Pfizer drug gets fast review in rare heart condition

The FDA has said Pfizer’s tafamidis is to get a fast-tracked development and review process for the rare, progressive and fatal heart condition transthyretin cardiomyopathy (TTR-CM).

The news is encouraging for Pfizer, which is trying to establish itself in the rare disease space.

Tafamidis is already approved under the brand name Vyndaquel in the EU for the related disease, transthyretin familial amylod neuropathy (TTR-FAP).

But in 2012 the FDA rejected the tafamidis in TTR-FAP on efficacy grounds, asking for a second study to provide more data, and the drug is not approved in that indication in the US.

This rare disease is associated with progressive heart failure and is universally fatal, and tafamidis is being evaluated in phase 3 development for its potential to reduce mortality and cardiovascular-related hospitalisations.

No other drug is approved for the condition in the US, and GSK recently pulled out of a partnership with Ionis to develop a drug for the similar condition transthyretin amyloidosis, or TTR amyloidosis.

Pfizer’s ATTR-ACT study is the first phase 3 double-blind placebo-controlled clinical study in TTR-CM. It includes both patients with variant transthyretin familial amyloid cardiomyopathy (TTR-FAC), which is the hereditary form of the disease, and those with wild-type TTR-CM, which is not hereditary and may occur as people age.

The study is fully enrolled and is anticipated to be completed in the first half of 2018. There are around 1,000 diagnosed patients with TTR-CM worldwide, although the disease is believed to be significantly underdiagnosed.

In TTR-CM, heart failure occurs when unstable tetramers dissociate resulting in misfolded proteins that aggregate into amyloid fibrils and deposit in the heart, and life expectancy averages three to five years from diagnosis.

The FDA’s Fast Track scheme allows for a faster development and review of new drugs and vaccines intended to treat or prevent serious conditions and address an unmet medical need.

Tafamidis is approved in TTR-FAP in 40 countries, including in Europe, Japan, Brazil Mexico, Argentina, Israel, Russia, and South Korea.