Hey, Pfizer watchers, don't forget Vyndaqel. The heart disease drug's zooming toward blockbuster land

Pfizer's rare heart disease drug Vyndaqel, also known as tafamidis, could reach $2.5 billion sales in 2021, SVB Leerink analyst Mani Foroohar said. (Pfizer)

All public attention for Pfizer these days is centered on its BioNTech-partnered COVID-19 vaccine. But while key phase 3 efficacy data for the experimental shot remain blinded, the company’s tafamidis franchise is cruising on a clear growth trajectory that now looks sure to take it to blockbuster status.

In the third quarter, tafamidis, marketed under the brands Vyndaqel and Vyndamax, sold $351 million, up 27% from its haul in the second quarter. Both the U.S. and international markets contributed to the growth.

As the drug’s market performance improves on every front, SVB Leerink analyst Mani Foroohar now projects the rare disease drug to reach $2.5 billion in 2021 global revenues, according to an investor note from last week.

Vyndaqel last May scored its long-awaited FDA nod to treat a rare heart disease called ATTR cardiomyopathy (ATTR-CM). Industry watchers immediately pegged its peak sales estimates in blockbuster territory, but both analysts and Pfizer management acknowledged that the drug’s success was dependent on the company’s ability to drive diagnosis rates.

Before Vyndaqel arrived, an estimated 1% to 2% of patients living with ATTR-CM were properly diagnosed. But Pfizer’s push to increase awareness and its use of noninvasive diagnostics are paying off. The U.S. diagnosis rate has steadily ticked upward to about 17% in Q3 from 15% in Q2, Pfizer CEO Albert Bourla told investors on a conference call last week.

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As of the end of Q3, over 17,500 U.S. patients have been diagnosed, more than 12,000 have gotten a prescription, and about 7,300 have received the drug, Bourla said. The conversion rate of prescribed patients to treated patients has improved slightly to 63% from 62%, Foroohar noted. In Q3, 82% of diagnosed patients who were deemed eligible for Vyndaqel were able to get a prescription, according to Pfizer Biopharmaceuticals Group president, Angela Hwang. That figure also represented an increase from 78% in Q2.

Vyndaqel’s $225,000-a-year sticker recently drew criticism as physicians complained about patients not being able to afford the drug’s out-of-pocket cost, which is part of the reason why some patients didn’t eventually get the medicine.

Lawmakers have recently proposed bills that would cap out-of-pocket costs in Medicare Part D. During the conference call, Bourla said the current insurance benefits system in the U.S. needs to change. “It seems like there is a general recognition in both sides of the aisle,” he said. “We will continue working with all, and we hope that we will see a change in the design of these benefits that will reduce the cost that the Americans have to pay out-of-pocket when they go to collect their medicines.”

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Outside the U.S., Pfizer in February won EU approval for Vyndaqel in ATTR-CM, about nine years after its initial approval there in ATTR-polyneuropathy, a neurologic form of ATTR. That green light helped Vyndaqel’s ex-U.S. sales tally swell 46% in Q3 over Q2 to reach $193 million.

Now, with Pfizer's Upjohn established medicines business on track to be folded in with Mylan in a new company called Viatris, Vyndaqel ranks fifth among Pfizer’s top-selling drugs by Q3 numbers. It trails only pneumococcal vaccine Prevnar 13, breast cancer drug Ibrance, Bristol Myers Squibb-shared anticoagulant Eliquis and JAK inhibitor Xeljanz.