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 the 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 hospitalised.

Pfizer’s first application is for a 20 mg capsule formulation of tafamidis meglumine, which has a proposed dose of 80 mg per day and is due for a speedy FDA verdict in July. The second application is for a single 61 mg capsule formulation of tafamidis free acid, which is bioequivalent to the 80 mg dose and so would reduce the pill burden for patients. It has an FDA action date in November.

The first drug to be approved for ATTR amyloidosis in the US was Alnylam’s gene-silencing drug Onpattro (patisiran), which was approved for polyneuropathy associated with the disease by the FDA last August and has since also got a green light in Europe.

Alnylam’s drug has since been followed by Ionis and Akcea’s antisense drug Tegsedi (inotersen), cleared by the FDA for the same polyneuropathy indication last October, and is also approved in Europe.

As it stands, Pfizer looks on course to become the first pharma company to get approval for a drug for ATTR-CM, leaving it free to build its brand in that patient group while Alnylam and Ionis/Akcea go head-to-head in the polyneuropathy category.

Pfizer also seems to have a lead over its rivals as neither Alnylam or Ionis/Akcea have clinical trials specifically in ATTR-CM yet, and tafamidis is an oral drug while Onpattro and Tegsedi are given by injection.

Discussing the prospects for tafamidis at the JP Morgan Healthcare conference last week, Pfizer’s CEO Albert Bourla said that the drug is “transformative,” but also warned that the company has a big job to do in raising awareness of ATTR-CM and improving diagnosis rates if it is to reach its commercial potential.

He would also not be drawn on Pfizer’s pricing plans for the drug, saying merely that Pfizer prices all its drugs “compared to the value that they bring to the healthcare system.” Both Onpattro and Tegsedi have launched with a list price of $450,000 per year, with Alnylam suggesting that Onpattro’s annual cost drops to around $345,000 after rebates and discounts.