Merrimack's Onivyde approved in USA for pancreatic cancer but shares slide on box warning

The US Food and Drug Administration has approved Onivyde (irinotecan liposome injection) from Merrimack (Nasdaq: MACK), in combination with fluorouracil and leucovorin in advanced pancreatic adenocarcinoma previously treated with gemcitabine-based chemotherapy.

The company said the FDA’s decision makes Onivyde “the first and only FDA-approved treatment option for patients in this setting.” The drug’s label, however, carries a box warning from the FDA about the risks of severe neutropenia and diarrhea, a caveat which has sent Merrimack shares plummeting as much as 28%. The FDA noted that Onivyde resulted in lymphopenia and neutropenia, with some Onivyde-treated patients dying from sepsis following neutropaenia.

Baxalta is responsible for the development and commercialization of Onivyde outside the USA and Taiwan under the terms of a 2014 agreement valued around $970 million.