Alnylam Pharmaceuticals Inc. said the U.S. Food and Drug Administration accepted for priority review the new drug application for its liver disease therapy.

Under the priority review, the FDA will evaluate givosiran in six months, compared to a standard review at 10 months. The U.S. regulator expects to decide on the application by Feb. 4, 2020. The FDA also said it is not planning an advisory committee meeting as part of givosiran's review.

The Cambridge, Mass.-based drugmaker is developing givosiran to treat acute hepatic porphyria, or AHP ⁠— a rare genetic disease of the liver that causes abdominal pain, weakness, nausea and fatigue.

Patients with AHP have an enzyme deficiency that results in debilitating and life-threatening attacks. There is no approved therapy to prevent attacks or to address the disorder's long-term effects.

Givosiran reduced the rate of attacks in patients with AHP and met the primary goal of the phase 3 trial called Envision. However, almost 90% of the 94 enrolled patients in the study reported adverse events.

The European Medicines Agency has also validated Alnylam's marketing application for givosiran. The European regulator will conduct an accelerated assessment of the therapy, which will reduce the review timeline from 210 to 150 days.

Givosiran holds the FDA's breakthrough therapy and orphan drug designations. Additionally, the EMA has granted Alnylam's liver treatment orphan drug status and priority medicines designation.

Alnylam specializes in RNA interference, or RNAi, therapeutics like givosiran that silence disease-causing genes. The drugmaker's pioneer product is Onpattro, the first RNAi drug to be approved by the FDA.