Investors Sink Tesaro Shares on Phase 3 Misses For Cancer Drug

12/23/13Follow @benthefidler

Waltham, MA-based Tesaro (NASDAQ: TSRO) is trumpeting some late-stage success for its lead cancer drug, rolapitant, but investors clearly aren’t buying the results.

Tesaro this morning released the top-line data from two Phase III trials for rolapitant, a drug it’s developing for chemotherapy-induced nausea and vomiting (CINV). The company emphasized that rolapitant hit the primary goal of each of those studies in that patients taking Tesaro’s drug in each of the two trials didn’t vomit or need rescue medication in the “delayed” phase, or between 24 and 120 hours after starting chemotherapy. But Tesaro also revealed that rolapitant whiffed on its secondary goals in both studies. Tesaro’s drug didn’t produce a statistically significant improvement between patients in different phases of chemotherapy: acute (beginning minutes to hours after starting, and lasting up to 24 hours,) and overall.

Tesaro said that data were good enough to begin putting together a new drug application to submit to the FDA in the middle of 2014. Investors, though, thought otherwise. Tesaro’s shares had plummeted by more than 23 percent as of 11:45 a.m. Eastern time on Monday.

Tesaro enrolled 1,369 patients undergoing “moderately” emetogenic chemotherapy—or, moderately likely to make them sick—in the first study. Patients were broken into two like-sized groups and randomly assigned either a combination of chemo-induced nausea treatment granisetron (Kytril) and dexamethasone, or that regimen plus rolapitant. Tesaro used the same design in the second study, only it enrolled 555 people on chemotherapy that is “highly” likely to make them sick.

Tesaro didn’t give much insight into the results. It said that rolapitant met its primary goals, but it didn’t give any numbers to support that assessment. And while the company said that a “greater proportion” of patients on its drug didn’t get sick than those taking the competing regimen in the acute and overall phases of chemotherapy, those numbers weren’t good enough to meet its predetermined goals. It’s currently running a third Phase III study of the drug, and plans to release the full details of the three studies at a future medical meeting.

If ultimately approved, Tesaro’s drug would compete with a number of drugs, including Merck’s aprepitant (Emend) that are approved to treat chemo-induced nausea. Many current treatments are generic. But Tesaro said that it still expects to be able to carve out a market for rolapitant.

“Despite the availability of preventative therapies and established treatment guidelines for CINV, a significant number of cancer patients still suffer from the debilitating side effects of delayed nausea and vomiting,” said Tesaro president Mary Lynne Hedley, in a statement. “We are enthusiastic about the potential for this product candidate, with a profile that may include an extended half life, convenient, single-dose oral and intravenous formulations, and a lack of CYP3A4-mediated drug interactions.”

Tesaro acquired rolapitant from Opko Health in 2010.

Ben Fidler is Xconomy's Deputy Biotechnology Editor. You can e-mail him at bfidler@xconomy.com Follow @benthefidler

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