Merck's Fumble Gives Pfizer a Win

It shelved a 10-year-old drug that’s provided a key component in a rival’s $17 billion Covid pill

- John Lauerman, with Susan Decker and Cynthia Koons

Almost as quickly as Covid-19 erupted in early 2020, so too did the rush to find drugs, either old or new, to treat the contagion spreading around the world. Although researchers soon identified some that quelled late-stage symptoms or weakly restrained the virus, Paxlovid, a pill from Pfizer Inc. that prevents severe disease, appears poised to take a solid lead in the lucrative coronavirus treatment market.

Yet an important component of Pfizer’s antiviral has links to a drug from rival Merck & Co.: boceprevir, developed decades ago to fight hepatitis C. That fragment accounts for at least 20% of Paxlovid’s coronavirus-fighting power—and perhaps much more—researchers estimate, and a key patent on the molecule it comes from resides with Merck.

Several labs have noted the potential of boceprevir, a protease inhibitor that Merck sold earlier under the brand name Victrelis. But as developers at universities began looking for ways to use it and similar compounds to make Covid drugs over the past two years, Merck sat on the sidelines.

Bypassing the drug while a rival seems set to profit handsomely from one of its key parts adds to Merck’s saga of Covid futility. Along with Sanofi and GlaxoSmithKline Plc, Merck is among the big drugmakers that have failed to devise a usable coronavirus vaccine in the world’s biggest infectious disease crisis in a century and partake in a market for Covid shots that health analytics firm Airfinity Ltd. estimates will be worth $85 billion this year.