Threshold shares slammed after lead cancer drug trips on survival goal

South San Francisco-based Threshold Pharmaceuticals ($THLD) sounded a sour note today in an important post script to its Phase IIb pancreatic cancer study for the closely-watched TH-302 program. Investigators noted that the drug failed to hit a key secondary endpoint on overall survival, but added that they're taking what they've learned in the mid-stage study to heart as they design a pivotal Phase III program for the lead drug.

The biotech's stock, which has soared 500% this year, skidded down 25% on the news. Merck KGaA partnered on the program back in February, agreeing to pay $60 million in near-term cash in a $525 million licensing pact. 

Threshold shares have rocketed up over the past year as TH-302 produced a string of upbeat events for the biotech. The drug hit its primary goal on progression-free survival--5.6 months in the drug/chemo arm compared to 3.6 months in the chemo-only control group. But the OS average for the combo hit only 9.2 months for the combo compared to 6.9 months, with a 4.5% drop in the risk of death. That was not statistically significant.

Threshold added that the trial wasn't designed to deliver solid OS results. Patients in the chemo-only arm were given their drug as well after investigators determined that their tumors had progressed. And that skewed the OS data, boosting survival results for the combo.

"We are pleased with the overall consistency of results from this study demonstrating activity of TH-302 and, as a consequence, a randomized Phase III trial of TH-302 in patients with advanced first-line pancreatic cancer is planned to be initiated together with our partner Merck KGaA," said Threshold CEO Barry Selick.  

- here's the press release

Related conversation on  Twitter :