Two patients died of sepsis in a Phase II trial of Progenics Pharmaceuticals' ($PGNX) in-development prostate cancer treatment, spurring concern that the drug is too toxic to merit further study and sending the biotech's shares down as much as 30%.
In a trial on 70 patients with castration-resistant prostate cancer, Progenics' PSMA ADC charted some antitumor activity, but the two deaths, coupled with some high rates of neutropenia, could signal serious problems with the treatment's safety profile. The antibody-drug conjugate appears to have "little benefit versus the apparent toxicity," Stifel Nicolaus analyst Brian Klein told Bloomberg, adding that PSMA ADC looks too dangerous to warrant a late-stage study.
Investigators revealed the two trial deaths in an abstract posted ahead of ASCO's 2014 Genitourinary Cancers Symposium in San Francisco, sending Progenics' shares as low as $4.31 on Wednesday. The company hasn't commented on the abstract, saying instead that it will host a conference call to discuss the trial following its presentation at the symposium on Thursday night.
The Tarrytown, NY-headquartered company is only about a year removed from shedding 26% of its staff after the FDA rejected a supplemental application for its pain drug Relistor, which led Progenics to miss out on a $40 million milestone payment from partner Salix Pharmaceuticals ($SLXP). In that restructuring, Progenics jettisoned some of its preclinical programs to clear the way for PSMA ADC, its most promising asset, along with Azedra, an orphan radiotherapy candidate also in Phase II.