Merck has agreed to buy Terns Pharmaceuticals for $6.7bn, the companies confirmed on 25 March, in one of the largest biotech acquisitions of the year so far.
The deal is squarely aimed at filling the revenue gap that will open when Keytruda, Merck's top-selling cancer immunotherapy, begins losing patent protection later this decade. Keytruda generated roughly $25bn in sales in 2024, making it the world's best-selling drug, and its patent cliff represents one of the most significant transition risks facing any large-cap pharma company.
Terns' principal asset is an oral treatment for chronic myeloid leukemia, a blood cancer typically managed with daily pills over many years. The drug has drawn attention as a potential rival to Novartis's Scemblix, which only received approval in 2021 but has already become a standard-of-care option in later-line CML. An oral challenger from a company with Merck's commercial infrastructure would represent a meaningful competitive threat.
Merck has been among the most active acquirers in pharma as it works to diversify beyond Keytruda. The Terns purchase follows a string of dealmaking that includes its $10.8bn acquisition of Prometheus Biosciences in 2023 and the $5.5bn purchase of Acceleron Pharma in 2021.
Terns is a clinical-stage company headquartered in Foster City, California, and had been developing treatments across oncology and metabolic disease. The all-cash structure removes financing uncertainty and reflects Merck's substantial balance sheet.
