T-cell immunotherapy by Penn researchers Levine and June

Included in the supplement is a short Perspective on CAR-based adoptive T-cell immunotherapy by Drs. Bruce L. Levine and Carl H. June of the Perelman School of Medicine at the University of Pennsylvania. It is entitled “Assembly line immunotherapy”. According to this Perspective, CAR technology [unlike the earlier tumor infiltrating lymphocyte (TIL) technology] enables researchers to ” efficiently produce large populations of T cells, approximating the mass of T cells in the human immune system”.

Drs. Levine and June further assert that by “using equipment and facilities developed for blood banks and stem-cell laboratories, and by automating production”, it will be possible to make CAR-based adoptive cellular immunotherapies (ACTs) widely available. Thus leukemia treatment may be on the brink of a revolution such as the auto industry experienced in recent years in moving from manual assembly lines to robotic automation.

Despite the issue of the pharmaceutical industry and regulatory agencies such as the FDA and the European Medicines Agency being geared to developing drugs, not individually-prepared cellular therapies, Drs. Levine and June cite the case of  organ, bone-marrow, and stem-cell transplants. These modalities were seen as exotic a few decades ago, but are now utilized in treatment of tens of thousands of people. The authors thus envision that ACT may also eventually be scaled up to treat the large numbers of patients who might benefit from this type of therapy. However, this will require innovation in regulatory agency oversight, and in the means by which the pharmaceutical industry might commercialize such individualized technologies. As we discussed in our September 2012 Biopharmconsortium Blog article, Novartis and Penn are leading the way.

Moving toward cures for chronic myeloid leukemia–Dr. Charles Sawyers’ Perspective

Another Perspective in the special supplement is authored by Charles L. Sawyers, M.D. [Chair, Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer (New York, NY), and Howard Hughes Medical Institute]. The Perspective, entitled “Combined forces”, focuses on chronic myeloid leukemia (CML). The first targeted kinase inhibitor for cancer, imatinib (Novartis’ Gleevec/Glivec) was initially approved for treatment of CML.

In our October 25, 2010 article on this blog, we discussed the classic proof-of-concept clinical trial that helped launch imatinib toward FDA approval. As we discussed in that article, Dr. Sawyers was a key leader of that trial. He was a co-recipient–with Drs.  Brian J. Druker and Nicholas B. Lydon, of the 2009 Lasker~DeBakey Award for Clinical Medical Research for his work on treatment of CML.

As we discussed in our Octotber 2010 article, imatinib is highly specific for the BCR-ABL fusion protein [which is generated as the result of the translocation that produces the Philadelphia (Ph) chromosome, the characteristic genetic abnormality of CML], as well as two other protein kinases. CML patients who are initially successfully treated with imatinib may experience resistance to that drug. As a result, two second-generation kinase inhibitors–dasatinib (Bristol-Myers Squibb’s Sprycel) and nilotinib (Novartis’ Tasigna) were developed to target imatinib-resistant mutated BCR-ABL proteins, and thus successfully treat imatinib-resistant CML. More recently–in September 2012–as mentioned in Dr. Sawyers’ Perspective, another second-generation agent, bosutinib (Pfizer’s Bosulif), has reached the market. A still newer agent, ponatinib (Ariad’s Iclusig) was approved in December 2012, under the FDA’s Accelerated Approval Program. Ponatinib is of special interest, since it  targets the T315I mutation, which confers resistance to all the other four targeted CML drugs.

In Dr. Sawyers’ Perspective, he discusses how oncologists might use the current armamentarium of targeted drugs for CML to move toward a cure for the disease. Resistance to imatinib occurs because of selection for resistant mutants of BCR-ABL . Second-generation agents inhibit BCR-ABL kinases with these mutations, thus restoring disease remission. The current armamentarium of kinase inhibitor drugs for CML covers all known resistance mutations; however, no single drug can prevent all forms of resistance.

The current paradigm for treatment of CML has been to start with imatinib, and keep treating with that agent until the patient develops resistance to that drug and disease recurs. Then the physician treats with one of the second-generation agents, which typically produces disease remission. However, this sequential treatment can select for cells with BCR-ABL molecules that contain multiple mutations, which will be resistant to all kinase inhibitors. (See a 2007 report by Dr. Sawyers and his collaborators demonstrating the hazard of sequential therapy with imatinib followed by dasatinib.)

Because the second-generation agents dasatinib and nilotinib are more potent than imatinib, they were approved for frontline therapy of CML instead of imatinib, subsequent to the publication of Dr.Sawyers’ 2007 article. They were approved for frontline therapy because of their superior clinical outcomes in head-to-head comparisons against imatinib. (Bosutinib and ponatinib are newer, and have not yet received frontline therapy approval.) However, Dr. Sawyers counsels caution, since  dasatinib and nilotinib have been studied for only 3–4 years compared with the 8–10 years of data that have amassed for imatinib. Thus replacing imatinib with one of these agents might still result in development of resistance down the road.

Dr. Sawyers postulates that Instead of focusing on which individual drug is best as a monotherapy, it is time for researchers to consider whether it might be better to use combination therapy with multiple kinase inhibitors instead of sequential therapy. Extrapolating from the experience with single- versus multi-agent therapy for tuberculosis and HIV/AIDS, a combination of two or three ABL inhibitors with non-overlapping BCR–ABL mutation resistance profiles would almost certainly prevent the emergence of drug resistance. This is particularly true in the light of ponatinib’s success against T315I.

In a recent French study cited by Dr. Sawyers, researchers found that patients with the best responses to treatment with imatinib alone (no BCR–ABL detectable for more than two years) may no longer need any kinase inhibitor drugs at all. In this study, 40% of patients had not relapsed after 18 months. This raises the possibility that these patients may be cured of their disease.

Dr. Sawyers hypothesizes that since next-generation BCR-ABL inhibitors have greater potency in clinical trials, and since two-drug combinations are superior to monotherapies in preclinical studies, upfront therapy with either a second-generation inhibitor or with a combination therapy may result in even higher percentages of patients who experience elimination of all CML cells.

Even though these more potent treatments would be even more costly than imatinib therapy, if these treatments are curative, their long-term cost will be lower than the current treatment. Therefore, they might be both medically and economically advantageous, as well as giving cancer patients what they really want–a cure.

Meanwhile, in the 18 July 2013 issue of Nature, Drs. Natalia L. Komarova (University of California Irvine, Irvine CA) and C. Richard Boland (Baylor University Medical Center, Dallas TX) published a News and Views article discussing recently published mathematical models that predict that combination therapy is more effective than sequential treatment in preventing drug resistance in cancer. These mathematical models were developed especially for treatment of CML and the solid tumors melanoma, pancreatic cancer, and colorectal cancer. But these types of models may apply to all cancers for which targeted therapies have been or are being developed.

Moving toward cures for chronic myeloid leukemia–the Novartis 27 June 2013 white paper

Bound with the Nature Outlook supplement on leukemia–immediately following the Levine & June article on adoptive immunotherapy–is a white paper by Novartis researchers (Szczudlo et al.), entitled “The Novartis research vision and approach for treating patients with chronic myeloid leukaemia”. Unfortunately, since this “sponsor feature” was not written under Nature’s “full responsibility for all editorial content”, this white paper is treated almost as an advertisement. It is not available in the online version of Nature, or anywhere else online. Perhaps Novartis will make this valuable white paper available online in the near future. As with other published reviews in scientific journals (and unlike advertisements), this white paper is signed by its authors, and has reference citations.

The subject of the white paper is developing approaches that will enable CML patients on tyrosine kinase inhibitor (TKI) therapy to safely and effectively suspend their drug therapy, while maintaining minimal residual disease (MRD) levels that are either undetectable or below the level at which there is a risk of progression to more advanced phases of disease. Such a condition is known as “treatment-free remission” (TFR).

The research that is the focus of the Novartis white paper does not involve treatment with combination therapies, but monotherapy with nilotinib (Novartis’ Tasigna). The TFR-focused clinical trials with nilotinib are made possible not only by the potency of this agent, but also the development of new diagnostic assays for level of residual disease. Traditional diagnostics for CML have been based on achieving a “complete cytogenetic response” (CCyR). A CCyR is defined as the state in which there are so few Philadelphia chromosome positive (Ph+) cells in a patient’s blood or marrow that they are undetectable by this assay.

The new diagnostic assays involves measuring levels of BCR-ABL messenger RNA (mRNA) transcripts using a real-time quantitative polymerase chain reaction (RQ-PCR). The results of these sensitive assays are reported as major molecular response [MMR–a 3-log reduction in BCR-ABL levels from the international scale (IS) baseline; molecular response ≥ 4.0 logs (MR4); and molecular response ≥ 4.5 logs (MR4.5)].

Using these assays, researchers are participating in new Novartis-sponsored clinical studies of

  1. patients who had previously been treated with imatinib, without achieving MR4.5, and who were then switched to nilotinib.
  2. patients treated do novo with nilotinib.

The strategy is to maintain patients on nilotinib who have achieved MR4.5 for one year at that level, and then discontinue drug treatment. These patients continue to be monitored, and must maintain ≤ MR4 in order to remain free of nilotinib treatment. Those who exceed this threshold will be put back on nilotinib. So far, in earlier studies, patients on imatinib or niolotinib who were ≤MR4 off-drug and who then exceeded this level, when put back on their drug went back to deeper levels of molecular response to therapy, and showed no drug resistance. These clinical trial protocols therefore appear to be safe.

For more information about the above clinical trials, see ClinicalTrials.gov, clinical trial number NCT01784068 and NCT01698905. Both of these trials are recruiting patients.

The Novartis white paper does discuss a different kind of combination therapy than the ones proposed by Dr. Sawyers–combination therapy with a potent TKI such as nilotinib and an agent that specifically targets leukemic stem cells (LSCs). TKI-insensitive leukemia stem cells have been implicated in the persistence of MRD, and LSCs could contribute to the re-emergence of disease following suspension of TKI treatment.

Novartis and its collaborators are now testing TKIs in combination with Novartis’ experimental agent sonidegib (LDE225). Sonidegib is an inhibitor of the hedgehog (Hh) pathway. Aberrant activation of the Hh pathway has been implicated in the activity of LSCs and of other types of cancer stem cells. A poster session that described an in vitro study of a combination of sonidegib and nilotinib in CML was presented at a scientific meeting in 2010. Sonidegib (which is also known as erismodegib) has also been undergoing preclinical studies as a potential inhibitor of prostate cancer stem cells.

Conclusions

We recommend the 28 June 2013 Science article by Jennifer Couzin-Frankel, and the special supplement on leukemia in the 27 June 2013 issue of Nature for your late summer reading. It is heartening to see that at least some researchers are moving towards cures for various types of leukemia–with potential implications for development of cures for other types of cancer.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to  your company,  please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Is Novartis building a viable business model for adoptive immunotherapy for cancer?

 

Tumor infiltrating lymphocytes (TILs) in a colorectal carcinoma. Source: Nephron. http://bit.ly/QdusBi

On April 27, 2011 we published an article on this blog entitled “Adoptive immunotherapy for metastatic melanoma?” This blog post, which was in part based on an article in the April 2011 issue of The Scientist, described a treatment for metastatic melanoma known as adoptive cell transfer (ACT), or adoptive immunotherapy. ACT is the only type of therapy that has resulted in high percentages of durable compete responses in metastatic melanoma. A durable complete response, which is tantamount to a cure, is the real desire of every cancer patient, and of their loved ones, and of caring physicians who treat them.

In ACT, a physician/researcher extracts a patient’s antigen-specific immune cells, which are usually found in tumor tissue. Such cells are known as “tumor infiltrating lymphocytes” (TILs). He or she then expands the numbers of the antitumor T lymphocytes in cell culture, using the T-cell growth factor, IL-2. The physician/researcher then infuses the cells, plus IL-2, intravenously into the patient. The infused T cells traffic to tumors and can mediate their destruction. Prior to TIL infusion, the patient may have his or her immune system temporarily ablated via “preparative lymphodepletion” with chemotherapy and sometimes also total-body irradiation. The preparative lymphodepletion treatment is associated with enhanced persistence of the transferred TILs.

In a clinical study of ACT published in 2011, the treatment resulted in the disappearance of all tumors in 20/93 patients (21.5%) with advanced metastatic melanoma. For 19 of these 20 patients (95%), the complete responses have been durable and long-lasting, in some cases lasting for over 7 years. (See also the Faculty of 1000 evaluation.)

Research on the mechanistic basis of adoptive immunotherapy, as well as on means to improve ACT technologies, is ongoing, so there is the potential to improve the durable complete response rate further. We featured a December 2012 Nature cancer immunotherapy review article that included a discussion of ways to improve ACT in the 2011 end-of-year article on our Biopharmconsortium Blog.

Despite the fact that ACT is the only type of therapy that has resulted in high percentages of durable compete responses in metastatic melanoma, it is not widely available. ACT is only available in a small number of cancer canters worldwide, and there has been little commercial interest in developing ACT.

Adoptive immunotherapies are still considered experimental, are not FDA-approved, and are not covered by third party payers. Thus only a handful of locations can bear the financial burden of administering adoptive immunotherapy. If a cancer center has a cell production facility with the required staff, the cost of producing a single dose of T-cells for adoptive transfer is approximately $20,000. ACT treatment also entails factoring in the cost of hospitalization. However, most patients only require a single dose.

The cost of ACT is, however, much lower than a full course of other immunotherapies, such as the dendritic cell vaccine Provenge (which is not indicated for melanoma) or the immunotheraputic MAb drug ipilimumab, both of which cost approximately $120,000. The total cost of a 6-month treatment with the targeted kinase drug vemurafenib is $56,400. None of these treatments result in durable complete responses, except in a very small number of patients.

The main problem with increasing the availability of ACT is the lack of a viable business model for its commercialization. Adoptive immunotherapies lack a clearly defined claim to intellectual property (IP), since the patient’s own cells are not a “drug” to be patented. It would be difficult for a private company to pursue clinical trials for FDA approval and commercialization of ACT. To conduct such trials, a company would need to build a specialized cell processing and treatment facility, with a highly trained and competent staff. If the therapies cannot be protected as IP, and would therefore not be considered proprietary, it would not be worth the effort and expense to commercialize them.

The Novartis/Penn agreement

Now comes an agreement (announced on August 6, 2012) between Novartis and the University of Pennsylvania (Penn) aimed at commercializing adoptive cellular immunotherapy.

The agreement is based on one of the improvements to ACT discussed in the December 2011 Nature cancer immunotherapy review, in which autologous T cells isolated from patient blood (not from tumors) are engineered with retroviral vectors carrying chimeric antigen receptors (CARs). This technology allows physician researchers to extend ACT beyond patients from whom TILs can be isolated and expanded. It also enables them to extend ACT beyond melanoma to include other types of solid tumors and leukemias and lymphomas. Unlike TILs, CAR-bearing T cells do not recognize surface antigens on tumor cells [presented by major histocompatibility complex (MHC) proteins] via their T-cell receptors. They instead recognize surface proteins on tumor cells via the affinity domain on the engineered CAR. This also expands the kinds of tumor cells that can be recognized, as compared to TILs.

In the Penn studies, led by David L. Porter, M.D. at the Perelman School of Medicine of the University of Pennsylvania, the researchers used this technology to treat patients with chronic lymphocytic leukemia (CLL). They designed a lentiviral vector expressing a chimeric antigen receptor with specificity for the B-cell antigen CD19, coupled with the T cell costimulatory receptor CD137 and CD3-zeta (a signal-transduction component of the T-cell antigen receptor) signaling domains. They used this vector to engineer autologous T cells, and infused the engineered cells into the patient after preparative lymphodepletion with chemotherapy. In a pilot study with one patient with refractory chronic lymphocytic leukemia (CLL), the infused cells exhibited in vivo expansion and anti-leukemia activity. The treatment resulted in complete remission, which was ongoing 10 months after initiation.

In a later study, the researchers treated three more patients with autologous engineered CAR T cells. The T cells expanded over 1000-fold in vivo, trafficked to bone marrow, and continued to express CARs at high levels for at least six months. The CAR T-cells showed anti-leukemia activity, with each engineered T cell eliminating approximately 1000 CLL cells. A CD19-specific immune response was demonstrated in the blood and bone marrow of two of three patients; these patents showed complete remission. Some of the cells in these patients persisted as memory CAR T cells and retained anti-CD19 effector activity. These results suggested that this technology has the potential to effectively treat B cell malignancies, and to induce durable complete remissions in at least a portion of patients.

As reported in August 2012, of the three patients who showed positive results with the anti-CD19 immunotherapy, two were still in complete remission over a year into the CART-19 trial, and the third patient maintained partial remission for more than seven months. An immune deficiency resulting from the treatment known as hypogammaglobulinemia, an expected chronic toxic effect of anti-B cell therapy, was corrected with infusions of intravenous immune globulin. Patients were also treated for symptoms associated with tumor lysis syndrome, an effect of tumor breakdown.

Under the agreement, Novartis acquired exclusive rights from Penn to CART-19, the investigational CAR immunotherapy that was the focus of the studies discussed earlier. The target of CART-19, CD19, is associated with several B-cell malignancies, including CLL, B-cell acute lymphocytic leukemia and diffuse large B-cell lymphoma. Novartis expects to initiate a Phase II clinical trial with CART-19 in collaboration with Penn during the fourth quarter of 2012.

To facilitate the discovery and development of additional types of CAR immunotherapy, Novartis and Penn will build the Center for Advanced Cellular Therapies (CACT) at Penn. This center will be established specifically to develop and manufacture adoptive T-cell immunotherapies under the research collaboration between Penn and Novartis.

Penn also granted Novartis an exclusive worldwide license to CARs developed through the collaboration for all indications, in addition to CART-19. In return, Novartis will provide an up-front payment, research funding, funding for the establishment of the CACT and milestone payments for the achievement of certain clinical, regulatory and commercial milestones as well as and royalties on any sales.

Business implications of the Novartis/Penn agreement

The feasibility of developing and commercializing CAR T-cell-based immunotherapy is based on the ability of Penn to patent and license its CAR technology. Such an approach in principle would apply to immunotherapies based on other types of engineered T cells, such as those engineered with retroviral vectors carrying cloned T-cell receptors, as discussed in the December 2011 Nature review article.

As discussed earlier, adoptive immunotherapies with engineered T cells would also address patients with a variety of types of cancer (not just melanoma) and from who TILs cannot be isolated. However, whether any therapies with engineered T cells can give the percentages of durable complete responses seen with TIL-based therapy of melanoma remains to be demonstrated in clinical trials.

The Novartis/Penn agreement represents an example of Novartis’ willingness to take risks, in order to “bring innovative therapies to patients”, as stated by Hervé Hoppenot, President, Novartis Oncology. Mark Fishman, President of the Novartis Institutes for BioMedical Research, sees cancer immunotherapy as “one of the exciting frontiers in cancer research,” and the CAR technology as showing “early promise as a new way for treating cancer.”

Novartis thus has not built a viable business model for TIL-based ACT. However, it is developing a parallel technology that is more protectable than TILs, which might result in bringing adoptive cellular immunotherapy to a much larger number of patients.

BiTE immunotherapy

Meanwhile another type of T-cell-based immunotherapy technology (also discussed in the Nature review) is now under development. This is bi-specific T-cell engager (BiTE) technology, originally developed by the German-American biotech company Micromet. Amgen acquired Micromet in April 2012, and is now developing the first BiTE agent, blinatumomab. Blinatumomab is a bispecific MAb that binds to CD19 on target B-cell malignancies and to CD3 (an invariant component of the T-cell receptor) on T cells. This results in the activation of the T cell to exert cytotoxic activity on the target cell. BiTE immunotherapy does not require isolation and culture of autologous T cells, and BITE technology and therapeutics derived from it are patentable as with other drugs.

In May 2012, Amgen reported that blinatumomab treatment gave a high rate (72 percent) of complete responses in a Phase 2 study in patients with relapsed or refractory B-precursor acute lymphoblastic leukemia (ALL). The rate of remission seen in this trial was a great improvement over the current standard of care. However, no durable complete responses were seen; median survival was 9 months.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or an initial one-to-one consultation on an issue that is key to your company’s success, please contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

Here we go again–Lilly’s Alzheimer’s drug solanezumab fails to show efficacy in Phase 3, but company is “encouraged” by secondary analysis

 

Amyloid precursor protein (APP)

As we mentioned in our August 19, 2012 article on Alzheimer’s disease (AD), the results of Phase 3 trials of Lilly’s amyloid-targeting monoclonal antibody (MAb) drug solanezumab, had been expected soon.

On August 24 2012, Lilly announced the top-line results of the two Phase 3, double-blind, placebo-controlled EXPEDITION trials of solanezumab in patients with mild-to-moderate Alzheimer’s disease. The primary endpoints, both cognitive and functional, were not met in either of these trials.

However, a pre-specified secondary analysis of pooled data across both trials showed statistically significant slowing of cognitive decline in the overall study population, and pre-specified secondary subgroup analyses of pooled data across both studies showed a statistically significant slowing of cognitive decline in patients with mild Alzheimer’s disease, but not in patients with moderate Alzheimer’s disease.

These results were reported in a press release.  What was absent was data from the trials. However, the Alzheimer’s Disease Cooperative Study (ADCS), (an academic national research consortium) will present its independent analysis of the data from the EXPEDITION studies at the American Neurological Association (ANA) meeting in Boston on October 8, 2012, and at the Clinical Trials on Alzheimer’s Disease (CTAD) meeting in Monte Carlo, Monaco, on October 30, 2012.

Once again, an amyloid pathway-targeting drug for Alzheimer’s disease that was taken into Phase 3 trials despite Phase 2 results that showed no statistically significant efficacy has failed in Phase 3. Solanezumab joins a list of such failed drugs that includes Myriad Pharmaceuticals’ Flurizan (tarenflurbil), Neurochem’s (now Bellus Health) Alzhemed (3-amino-1-propanesulfonic acid), and as of July 2012, Pfizer/Janssen’s bapineuzumab (“bapi”). Nevertheless, as in the Phase 2 results with bapi, Lilly sees hope for the drug in the results of secondary analyses.

On the day of the Lilly announcement, August 24 2012, Lilly executives and stock analysts turned the results of these trials into something “positive”, as the result of the secondary analysis. This resulted in a one-day 3.4 percent increase in the price of Lilly stock. However, the results of the secondary analysis do not give Lilly any basis for going to the FDA with a New Drug Application (NDA) for solanezumab. Nor do they provide any realistic hope for AD patients, the physicians who treat them, or caregivers of AD patients.

At best, Lilly’s secondary analysis gives rise to a hypothesis–that solanezumab–and presumably other anti-amyloid MAbs–will be effective in treating earlier-stage AD patients, especially those who have not suffered extensive, irreversible brain damage. This is the very same hypothesis that is now being tested by Roche/Genentech in its clinical trials of its anti-amyloid MAb crenezumab, as we discussed in our August 19, 2012 article. Genentech is testing its drug candidate in a Phase 2a trial in a very special population–members of a large Colombian kindred who harbor a mutation in presenilin 1 (PS1) that causes dominant early−onset familial AD.

A News Focus article in the 17 August 2012 issue of Science, written by science writer Greg Miller, PhD, discusses three upcoming clinical trials designed to test the “treat early-stage or presymptomatic AD with anti-amyloid MAbs” hypothesis. One of these studies is the Genentech trial of crenezumab in the extended family in Colombia.

Another of these studies is being conducted in conjunction with the Dominantly Inherited Alzheimer Network (DIAN), a consortium led by researchers at Washington University School of Medicine (St. Louis, MO). This study will include people with mutations in any of the three genes linked to early-stage, dominantly-inherited AD–PS1, PS2, and amyloid precursor protein (APP).

Initial studies, published ahead of print in the July 11 issue of the New England Journal of Medicine (NEJM) looked at changes in biomarkers and in cognitive ability as a function of expected age of AD onset in people with these mutations. Concentrations of amyloid-β1–42 (Aβ42) in the cerebrospinal fluid (CSF) appeared to decline 25 years before expected symptom onset. This decrease may reflect impaired clearance of Aβ42 from the brain, which may be a factor in the amyloid plaque increase that is associated with AD. Amyloid accumulation in the brain was detected 15 years before expected symptom onset. Other biomarkers, as well as cognitive impairment, were also followed in the study published in the NEJM. In the first stage of the actual trial, three drugs (which have not yet been selected) will be tested in this population, and changes in biomarkers and cognitive performance will be followed.

The third study, known as the Anti-Amyloid Treatment of Asymptomatic Alzheimer’s (A4) trial, will involve treating adults without mutations in any of the above three genes, whose brain scans show signs of amyloid accumulation. A4 is thus designed to study prevention of sporadic AD (by far the most common form of the disease). It will enroll 500 people age 70 or older who test positive on a scan of amyloid accumulation in the brain. (This is in contrast to the two trials in subjects with gene mutations, who are typically in their 30s or 40s.) A4 will also have a control arm of 500 amyloid-negative subjects. Amyloid-positive and control subjects will be entered into a three-year double-blind clinical trial that will look at changes in cognition with drug treatment. The A4 researchers [led by  Reisa Sperling, Brigham and Women’s Hospital/Harvard University (Boston, MA), and Paul Aisen, University of California, San Diego] plan to select a drug for testing by December 2012.

If Lilly wishes to test solanezumab in early-stage (or presymptomatic) sporadic AD, it will need to follow a similar methodology to the studies outlined in the new Science article, especially with respect to the use of biomarkers to define “early-stage” AD and to track the effects of the drug. Studies such as the DIAN biomarker study published in the NEJM used the positron emission tomography (PET) ligand Pittsburgh Compound-B (PiB-C11), to image amyloid plaques. However, the use of this compound is limited by the short half-life of carbon-11 (20.4 minutes). A new PET amyloid imaging agent, Amyvid (florbetapir F18 Injection) was developed by Lilly and approved by the FDA in April 2012. This compound contains fluorine-18, which has a half-life of 109.8 minutes. A recent study indicates that Amyvid provides comparable information to PiB-C11. If Lilly wishes to conduct new studies of solanezumab in early-stage or presymptomatic sporadic AD, it may wish to use Amyvid, as suggested in a comment to an August 24, 2012 solanezumab post in Derek Lowe’s blog “In the Pipeline”. However, the FDA, in its press release announcing the approval of Amyvid, warns that increased amyloid plaque content (as detected by Amyvid or Pittsburgh Compound-B) may be present in the brains of patients with non-AD neurologic conditions, and in older people with normal cognition. Thus defining or detecting “early-stage (or presymptomatic) sporadic AD” is difficult.

In any case, for Lilly to follow up on its secondary analyses of the Phase 3 clinical trials of solanezumab will necessitate additional long and expensive clinical trials, with no assurance of success. Lilly executives will need to determine if such a course is worth the risk, or whether it should invest in other R&D efforts that might have a higher probability of success.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to  your company, please click here. We also welcome your comments on this or any other article on this blog.

New genetics study supports the amyloid hypothesis of Alzheimer’s disease–but the drugs still don’t work!

 

The APP processing pathway

An exciting new study on Alzheimer’s disease (AD) was published in the 2 August issue of Nature. The study was carried out by researchers at deCode Genetics (Reykjavik Iceland) and their collaborators at Genentech and several academic institutions. A News and Views article by leading AD researcher Bart De Strooper and genomics researcher Thierry Voet (both at KU Leuven, Leuven, Belgium) analyzes this study and its implications.

Amyloid plaques are a central feature of AD.  They largely consist of amyloid-β (Aβ) peptides. Aβ peptides are formed via sequential proteolytic processing of the amyloid precursor protein (APP), catalyzed by two aspartyl protease enzymes–β-secretase and γ-secretase.  The β-site APP cleaving enzyme 1 (BACE1) cleaves APP predominantly at a unique site. However, γ-secretase cleaves the resulting carboxy-terminal fragment at several sites, with preference for positions 40 and 42. This leads to formation of amyloid-β1–40 (Aβ40) and Aβ1–42 (Aβ42) peptides. APP processing to yield Aβ peptides is illustrated by the figure at the top of this article.

By studying rare, familial cases of early-onset AD, human geneticists have identified three disease genes in these conditions— genes for APP, and for two presenilins, PS1 and PS2. The presenilins are components of γ-secretase, which exists as an intramembrane protease complex. Mainly because of these genetic studies, as well as studies in animal models and postmortem studies of AD brains, the majority of AD researchers have focused on the APP processing pathway and/or on aggregation of Aβ to form plaques as intervention points for therapeutic strategies. The hypothesis that this is the central AD disease pathway is called the “amyloid hypothesis”.

Up until the publication of the new deCode report, of the 30-odd coding mutations in APP that have been found, around 25 are pathogenic, usually resulting in autosomal dominant early-onset Alzheimer’s disease. Coding mutations at or near the β- or γ-proteolytic sites have appeared to result in overproduction of either total Aβ or a shift in the Aβ40:Aβ42 ratio towards formation of Aβ42, which is the more toxic of the two Aβ peptide. Until now, mutations in APP have not been implicated in the common, late-onset form of Alzheimer’s disease.

In the new deCode study, the researchers studied coding variants in APP in a set of whole-genome sequence data from 1,795 Icelanders. They identified a single nucleotide polymorphism (SNP), designated as rs63750847. The A allele of this SNP (rs63750847-A) results in an alanine to threonine substitution at position 673 in APP (A673T). The A673T mutation was found to be significantly more common in the elderly (age 85-100) control group (i.e., those without AD) than in the AD group. The researchers therefore concluded that the mutation is protective against AD.

The researchers also found that in a cohort of individuals over 80, those who were heterozygous for the A673T mutation performed better in a test of mental capacity than did control subjects. The authors concluded that the A673T mutation not only protects against AD, but also against the mild cognitive decline that is normally associated with old age.

In cellular studies (i.e., studies in cultured cells transfected with genes coding for wild type or mutant APP) and in biochemical studies, the researchers found that APP carrying the A673T mutation undergoes about 40% less cleavage by BACE1 than does wild-type APP, resulting in 40% less production of both Aβ40 and Aβ42.

The researchers conclude that the strong protective effect of the A673T mutation against AD provides proof of principle for the hypothesis that reducing the β-cleavage of APP (e.g., by use of BACE1 inhibitors, such as those being  developed by some pharmaceutical companies) may protect against the disease. (However, success in developing BACE1 inhibitors has been elusive.) Moreover, since the A673T allele also protects against cognitive decline in elderly individuals who do not have AD, AD and age-related mild cognitive decline may be mediated through the same or similar mechanisms.

Despite this compelling genetic finding, amyloid pathway-targeting drugs have not shown efficacy in Phase 3 trials

In our January 26, 2010 blog article, we discussed Phase 2 clinical trials of bapineuzumab, a monoclonal antibody (MAb) drug that is specific for Aβ, in mild to moderate AD. In that article, we referred to the drug as “Elan/Wyeth’s bapineuzumab”, after the original developers of the drug. As the result of mergers and acquisitions, the drug is now referred to as “Pfizer/Janssen’s bapineuzumab”. Many commentators call it “bapi” for short.

As we discussed in that article, the overall result of the Phase 2 trial was that there was no difference in cognitive function between patients in the bapi-treated and the placebo groups. However, the study did not have sufficient statistical power to exclude the possibility that there was such a difference. Retrospective analysis of the data from the trial suggested that bapi-treated patients who were not carriers of the apolipoprotein E epsilon4 allele (ApoE4) showed improved cognitive function as compared to placebo treatment. Given that this conclusion was reached via retrospective analysis, the idea that the bapi was efficacious in ApoE4 noncarriers was only a hypothesis, which would require prospective clinical trials to confirm. Janssen and Pfizer had been conducted large Phase 3 trials of bapi, which they prospectively segregated into ApoE4 carrier and noncarrier groups in order to test this hypothesis.

As of the past several weeks, the results of these Phase 3 trials have come in. On July 23rd, 2012, Pfizer announced the top-line results of an 18-month Janssen-led Phase 3 study of intravenous bapi in approximately 1,100 patients with mild to moderate Alzheimer’s disease who carry at least one ApoE4 allele. The drug failed to meet its co-primary endpoints (change in cognitive and functional performance compared to placebo) in that study. On August 6, 2012, Pfizer announced the top-line results of the corresponding Phase 3 study of intravenous bapi in patients with mild-to-moderate Alzheimer’s disease who do not carry the ApoE4 genotype. Once again, the co-primary clinical endpoints were not met. Based on these results, the companies decided to discontinue all other intravenous bapi studies in patients with mild-to-moderate Alzheimer’s disease.

The bapi development program continues a history of amyloid pathway-targeting drugs that were taken into Phase 3 trials despite Phase 2 results that showed no statistically significant efficacy. For example, we cited the cases of Myriad Pharmaceuticals’ Flurizan (tarenflurbil) and Neurochem’s (now Bellus Health) Alzhemed (3-amino-1-propanesulfonic acid) in our January 26, 2010 blog article.

Leading industry commentator Matthew Herper of Forbes referred to the failure of bapi as “the latest piece of evidence of the drug industry’s strange gambling problem.” Johnson & Johnson (the parent company of Janssen) spent more than $1 billion to invest in Elan and get one-quarter of bapi, and Wyeth (later Pfizer) and Elan put the drug into Phase 3, despite the Phase 2 failure of bapi.

The temptation for pharmaceutical companies to take a chance on an AD drug such as bapi, Flurizan, and Alzhemed is driven by the complete lack of disease-modifying AD drugs, and the thinking that even a not-very-effective drug that receives FDA approval might generate billions of dollars in annual sales. In the case of bapi there was also that tantalizing suggestion that bapi might show efficacy in the subset of patients who lacked ApoE4.

In an August 16, 2012 article in Forbes, Dr. John LaMattina (the former President of Pfizer Global R&D) engages in informed speculation as to why bapi was moved into Phase 3. Dr. LaMattina (in contrast to critics like Mr. Herper, who discounted the ApoE4 retrospective analysis as “data-dredging” that was “likely to be due to chance”) referred to the efficacy signal of the Phase 2 trials as “mixed” due to the ApoE4 analysis. He stated that such “mixed results” present an “agonizing” dilemma for a pharmaceutical company.

In deciding whether to go forward Phase 3 trials of bapi, Dr. LaMattina further speculates that the decision might have been influenced by stakeholders such as AD patient advocates, and scientists who strongly believed in the science behind bapi, especially the amyloid hypothesis. Moreover, bapi had been shown to be relatively safe. In addition, dropping bapi would have caused public relations damage. Dr. LaMattina concludes, based on this analysis, “…this was a situation where these companies were in possession of a relatively safe drug, with a modest chance of success in being efficacious in what may be the biggest scourge that society will face.  How can you not make this investment?” He reminds us that pharmaceutical R&D “is a high risk, high reward business”.

Nevertheless, bapi joined Flurizan and Alzhemed on the list of high-profile amyloid-pathway failures. Now a Phase 3 trial of Lilly’s solanezumab, another MAb drug that targets Aβ, is nearing completion, with the results expected in September. Published Phase 2 results were designed to test safety, not efficacy, and 12 weeks of drug treatment gave no change in cognitive function. Although the results of the Phase 3 trial will not be known until they are reported, analysts expect the drug to fail because of its similarity to bapi.

Why don’t amyloid pathway-targeting drugs show efficacy in clinical trials, despite the compelling genetic evidence for the amyloid hypothesis?

The almost standard answer to that question given by scientists and clinicians who support the amyloid hypothesis is that we have been testing the drugs too late in the course of AD progression, after the damage to the brain has become irreversible. Roche/Genentech is testing this idea in its clinical trials of its drug candidate crenezumab (licensed from AC Immune), which is yet another MAb drug that targets Aβ. In a 5-year Phase 2a clinical trial, Genentech is testing intravenous crenezumab in 300 cognitively healthy individuals from a large Colombian kindred who harbor the Glu280Ala (codon 280 Glu to Ala substitution) PS1 mutation. This mutation causes dominant early−onset familial AD, and is associated with increased levels of Aβ42 in plasma, skin fibroblasts, and the brain. Family members with this mutation begin showing cognitive impairment around age 45, and full dementia around age 51.

Genentech is conducting this trial in collaboration with the Banner Alzheimer’s Institute and the National Institutes of Health. The company says that this trial is the first-ever AD prevention study in cognitively healthy individuals. Genentech further says that the trial may help to determine if the amyloid hypothesis is correct–more specifically, it may help to determine if a drug that works by depleting amyloid plaques can be effective in preventing and/or treating AD.

Moreover, Genentech states that there is significant unmet medical need within this Colombian population. This large extended family may have as many as 5,000 living members, and no other population in the world offers a sufficiently large number of mutation carriers close to the age of potential disease onset for a study to determine whether a prevention treatment may work. This effort by Genentech thus represents an application of a rare disease strategy to AD.

It is also possible, however that drugs that work by lowering levels of Aβ will not be efficacious in treating AD, even if administered early in the disease process. This may be true despite the findings of the new genetic study by the deCode Genetics group. For example, in their Nature News and Views article, Drs. De Strooper and Voet remind us that if the A673T mutation indeed works via lowering of Aβ levels, it works via lifelong lowering of Aβ, not lowering of Aβ in patients who already have AD, as in all clinical trials so far of anti-Aβ antibodies. (Even Genentech’s Colombian trial may involve lowering of Aβ levels relatively late in the course of exposure of patients to a disease process that will result in AD.)

Moreover, as these authors speculate on the basis of work on another mutation at the same site in the APP protein, it is possible that the protective effect of the A673T mutation may be due to changing the aggregation properties of Aβ peptides, resulting in a less-toxic form of Aβ. If true, this would mean that the protective effect of the A673T mutation is due to qualitative, rather than quantitative changes in Aβ. In that case, the finding of protection from AD by the A673T mutation might not be as predictive of the efficacy of such Aβ-lowering treatments as the use of anti-Aβ MAb drugs as drug developers might like.
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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to  your company, please click here. We also welcome your comments on this or any other article on this blog.

Cancer immunotherapy: The star of the 2012 ASCO Annual Meeting

 


The American Society of Clinical Oncology (ASCO) held its 2012 Annual Meeting on June 1-5, 2012. Arguably the highlight of the meeting was the June 2, 2012 presentation by Bristol-Myers Squibb (BMS) on its Phase 1 immunotherapeutic, anti-PD-1 (BMS-936558). The results of this study were also published ahead of print on June 2, in the online version of the New England Journal of MedicineNature published a “News in Focus” article on the same subject by Nature staff writer Erika Check Hayden in its 6 June issue.

BMS acquired its anti-PD-1 MAb product BMS-936558 (MDX-1106) via its 2009 acquisition of Medarex. This is the same way in which BMS acquired its now-marketed immunotherapy, ipilimumab (Yervoy), which was approved by the FDA in March 2011. Both BMS-936558 and ipilimumab are monoclonal antibodies (MAbs). Ono Pharmaceuticals has been a partner in the development of anti-PD-1 MAb since its original collaboration with Medarex; Ono retains the right to exclusively develop and market the agent (which is also designated as ONO-4538) in Japan, Korea and Taiwan.

PD-1 (“programmed cell death-1”) is a receptor on the surface of activated T lymphocytes of the immune system. PD-1 is a member of the CD28/CTLA4 family of T cell regulators. Like CTLA4, the target of ipilimumab, PD-1 is a negative regulator of T-cell receptor signals. When a protein on the surface of some tumor cells, known as PD-1 ligand (PD-L1), binds to PD-1 on T cells that recognize antigens on these tumors cells, this results in the blockage of the ability of the T cells to carry out an anti-tumor immune response. Anti-PD-1 MAb binds to PD-1 on T cells, thus preventing PD-L1 on tumor cells from binding to the PD-1 and initiating an inhibitory signal. Anti-tumor T cells are then free to initiate immune responses against the tumor cells. This mechanism of action is completely analogous to that of ipilimumab, which binds to CTLA4 and thus prevents negative signaling from that molecule.

Phase 1 clinical study of Medarex/BMS’s anti-PD-1

The Phase 1 clinical study was carried out by a multi-institution team of investigators, led by Suzanne L. Topalian, M.D. (Johns Hopkins University School of Medicine, Baltimore, MD.) The researchers enrolled patients with advanced melanoma, non-small-cell lung cancer (NSCLC), prostate cancer, renal cell cancer (RCC), or colorectal cancer. Patients received anti-PD-1 at a dose between 0.1 and 10.0 milligrams per kilogram of body weight every two weeks. Tumor response was determined after each 8-week treatment cycle. Patients received up to 12 cycles of treatment until either unacceptable adverse events, disease progression or a complete response occurred. A total of 296 patients received treatment through February 24, 2012.

Among the 236 patients in whom tumor responses could be evaluated, objective responses were observed in patients with NSCLC, melanoma, or RCC. Cumulative response rates (among patients treated with all doses of anti-PD-1) were 18% among patients with NSCLC, 28% among patients with melanoma, and 27% among patients with RCC.  These responses were durable–20 of 31 responses lasted 1 year or more in patients with 1 year or more of follow-up. Anti–PD-1 produced objective responses in approximately one in four to one in five patients with NSCLC, melanoma, or RCC.

In addition to patients with objective responses, other patients treated with anti-PD-1 exhibited stable disease lasting 24 weeks or more–5 patients (7%) with NSCLC, 6 patients (6%) with melanoma, and 9 patients (27%) with RCC.

Significant drug-related adverse effects were seen in 11% of the patients, including three deaths due to pulmonary toxicity. In most cases, adverse effects were reversible, and the observed adverse-event profile does not appear to preclude the use of the drug. A maximum tolerated dose was not reached in this study.

The exciting finding of this study is that anti-PD-1 produced durable responses not only in melanoma and RCC (the two types of cancer that are deemed to be “immunogenic”), but also in NSCLC, a much more common cancer that kills more people per year than any other cancer. Moreover, response rates with anti-PD-1 were much higher that those achieved with the other recently approved immunotherapeutics. In the Phase 3 clinical trial of ipilimumab that led to its approval, this drug gave response rates of 11% in melanoma patients. The other recently approved immunotherapeutic, the prostate cancer-specific dendritic cell vaccine Sipuleucel-T (Dendreon’s Provenge, APC8015), gives very low response rates and no complete responses. According to Antoni Ribas (Jonsson Comp­rehensive Cancer Center, University of California, Los Angeles CA) as quoted Ms. Hayden’s Nature “News in Focus” review, if an immunotherapy “breaks the 10% ceiling” as did anti-PD-1, it becomes “even more important and clinically relevant”.

Despite the exciting efficacy results with anti-PD-1, and despite the fact that it was deemed that the adverse-event profile did not appear to preclude the use of the drug, researchers would still like to get away from the serious adverse effects (including three deaths) seen with anti-PD-1. As with other immunotherapeutics (e.g., ipilimumab), researchers hypothesize that anti-PD-1’s serious adverse effects were due to autoimmune responses.

Phase 1 clinical study of Medarex/BMS’ anti-PD-L1

A potential way of achieving similar efficacy to anti-PD-1 with an improved safety profile is provided by another Phase 1 immunotherapeutic,  anti-PD-L1. Anti-PD-L1 MAb drugs are being developed by Medarex/BMS, Roche/Genentech, and other companies. As mentioned earlier, PD-L1 is the binding partner of PD-1 that is expressed on some tumor cells. As quoted in the Nature “News in Focus” review, Ira Mellman (vice-president of research oncology at Genentech), believes that anti-PD-L1 might have fewer adverse effects than anti-PD-1. That is because anti-PD-L1 would target tumor cells while leaving T cells free to participate in immune networks that work to prevent autoimmune reactions.

The results of a Phase 1 clinical study of BMS/Medarex’ anti-PD-L1 (also known as MDX-1105) were also published ahead of print in the online version of the New England Journal of Medicine on June 2, 2012; this was a “companion study” to the Phase 1 study of anti-PD-1. This study was also carried out by a multi-institution team of investigators, led by Julie R. Brahmer, M.D. (Johns Hopkins University School of Medicine, Baltimore, MD.); Dr. Topalian, among other investigators on the anti-PD-1 trial, also participated in the study.

This Phase 1 trial was a dose escalation study that was carried out via a similar protocol to the anti-PD-1 trial discussed earlier. As of February 24, 2012, a total of 207 patients — 75 with NSCLC, 55 with melanoma, 18 with colorectal cancer, 17 with RCC, 17 with ovarian cancer, 14 with pancreatic cancer, 7 with gastric cancer, and 4 with breast cancer — had received anti–PD-L1 antibody, for a median duration of 12 weeks. Among patients with an evaluable response, an objective response (i.e., a complete or partial response) was seen in 17% of patients with melanoma, 12% of patients with RCC, 10% of patients with NSCLC, and 6% of patients with ovarian cancer. Responses lasted for 1 year or more in 8 of 16 patients with at least 1 year of follow-up. Prolonged disease stabilization was seen in 12-41% of patients with advanced cancers, including NSCLC, melanoma, and RCC.

Significant drug-related adverse effects were seen in 9% of patients.

Although the two agents were not compared directly in a randomized trial, the frequency of objective responses for anti–PD-L1 MAb appears to be somewhat lower than that observed for anti–PD-1 MAb in initial Phase 1 trials; the frequency and severity of significant drug-related adverse events also appears to be lower. However, whether these differences will hold up in Phase 2 and 3 clinical trials remains to be determined. The clinically appropriate dose of anti–PD-L1 will also require further definition later studies. Nevertheless, the Phase 1 trial showed that anti-PD-L1 MAb induced durable tumor regression (objective response rate of 6-17%) and prolonged disease stabilization (rate of 12-41% at 24 weeks) in patients with select advanced cancers, including NSCLC, a tumor type that had been deemed to be “non-immunogenic”. This is essentially the same result that was observed for anti-PD-1MAb.

A predictive biomarker for treatment with anti-PD-1?

As with other modes of cancer therapy, it would be very useful to have mechanism-based predictive biomarkers to identify appropriate candidates for treatment with anti-PD-1 or anti-PD-L1 immunotherapy. The findings of the Phase 1 anti-PD-1 study suggest that PD-L1 expression in tumors is a candidate biomarker that warrants further evaluation for use in selecting patients for immunotherapy with anti–PD-1 MAb. The researchers found that 36% of patients with PD-L1–positive tumors achieved an objective response, while no patients with PD-L1–negative tumors achieved such a response. These results suggest that PD-L1 expression on the surface of tumor cells in pre-treatment tumor specimens may be associated with an objective response. However, further studies will be necessary to define the role of PD-L1 as a predictive biomarker of response to anti–PD-1 therapy. Similarly, it appears reasonable that tumor expression of PD-L1 may be a predictive biomarker of response to anti-PD-L1 therapy. However, this hypothesis must also be tested in further clinical studies.

Further studies of anti-PD-1 MAb

Two studies of BMS-936558/MDX-1106 anti–PD-1 MAb, both in advanced/metastatic clear-cell RCC, are now recruiting patients. One trial is a Phase 1 biomarker study involving immunologic and tumor marker correlates of efficacy (progression-free survival and tumor response). The other trial is a Phase 2 efficacy (progression-free survival and tumor response) study; this is a dose ranging study that is designed to determine if a dose response exists. Phase 3 studies of BMS-936558/MDX-1106 anti–PD-1 MAb for the treatment of non–small-cell lung cancer, melanoma, and renal-cell cancer are also being planned.

Conclusions

The exciting results of the studies with BMS’ anti-PD-1 and anti-PD-L1 have only been in Phase 1 studies. Thus caution is advisable in interpreting these results, pending the results of further clinical studies. Nevertheless, these results, together with the recent approval of ipilimumab (Medarex/Bristol-Myers Squibb’s Yervoy) and of Sipuleucel-T (Dendreon’s Provenge), indicate that cancer immunotherapy, a field that not so long ago was regarded as an impractical dream, is very much alive and well. In addition to clinical development and approval of immunotherapeutic agents, exciting basic and drug discovery research in this field is ongoing. This was recognized by the awarding of the 2011 Nobel Prize in Physiology or Medicine for research with profound implications for the development of cancer immunotherapies.

The Biopharmconsortium Blog has been covering new developments in cancer immunotherapy since the spring of 2011. Our earlier articles on this subject (with links) are listed in our December 31, 2011 article, entitled “Read the cancer immunotherapy review in the 22 December 2011 issue of Nature!”

Cancer immunotherapy represents one of several “scientifically premature” or “frontier science” areas discussed in this blog that are providing new opportunities for drug discovery and development–for young entrepreneurial biotech start-ups and for more established biotechnology and pharmaceutical companies. Corporate strategists would do well to explore such areas for potential new R&D programs for their companies.

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As the producers of this blog, and as consultants to the biotechnology and pharmaceutical industry, Haberman Associates would like to hear from you. If you are in a biotech or pharmaceutical company, and would like a 15-20-minute, no-obligation telephone discussion of issues raised by this or other blog articles, or of other issues that are important to  your company, please click here. We also welcome your comments on this or any other article on this blog.