Thursday, March 31, 2016
Wednesday, March 2, 2016
Coincidentally, a few days before the conference, Ocrelizumab received “fast-track status” by the FDA (click here). The “Fast-Track” designation is given to drugs which promise to fill a prior unmet need, and generally shortens the approval process from 10 to 6 months. Since PPMS has no approved treatments, Ocrelizumab fits the requirements for the designation. Though fast-track designation means that Ocrelizumab will have an expedited approval process, it does not guarantee that the drug will ultimately be approved.
The anticipation over Ocrelizumab, which was developed by Roche Pharmaceuticals subsidiary Genentech, stems from the fact that trial results appear to demonstrate the drug to be effective in slowing down progression of disability in PPMS patients. In results presented at ACTRIMS, Ocrelizumab showed itself to be very potent in treating RRMS (click here), and in PPMS the drug slowed down disability progression by 24% (click here), making it the first major pharmaceutical product to demonstrate effectiveness in treating Primary Progressive Multiple Sclerosis in a scientifically rigorous placebo-controlled trial.
The data set presented at ACTRIMS confirmed info originally released last year, but the numbers revealed at the recent conference provided more details on the patient population included in the study (click here). Specifically, results were provided for two different subsets of patients – those with enhancing lesions (which signify acute immune activity within the central nervous system) and those without enhancing lesions. Only about 15% of patients with PPMS display enhancing lesions on their MRIs, and it was widely assumed that Ocrelizumab would likely only be effective in treating those patients. The results provided by Genentech at ACTRIMS , however, demonstrated that the drug appears to be just as effective in patients whose MRIs did not show any signs of enhancing lesions.
Great news, right? Well, if the numbers hold up it is great news, but there are certain aspects of the Ocrelizumab PPMS trials that raise some red flags. Ocrelizumab is a close cousin of the decades old drug Rituxan, which is also manufactured by Genentech. Both drugs work in almost the exact same fashion, by targeting and destroying immune system B cells, effectively ridding the body of the cells for periods of at least six or seven months. Ocrelizumab, like Rituxan, is administered approximately every six months, in two intravenous doses given one or two weeks apart.
Rituxan was originally intended for use against blood cancers, but was later found to be effective in treating a variety of autoimmune diseases, including Lupus, Rheumatoid Arthritis, and Relapsing Remitting Multiple Sclerosis. The human immune system consists of a wide variety of cells, but is primarily made up of B cells and T cells. Therefore, Ocrelizumab and Rituxan both eliminate a major component of the very complex immune system, which, it’s assumed, is why they are effective in treating so-called autoimmune diseases. Though Rituxan was never officially approved for use in MS, many MS neurologists prescribe the drug “off label” for their RRMS patients, in whom it has proven to be very effective in reducing relapses and the occurrence of MS lesions.
Back in 2008, trials of Rituxan on PPMS patients were deemed a failure, much to the intense disappointment of many patients, myself included. Subsequent analysis of the data generated by that failed trial, however, revealed that a subset of patients did seem to have a somewhat positive response to Rituxan – namely younger patients who displayed enhancing lesions, had been more recently diagnosed, and were less disabled than other trial participants (click here). Instead of pursuing more targeted trials with Rituxan, though, the drug’s manufacturer, Genentech, decided to develop a newer version of the compound, and thus Ocrelizumab was born.
Why invent a new version of an older, proven drug that uses the exact same mechanism of action as that older drug? Well, Genentech says it was done to develop a safer, more effective product, but a cynical person might point out that Rituxan had already proven itself to be relatively safe and quite effective but was due to come off patent in 2015, meaning that its window for generating tremendous profits was rapidly closing. By the time new trials were completed, Rituxan would no longer have patent protection. A new version of the drug, on the other hand, could be a golden egg laying goose. But, of course, only a very cynical person would point that out, not someone is bright eyed and bushy tailed as me.
Anyway, back to the current Ocrelizumab PPMS trials. Based on the lessons learned from the failed Rituxan trials, it looks like Genentech populated the Ocrelizumab PPMS trials with patients who were selected specifically because they were more likely to respond to treatment (click here). Whereas only about 15% of PPMS patients display enhancing lesions on their MRIs, the Ocrelizumab trial included about 27% of such patients. When compared to the trial’s placebo group, the patients that received the actual drug had twice as many enhancing lesions, meaning their disease was much more immunologically active. In addition, compared to other PPMS trials (all failed), patients in the Ocrelizumab trial were generally more recently diagnosed, and were much less likely to have been on any prior disease modifying medications (in the parlance of the medical research community, most of the patients were “treatment naïve”).
Still, when the numbers were broken down at ACTRIMS, they showed that the drug decreased the rate of disability progression by about 24% in both patients with enhancing lesions and without enhancing lesions. However, each subset of patients was too small to make these results statistically significant, meaning that the trial was, in the parlance of the medical research community, “underpowered”. Knowing that this was sure to be a very important issue, why would Genentech go ahead with a trial that was underpowered in this regard? Wouldn’t logic dictate that they design the trial to settle this vital issue in a statistically definitive manner? Seems kind of strange, no?
What may ultimately turn out to be the most troubling aspect of the Ocrelizumab PPMS trial, however, is that 11 cancers were detected in patients taking Ocrelizumab, versus only two in the placebo group. Eight of the cancers in the Ocrelizumab patients were breast cancers, versus zero in the placebo group. This is especially concerning because back in 2010, when Ocrelizumab was first developed, trials were started not only in MS but also on lupus and rheumatoid arthritis patients. Both the lupus and rheumatoid arthritis trials were halted because of patient deaths (due mostly to opportunistic infections), but the MS trials were allowed to continue because it was thought that MS patients would have a higher tolerance for risk (click here). Interestingly, in the Ocrelizumab RRMS trials, which actually included more patients than the PPMS trials, “only” four cancers were detected in the drug group, versus two in the placebo group.
Incidentally, in its over two decades of service, Rituxan has not been associated with the development of cancers or an alarming number of opportunistic infections, although rare instances of PML (the brain infection that is so concerning in patients taking Tysabri) have been seen in patients taking the drug.
If anything derails an FDA approval for Ocrelizumab in treating PPMS it may very well turn out to be the cancer issue. Even though the positive effect on PPMS generated by Ocrelizumab isn’t overwhelming (a 24% decrease in progression rates is nothing to sneeze at, but then again it’s hardly the dramatic effect PPMS patients are desperately seeking), on its own it would seem encouraging enough to garner an approval. However, given some of the questions regarding trial design and safety issues, it will be very interesting to see what the FDA decides. Another one time promising MS drug, Cladribine, was rejected by the FDA primarily because of cancers detected during drug trials (click here).
For some expert opinions on Ocrelizumab, here are two videos. The first is a video of Ottawa MS neurologist Dr. Mark Freedman discussing progressive MS in general, and then commenting specifically on the Ocrelizumab PPMS trial results. For those of you with short attention spans, he starts talking about Ocrelizumab at the 3:50 mark of the video. Dr. Freedman has some very interesting comments regarding the drug and its effectiveness, and B cell therapy in general. The video is well worth watching.
Here’s another MS neurologist, Dr. Clyde Markowitz, Director of the MS Center at the University of Pennsylvania, who seems much more enthusiastic about Ocrelizumab and its prospects for treating PPMS:
Being the always curious person that I am, and also hyperaware that drug companies often funnel money to doctors who prescribe their products, I did some quick checking and found that Dr. Markowitz received $64,461 from various pharmaceutical companies between August 2013 to December 2014, mostly for “consulting” and “honoraria” fees (click here). At least $6000 of this rather large sum came from Genentech, which, it turns out, was the number one drug company in handing out payments to doctors during that period (click here). And this was before the Ocrelizumab trials were completed.
One can only imagine that Genentech is now going all out to, um, “influence” key doctors in its efforts to get the drug approved, much like politicians target key precincts and states in their quest to get elected. I’ve done plenty of ranting on the subject of drug companies making direct payments to the doctors who prescribe their products in previous blog posts, so I’ll refrain from launching into yet another insane tirade here, but suffice it to say I’ve yet to find any logical argument as to why this practice is tolerated, much less legal.
In all fairness, since Dr. Freedman practices in Canada, I was not able to find any info on payments he might’ve taken from drug companies. The truth is that very few MS neurologists are not on the pharmaceutical company dole. I’d encourage you to enter your doctor’s name in the “Dollars for Docs” database (click here), and see if your neuro has his hand in the cookie jar. Again, this doesn’t mean that the doctors named in the database allow pharmaceutical company money to affect their decision making process, but then again, the pharmaceutical companies wouldn’t be doling out millions and millions of dollars if they weren’t getting an appreciable return on investment.
Okay, sorry, I got a little sidetracked there. I certainly hope that all of my concerns about Ocrelizumab turn out to be completely unfounded, as having even a modestly effective treatment readily available for PPMS would be a major step forward in fighting the disease. However, it seems clear (to me, at least) that going after the immune system isn’t going to be the magic bullet that solves the Progressive Multiple Sclerosis problem, or the broader overall Multiple Sclerosis riddle.. Researchers urgently need to step outside the box and start coming at the issue from new angles if any truly dramatic progress is ever going to be made. In the meantime, here’s to hoping that Ocrelizumab proves itself to be a safe and reliable option for Primary Progressive patients, whose desperation for proven treatment options is beyond words.