Roche’s GA101 (obinutuzumab): Engineering an antibody to beat Rituxan
Jul29

Roche’s GA101 (obinutuzumab): Engineering an antibody to beat Rituxan

The following is a guest post from Sally Church (known to many in the twittersphere as @MaverickNY), from the Pharma Strategy Blog. Survival rates for people with B-cell driven blood cancers, such as non-Hodgkin’s Lymphoma and chronic lymphocytic leukemia, have vastly improved in the last decade thanks to the introduction of Rituxan, marketed by Biogen Idec and Genentech. But the drug, a chimeric monoclonal antibody targeting CD-20, a protein that sits on the surface of B-cells, has its limitations: not all patients respond at first, and others become resistant to the drug over time. As a result, companies are tinkering with the sugar molecules that decorate antibodies in hopes of coming up with a drug that binds better to its target and, ultimately, is more effective at battling cancer. At the American Society of Clinical Oncology annual meeting, held earlier this year in Chicago, Roche offered Phase III data showing its glycoengineered antibody GA-101 worked better than Rituxan at delaying the progression of CLL. If all goes well with FDA, the drug could be approved by the end of the year. BACKGROUND: Although the CD20 antigen is expressed on both normal and malignant cells, it has proven to be a useful target therapeutically.  Rituximab, ofatumumab and most of the anti-CD20 antibodies in earlier development are Type I monoclonal antibodies, which means that they have good complement-dependent cytotoxicity (CDC) and Ab-dependent cell mediated cytotoxicity (ADCC), but are weak inducers of direct cell death. In contrast to Type I monoclonal antibodies, next generation monoclonals are increasingly Type II, such as GA101 (obinutuzumab) in CLL and NHL and mogamulizumab (anti-CCR4), for T-cell leukemias and lymphomas.  They have little CDC activity, but are much more effective at inducing ADCC and also direct cell death, at least based on in vitro studies performed to date. How does glycoengineering make a difference? Glycoengineering is the term used to refer to manipulation of sugar molecules to improve the binding of monoclonal antibodies with immune effector cells, thereby increasing ADCC. Obinutuzumab is a very different molecule from rituximab, in that it is a novel compound in its own right (originally developed by scientists at Glycart before being bought by Genentech).  It is not a biosimilar of rituximab.  It is also a glycoengineered molecule designed specifically to improve efficacy through greater affinity to the Fc receptor, thereby increasing ADCC activity. The overall intent with the development of obinutuzumab was to significantly improve efficacy over rituximab and Type I monoclonal antibodies in B-cell malignancies using glycoengineering techniques. At the recent ASCO annual meeting, data from a phase III trial was presented to evaluate rituximab or obinutuzumab in combination with the chemotherapy...

Read More

Biotech, Pharma, & VCs Offer Rare Disease Patient Groups Some Advice

Today’s issue examines the surge of interest in rare disease drugs, which in the past few years have attracted significant interest from biotech firms, big pharma, and venture capitalists alike. In addition to exploring the business and policy drivers behind increased investment in orphan drugs, the multi-part story looks at the critical role patient organizations play in drawing attention to rare diseases. As such, it seemed worth highlighting advice from various stakeholders on what patient groups can do to entice drug developers to work on their disease: —Organize yourselves. Find as many patients as possible, and establish a registry that will make it easy for a drug firm to begin a clinical trial. “Beginning to identify people, getting them into a registry, and collecting natural history data is one of the most valuable things a developer can have when they’re thinking about a program,” says Genzyme’s CEO David Meeker. “Among the most helful things that patient advocates can do is to help us to understand the natural history of disease,” agrees Kevin Lee, CSO of Pfizer’s rare disease unit. “Without that understanding of how the disease progresses, and what the endpoints can be, its almost impossible to do drug development.” –Find a way to collaborate with one another. In even the smallest of diseases, patient groups tend to proliferate. And while its natural and understandable for advocates to want to do all they can to help their own child or family member, it can lead to duplicative efforts. The disparate groups can also make it tougher for drug developers to access. “We all need to give everybody a lot of space here to do what they think is best, but in an optimal world, there are tremendous advantages to being coordinated,” Meeker says. —Be connectors. Patient organizations have the amazing ability to bring together academics who had previous not collaborated. “What I have found over and over again is that patient advocates know the investigators in their field far better than the investigators themselves do,” says Christopher Austin, director of NIH’s National Center for Advancing Translational Science (NCATS). “They can be instrumental there.” —Get the right researchers interested. Often only a handful of academic researchers are working on a given rare disease, and drug developers say attracting new scientists into the field, while also giving careful consideration about who to fund is key. Patient groups should look for someone who can use advocacy funds to attract larger grants. “If they can get some grant support, you’ll get more done,” says Emil Kakkis, CEO of Ultragenyx. “If they can’t get any grant support, you’ll have to wonder if it was just...

Read More

New Targets in Advanced Prostate Cancer

The following is a guest post from Sally Church (known to many in the twittersphere as @MaverickNY), from the Pharma Strategy Blog. Much hullabaloo has been in the medical news over the past year over new options for the treatment of metastatic castrate resistant prostate cancer (CRPC). FDA approval for two new drugs, abiraterone acetate (J&J’s Zytiga) and enzalutamide (Astellas/Medivation’s Xtandi), has meant a sharp focus on drugs that target the androgen receptor. But at the the American Society of Clinical Oncology Genitourinary (ASCO GU) symposium, held last month in Orlando, intriguing data on new targets for CRPC emerged. Zytiga and Xtandi target the androgen receptor (AR) in very different ways, but the overall effect is similar, in that they can effectively reduce the levels of prostatic serum antigen (PSA), which is reactivated in tumors with advanced disease. Zytiga acts high up in the steroidogenic pathway and one side effect associated with monotherapy is the development of mineralcorticosteroid effects, leading to over stimulation of the adrenal glands and hypokalaemia.  This toxicity must therefore managed with concomitant prednisone therapy. Xtandi, meanwhile, more directly targets the androgen receptor, which tends to be amplified in advanced prostate cancer. The drug doesn’t have same effect on cortisol production as Zytiga, and can therefore be taken without steroids. The androgen receptor isn’t the only valid target in CRPC, however.  Aldo-keto reductase 1C3 (AK1C3), an enzyme that can facilitate androstenedione conversion to testosterone, is also over-expressed in advanced prostate cancer. Several new agents in early development appear to specifically target AK1C3. At ASCO GU, a couple of abstract particularly caught my eye and are worth highlighting here: 1) Bertrand Tombal et al., presented the initial data on Xtandi monotherapy in advanced prostate cancer in the hormone-naive setting, that is prior to CRPC.  Traditionally, Androgen Deprivation Therapy (ADT) is given to patients with high risk disease.  In the US, LHRH antagonists are used first-line, followed by AR antagonists such as bicalutamide, giving a basis for the rationale testing Xtandi, which is a more complete antagonist of the AR than bicalutamide. In this trial, the single arm design sought to determine whether not enzalutamide would have activity in patients who had not received standard ADT therapy. The waterfall plots in this study (n=67) were impressive. The results showed that: a) Ninety-three percent of study participants experienced a ≥80% PSA decrease at week 25. b) Median change in PSA was -99.6% (range -100% to -86.5%). In other words, most of the men in this trial responded well to Xtandi, suggesting that a randomized trial is well worth pursuing next. You can read more about the specifics of this new development and what Dr Tombal had to say...

Read More

New developments in Advanced Pancreatic Cancer from ASCO GI 2013 – Part 2

The following is a guest post from Sally Church (known to many in the twittersphere as @MaverickNY), from the Pharma Strategy Blog. In my last post on The Haystack, we discussed the phase III data from the Abraxane MPACT trial in advanced pancreatic cancer that was presented at the recent ASCO GI meeting in San Francisco. Two other late-stage studies in pancreatic cancer caught my eye—fresh data for AB Science’s kinase inhibitor masitinib and Sanofi’s multidrug pill S1. Masitinib is an oral tyrosine kinase inhibitor from AB Science that targets KIT, PDGFR, FGFR3 and has shown activity in gastrointestinal stromal tumours (GIST). A different version of the drug (Masivet, Kinavet) is also approved in France and the US for the treatment of a dog mast cell (skin) cancers, which are also known to be KIT-driven. S1 is multidrug pill from Sanofi and Taiho that consists of tegafur (a prodrug of 5FU), gimeracil (5-chloro-2,4 dihydropyridine, CDHP) which inhibits dihydropyrimidine dehydrogenase (DPD) enzyme, and oteracil (potassium oxonate, Oxo), which reduces gastrointestinal toxicity. Previous Japanese studies have demonstrated effectiveness of this agent in gastric and colorectal cancers, so a big unaswered question is whether it is effective in pancreatic cancer. So what was interesting about the latest data at this meeting? At the ASCO GI conference in 2009, French oncologist Emmanuel Mitry presented data from a small Phase II study of the effect of combining masitinib and Eli Lilly’s Gemzar in advanced pancreatic cancer. The study had just 22 patients, but the median overall survival of 7.1 months in was not a large improvement over what is often seen with the standard of care, Gemzar given alone, or with a combination of Gemzar and Genentech’s Tarceva. Over the years, many combination therapies based on Gemzar have failed to show superiority over single agent therapy. It’s both a high unmet medical need and a high barrier to beat.  Thus, the phase III data for the combination of masitnib and Gemzar was highly anticipated at this year’s ASCO GI meeting. Gael Deplanque and colleagues compared masitinib plus Gemzar to Gemzar plus placebo.  Although the overall trial results for median overall survival were slightly higher than in the phase II study, they were not significant (7.7 versus 7.0 months, P=0.74; HR=0.90). Some promising data was observed, however, in a subset of the population identified by a profile of biomarkers that the authors vaguely described as, “a specific deleterious genomic biomarker (GBM) consisting of a limited number of genes.” No other details on the actual genes or biomarkers were was provided, but the subset was described as having an improved MOS to 11.0 months compared to the Gemzar...

Read More

New Developments in Advanced Pancreatic Cancer from ASCO GI 2013 – Part 1

The following is a guest post from Sally Church (known to many in the twittersphere as @MaverickNY), from the Pharma Strategy Blog. The cancer research conference season kicked off in earnest in 2013 with the American Society of Clinical Oncology (ASCO)’s Gastrointestinal Symposium, held in San Francisco in late January. Some of the most anticipated data to be presented at ASCO GI was for drugs that treat pancreatic cancer, with three drugs—Celgene’s Abraxane, AB Science’s masitinib, and Sanofi’s S1, generating the most interest. With this post, we’ll take a closer look at the most advanced of the three agents, Abraxane, which generated encouraging results in a Phase III study. Later this week, we’ll tackle masitinib and S1. Abraxane is a nanoparticle albumin-bound form of the breast cancer drug paclitaxel, and is designed to improve the activity of the active ingredient. Abraxane is already approved in the US for advanced breast and lung cancers, and recently showed signs of activity in metastatic melanoma. At ASCO GI, Daniel Von Hoff, director of the Translational Genomics Research Institute, presented data from a randomized phase III study called MPACT that compared the effects of Lilly’s Gemzar, the current standard of care, to a once weekly combination of Gemzar and Abraxane in patients with metastatic adenocarcinoma of the pancreas. With 861 patients, this was a large global study that sought to determine whether the combination would outdo the regulatory standard of care. A note on the trial design: Although this study uses Gemzar as the standard of care, in practice, many leading oncologists prescribe FOLFIRINOX (fluorouracil, leucovorin, irinotecan and oxaliplatin) for advanced pancreatic patients. But because FOLFIRINOX is generic, and is not formally approved by FDA for advanced pancreatic cancer, Phase III studies tend to match new drug candidates up against Gemzar. As Hedy Kindler, director of gastrointestinal oncology at the University of Chicago, explained, FOLFIRINOX is widely used because the regimen has “the higher response rate, and that has the longer median survival.” However, FOLFIRINOX also has unpleasant side effects, and in private practice settings, oncologists prefer to use less toxic combinations based on Gemzar—namely, Gemzar alone, GemOx (with oxaliplatin), or GemErlotinib (with Tarceva, an EGFR TKI). To provide context, FOLFIRINOX typically has an improved survival of approximately 11 months, while gemcitabine or gemcitabine plus erlotinib elicit a 6-7 month improvement in median overall survival (MOS).  Erlotinib added 12 days of extra survival over gemcitabine alone, but unfortunately we have no way of selecting those advanced pancreatic patients most likely to respond to EGFR therapy. Celgene is exploring the combination of Abraxane and Gemzar based on preclinical work that suggests Abraxane can knock out the...

Read More