Despite Effectiveness, Accelerated Approval For Acute Hepatic Porphyria Drug in Doubt

According to a story from, the drug development company Alnylam Pharmaceuticals has recently stated that it is looking less likely that its gene silencing therapy givosiran will be getting Accelerated Approval any time soon. Although the drug has been effective in trials as a treatment for acute hepatic porphyria, in a recent communication with the US Food and Drug Administration, the agency suggested that it may need more data before moving forward.

About Porphyria and Acute Hepatic Porphyria

Porphyria is a group of diseases which are most characterized by the accumulation of porphyrins in the body, which can cause harm to the skin and nervous system. These genetic inherited diseases, are either acute or chronic in form and are caused by mutations that cause a deficiency of a certain enzyme that normally processes porphyrins. Acute hepatic porphyria is a specific form in which the deficient enzyme occurs in the liver and in which symptoms appear rapidly and severely. An attack can be triggered by a variety of drugs, alcohol, smoking, stress, fasting, or hormonal changes. Symptoms include severe abdominal pain, convulsions, sensory changes, muscle weakness, hallucinations, anxiety, confusion, and irritability. An acute hepatic porphyria attack is a medical emergency and an infusion of heme arginate should be administered immediately. To learn more about acute hepatic porphyria, click here.

A Bump In The Road

Alnylam was hoping to apply for Accelerated Approval before their clinical trial was completed. However, it seems like there is a good chance that the FDA will ask the company wait until the full data from the trial is released. The trial still has six months to go. It is likely that some of the agency’s hesitation is, unfortunately, related to some of the safety data that has been released so far. In the trial, 22 percent of patients using givosiran experienced serious adverse side effects compared to just 10 percent in the control group.

This does not necessarily disqualify the drug for approval, as givosiran was able to reduce the levels of aminolevulinic acid, a protein that has been linked to increased attacks in patients with acute hepatic porphyria. There are currently no approved drugs specifically for the treatment of acute hepatic porphyria.

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