Pfizer Inc. (NYSE:PFE) said tafamidis meglumine met the primary endpoint in the Phase III ATTR-ACT trial to treat transthyretin (TTR) cardiomyopathy. Compared with placebo, the therapy reduced a combination of all-cause mortality and frequency of cardiovascular-related hospitalizations at 30 months.
Tafamidis is a small molecule that stabilizes the TTR protein and prevents its misfolding.
Alnylam Pharmaceuticals Inc. (NASDAQ:ALNY) and Ionis Pharmaceuticals Inc. (NASDAQ:IONS), both of which have compounds targeting TTR under regulatory review, each lost value Thursday after Pfizer reported the news during market hours. Alnylam dipped $10.77 to $119.10 and Ionis lost $1.85 to $44.08. U.S. markets were closed on Friday.
Pfizer said it plans to discuss the data with regulators to determine a path forward.
ATTR-ACT enrolled 441 patients and included patients with both types of TTR cardiomyopathy -- TTR familial amyloid cardiomyopathy (FAC), which is the hereditary form of the disease, and wild-type TTR cardiomyopathy, a non-hereditary form of the disease also know as senile systemic amyloidosis (SSA).
Tafamidis is approved as Vyndaqel in the EU to treat TTR familial amyloid polyneuropathy (FAP), but received a complete response letter from FDA for the indication in 2012 after it missed both co-primary endpoints in a pivotal Phase II/III trial (see BioCentury Extra, June 18, 2012).
Ionis' inotersen is under Priority Review by FDA to treat hereditary TTR amyloidosis, with a July 6 PDUFA date. The TTR antisense inhibitor is also under accelerated assessment by EMA (see BioCentury Extra, Jan. 8).
Alnylam's patisiran (ALN-TTR02) is an IV RNAi therapeutic targeting the TTR gene. The product is under Priority Review by FDA to treat hereditary TTR-mediated amyloidosis, with an Aug. 11 PDUFA date. Patisiran is also under accelerated assessment by EMA (see BioCentury Extra, Feb. 1).