Merck Just Bet $6.7 Billion on a Drug Most People Haven't Heard Of
Merck is spending $6.7 billion on a cancer drug that's still in early trials, and the logic behind it says everything about how desperate Big Pharma gets when a $30 billion product is about to lose patent protection.
Two years ago, Terns Pharmaceuticals was a small-cap biotech quietly pivoting away from liver disease toward cancer. Last week, Merck wrote them a check for $6.7 billion. That's not a typo. And the drug at the center of this deal? It's still in early-stage clinical trials.
Welcome to the most desperate, most expensive game of musical chairs in pharma: what happens when your best-selling drug is about to lose patent protection, and you need to find the next one before the music stops.
The Keytruda Problem
Keytruda is Merck's crown jewel. It's the world's top-selling cancer drug, pulling in over $30 billion in 2025 alone. That's more than a third of Merck's entire revenue. If Keytruda were a country's GDP, it would rank ahead of Iceland.
But Keytruda's patents start expiring in 2028, and cheaper copycat versions (called biosimilars) are already lining up at the door. When biosimilars hit the market, they typically slash prices by 50 percent or more and grab market share fast. For a drug generating $30 billion a year, even a modest erosion means billions evaporating from the balance sheet.
Merck's 2026 sales guidance of $65.5 to $67 billion already came in below analyst expectations, a sign the cliff's shadow is getting longer. CEO Robert M. Davis has been blunt about the strategy: grow through the patent loss by buying the next generation of drugs before someone else does.
So What Did $6.7 Billion Actually Buy?
The centerpiece of the Terns deal is a drug called TERN-701, a treatment for chronic myeloid leukemia (CML), a type of blood cancer. Specifically, it's an allosteric BCR-ABL inhibitor, which is a fancy way of saying it blocks a protein that drives certain leukemia cells to grow out of control. Think of it like jamming a wrench into a machine's gears; TERN-701 targets those gears from an unusual angle that existing drugs can't easily reach.
Merck's head of research, Dean Li, called TERN-701 "meaningfully differentiated" based on early clinical data, comparing its potential to Novartis's Scemblix, a drug already making waves in the CML space. The company is billing it as a "potential best-in-class candidate."
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