Isis falls on mipomersen briefing docs

Isis Pharmaceuticals Inc. (NASDAQ:ISIS) fell $2.88 (22%) to $10.27 on Tuesday after FDA reviewers raised several safety concerns in briefing documents for mipomersen to treat homozygous familial hypercholesterolemia (hoFH), including a higher rate of neoplasms compared to placebo (3.1% vs. 0.9%). Reviewers said the imbalance will need to be assessed further, noting that there are "several confounding factors that make it difficult to conclude that mipomersen is playing a dominant role in this cancer imbalance."

Reviewers also expressed concerns about malignant tumors seen in mice receiving mipomersen, and increases in liver-related adverse events seen in all four Phase III trials of mipomersen. The documents were released ahead of Thursday's Endocrinologic and Metabolic Drugs Advisory Committee to discuss an NDA for mipomersen. The application has a Jan. 29, 2013, PDUFA date. ...