Glioblastoma multiforme is an extremely aggressive and deadly form of brain cancer that has proven to be stubbornly resistant to nearly all forms of treatment. Perhaps the worst part is that median survival for this type of cancer hovers around a paltry 12 months from the time of diagnosis.
Patients with a certain form of the disease, known as EGFRvIII-positive, have three-year survival rates as low as 5% when taking standard forms of chemotherapy such as Merck's Temodar. Of newly diagnosed cases of gliobastoma multiforme, about 44% turn out to be EGFRvIII-positive. That translates into roughly 4,000 patients in the U.S. alone.
This experimental vaccine may be a game-changer
Celldex Therapeutics (NASDAQ:CLDX) is developing a vaccine, Rintega, designed to elicit a powerful immune response against EGFRvIII-positive brain tumors. At the 2015 American Society of Clinical Oncology meeting, the company provided a clinical update on the vaccine's midstage trial, ReACT, as a treatment for patients that have relapsed, and the results were quite impressive.
When used in conjunction with Roche's Avastin -- which is known to have a minor clinical benefit in terms of progression-free survival in this indication -- Rintega was able to essentially double overall survival (30% vs. 15%) at the six-month mark, per the intent-to-treat analysis, compared to patients on Avastin alone.
Not only did the combo of Avastin plus Rintega extend overall survival, it also led to a notable reduction in steroid use among patients, and it appears to confer a long-term survival benefit in a handful of individuals.
Based on these encouraging results, Celldex plans on sitting down with the FDA soon to discuss a possible accelerated regulatory filing. And if the FDA does agree to accept such a filing, this event would be a major catalyst for Celldex shares, given that the vaccine's peak sales for recurrent patients stands at $400 million.
The FDA might indeed agree to accelerated regulatory review because...
Patients with this particular mutation that have relapsed after standard chemotherapy have extremely poor odds of living even three months longer in absolute terms, much less six. So there is a clear unmet medical need Rintega could fill.
Next up, the FDA previously granted Rintega breakthrough designation for this patient population, meaning the agency recognizes the serious need for new therapeutic options for this life-threatening condition. And last but not least, this vaccine has now completed multiple midstage trials -- and is in the midst of large late-stage trial -- without raising an alarm bell on the safety front.
Rintega thus appears to have a favorable risk-to-reward ratio for a patient population with basically no remaining medical options. Put simply, it appears to be safe in general, and effective, at least in some patients.
Given that Rintega has breakthrough designation, Celldex should be able to schedule a meeting with the FDA within the next few weeks, or perhaps even days. A no-go decision by the agency probably won't affect the stock much because the Street wasn't expecting an accelerated filing in the first place. But a green light from the FDA should drive shares much higher because of the vaccine's potential as a major revenue source for years to come.
After all, the FDA rarely rejects cancer drugs being reviewed on an accelerated basis. AstraZeneca's ovarian cancer drug Lynparza, for instance, got creamed in its Advisory Committee meeting ahead of an accelerated review (11 to 2 voted against approval), only to get approved a couple of months later, over the objections of this expert panel.
So, the FDA's decision to accept or deny an early regulatory filing for Rintega is a key event that shareholders should be on the lookout for moving forward.