Pfizer’s blockbuster-in-waiting drug tafamidis has gained FDA approval to treat cardiomyopathy in patients with rare disease ATTR.
Analysts say the drug could be a potential blockbuster, earning more than $1bn in forecast peak sales. The drug will represent competition for the two existing ATTR treatments already on the market, Alnylam’s Onpattro and Ionis’ Tegsedi, even though they currently target different patient sub-types.
Cardiomyopathy (CM) is the most serious of the symptoms seen in patients with hereditary or wild-type transthyretin-mediated amyloidosis (ATTR), a condition that means a protein known as transthyretin fails to operate as it should.
Pfizer filed the drug in two oral formulations, one known as Vyndaqel (tafamidis meglumine), dosed at 80 mg orally once-daily, taken as four 20 mg capsules and a more patient friendly version called Vyndamax, which is a 61mg orally once-daily tablet taken as a single capsule.
Both Vyndamax and Vyndaqel are expected to reduce cardiovascular mortality by 30% and cut cardiovascular related hospitalisation by 32%, strong claims which will help fuel their uptake.
The FDA approval means these treatments are the first medicines approved to treat the cardiovascular-related subtype of ATTR, both in the hereditary or wild-type groups, representing around 5,000 diagnosed patients worldwide.
Alnylam’s Onpattro is indicated for a different disease ATTR subtype, hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) where patients suffer polyneuropathy complications from the condition. Tafadamis was already approved for these patients in Europe, but its approval for CM patients opens up a more lucrative market for Pfizer.
Vyndaqel has been priced at $225,000 per year, half the price of Onpattro – signalling both that this subtype is more common, and also suggesting direct competition in the future.
Evercore ISI analyst Umer Raffat highlighted the differences and similarities between Vyndagel and Vyndamax, including bioequivalence to the point where the label specifically mentions that every 20mg of Vyndaqel is equivalent to 12.2mg of Vyndamax.
Phase 3 data shows similar efficacy at both 20mg and 80mg doses, but Raffat quashed any idea that patients might be able to take just the 20mg option, at a lower price of $55,000 per year, as he expects Pfizer to phase out the 80mg later in the year, which will prevent this from happening.
Despite the different indications, analysts have predicted that there will still be competition from the two drug makers since many hATTR patients are likely to have both cardiomyopathy and polyneuropathy.
Given their current licences, Pfizer will be able to carve out the ATTR-CM market, but Onpattro will lead in the polyneuropathy subtype.
However Alnylam is preparing to launch its APOLLO-B phase 3 study to support the Onpattro’s use in cardiomyopathy patients.
Alnylam also has a subcutaneous follow-up to Onpattro, known as ALN-TTRsc02 or vutrisiran, entering its HELIOS-A phase 3 study. The company is considering a potential head-to-head trial with Pfizer’s drug in cardiomyopathy patients, which would further ramp up competition within the therapy area.