Pfizer Inc. (NYSE:PFE) announced on 5/22/18 that tafamidis received Breakthrough Therapy designation from the US Food and Drug Administration (FDA) for the treatment of patients with transthyretin cardiomyopathy, a rare, fatal, and underdiagnosed condition associated with progressive heart failure.

The prevalence of transthyretin cardiomyopathy is presently unknown; however, it is estimated that less than 1% of people with the disease are diagnosed. Currently, there are no approved pharmacological treatments specifically indicated for this disease, and the average life expectancy is 3 to 5 years from diagnosis.

This decision is supported by topline results from the tafamidis Phase 3 Transthyretin Cardiomyopathy (ATTR-ACT) study, in which tafamidis demonstrated a statistically significant reduction in the combination of all-cause mortality and frequency of cardiovascular-related hospitalizations.

“This designation is an important step forward in the path to bringing a potential new treatment option to those with transthyretin cardiomyopathy, a rare, fatal disease,” said Brenda Cooperstone MD, Senior Vice President and Chief Development Officer, Rare Disease, Pfizer Global Product Development. “We look forward to working with the FDA through this expedited process to fulfill an unmet patient need.”

Pfizer released top-line results from a phase III study of tafamidis in March. In the study, tafamidis met its primary endpoint, demonstrating a statistically significant reduction in the combination of all-cause mortality and frequency of cardiovascular-related hospitalizations compared to placebo at 30 months.

Tafamidis was originally developed as a treatment for familial amyloid polyneuropathy. Though it was approved in  Europe and Japan, it was rejected by the FDA for that indication.