) -- New details about failed lung cancer immunotherapy from
were revealed for the first time Wednesday night in a research abstract for the American Society of Clinical Oncology (ASCO) annual meeting.
Stimuvax reduced the risk of death by 12 percent compared to a placebo -- a difference that failed to reach statistical significance by a wide margin, according to detailed results from the phase III study contained in the ASCO abstract.
Oncothyreon and partner
announced last December that the
Stimuvax lung cancer study failed to meet its overall survival primary endpoint
, but specific data were not disclosed at that time.
The study enrolled 1,513 patients with Stage III non-small cell lung cancer who did not progress after initial treatment with chemotherapy and radiation. The patients were randomized to receive injections of Stimuvax or a placebo.
Oncothyreon and Merck designed the study with the assumption that placebo-treated patients would live approximately 20 months and that Stimuvax would prolong survival by approximately 6 months, or a 33% relative reduction in the risk of death.
In reality, the median overall survival for the placebo-treated patients was 22.3 months compared to 25.6 months for Stimuvax patients. A three-plus month difference in median overall survival favoring Stimuvax seems like a long time but the cancer vaccine's effect on overall survival was far smaller, which is why the study failed.
And then there was
made by Oncothyreon and Merck last December:
"Despite not meeting the primary endpoint, notable treatment effects were seen for [Stimuvax] in certain subgroups."
That pre-defined subgroup was the 65% of lung cancer patients who entered the trial following concurrent chemo-radiation treatment (as opposed to the 35% of patients treated with subsequent chemo-radiation.)
In the concurrent chemo-radiation subgroup, treatment with Stimuvax led to a 22 percent reduction in the risk of death compared to placebo. The risk of death was actually increased by 12% for Stimuvax patients treated previously with subsequent chemo-radiation.
The abstract released Wednesday night does not include an explanation for why Stimuvax might be more effective following concurrent chemo-radiation therapy.
-- Reported by Adam Feuerstein in Boston.