Pfizer's Solid Phase III Data; Alnylam and Ionis Shares Fall

Pfizer could be eying the green light for a first-ever regulatory approved treatment for transthyretin cardiomyopathy (TTR) following positive topline results from a late-stage study.

On Thursday the pharma giant released topline results for its Phase III trial (ATTR-ACT) testing Tafamidis for the treatment of transthyretin cardiomyopathy. Topline results show the therapy met its primary endpoint. The drug demonstrated a statistically significant reduction in the combination of all-cause mortality and frequency of cardiovascular-related hospitalizations compared to placebo at 30 months, the company said. The good news for Pfizer was bad news for Alnylam and Ionis, both of which are also testing experimental treatments for hereditary forms of the disease. Shares of Alnylam and Ionis fell 8 percent and 4 percent respectively on Thursday.

In its study of 441 patients, Pfizer included those who had the hereditary form of the disease, as well as the “wild-type form,” meaning it can occur as people age. Pfizer tested a 20 mg and 80 mg dose of Tafamidis meglumine capsules compared to placebo. Topline results showed that at 30 months the Pfizer drug caused a statistically significant reduction in mortality and disease-related hospitalization.

Brenda Cooperstone, chief development officer for Pfizer’s rare disease division, said the topline results bring the company “one-step closer to realizing the potential” of having a newly approved treatment for ATTR patients.  

“Pfizer Rare Disease has been at the forefront of improving the understanding of transthyretin cardiomyopathy, and we thank the patients who participated in the trial and their families, as well as the physicians and investigational sites that contributed to this important study. We look forward to sharing the detailed results of the study with the cardiovascular community and discussing these data with health authorities to determine an appropriate regulatory path forward,” Cooperstone said in a statement.

Pfizer has tried for approval of Tafamidis before but was soundly rejected by the U.S. Food and Drug Administration. Pfizer acquired Tafamidis in 2010 as part of the deal for FoldRx.

Transthyretin cardiomyopathy is a rare and underdiagnosed condition associated with progressive heart failure. The disease is fatal. The average life expectancy for people with transthyretin cardiomyopathy is between three and five years from diagnosis. In its announcement, Pfizer said it is estimated that less than 1 percent of people with the disease are diagnosed. Tafamidis has been approved in Europe for transthyretin familial amyloid polyneuropathy (TTR-FAP). It is sold there under the brand name Vyndaqel.

Last year the FDA granted Fast Track designation to Tafamidis for transthyretin cardiomyopathy. It also received a similar designation in Japan earlier this year.

In February the FDA accepted Alnylam’s New Drug Application for patisiran, its investigational RNAi therapy targeting transthyretin (TTR) for the treatment of hereditary ATTR (hATTR) amyloidosis. The FDA granted Alnylam a Priority Review and set a target action date of Aug. 11.

Ionis is expecting the FDA to make a ruling on its hereditary TTR amyloidosis therapeutic Inotersen by July 6.