Isis Pharma/Genzyme FDA Panel Live Blog

An FDA advisory panel meets today to review Isis Pharmaceuticals' (ISIS) mipomersen for the treatment of Homozygous familial hypercholesterolemia (HoFH). Genzyme, a unit of the French drug giant Sanofi (SNY), co-developed mipomersen.

Homozygous familial hypercholesterolemia (HoFH) is a rare and life-threatening genetic condition in which a person inherits damaged genes from both parents, rendering the body unable to clear LDL cholesterol -- the "bad" form of cholesterol -- from their bloodstream. HoFH patients, an estimated 3,000 in the U.S., can have LDL cholesterol levels four to ten times higher than normal people and cannot be reduced with conventional lipid-lowering drugs. As a result, these patients have severely clogged arteries that lead to heart attacks in their 20s and death in their 30s from cardiovascular disease.

Mipomersen is a once-weekly injection that inhibits apo-B, a protein that carries forms of cholesterol, including LDL-cholesterol, throughout the bloodstream. Isis and Genzyme, a subsidiary of Sanofi, are developing mipomersen for broader range of high cholesterol-related disease than just HoFH -- heterozygous hypercholesterolemia, severe hypercholesterolemia and patients with high cholesterol at risk for heart disease.

Thursday's panel will only review mipomersen as a treatment for HoFH. In a phase III study, 34 patients treated with mipomersen for 26 weeks saw 25% reduction in LDL cholesterol compared to a 3% reduction in patients treated with a placebo.

Like with Aegerion Pharmaceutical's (AEGR) lomitapide, fatty liver and elevated liver enzyme levels were worrisome side effects recorded in the mipomersen phase III trial. A single patient died due to liver failure. Injection site reactions were also reported by 76% of mipomersen patients.

The FDA has also raised concerns about a higher rate of benign and cancerous tumors founded in mipomersen-treated patients compared to placebo.

-- Reported by Adam Feuerstein in Boston.

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