Medarex shares dented on analysts' skepticism

Investors dented the value of Medarex shares after analysts doused its recent claims concerning its late-stage cancer drug ipilimumab with cold water. BMO Capital Market's Jason Zhang says that Medarex doesn't have the data to back up claims that a combination of ipilimumab and dacarbazine work better than ipilimumab alone. Its shares slipped seven percent on the news.

"There is no randomized data with a chemotherapy control supporting ipilimumab's survival-prolonging abilities," said Zhang in a note. Mid-stage study data demonstrated median overall survival of 449 days on the combo therapy compared to 351 days with ipilimumab alone. That was not a statistically significant difference in survival.

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