The FDA has raised safety concerns about tumors spotted in patients treated with the developmental LDL-lowering therapy, Kynamro. The drug is under review after a New Drug Application was accepted by the FDA in May of this year, and will go before the Endocrinologic and Metabolic Drugs Advisory Committee on Thursday. Kynamro is being developed by Isis Pharmaceuticals (NASDAQ:ISIS) and is partnered with Sanofi’s (NYSE:SNY) subsidiary Genzyme. On Tuesday morning, shares of Isis gapped down 15% on fears that the advisory committee will either delay Kynamro’s commercialization through further trials, request a limiting Risk Evaluation and Mitigation Strategy, or vote to deny the approval. The injectable drug, known as mipomersen chemically, was filed as a treatment for homozygous familial hypercholesterolemia (HoFH), a genetic disorder for which patients already taking standard lipid lowering therapies are unable to maintain low enough LDL-C levels.
The FDA’s report, released ahead of a Thursday advisory panel meeting, raised concerns about an imbalance in neoplasms (tumors), stating, “The incidence of reported neoplasms (benign and malignant) was 3.1% (23/749) in mipomersen treated patients versus 0.9% (2/221) in placebo-treated patients.” The reviewer ends by commenting, “There are several confounding factors that make it difficult to conclude that mipomersen is playing a dominant role in this cancer imbalance.” There was no consistency, for instance, in the location of the tumors. What that means for Kynamro’s approval is not entirely clear, but the neoplasm imbalance is news to shareholders, hence today’s weakness. Already Piper Jaffray lowered their ISIS target price from $18 to $10 and downgraded the company to neutral. Thursday’s advisory panel will also be considering Kynamro’s effects on the liver, an acknowledged problem, and will weigh the potential for a risk-mitigation plan to accompany the drug’s approval. As Isis’ most advanced candidate, the loss of Kynamro – a negative vote and negative approval outlook – will have a major effect on the stock, regardless of the company’s extensive pipeline. Kynamro is already being partly discounted from ISIS’ valuation today, but the shares still have room to fall on any concrete news.