Lisa H. asks: "What is your outlook for
(THLD - Get Report)
in pancreatic cancer now that
(CELG - Get Report)
has underwhelmed with Abraxane results? I think this is good for Threshold. Do you agree? Appreciate your response."
Celgene left the door open for a competing pancreatic cancer drug or regimen, so that's a plus for Threshold. Were the Abraxane data underwhelming? I don't think that's necessarily true.
As reported Tuesday, Abraxane plus gemcitabine yielded a
median overall survival of 8.5 months compared to 6.7 months for gemcitabine alone
-- a 1.8-month or 8-week survival benefit that was highly statistically significant. The result was either in line or on the low end of expectations, depending on whom you talk to.
Median overall survival is easy to understand, but it's not the best way to measure a cancer drug's overall efficacy. Median means middle, so with median overall survival, you're getting a snapshot from a small slice of patients enrolled in the study.
Better to look at the study's hazard ratio, which compares the benefit of an experimental drug to its control over the entire trial. A hazard ratio of 1 in a survival trial means no benefit for a drug over its control. Overall survival is the same. What you're looking for is a hazard ratio less than 1, with a smaller hazard ratio equating to a larger survival benefit.
The overall survival hazard ratio in Celgene's Abraxane pancreatic cancer trial is 0.72. There's nothing underwhelming about that result. [Interpreted another way, you can say Abraxane reduced the risk of death by 28% compared to control.]
The Abraxane hazard ratio for overall survival is not as strong as the 0.57 hazard ratio observed in the FOLFIRINOX study. [At the median, FOLFIRINOX boosted overall survival by four months over gemcitabine.] However, FOLFIRINOX -- a cocktail of four chemotherapy drugs -- is much more toxic and harder for pancreatic patients to tolerate.
Getting back to Threshold. Recall, in the phase II study reported last year, the high dose of TH-302 plus gemcitabine yielded a median overall survival of 9.2 months compared to 6.9 months for gemcitabine alone -- a difference of 2.3 months. Looks good relative to Abraxane.
But the overall survival hazard ratio for TH-302 was just 0.95 -- not robust at all.