FDA Approves Kynamro for Homozygous Familial Hypercholesterolemia

The FDA approved Kynamro, a new drug for homozygous familial hypercholesterolemia that relies on antisense RNA.

The FDA approved a new drug yesterday for the treatment of homozygous familial hypercholesterolemia, or HoFH, a condition that causes extremely high cholesterol levels and heart attacks at an early age.

The drug, called Kynamro (mipomersen sodium), was developed by Isis Pharmaceuticals and will be marketed by Sanofi’s Genzyme division. It will serve as a competitor to Aegerion Pharmaceuticals’ Juxtapid (lomitapide), which was approved by the FDA late last year.

Kynamro is particularly significant because, as Forbes’ author Matthew Herper points out, it was developed using antisense RNA. Rather than working on specific proteins like many other pharmaceuticals, Kynamro works by inhibiting the translation of messenger RNA. In the case of Kynamro specifically, the drug works by inhibiting action of apolipoprotein B, a gene that is involved in carrying cholesterol in the blood to tissue.

Although the first antisense drug to gain FDA approval was Vitravene (fomivirsen) to treat cytomegalovirus retinitis in immunocompromised patients in 1998, some other proposed antisense therapies before that time fell flat because the antisense compounds failed to enter the cells they were targeting.

According to an FDA release announcing the approval, “Kynamro carries a Boxed Warning on the serious risk of liver toxicity because it is associated with liver enzyme abnormalities and accumulation of fat in the liver, which could lead to progressive liver disease with chronic use.”

Kynamro, like Juxtapid, has orphan drug status, as the disease it treats affects fewer than 200,000 people. Although no price has been announced for Kynamro, the price may be similar to that of Juxtapid—which was estimated to cost $250,000 a year by thestreet.com