FDA fast-tracks review process for cardiac amyloidosis drug

Tafamidis, Pfizer’s treatment for transthyretin amyloid cardiomyopathy (ATTR-CM), has been granted a priority review designation from the FDA, potentially speeding its path to approval.

Priority review is typically reserved for therapies that may offer significant breakthroughs or provide options where few or no other treatments exist. Tafamidis may fit both of those criteria, as it is the only drug for ATTR-CM that has completed a Phase 3 trial evaluating its safety and efficacy.

That trial, presented at the 2018 European Society of Cardiology Congress and published in the New England Journal of Medicine, found patients randomized to tafamidis instead of a placebo were 30 percent less likely to die over 30 months of follow-up and 32 percent less likely to be hospitalized for cardiovascular causes. The all-cause mortality rates were 42.9 percent in the placebo group and 29.5 percent in the tafamidis group, demonstrating the severity of a condition which was previously considered rare and untreatable.

A growing contingent of researchers now believe ATTR-CM, which occurs when deposits of misfolded protein affect the heart tissue and cause cardiomyopathy, is not as uncommon as once thought but may be significantly underdiagnosed.

“The diagnosis of ATTR-CM is often delayed, primarily because disease awareness is low and patients often present with symptoms similar to more common causes of heart failure,” Brenda Cooperstone, MD, chief development officer for rare disease at Pfizer, said in a press release. “In fact, we believe less than one percent of patients living with this disease are currently diagnosed. The FDA’s filing acceptance is an encouraging step toward our goal of further raising awareness and providing a treatment option for ATTR-CM patients who are in desperate need of an approved pharmacologic therapy.”

With the priority review pathway, the FDA is expected to make a decision on whether to approve tafamidis meglumine 20 mg capsules by July, according to Pfizer.

The company also submitted a standard review filing for tafamidis free acid 61 mg pills, which Pfizer said are bioequivalent to the 80 mg tafamidis meglumine dose—taken in four 20 mg pills—that was administered in the pivotal trial published in NEJM.

An FDA decision on tafamidis free acid is targeted for November. According to Pfizer, that form of the drug was developed so patients would need to take just one capsule daily.