Pfizer set for July FDA verdict on rare heart disease drug

Pfizer is finally closing on approval of its rare disease therapy tafamidis in the US, several years after it first reached the market in Europe. The FDA has accepted two separate marketing applications for the drug – both for cardiomyopathy associated with the rare disease ATTR amyloidosis – and awarded a priority review for one of them. Pfizer has said it thinks tafamidis has the potential to become a blockbuster. In ATTR amyloidosis, transthyretin (TTR) protein misfolds and accumulates as amyloid deposits throughout the body. Transthyretin amyloid cardiomyopathy or ATTR-CM is a rare, fatal under-diagnosed form of the disease in which amyloid accumulates in the heart. The average life expectancy for people with ATTR-CM is three to five years from diagnosis.
Tafamidis has been available in Europe for several years as Vyndaqel for nerve damage (polyneuropathy) associated with ATTR amyloidosis but was rejected by the FDA for this indication in 2012. Pfizer switched its attention to cardiomyopathy, and last year reported impressive data for the drug in phase III ATTR-ACT trial, which showed that patients with ATTR-CM who were treated with tafamidis were 30% less likely to die than those treated with placebo, and 32% less likely to be hospitalized.