Survival Data Still Key for Medarex

The abstracts released Thursday, ahead of the American Society of Clinical Oncologists' annual meeting, contained more data.

"The best objective response rates (BORR) from the three second-line trials (top-line data reported December '07) were essentially in-line with previous disclosures and ranged from 5.8% (study -008, 10mg/kg) to 15.8% (study -007, 10mg/kg + budesonide)," wrote UBS analyst Jeff Elliott. "Although the BORR from study -008 was closer to the low end of previously observed responses, we maintain our view that response rate is not the most important efficacy measure for ipilimumab and that survival data will be key."

Here's why: On April, 25, Medarex and Bristol-Myers Squibb (BMY Quote) announced that after meeting with the FDA, they would delay their submission for ipilumumab (previously expected in mid-2008) because the FDA had requested additional overall survival data to demonstrate the benefit of the drug.

The company disclosed with the filing delay that it's in discussions with U.S. regulators to change the endpoint of this trial from progression free survival to overall survival.

Medarex and partner Bristol-Myers are running a phase III trial in previously untreated patients, looking at ipilimumab plus dacarbazine vs. darcarbazine by itself. Results are expected in 2009. An eventual FDA filing will include survival data from this randomized phase III first-line trial and also phase II second-line studies mentioned above that will be presented at the ASCO meeting later this month.

"Included in the abstracts were a number of analyses of overall survival, which suggested a potential benefit when compared to historical data. The utility of these analyses is limited however, reaffirming the importance of the ongoing first-line, placebo-controlled trial," Wrote UBS' Elliott, who has a buy rating and a $12 price target for the stock.