The FDA granted Breakthrough Therapy status to Genzyme’s experimental enzyme-replacement therapy olipudase alfa, based on a Phase-1b study of five adults.

The pipeline therapy is being developed to treat Niemann-Pick disease Type B, which has non-neurological symptoms, unlike Niemann-Pick disease Type A. The condition is found in around 1 of every 250,000 people, according to the National Institutes of Health.

Both the A and B forms of the disease—there are four types of Niemann-Pick disease—are referred to as acid sphingomyelinase deficiency. Patients cannot sufficiently break down sphingomyelin, resulting in toxic levels of the lipid.

Drugs that are granted Breakthrough Therapy status by the FDA undergo an expedited review process that includes regular contact with the FDA prior to review. Breakthrough Therapy drugs that received FDA approval include Pfizer’s cancer medication Ibrance and Bristol-Myers Squibb’s cancer drug Opdivo.