Friday, May 11, 2007

Provenge, the Pazdur effect, and looking for a silver lining

Dendreon’s "approvable" letter for its cutting-edge prostate cancer vaccine Provenge this week asks for—among other things like further manufacturing specs—more clinical data, a request that sliced over 60% from the biotech’s market cap. (For more on Provenge’s rollercoaster background, see here and here.)

But why were Dendreon shares priced so high to begin with? An FDA advisory committee shocker in March, where FDA’s advisors voted 13-4 in favor of approving the vaccine. Indeed Provenge’s prospects for a positive ruling from the FDA panel looked slim going into that meeting: two Phase III studies supporting the application missed the primary endpoint target of time to progression as well as failing to meet secondary endpoints of clinical and pain progression and treatment failure.

And that’s not a good thing when you’re trying to prove you’ve got an effective product.

What won over the committee? Two things: First, an analysis of data from a subset of patients in one of the Phase III trials demonstrated a statistically significant increase in time to progression. Second, and perhaps as importantly, the review of the therapeutic vaccine falls under the purview of the agency’s Center for Biologic Evaluation & Research—not the Center for Drug Evaluation & Research’s Office of Oncology.

Provenge therefore avoided CDER’s Oncology Drugs Advisory Committee, which is now considered to be a stricter committee to go through because of the tone set by oncology director Richard Pazdur, MD.

One scenario that did not bode well for Provenge is the involvement of Pazdur himself in the review. When cancer drug reviews were organized under a newly created Office of Oncology in 2004, biologics and chemo-preventative drugs fell under the CDER office, while vaccines remained under the CBER umbrella. But Pazdur still has a hand in cancer vaccine reviews; for example, he consulted on the approval of Merck’s human papillomavirus vaccine Gardasil and has helped evaluate GSK’s competing HPV vaccine Cervarix.

Whether Pazdur is personally involved or not, FDA officials often say that they pay just as much attention to minority opinions as those in the majority when it comes to advisory committees. And the minority "no" opinions for Provenge were particularly unwavering.

It’s tough to say where Dendreon goes from here. Recovery from an FDA rejection can be agonizingly slow (see, for example, Xoma). Dendreon can at the very least hang its hat on the positive panel review as evidence of advocacy by a key body in the regulatory process. And the market potential for cancer vaccines—analysts expect it could grow to $6 billon by 2010--could dull the market effect of a negative FDA decision as investors hold firm with an eye toward the long-term possibilities.

Sanofi-Aventis’ recent acquisition of OxfordBiomedica’s renal cancer vaccine Trovax for approximately $700 million is hard evidence of interest in the field. That sustained interest could be Dendreon’s saving grace.

1 comment:

Anonymous said...

The Unavailability of Provenge and the Disappointment of Those With Deadly Prostate Cancer

*FDA’s mission statement: To promote and protect public health

Terminal patients are those who are not expected to live due to usually illness such as advanced prostate cancer (cT3). If the patient has 6 months or less to live, those patients are considered terminally ill. Regardless, if a patient is terminal, they are without a cure or tolerable treatment for their illness presently. Since such patients will likely die in a short period of time, treatment options, even if they are not entirely unproven, are often desired by such patients. This is understandable, because at such a severe stage of illness, such as prostate cancer, possible extension of their lives with comfort is worth it to them, regardless of lack of evidence of proof of whatever treatment that may be advantageous to them regarding these issues. The FDA, however, claims authority on the treatment options of such patients, although that administration has proven itself over the years to be rather inadequate with its frequent drug recalls and black box warnings, and they do these things only under pressure from the public, usually. Reform has to start somewhere at some time.
Prostate cancer is a rather frequent occurrence- with between 10 to 20 percent of men predicted to acquire the disease during their lifespan, resulting in about 30,000 deaths a year from this disease of the one million men. Furthermore, out of all cancer types more are dying from prostate cancer now than other cancer diagnoses.
For those unaware, there are different stages of prostate cancer, and the more severe the prostate cancer cases are which is determined by such methods as bone scans and Gleason’s scores, which is a score that assesses prostate tissue after it is biopsied and if it is determined that the stage of cancer is severe by this and to estimate proper treatment options if proven to be malignant. Typically, the initial suspicion of prostate cancer is determined by the results of what is called a PSA blood test, as PSA is a protein produced by prostate cancer cells. If the PSA blood test is above normal limits, a prostate biopsy is performed to determine and confirm not only the presence of cancer, but also the severity of the disease on such a patient.
Yet fortunately, and as you will read, innovation still exists in medicine. A few years ago, a small Biotechnology company called Dendreon was working on a conceptually new treatment for the worst prostate cancer patients, and this treatment therapy created by Dendreon was named Provenge. Provenge is the first immunotherapy biologic treatment for the progressed prostate cancer patients, and has proven to be a very novel and innovative treatment option for advanced prostate cancer patients who are terminally ill. Usually, these patients are unresponsive to usual treatment methods for prostate cancer, and are left with chemotherapy as their only treatment option at such a traumatic stage of prostate cancer. Understandably, most patients at this stage refuse treatment entirely, largely due to the brutal side effects of such chemotherapy treatments as taxotere. The immunotherapy method developed by Dendreon required the removal of white blood cells of the diseased patient and, after altered, are re-injected into this patient now designed to attack what is called PAP, which is on prostate cancer cells only. This treatment required only three such injections in a period of six weeks. This resulted in life extension twice that of chemotherapy treated prostate cancer patients of this severity, and without the concerning side effects of chemotherapy. The medical community and survivors of prostate cancer were elated and waited with great anticipation for access to this treatment method.
Fortunately, as the years passed, Provenge, by 2007, had convinced others of its safety and efficacy in its benefit for severe prostate cancer patients. This caused great joy to such patients and their families. Perhaps greater elation was experienced by the caregivers and specialists of such a disease, such as Urologists and Oncologists who treat such patients. While Provenge was on fast track status at this time at the FDA, the FDA panel thankfully recommended with clarity the approval of Provenge based on its proven and substantial efficacy and safety demonstrated in its performance in past trials. The FDA announced this to the public in the early Spring of 2007, I believe.
Now for the bad news: With great shock and surprise, the FDA agency rejected the approval of this great treatment for very sick patients due to, they said, ‘lack of data’ in May of 2007. This contradicts their favorable opinion of Provenge weeks before delivering this terrible news. Especially when one considers the FDA Commissioner is a prostate cancer survival himself!
Soon after this judgment was passed by the FDA, conflicts of interest were discovered by others. For example, a member of the FDA agency who was evaluating Provenge, Dr. Scher, was found to have a financial commitment to a future competitor of Provenge that was being produced by a company called Novacea, and this company had signed a co-promotion agreement with Schering with this similar prostate cancer drug being developed by this company. Dr. Scher never disclosed this conflict during the approval process of Provenge. As it turns out, this anticipated prostate cancer drug made by Novacea was discovered to have serious flaws, and Schering pulled out of the agreement with Novacea. In addition to this incident and before May of 2007, baseless letters were anonymously delivered to the FDA stating negative qualities about Provenge that were without Merit and speculative claims about the treatment. Yet overall, the disapproval by the FDA of Provenge angered many, and a newly formed advocacy group called Care to Live filed a lawsuit against the FDA for their clear lack of protocol or knowledge about such complex treatment agents as Provenge at the end of last year.
Terminal patients, I surmise, desire comfort during their progressive disease that has placed them in the last chapter of their lives, and certainly should have a right to choose any treatment that possibly could benefit them. At this stage of such a patient, one could argue, safety of any treatment option is not of concern to these patients, because they are going to die anyway. Yet the FDA, with reckless disregard and overt harshness for these very ill patients, ultimately harmed others more by not approving Provenge with deliberate intent.
The FDA does in fact presently have the ability to grant what is called conditional approval for such treatment methods as Provenge, and why they have not expanded this approval process to all terminally ill patients remains completely unknown. What is known is that they are harming those they pledged to protect so long ago by depriving such patients in need of treatment, as no other options are viable presently that are as safe and effective with great tolerability associated with Provenge. So now the FDA appears to be a bought, corrupt, and incompetent administration without loyalty and dedication to the public and its health. This needs to be corrected in any way possible for the lives of others. A terminally ill patient has a personal right to obtain and access such treatments upon their own volition as well as the discretion of their doctor, just as a terminally ill patient is granted an individual right to die, if they choose to do so. It is an individual decision in such cases that should be void of interference from others.
“Politics is the systematic organization of hatreds.” --- Henry Adams
Dan Abshear
Author’s note: What has been written is based upon information and belief