14 January 2019 - - The US Food and Drug Administration accepted for filing the company's New Drug Applications for tafamidis for the treatment of transthyretin amyloid cardiomyopathy (ATTR-CM). Pfizer has submitted two NDAs based on two forms of tafamidis: meglumine salt and free acid, US-based pharmaceutical company Pfizer Inc. (NYSE: PFE) said.

Tafamidis is the only product to complete a Phase 3 trial evaluating its efficacy, safety, and tolerability in patients with ATTR-CM, a rare, fatal, and underdiagnosed condition.

The tafamidis meglumine form (20 mg capsule) has been granted Priority Review. The FDA grants Priority Review to medicines that may offer significant advances in treatment or may provide a treatment where no adequate therapy exists. The target Prescription Drug User Fee Act (PDUFA) action date for a decision by the FDA is in July 2019.

The tafamidis free acid form (61 mg capsule) will be under Standard Review.

This form is bioequivalent to the 80 mg tafamidis meglumine dose, which was administered as four 20 mg capsules in the pivotal trial; it was developed for patient convenience to enable a single capsule for daily administration. The target PDUFA action date for a decision by the FDA is in November 2019.

The submission is based on findings from the pivotal Phase 3 Transthyretin Amyloid Cardiomyopathy (ATTR-ACT) study, which evaluated the efficacy, safety, and tolerability of tafamidis meglumine compared to placebo for the treatment of patients with ATTR-CM.

In the primary analysis of the study, tafamidis met the primary endpoint, demonstrating a significant reduction in the hierarchical combination of all-cause mortality and frequency of cardiovascular-related hospitalizations compared to placebo over a 30-month period in patients with wild-type or hereditary ATTR-CM (P=0.0006).

Tafamidis was well tolerated, with an observed safety profile comparable to placebo.

The primary results were presented in a Hot Line session at the ESC Congress 2018 in Munich, Germany, and simultaneously published online in the New England Journal of Medicine in August 2018.

Tafamidis is an oral, investigational product being evaluated as a potential treatment for ATTR-CM. Tafamidis is a small molecule that selectively binds at specific sites on the transthyretin tetramer to prevent destabilization of the transthyretin transport protein and formation of amyloid that causes ATTR-CM.

Tafamidis is not approved for any use in the United States.

Tafamidis was granted Orphan Drug Designation for ATTR-CM in both the EU and US in 2012 and in Japan in 2018. In June 2017 and May 2018, respectively, the FDA granted tafamidis Fast Track and Breakthrough Therapy designations for ATTR-CM.

In November 2018, the FDA granted Priority Review designation for the NDA for tafamidis meglumine. Additionally, in March 2018, the Ministry of Labor Health and Welfare in Japan granted SAKIGAKE designation to tafamidis for this indication.

Following the SAKIGAKE designation, a regulatory marketing application for tafamidis for ATTR-CM was submitted to the Pharmaceuticals and Medical Devices Agency in November 2018.

ATTR-ACT is a Phase 3 international, multicenter, double-blind, placebo-controlled, randomized, 3-arm clinical study in 441 patients with ATTR-CM that investigated the efficacy, safety, and tolerability of an oral daily dose of 20 mg or 80 mg tafamidis meglumine compared to placebo.

The study included both patients with the hereditary form of the disease, and those with wild-type form, which is not hereditary and may occur as people age. The primary analysis of the study, which compared a pooled tafamidis (80 mg and 20 mg) treatment group to placebo, was the hierarchical combination of all-cause mortality and frequency of cardiovascular-related hospitalizations over a 30-month period in patients with transthyretin amyloid cardiomyopathy.

ATTR-CM is a rare and progressive disease caused by destabilization of a transport protein called transthyretin, which is composed of four identical subunits (a tetramer). In ATTR-CM, heart failure occurs when unstable tetramers dissociate, resulting in misfolded proteins that aggregate into amyloid fibrils and deposit predominantly in the heart.