With New Data, Alnylam Could Seek Speedy OK For Second RNAi Drug

Xconomy Boston — 

Alnylam Pharmaceuticals was just cleared to market the first-ever RNA interference medicine. The second one may not be that far behind.

Alnylam (NASDAQ: ALNY), of Cambridge, MA, said this morning that it could soon file for accelerated approval of an RNAi drug, givosiran, that the company is developing for acute hepatic porphyria, a rare genetic disease that causes potentially deadly bouts of abdominal pain.

The company isn’t providing details, but said that in the interim look at a 43-patient, Phase 3 study, givosiran led to a statistically significant reduction of aminolevulinic acid, or ALA, in patients’ urine—a marker of the disease—after three months of treatment.

The FDA has already said that dropping patients’ ALA levels should predict whether a drug for acute hepatic porphyria will work. As such, Alnylam plans to discuss the data with the FDA and, depending on the outcome of the talks, file an application by the end of the year seeking accelerated approval.

Such approval decisions are made when a drug is likely to produce a meaningful clinical benefit, based on its impact on a surrogate marker. The primary goal of Alnylam’s trial isn’t to drop ALA—it’s to show whether givosiran can reduce the rate of the disease’s hallmark attacks after six months of treatment, compared to a placebo.

Alnylam didn’t disclose the magnitude of givosiran’s benefit on ALA. It did offer a glimpse at the drug’s safety profile, however. As of Aug. 22, the cut-off date for the data, five of 23 patients on givosiran suffered unspecified serious side effects; one patient stopped treatment due to a dangerous spike in liver enzymes, an indication of possible liver damage. By comparison, two of 20 placebo patients had serious side effects and no one stopped treatment.

While the side effects disclosed do raise questions, Stifel analyst Paul Matteis wrote, the data “do not suggest that there’d ultimately be a regulatory/commercial risk with the drug” assuming the benefits are similar to what givosiran showed in earlier testing.

Alnylam has already completed enrolling all 94 patients in the study, and plans to release the full results early next year.

The news comes just two months after Alnylam—after 16 years of scientific work—was cleared to sell its first product. It made history when the FDA approved patisiran (Onpattro), a drug for patients with an inherited form of the rare disease transthyretin amyloidosis. Patisiran was the first-ever approval for a medicine that uses RNAi, a method cells can use to silence a gene before it makes a harmful protein.

Alnylam shares ticked up 4 percent in pre-market trading on Thursday.