Maraviroc

Maraviroc

In April 2012, Informa’s Scrip Insights published our book-length report, “Advances in the Discovery of Protein-Protein Interaction Modulators.” We also published a brief introduction to this report, highlighting the strategic importance of protein-protein interaction (PPI) modulators for the pharmaceutical industry, on the Biopharmconsortium Blog.

The report included a discussion on discovery and development of inhibitors of chemokine receptors. Chemokine receptors are members of the G-protein coupled receptor (GPCR) superfamily. GPCRs are seven-transmembrane (7TM) domain receptors (i.e. integral membrane proteins that have seven membrane-spanning domains). Compounds that target GPCRs represent the largest class of drugs produced by the pharmaceutical industry. However, in the vast majority of cases, these compounds target GPCRs that bind to natural small-molecule ligands.

Chemokine receptors, however, bind to small proteins, the chemokines. These proteins constitute a class of small cytokines that guide the migration of immune cells via chemotaxis. Chemokine receptors are thus a class of GPCRs that function by forming PPIs. Direct targeting of interactions between chemokines and their receptors (unlike targeting the interactions between small-molecule GPCR ligands and their receptors) thus involves all the difficulties of targeting other types of PPIs.

However, GPCRs–including chemokine receptors–appear to be especially susceptible to targeting via allosteric modulators. Allosteric sites lie outside the binding site for the protein’s natural ligand. However, modulators that bind to allosteric sites change the conformation of the protein in such a way that it affects the activity of the ligand binding site. (Direct GPCR modulators that bind to the same site as the GPCR’s natural ligands are known as orthosteric modulators.) In the case of chemokine receptors, researchers can in some cases discover small-molecule allosteric modulators that activate or inhibit binding of the receptor to its natural ligands. Discovery of such allosteric activators is much easier than discovery of direct PPI modulators.

Chemokines bind to sites that are located in the extracellular domains of their receptors. Allosteric sites on chemokine receptors, however, are typically located in transmembrane domains that are distinct from the chemokine binding sites. Small-molecule allosteric modulators that bind to these sites were discovered via fairly standard medicinal chemistry and high-throughput screening, sometimes augmented with structure-based drug design. This is in contrast to attempts to discover small molecule agents that directly inhibit binding of a chemokine to its receptor, which has so far been extremely challenging.

Our report describes several allosteric chemokine receptor modulators that are in clinical development, as well as the two agents that have reached the market. One of the marketed agents, plerixafor (AMD3100) (Genzyme’s Mozobil), is an inhibitor of the chemokine receptor CXCR4. It is used in combination with granulocyte colony-stimulating factor (G-CSF) to mobilize hematopoietic stem cells to the peripheral blood for autologous transplantation in patients with non-Hodgkin lymphoma and multiple myeloma. The other agent, which is the focus of this blog post, is maraviroc (Pfizer’s Selzentry/Celsentri).

Maraviroc is a human immunodeficiency virus-1 (HIV-1) entry inhibitor. This compound is an antagonist of the CCR5 chemokine receptor. CCR5 is specific for the chemokines RANTES (Regulated on Activation, Normal T Expressed and Secreted) and macrophage inflammatory protein (MIP) 1α and 1β.  In addition to being bound and activated by these chemokines, CCR5 is a coreceptor (together with CD4) for entry of the most common strain of HIV-1 into T cells. Thus maraviroc acts as an HIV entry inhibitor; this is the drug’s approved indication in the U.S. and in Europe. Maraviroc was discovered via a combination of high-throughput screening and optimization via standard medicinal chemistry.

New structural biology studies of the CCR5-maraviroc complex

Now comes a report in the 20 September 2013 issue of Science on the structure of the CCR5-maraviroc complex. This report was authored by a mainly Chinese group led by Beili Wu, Ph.D. (Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai); researchers at the University of California at San Diego and the Scripps Research Institute, San Diego were also included in this collaboration. A companion Perspective in the same issue of Science was authored by P. J. Klasse, M.D., Ph.D. (Weill Cornell Medical College, Cornell University, New York, NY).

As described in the Perspective, the outer surface of the HIV-1 virus displays numerous envelope protein (Env) trimers, each including the outer gp120 subunit anchored in the viral membrane by gp41. When gp120 binds to the cell-surface receptor CD4, this enables interaction with a specific chemokine receptor, either CCR5 or CXCR4. Interaction with both CD4 and the chemokine receptor triggers complex sets of changes in the Env complex, eventually resulting in the fusion of the viral membrane and the cell membrane, and the entry of the virus particle into the host cell.

HIV-1 gp120 makes contact with CCR5 at several points. The interactions between CCR5 and the variable region of gp120 called V3 are especially important for the tropism of an HIV-1 strain, i.e., whether the virus is specific for CCR5 (the “R5 phenotype”) or CXCR4 (the “X4 phenotype”). In the case of R5-tropic viruses, the tip of the V3 region interacts with the second extracellular loop (ECL2) of CCR5, while the base of V3 interacts with the amino-terminal segment of CCR5. Modeling of the interactions between the V3 domain of gp120 of either R5 or X4-tropic viruses with CCR5 or CXCR4 explains coreceptor use, in terms of forming strong bonds or–conversely–weak bonds and steric hindrance.

Monogram Biosciences (South San Francisco, CA) has developed and markets the Trofile assay. This is a molecular assay designed to identify the R5, X4, or mixed tropism of a patient’s HIV strain. If a patient’s strain is R5-tropic, then treatment with maraviroc is appropriate. However, a patient’s HIV-1 strain may undergo a tropism switch, or may mutate in other ways to become resistant to maraviroc.

Dr Wu and her colleagues determined the high-resolution crystal structure of the complex between maraviroc and a solubilized engineered form of CCR5. This included determining the CCR5 binding pocket for maraviroc, which was determined both by Wu et al’s X-ray crystallography, and by site-directed mutagenesis (i.e., to determine amino acid residues that are critical for maraviroc binding) that had been published earlier by other researchers.

The structural studies of Dr. Wu and her colleagues show that the maraviroc-binding site is different from the recognition sites for gp120 and for chemokines, as expected for an allosteric inhibitor. The X-ray structure shows that maraviroc binding prevents the helix movements that are necessary for binding of g120 to induce the complex sequence of changes that result in fusion between the viral and cellular membranes. (These helix movements are also necessary for induction of signal transduction by binding of chemokines to CCR5.)

Structural studies of CXCR4 and its inhibitor binding sites

In addition to their structural studies of the CCR5-maraviroc complex, Dr. Wu and her colleagues also published structural studies of CXCR4 complexed with small-molecule and cyclic peptide inhibitors in Science in 2010. These inhibitors are IT1t, a drug-like orally-available isothiourea developed by Novartis, and CVX15, a 16-residue cyclic peptide that had been previously characterized as an HIV-inhibiting agent. IT1t and CVX15 bind to overlapping sites in CXCR4. Other researchers have found evidence that the binding site for plerixafor also overlaps with the IT1t binding site.

As discussed in Wu et al’s 2013 paper, CCR5 and CXCR4 have similar, but non-identical structures. The binding site for IT1t in CXCR4 is closer to the extracellular surface than is the maraviroc binding site in CCR5, which is deep within the CCR5 molecule. The entrance to the CXCR4 ligand-binding pocket is partially covered by CXC4’s N terminus and ECL2, but the CCR5 ligand-binding pocket is more open.

Mechanisms of CXCR4 and CCR5 inhibition, and implications for discovery of improved HIV entry inhibitors

The chemokine that specifically interacts with the CXCR4 receptor is known as CXCL12 or stromal cell-derived factor 1 (SDF-1). Researchers have proposed a hypothesis for how CXCL12 interacts with CXCR4; this hypothesis appears to be applicable to the interaction between other chemokines and their receptors as well. This hypothesis is know as the “two-step model” or the “two-site model” of chemokine-receptor activation. Under the two-site model, the core domain of a chemokine binds to a site on its receptor (known as the “chemokine recognition site 1” or “site 1”) defined by the receptor’s N-terminus and its ECLs. In the second step, the flexible N-terminus of the chemokine interacts with a second site (known as “chemokine recognition site 2” or “site 2” or the “activation domain”) deeper within the receptor, in transmembrane domains. This result in activation of the chemokine receptor and intracellular signaling.

Under the two-site model, CXCR4 inhibitors (e.g., IT1t, CVX15, and  plerixafor), which bind to sites within the ECLs of CXCR4, are competitive inhibitors of binding of the core domain of CXCL12 to CXCR4 (i.e.., step 1 of chemokine/receptor interaction). They are thus orthosteric inhibitors of CXCR4. (This is contrary to the earlier assignment of plerixafor as an allosteric inhibitor of CXCR4.)  The CCR5 ligand maraviroc, however, binds within a site within the transmembrane domains of CCR5, which overlaps with the activation domain of CCR5. Dr. Wu and her colleagues propose two alternative hypotheses: 1. Maraviroc may inhibit CCR5 activation by chemokines by blocking the second step of chemokine/chemokine receptor interaction, i.e., receptor activation. 2. Maraviroc may stabilize CCR5 in an inactive conformation. It is also possible that maraviroc inhibition of CCR5 may work via both mechanisms.

Dr. Wu and her colleagues further hypothesize that the interaction of  HIV-1 gp120 with CCR5 (or CXCR4) may operate via similar mechanisms to the interaction of chemokines with their receptors. As we discussed earlier in this article, the base (or the stem region) of the gp120 V3 domain interacts with the amino-terminal segment of CCR5. The tip (or crown) of the V3 domain interacts with the ECL2 of CCR5, and–according to Dr. Wu and her colleagues–also with amino acid residues inside the ligand binding pocket; i.e., the activation site of CCR5. The HIV gp120 V3 domain may thus activate CCR5 via a similar mechanism to the two-step  model utilized by chemokines.

Based on their structural biology studies, Dr. Wu and her colleagues have been building models of the CCR5-R5-V3 and CXC4-X4-V3 complexes, and are also planning to determine additional structures needed to fully understand the mechanisms of HIV-1 tropism. The researchers will utilize their studies in the discovery of improved, second-generation HIV entry inhibitors for both R5-tropic and X4-tropic strains of HIV-1.

The bigger picture

The 17 October 2013 issue of Nature contains a Supplement entitled “Chemistry Masterclass”. In that Supplement is an Outlook review entitled “Structure-led design”, by Nature Publishing Group Senior Editor Monica Hoyos Flight, Ph.D. The subject of this article is structure-based drug design of modulators of GPCRs.
This review outlines progress in determining GPCR structures, and in using this information for discovery of orthosteric and allosteric modulators of GPCRs.

According to the article, the number of solved GPCR structures has been increasing since 2008, largely due to the efforts of the Scripps GPCR Network, which was established in that year. Dr. Wu started her research on CXCR4 and CCR5 as a postdoctoral researcher in the laboratory of Raymond C. Stevens, Ph.D. at Scripps in 2007, and continues to be a member of the network. The network is a collaboration that involves over a dozen academic and industrial labs. Its goal has been to characterize at least 15 GPCRs by 2015; it has already solved 13.

Interestingly, among the solved GPCR structures are those for the corticotropin-releasing hormone receptor and the glucagon receptor. Both have peptide ligands, and thus work by forming PPIs.

One company mentioned in the article, Heptares Therapeutics (Welwyn Garden City, UK), specializes in discovering new medicines that targeting previously undruggable or challenging GPCRs. In addition to discovering small-molecule drugs, Heptares, working with monoclonal antibody (MAb) leaders such as MorphoSys and MedImmune, is working to discover MAbs that act as modulators of GPCRs. Among Heptares’ targets are several GPCRs with peptide ligands.

Meanwhile, Kyowa Hakko Kirin Co., Ltd. has developed the MAb drug mogamulizumab (trade name Poteligeo), which is approved in Japan for treatment of relapsed or refractory adult T-cell leukemia/lymphoma. Mogamulizumab targets CC chemokine receptor 4 (CCR4).

Thus, aided in part by structural biology, the discovery of novel drugs that target GPCRs–including those with protein or peptide targets such as chemokine receptors–continues to make progress.

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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.

Lumacaftor (Vertex’ VX-809)

Lumacaftor (Vertex’ VX-809)

I was quoted in an article in the March 11, 2013 issue of Elsevier Business Intelligence’s The Pink Sheet by senior writer Joseph Haas. The article is entitled “Cystic Fibrosis Market Snapshot: Disease-Modifying Drugs Elusive 24 Years After Discovery Of Root Cause”. A subscription is required to view the full text of this article.

The article focused on the newly-approved disease modifying drug ivacaftor (Vertex’ Kalydeco), as well as programs in drug discovery and development of disease-modifying drugs for cystic fibrosis (CF) at Vertex, PTC Therapeutics, Proteostasis Therapeutics, Pfizer, and Genzyme. It also discussed pipeline products aimed at treating or preventing life-threatening infections in CF patients at such companies as KaloBios, Insmed, and Savara.

Mr. Haas interviewed me for this article. Most of the content of our interview is available in our February 15, 2013 article on the Biopharmconsortium Blog. One company whose R&D program we did not cover in that article is Proteostasis. Proteostasis’ CF program, which is being carried out in collaboration with the Scripps Research Institute, is aimed at discovery and development of compounds that promote CFTR ΔF508 folding and trafficking. This program is in the research and lead optimization stage. We discussed R&D programs at other companies (Vertex, Pfizer) that are also aimed at correction of improper CFTR ΔF508 folding and trafficking in our February 15, 2013 article.

KaloBios’ KB001-A, a bacterial virulence factor-targeting agent

Among the agents aimed at ameliorating life-threatening infections in CF patients that were discussed in the Pink Sheet article is KB001-A, a monoclonal antibody (MAb) agent being developed by KaloBios (South San Francisco, CA). KB001-A is now in Phase 2 development for prevention of Pseudomonas aerguinosa infections in the lungs of CF patients. KB001-A targets an extracellular component of the bacterium’s type III secretion system. This system enables the bacteria to kill immune cells by injection of protein toxins into these cells.

The type III secretion system is an example of a virulence factor. Virulence factors are not expressed by a strain of pathogenic bacteria in vitro, but are expressed only when the bacteria infect a host. Once expressed, they enable the bacteria to colonize the host and cause disease.

In our June 11, 2012 article on this blog, we discussed an antibacterial drug discovery strategy aimed at targeting two related physiological systems that are important in the ability of pathogenic bacteria to cause disease, but are not essential for bacterial proliferation or survival. These systems are virulence factors and quorum sensing. At least by hypothesis, agents that disrupt these systems will prevent pathogenic bacteria from causing disease without selecting for resistant strains of the bacteria. This will give such agents an advantage over conventional antibiotics, which notoriously generate resistant strains when used to treat infections. According to the Pink Sheet article, KaloBios believes that P. aerguinosa bacteria will not develop resistance to KB001-A, which is in accord with this hypothesis.

Another issue with anti-infectives used to treat CF that is discussed in the Pink Sheet article is the definition of a “disease-modifying” agent for CF. We define disease-modifying agents as drugs that ameliorate or cure a disease by targeting the root cause of that disease. However, KaloBios considers KB001-A to be a disease-modifying agent. That is because the company believes that most CF patients die of the effects of P. aerguinosa infection, which causes deterioration of the patients’s lungs. Thus an effective anti-P. aerguinosa agent may produce dramatic increases in patients’ lifespans.

Perhaps the real issue is that one should not classify CF drugs as “disease-modifying” agent and agents that merely treat “symptoms” (as is done in the Pink Sheet article) but should define infections of CF patients as “complications” of the disease. Thus anti-infectives such as KB001-A may effectively treat a major life-threatening complication of CF, without modifying the underlying disease. Such an agent would result in increased lifespans (and improved quality of life) for CF patients, without affecting their underlying disease. As KaloBios asserts, anti-infective agents like KB001-A would be complementary to such disease-modifying agents as ivacaftor.

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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.

 

Quorum sensing synthetic biology project http://bit.ly/LO1ynR

Way back in May 2000, Decision Resources published my short report entitled “New approaches to small-molecule antibacterial drug discovery” as part of its Spectrum Life Sciences series. As might be expected, the report is now out of print.

The report was a brief review of then-novel approaches to antibacterial drug discovery, in the face of the increasing level of antibiotic resistance in pathogenic bacteria. These approaches included genomics and such technologies as high-throughput screening against bacterial-specific targets.

However, the most interesting part of the report was a section on using the study of bacterial physiology to identify targets that are important for the ability of bacteria to cause disease, but are not essential for bacterial proliferation or survival. The hypothesis behind these studies was that it might be possible to develop compounds that prevent these bacteria from causing disease, without selecting for resistant strains of the bacteria.

Antibiotics typically kill or prevent proliferation of bacteria by targeting biomolecules involved in such essential processes as cell wall synthesis, DNA proliferation, or protein synthesis. Treating large populations of bacteria with such agents inevitably selects for a few resistant mutant cells. These proliferate, mutate further, and give rise to antibiotic resistant populations. However, if a therapeutic targets a nonessential pathway that is involved in pathogenesis, resistant populations might not be selected for. That was the hypothesis.

This field of bacterial physiology for drug discovery focused on two related areas–virulence factors and quorum sensing. Virulence factors are not expressed by a strain of pathogenic bacteria in vitro, but are expressed only when the bacteria infect a host. Once expressed, they enable the bacteria to colonize the host and cause disease. Examples of such virulence factors include secretion systems that deliver bacterial effector proteins into host cells. These effector proteins may, for example, kill host cells, inhibit cytokine production or phagocytosis, or may mediate bacterial entry into the host cells.

Quorum sensing is a system by which certain bacteria can monitor their own population density. They accomplish this by secreting specific autoinducer molecules. When the concentration of an autoinducer reaches a critical threshold value (as the result of an increase in bacterial population density), it triggers specific response systems, causing the induction of sets of genes that are only expressed at high population density.

For example, many gram-negative bacteria (e.g., Pseudomonas aeruginosa, Vibrio cholerae, and Escherichia coli) use specific acyl homoserine lactones (AHSLs) as their autoinducers. P. aeruginosa has two quorum sensing systems that use the AHSL autoinducers butyrylhomoserinelactone and 3-oxododecanoylhomoserinelactone, respectively. These systems (operating via specific receptors for the auotoinducers and interacting with each other) control the induction of several genes, some of which are virulence factors. Some of these genes enable the bacteria, when they are at sufficient density, to form biofilms (slimy mats of bacteria and polysaccharide matrix).

P. aeruginosa is an opportunistic pathogen, causing infection in the lungs of people with cystic fibrosis, burn patients, and other hospitalized patients. These infections cause death in over 80% of cystic fibrosis patients. The ability to form biofilms renders the bacteria resistant to antibiotics and to the patient’s own immune system.

Other gram-negative bacteria that form biofilms have been implicated in dental caries, peridontitis, osteomyelitis, and numerous nosocomial infections. Bacterial biofilms can also form on the surface of implanted medical devices, such as catheters and mechanical heart valves, and cause device-related infections.

The gram-positive human pathogen Staphylococcus aureus also has a quorum sensing system. However, it does not use an AHSL as an autoinducer. The S. aureus autoinducers are peptides that contain an unusual thiolactone structure (i.e., a thol ester-linked cyclic structure). The S. aureus quorum sensing system controls the synthesis of virulence factors responsible for the pathogenicity of this organism in vivo. Although specific peptides induce virulence factors in a given strain of S. aureus, there are other specific peptides that inhibit the induction of virulence in strains of the organism other than the one secreting the inhibitory peptides. That finding suggested that researchers should be able to develop specific agents to shut down S. aureus pathogenesis by targeting the quorum sensing system.

Interestingly, quorum sensing-based systems have been used in projects for the International Genetically Engineered Machine (iGEM) competition, an annual undergraduate synthetic biology competition. See the figure above, which was taken from the 2009 Chiba University (Japan) iGEM project.  [http://2009.igem.org/Team:Chiba/Project/Signaling-system]

Quorum Sciences and Vertex Pharmaceuticals’ research on quorum sensing

At the time of the writing and publication of our antibacterial drug discovery report, there was a company, Quorum Sciences (Iowa City, IA) that had been established to commercialize the findings of leading researchers on bacterial quorum sensing. As the result of two successive acquisitions in 2000 and 2001, Quorum Sciences passed into the hands of Vertex Pharmaceuticals (Cambridge, MA). In 2006, Vertex researchers and their academic collaborators published a report on the discovery of novel specific inhibitors of the P. aeruginosa quorum sensing system. The last author of this report was quorum sensing pioneer E. Peter Greenberg, formerly of the University of Iowa and chief scientific officer at Quorum Sciences, and from 2005 to the present at the University of Washington School of Medicine. The compounds identified in the 2006 report, discovered via high-throughput screening of a diverse 200,000-compound chemical library, resembled the natural AHSL that binds to the P. aeruginosa quorum sensing receptor LasR. (LasR is a transcription factor that when bound to its specific AHSL, mediates the expression of a set of downstream genes, including those that encode virulence factors.) The researchers concluded that the novel quorum sensing inhibitors might be useful chemical tools, but not drug leads.

In 2010, other academic researchers published a report on the discovery of novel antagonists and agonists of the P. aeruginosa quorum sensing receptor LasR, which were of lower molecular weight and otherwise structurally distinct from the natural P. aeruginosa AHSL. However, these compounds were still deemed to be scaffolds for chemical tools, not drug leads. Nevertheless, the researchers speculated that the compounds “could, with further development, provide a pathway for the design of novel antivirulence agents”. Other researchers are continuing studies aimed at discovery of quorum sensing receptor antagonists, whether synthetic organic molecules or natural products. These involve studies with quorum sensing systems of both gram-positive and gram-negative bacteria.

The 2006 report appears to be the last Vertex publication on quorum sensing. However, Vertex continues to conduct research on antibacterial agents. And the company has a facility in the University of Iowa BioVentures Center (Coralville, IA),  which is a continuation of the old Quorum Sciences Iowa facility. As of 2009, Vertex’s Iowa-based team consisted of seven full-time scientists, working on development of antibacterials, and agents to treat hepatitis C and cystic fibrosis, among other areas. The Iowa group participated in the development of Vertex’ now-marketed anti-hepatitis C virus (HCV) agent Incivek (telaprevir).

The May 2012 article “Freezing Time” in The Scientist, and discovery of novel quorum sensing inhibitors

The May 2012 issue of The Scientist contains an article entitled “Freezing Time”, by Vern L Schramm, Ph.D. (Albert Einstein College of Medicine (Bronx, NY). The article focused on design of “transition state analogues”, i.e., compounds with a chemical structure that resembles the transition state of a substrate in an enzyme-catalyzed reaction. Transition state analogs usually act as enzyme inhibitors by blocking the enzyme’s active site. They are exquisitely potent and specific inhibitors, which act at extremely small doses. This makes these compounds potentially attractive as drugs.

A transition state analogue inhibitor that was designed by Dr. Schramm and his colleagues in the early 2000s as an early proof-of-concept molecule is immucillin-H, or forodesine. This is a transition-state analog inhibitor of purine nucleoside phosphorylase.  Forodesine is being developed by BioCryst Pharmaceuticals for treatment of relapsed B-cell chronic lymphocytic leukemia, and the results of a Phase 2 trial were published in 2010.

As described in Dr. Schramm’s May 2012 article, his laboratory has been applying their transition-state analogue technology to the field of quorum sensing in bacteria. Instead of targeting the recognition of AHSLs by quorum sensing receptors such as LasR, the researchers targeted the key enzyme in the AHSL biosynthesis pathway in gram-negative bacteria, known as 5′-methylthioadenosine nucleosidase (MTAN). The biosynthetic pathway for the production of AHSLs, including the key role of MTAN, had been elucidated by Dr. Greenberg and his colleagues in the late 1990s.

Dr. Schramm and his colleagues published the results of studies of three transition state analogues that potently inhibited MTANs of gram-negative bacteria. For example, they inhibited the Vibrio cholerae MTAN with dissociation constants of 73, 70, and 208 pM, respectively. They inhibited MTAN in cell of a virulent strain of V. cholerae with IC50 values of 27, 31, and 6 nM respectively, disrupting autoinducer production in a dose-dependent manner without affecting bacterial growth. The compounds were also potent inhibitors of autoinducer production in an enterohemorrhagic strain of Escherichia coli. The transition-state analogues did not inhibit growth in either V. cholerae or E. coli, but one such compound reduced biofilm production by 18% in E. coli and 71% in V. cholerae.

Moreover, the MTAN inhibitors did not appear to select for bacterial resistance in vitro. When V. cholerae bacteria were grown for 26 generations in the presence of a large excess of MTAN inhibitors, subsequent generations of these bacteria were equally sensitive to inhibition by these compounds as bacteria that had not been previously exposed to the inhibitors. These results are consistent with the hypothesis that agents that inhibit targets that are important in the ability of bacteria to cause disease, but are not essential for bacterial proliferation or survival might not select for drug resistance.

As Dr. Schramm said in the May 2012 article in The Scientist, it remains to be seen whether the MTAN-targeting transition-state analogs developed in his laboratory can translate into novel antibiotics that do not select for resistant pathogens. As of March 2009, Dr. Schramm’s team had developed over 20 potent MTAN inhibitors, which will be specific for bacteria and should have no effect on human metabolism. These compounds have been licensed to Pico Pharmaceuticals (Melbourne, Australia), which plans to develop and initiate clinical trials. Dr. Schramm is a Pico Pharmaceuticals co-founder and chairman of its scientific advisory board. Pico claims that one of its quorum sensing inhibitors, designated as PC0208, has demonstrated proof-of-concept in preclinical studies, and now has “pre-IND” status.

Lessons from these studies

Dr. Schramm’s discovery of novel quorum sensing inhibitors was made possible by a strategy that involved a combination of biology-driven drug discovery and sophisticated chemistry technology. The biology-driven drug discovery strategy involved a combination of 1. Building on the quorum sensing studies of Dr. Greenberg and others, and adopting the strategy, as reviewed in our 2000 Spectrum report, of targeting the quorum sensing system in order to discover agents that would have the possibility of not triggering resistance, and 2. Targeting a critical, bacterial-specific pathway enzyme that is upstream of the recognition of AHSLs by quorum sensing receptors (the usual target of most researchers in this area). This enzyme, MTAN, has a key role in the biosynthesis of AHSLs.

The sophisticated chemical technology employed by Dr. Schramm and his colleagues was of course the transition state analogue technology developed in his own laboratory. Combined with the biology-driven strategy described in the last paragraph, Dr. Schramm’s approach has succeeded in the discovery of compounds that are potential drug candidates, while approaches based on high-throughput screening for AHSL antagonists have so far failed to produce any such compounds. Dr. Scharamm’s laboratory has also obtained evidence that treatment with their compounds should not result in the selection of resistant strains of pathogenic bacteria.

It is possible that other chemistry approaches might be successfully employed to discover quorum sensing inhibitors, both for gram-negative bacteria and gram-positive organisms such as S. aureus.

As we have discussed in numerous articles on this blog, biology-driven drug discovery strategies, often coupled with innovative approaches to chemistry (in the case of small-molecule drug discovery) are applicable to very many different targets involved in a whole range of human diseases. (Biology-driven drug discovery has also been central to discovery and development of many successful large-molecule drugs.) The quorum sensing case study in this article is a simple, understandable, and elegant example of such a strategy.

In addition to the scientific, clinical, and medical aspects of antibacterial drug discovery, the other major issue is the business of antibacterial discovery and development. The economics of drug discovery and development have shifted pharmaceutical industry investment away from the development of drugs targeting short course therapies for acute diseases (such as antibacterials) and towards long-term treatment of chronic conditions.  At the same time, discovery of novel antibacterials has gotten more difficult. As a result, during the 2000-2010 period, such companies as Wyeth, Aventis, Eli Lilly, GlaxoSmithKline, Bristol-Myers Squibb, Abbott Laboratories, Proctor & Gamble, and Merck have either deprioritized anti-bacterial R&D or left the field altogether. Meanwhile, antibiotic resistance, which was a problem in 2000, has become an even greater problem in 2012, in some cases reaching crisis proportions [e.g, methicillin resistant S. aureus (MRSA) that is also resistant to the drug of last resort, vancomycin].

As a result of these economic, scientific, and medical challenges, a €223.7 consortium of five pharmaceutical companies and leading academics, called NewDrugs4BagBugs (ND4BB) was launched in Europe in May 2012. The program is envisioned to involve a three-stage approach – to improve the understanding of antimicrobial resistance, to design and implement efficient clinical trials, and finally, to take novel drug candidates through clinical development.

And at least one venture capitalist has observed that biotechs that specialize in antibacterial drug development (as well as those that specialize in other areas that have been deemphasized by Big Pharmas) have provided “contrarian opportunities” in biotech venture. According to a June 2 2012 article by Bruce Booth of Atlas Venture published in Forbes, what has been deprioritized by some (or several) Big Pharmas, are likely be re-prioritized by others several years later. Such antibacterial drug developers as Calixa, Cerexa, Novexel, Neutec, Paratek, Pennisula, Protez, and Vicuron have produced some of the best returns in biotech venture capital from merger/acquisition exits. These biotechs included companies that were built around compounds outlicensed from Big Pharma, and others that conducted new research on novel targets, especially for MRSA and other resistant bacteria.  By taking advantage of a strategic depriorization in Pharma, these biotechs and their venture backers were able to create considerable value in the past decade out of antibacterial drug development.

Meanwhile, antibiotic specialist Cubist Pharmaceuticals (Lexington, MA) remains an independent, and profitable, biotech company that is continuing to conduct R&D, including on discovery and development of agents to treat pathogens that are resistant to current antibiotics. It has expanded into development and marketing of peripheral mu-opioid receptor antagonists (including via acquisition of Adolor in 2011), and has recently expanded its R&D facilities.

Can Pico Pharmaceuticals (which has oncology programs in addition to antibacterials) experience similar 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 contact us by phone or e-mail. We also welcome your comments on this or any other article on this blog.

 

Blood cells

Our November 25, 2011 article on this blog focused on Ralph Steinman, one of the three winners of The Nobel Prize in Physiology or Medicine for 2011. That article focused on dendritic cell-based vaccines for cancer, and the application of this area of science and technology to treating Dr. Steinman’s own pancreatic cancer. Dr. Steinman died on September 30, 2011 after a four-and-a-half year battle with his disease, and was awarded the Nobel Prize three days later. He is the only person to ever have been awarded a Nobel Prize posthumously.

Now comes a Nobel Prize Essay, in the December 9, 2011 issue of Cell, entitled “Bridging Innate and Adaptive Immunity”, written by William E. Paul (Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, NIH”). It is immediately followed by an obituary for Ralph Steinman, written by Antonio Lanzavecchia and Federica Sallusto (Institute for Research in Biomedicine, Bellinzona, Switzerland).

The Nobel Prize in Physiology or Medicine for 2011 was divided, one half awarded jointly to Drs. Bruce A. Beutler (Scripps Research Institute, LA Jolla, CA and University of Texas Southwestern Medical Center, Dallas, TX) and Jules A. Hoffmann [National Center of Scientific Research (CNRS), Strasbourg, France] “for their discoveries concerning the activation of innate immunity” and the other half to Dr. Ralph M. Steinman (Rockefeller University, New York, NY) “for his discovery of the dendritic cell and its role in adaptive immunity”. So the focus of this year’s Nobel Prize in Physiology or Medicine is on the two arms of the immune response–innate and adaptive immunity, and the relationship between the two.

Innate and adaptive immunity in the early to mid-20th century

Dr. Paul’s essay is a historical exposition of how researchers came to understand the basis of the innate and the adaptive immune responses, and how they work together as a coherent system. Adaptive immunity focuses on the ability of a vertebrate organism to “learn” to respond to a specific new antigen, and to “recall” and respond to an antigen that it had been exposed to in the past. Innate immunity focuses on the ability of nearly all multicellular life forms, including plants, to respond rapidly to protect themselves against pathogens, using the inflammatory system.

The essay begins with the first ever Nobel Prize given for a discovery in immunology, in 1908. This was shared by two pioneers in the field–Paul Ehrlich and Ilya (or Élie) Metchnikoff. Ehrlich pioneered the study of what is now called adaptive immunity. His work in immunology focused on the ability of humans and animals to develop specific antibodies to toxins such as tetanus toxin and diphtheria toxin. Metchnikoff pioneered the study of what is now called innate immunity. His work resulted in the discovery of phagocytosis, the process by which certain white blood cells can ingest and destroy harmful microbes.

As outlined in Dr. Paul’s article, most of the attention of immunologists between the awarding of the 1908 Nobel Prize and the modern era was on adaptive immunity, focused on the clonal selection theory of immunity and on discoveries in the the cellular (e.g., T cells) and humoral (e.g., antibodies) arms of adaptive immunity. A key practical application of the study of adaptive immunity–from Ehrlich’s day to the present–has been the development of vaccines.

Adjuvants and Charles Janeway’s pattern recognition hypothesis

However, mid-20th century immunology had a “dirty little secret”. Immunization with a pure antigen produces either a very weak immune response, or immune tolerance. In order to obtain a strong immune response, it is necessary to co-inject an adjuvant along with the antigen. The creation of adjuvants–which is involved not only in experimental immunology, but in such practical applications as vaccines–has been something of a black art. Adjuvants used in vaccines include  oil emulsions (which are thought to serve as depots for an antigen) and aluminum hydroxide (which is thought to act as an irritant). The most famous adjuvant in experimental immunology is complete Freund’s adjuvant, a strong adjuvant that consists of killed Mycobacteria tuberculosis bacteria in a water-in-oil emulsion. (Complete Freund’s adjuvant is too toxic for use in humans.)

In 1989, the late Dr. Charles Janeway (Yale University, New Haven, CT) proposed a hypothesis to explain the need for adjuvants; this hypothesis was very fruitful in stimulating further research on the immune response. Dr. Janeway hypothesized that the immune system required both an antigen/receptor interaction (as in classic adaptive immunity) and a recognition of pathogen-associated molecular patterns (PAMPs). PAMPs would be recognized by “pattern-recognition receptors” (PRRs), which would be broadly expressed by immune and inflammatory cells. Recognition of PAMPs by cells carrying PRRs would result in an innate immune response, which would be interpreted by cells of the adaptive immune system, the lymphocytes, as “permission” to mount an adaptive response when they recognized a specific antigen. In vaccination, the function of an adjuvant would be to provide the needed PAMPs.

Drs. Hoffman and Beutler and innate immunity

Beginning in 1996, Jules Hoffmann and his colleagues elucidated the innate immune response pathway in the fruit fly Drosophila, which enables the fly to produce the antifungal peptide drosomycin, and thus to become resistant to fungal infection. This pathway is initiated by the cell surface receptor Toll, and is homologous to the interleukin 1 (IL-1)/NF-κB signaling pathway, which is a key pathway in vertebrate immune and inflammatory responses.

Dr. Janeway and his colleagues then followed up on this study, in order to identify the corresponding microbial sensors in humans. They first scanned a molecular biology database, and identified a transcript that encoded a human homologue of Drosophila Toll, which they named a “Toll-like receptor” (TLR). Since Dr. Janeway and his colleagues did not know the ligand for their TLR, they constructed a chimeric molecule in which the extracellular domain of CD4 was linked to the cytoplasmic domain of the TLR. They expressed this chimera in a human monocyte cell line. When the chimera was crosslinked with an anti-CD4 antibody, NF-κB was activated, resulting in the production of the proinflammatory cytokines IL-1, IL-6, and IL-8. This showed that humans had at least one Toll homolog (Dr. Janeway’s TLR turned out to be TLR4) and that it controlled a signaling pathway similar to those controlled by Drosophila Toll or human IL-1. The ligands for human TLRs remained unknown, as did whether TLRs were the microbial sensors/PRRs postulated by Dr. Janeway had postulated.

It was Bruce Beutler who first determined the nature of TLR recognition specificity. In the 1990s, he worked to identify the genetic defect that rendered some mice unresponsive to lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, which acts as an endotoxin in humans and other mammals. He used two closely related mouse strains, one of which was responsive to LPS (the “wild type” strain), and the other that was unresponsive (the “mutant” strain). Upon stimulation with LPS, macrophages from the wild type mouse produced tumor necrosis factor alpha (TNFα), while macrophages from mutant mice did not. Dr. Beutler used positional cloning to determine the gene that was mutant in the LPS unresponsive mice. In 1998, he and his colleagues reported that that gene was Tlr4, which codes for the very same TLR identified by Dr. Janeway and his colleagues a year earlier. Dr. Beutler’s study indicated that LPS was a direct or indirect ligand for TLR4. It also showed that one type of molecule that would fulfill the criteria for a “PAMP”, namely LPS, working via TLR4 as a “PRR”, could activate the NF-κB-IL-1 pathway.

Since the initial identification of TLR4 by Dr. Beutler and his colleagues, other researchers have identified numerous other TLRs, which are activated by a variety of bacterial and viral molecules. These include such types of molecules as single- and double-stranded RNAs, CpG oligodeoxynucleotides, bacterial flagellin, lipopeptides, and zymosan, all of which fit with Dr. Janeway’s PAMP hypothesis. Different TLRs occupy different subcelluar locations–some are on the cell surface, others in intracellular vesicles. In addition to TLRs, other types of molecules may also act as PRRs.

Dr. Steinman, dendritic cells, and the unification of innate and adaptive immunity

Now we come to the work of Ralph Steinman and his colleagues on the role of dendritic cells in adaptive immune responses, and their relationship to innate immunity.

Antibodies (whether free antibodies or antibodies on the surface of B cells) can recognize molecules on the surface of pathogens. T cell receptors, however, recognize small antigenic peptides carried by major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APCs). This recognition, together with the activity of other signaling molecules on APCs, results in the activation of the T cell.

The requirement for an APC in T-cell activation was first recognized in the late 1960s and early 1970s. At that time, immunologists generally believed that macrophages and perhaps B cells were the major APCs. In 1973, Ralph Steinman and Zanvil Cohn identified mouse dendritic cells, which are rare cells in the spleen and lymph nodes that have a stellate morphology. In 1978, Dr. Steinman and his colleagues published evidence that dendritic cells had potent immunostimulatory activity, and were over 100 times as effective in immunostimulation as macrophages and B or T cells.

Researchers were initially skeptical about Dr. Steinman’s studies, largely based on the widely held view that the far more numerous macrophages were the major APCs. However, a series of studies by Dr. Steinman and his colleagues showed that dendritic cells are the key APCs for nearly all aspects of T cell activation, and that the potency of dendritic cells as APCs far exceeds that of macrophages and B cells.  Indeed, modern techniques that led to the deletion of dendritic cells result in a profound inability to mount adaptive immune responses.

Dendritic cells are found in perhaps every type of tissue, where they exist in an immature state. For example, the population of immature dendritic cells in the skin are known as Langerhans cells–these cells are illustrated in the figure at the top of our November 25, 2011 article. Immature dendritic cells in tissues act as sentinels of microbial infection, and function to capture antigens (e.g., antigens from pathogenic microbes, or from cells infected by viruses or bacteria). They also express TLRs.

When tissue dendritic cells are stimulated via their TLRs (e.g., by TLR4 binding to bacterial LPS), the dendritic cells change to a mature phenotype, which is specialized in antigen presentation. These mature dendritic cells migrate from the tissue into the draining lymph node. The stimulated dendritic cells in the lymphoid system upregulate class II MHC molecules and other cell surface molecules involved in antigen presentation, and they also produce cytokines involved in T cell activation. The dendritic cells thus activate T cells, and the antigens presented on their surface, as well as the pattern of cytokines they produce, determine the specificity and the type of activated T cells that will result from their actions.

Thus, the work of Dr. Steinman and his colleagues serves to integrate studies of innate and adaptive immunity, and to elucidate how these two branches of the immune system work together to enable humans and other vertebrates to mount immune responses against pathogens and other insults such as tumors.

Despite the major advances in the relationship between innate and adaptive immunity that have been made in recent years, their are still many unknowns. For example, there are minority types of T cells such as natural killer T (NKT) cells and gamma-delta (γδ) T cells, which are conventionally thought to be involved in bridging innate and adaptive immunity. However, their functions are not well understood. Moreover, there are also numerous subsets of dendritic cells, and the functions of these subsets is also not well understood. These cell types, and other unknowns in the relationship between innate and adaptive immunity might, for example, be involved in the pathogenesis of steroid-resistant asthma, the most serious type of asthma.

Implications for drug discovery and development

Our previous article on Ralph Steinman and dendritic cells emphasized the development of dendritic cell vaccines, especially those for cancer. However the broad area of the relationship between innate and adaptive immunity has been and is expected to be a major factor in discovery and development of many types of drugs, vaccines, and immunotherapies.

  • Numerous cytokine-based therapies (e.g., interferons, interleukins, and TNF-related therapeutics) have already been developed and marketed. Dr. Beutler himself was the co-discoverer of TNFα in 1985,  and now there are several types of TNF inhibitors on the market.
  • In the vaccine area, Dr. Steniman’s work may allow researchers to design more effective adjuvants, a key need in the design of novel anti-viral and anti-cancer vaccines.
  • Several companies are developing TLR modulators as drugs or vaccine adjuvants. These include TLR agonists and antagonists. For example, Pfizer is developing the oligonucleotide TLR9 agonist vaccine adjuvant CpG7909 (in Phase 3 trials with GlaxoSmithKline’s MAGE-A3 melanoma vaccine), and another oligonucleotide TLR9 agonist product agatolimod, in combination with trastuzumab (Genentech/Roche’s Herceptin) in treatment of breast cancer (Phase 2). [Pfizer’s TLR agonists were originally developed by Coley Pharmaceuticals (Cambridge, MA), which Pfizer acquired in 2008.] TLR antagonists in development include Eisai’s eritoran tetrasodium, a TLR4 antagonist in Phase 3 trials for the treatment of sepsis and septic shock.
  • Research on the role of various immune cell populations that are thought to link innate and adaptive immunity (e.g. Th17 cells, NKT cells, and γδ T cells) in steroid-resistant asthma may lead to the design of new medicines to treat this serious condition.

There are likely to be numerous other drug discovery and development applications of research on the relationship between innate and adaptive immunity that will emerge as work in this very complex area continues.
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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.

Source: Mnolf http://bit.ly/gEg5yo

In our November 11, 2010 blog post, we discussed the September 2010 acquisition of Seattle biotech firm ZymoGenetics by Bristol-Myers Squibb (BMS). Also in November 2010, Nature Biotechnology published an article about this acquisition, in which I was quoted.

As our blog post states, most commentators believe that BMS’ main motivation for acquiring ZymoGenetics was to gain full ownership of ZymoGenetics’ pegylated interferon-lambda (Peg-IFN-λ) program for treatment of hepatitis C (HepC). The two companies had been been collaborating to develop Peg-IFN-λ since January 2009. However, ZymoGenetics was much more than a one-product company. Its other pipeline drugs included interleukin-21 (denenicokin) for treatment of metastatic melanoma, which is now in Phase 2b development.  And over the years, ZymoGenetics has proven to be an important drug discovery engine, from the days in which it was a division of Novo Nordisk, and continuing on into 2010.

Now–as of the first week of January 2011–we learn that former ZymoGenetics CEO Douglas E. Williams Ph.D. has been named as Executive Vice President, R&D., at Biogen Idec (Weston, MA).

Dr. Williams has over 20 years of biotech R&D and senior leadership experience. He was the chief technology officer at Seattle biotech firm Immunex, and played a significant role in the discovery and development of the blockbuster tumor necrosis factor (TNF) inhibitor etanercept (Enbrel). After Amgen’s 2002 acquisition of Immunex, Dr. Williams resigned from Amgen later in 2002, and moved on to Seattle Genetics in 2003 as chief scientific officer (CSO). In 2004, he joined ZymoGenetics as chief scientific officer (CSO). On January 1, 2009, he became ZymoGenetics’ CEO.

During his tenure as CSO and then CEO of ZymoGenetics, the company achieved considerable success in the development of its pipeline products, especially Peg-IFN-λ and  interleukin-21. And the company entered into its $1.1 billion agreement with BMS to codevelop Peg-IFN-λ. However, during Dr. Williams’ tenure as CEO, ZymoGenetics had some financial rough spots, mainly caused by the lack of commercial success of the company’s first self-marketed product, recombinant thrombin (Recothrom). This was compounded by failed clinical trials of the company’s immunomodulatory drug atacicept, which is now being developed by Merck Serono. After a series of downsizing moves, ZymoGenetics agreed to be acquired by BMS in October 2010. In November 2010, Dr. Williams left ZymoGenetics and became a “free agent”, followed by his joining Biogen Idec in January 2011.

Biogen Idec, which was founded as Biogen in 1978 and merged to form Biogen Idec in 2003, is one of the world’s major biotech companies, and has long been a major fixture of the Boston-Cambridge biotech scene. The company had 2009 revenue of $4.38 billion. However, Biogen Idec had some ups and downs of its own in recent years. It has been targeted for reorganization, breakup, or sale by activist investor Carl Icahn, who currently owns 5.4% of the company’s shares, and who controls three seats on Biogen Idec’s board as the result of  series of proxy fights.

During 2010, long-time CEO (and Icahn target) James Mullen retired from the company, and was succeeded by former Exelixis (South San Francisco, CA) CEO George Scangos, Ph.D. In January 2011, at the same time as Dr. Williams joined Biogen Idec, the company announced that Steven H Holtzman (who was formerly the CEO of Cambridge MA biotech Infinity Pharmaceuticals) would be executive vice president of corporate development.

Biogen Idec derives most of its revenues from three drugs–multiple sclerosis (MS) treatments Avonex (interferon beta-1a) and Tysabri (natalizumab), and Rituxan (rituximab), a treatment for non-Hodgkin’s lymphoma. Tysabri is also approved for treatment of Crohn’s disease and is co-marketed with Élan, and Rituxan is also approved for rheumatoid arthritis and is co-marketed with Roche/Genentech.

Among these products, Avonex (which was introduced in 1996, and is Biogen Idec’s largest selling drug) and Rituxan are maturing. In particular, Avonex faces increased competition from newer products. Growth in sales and revenues from these two products is slowing.

Tysabri is intended to be Biogen Idec’s growth driver. However, Tysabri has had major issues. Soon after its launch in 2004, Biogen Idec withdrew Tysabri from the market, after it was linked with three cases of the rare neurological condition progressive multifocal leukoencephalopathy (PML), when co-administered with Avonex.  PML is caused by the JC virus, which is normally controlled by he immune system, but which can rarely cause disease in patients under immunosuppresive therapies such as the Tisabri/Avonex combination. After a safety review and no further deaths, the drug was returned to the US market in 2006 under a special prescription program, in part as the result of pleas by MS patients. However, since then additional cases of PML–including fatalities–have occurred.

In December 2010, Biogen Idec and Elan submitted a supplemental Biologics License Application (sBLA) to the FDA and a Type II Variation to the European Medicines Agency (EMA), proposing updated product labeling to include anti-JC virus antibody status. The companies propose using this test to help stratify the risk of developing PML in patients treated with Tysabri. Biogen Idec expects that a commercial anti-JC virus antibody test will be available later in 2011. It is expected that this test will help to lower the risk of Tysabri-associated PML, which is low to begin with.

In addition, Tysabri faces potential strong competition from the first approved oral treatment for MS, fingolimod (Novartis’ Gilenya), which the FDA approved in September 2010. The day that Gilenya was approved, Biogen Idec issued a press release acknowledging the desire of MS patients for an oral treatment, and noting that it also has an oral MS treatment in Phase 3 trials, BG-12.

Biogen Idec estimated that as of the end of 2010, approximately 56,600 MS patients were using Tysabri worldwide. That represented an increase of 1,700 patients in the fourth quarter and 8,200 patients over the course of 2010.

In November 2010, Dr. Scangos announced a reorganization of Biogen Idec. As of that date, the company would focus on neurology, and leverage its strengths in biologics research and development (R&D) and manufacturing to pursue select, high-impact biologic therapies and to be a leading collaborator in the biotechnology industry. (Biogen Idec’s efforts in biologics might, for example, include entering the biosimilars market.) Biogen Idec also terminated its efforts in cardiovascular medicine, and is seeking to spin out or outlicense its oncology programs.

The restructuring also involved consolidating its sites, and reducing its work force by 13%, or 650 full-time positions. As a result of the restructuring, the company expected to save approximately $300 million annually. Dr. Scangos said that the restructuring would enable Biogen Idec to gain focus and to become more nimble.

The company intends to become a global leader in neurological diseases. This will involve not only maximizing the potential of its two marketed MS drugs, but also bringing forward its MS pipeline products. Biogen Idec will also pursue programs in amyotrophic lateral sclerosis (ALS)/Lou Gehrig’s disease and Parkinson’s disease.

Biogen Idec’s late-stage products in neurology are shown in the table. (Please click on the table to read it clearly.) The company intends to launch five new products by 2015.

Source: Haberman Associates

Although Biogen Idec now has several late-stage products moving toward commercialization, the company’s R&D productivity has lagged in recent years. The company has not launched a new drug since Tysabri was approved in 2004. Dr. Williams says that he is planning a review of he company’s R&D organization and its pipeline. He intends especially to focus on Biogen Idec’s early- and mid-stage programs. Dr. Williams intends to boost these programs both via internal R&D and via licensing and acquisition to bring in externally developed compounds.

Overall, Dr. Williams hopes to return Biogen Idec to the culture of a biotech start-up. “We don’t have the luxury of sitting back. We have to push hard like we are a scrappy, hungry, cash-starved biotech,” he says. Dr. Williams’ statement is in accord with that of Dr. Scangos, who speaking at the J.P. Morgan 29th Annual Healthcare Conference in January 2011, said that Biogen Idec had the choice of being either a small pharma or a big biotech. The company has chosen to be a big biotech.

We wish Dr. Williams–working together with George Scangos and Steven Holtzman–well as they work to return Biogen Idec to productive and innovative R&D.

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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.