Threshold's Pancreatic Cancer Drug May be Obsolete Before Launch

NEW YORK (TheStreet) --Threshold Pharmaceuticals (THLD) reported positive pancreatic cancer survival data this weekend from a Phase IIb study of TH-302, a prodrug that releases chemotherapy under hypoxic (low oxygen) conditions, at the European Society for Medical Oncology (ESMO) conference. Unfortunately, the TH-302 results show lots of variability and the comparison arm in the study may soon be outdated, making the drug's prospects difficult to interpret.

Given Threshold's $399 million market capitalization, estimated $60 million in cash, and the long wait for definitive phase III data in pancreatic cancer, I'm not sure there's much to do with the stock at current levels. [Threshold closed Friday at $7.24.]

I don't have a strong view about Threshold but I lean negative, especially because the company will likely need to raise additional capital.

Threshold's phase IIb study enrolled 214 pancreatic cancer patients randomized to receive TH-302 (at doses of 240 mg or 340 mg) plus gemcitabine or gemcitabine plus a placebo. (Eli Lilly (LLY) sold a branded version of gemcitabine under the Gemzar label until the chemotherapy drug went generic in 2010).

Earlier this year, Threshold reported progression-free survival (PFS) in the TH-302 high dose arm reached 6.0 months, slightly outperforming the low dose and significantly exceeding the PFE of 3.6 months observed for the control group. Response rates supported the PFS benefit. At the higher dose, TH-302 recipients had a 26% overall response rate (ORR), including two complete responses, compared to a 17% and 10% ORR for the low-dose and control arms, respectively.

At ESMO this weekend, we learned that patients in the TH-302 high and low dose groups had a median overall survival of 9.2 months and 8.7 months, respectively, versus 6.9 months for gemcitabine alone. Although the hazard ratio (HR) -- a measure of relative risk between drug and control -- barely shows a benefit (HR = 0.96 for both arms), investigators noted that post-progression crossover muddled the results. The adjusted survival data were excluded from the ESMO slides, but post hoc analysis shows a modestly greater survival benefit for TH-302 recipients once crossover patients are excluded (HR = 0.77 and 0.76 for the high and low dose groups, respectively).

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