The centerpiece of the acquisition is petosemtamab, Merus’ bispecific antibody targeting EGFR and LGR5, which in May demonstrated best-in-class potential for head-and-neck cancer.
Genmab has won the race to buy cancer biotech Merus, putting down $8 billion to take over the Netherlands-based biotech and its oncology pipeline of bispecific antibodies.
Under the acquisition agreement, Genmab will purchase all of Merus’ common shares for $97 apiece, which represents a 41% premium to the biotech’s closing price on Friday. The companies expect to complete the transaction in the first quarter of 2026, pending regulatory clearances and the approval of at least 80% of Merus shareholders.
Reporting from Bloomberg News on Sunday revealed that several pharmas have been courting the cancer biotech in recent weeks, and that Genmab appeared to have been leading the pack. Genmab and Merus were in advanced talks, according to Bloomberg, which cited sources who requested anonymity and who cautioned that, at the time, a deal was not guaranteed.
BMO Capital Markets addressed the rumors in an investor note Monday morning, ahead of the official acquisition announcement. While the analysts conceded that the takeover talks come “as a little surprise” given how Merus’ pipeline has been performing, such a deal would nevertheless point to the “growing interest” in the biotech. Merus’ shares have shot up 63% year-to-date.
In a prepared statement on Monday alongside the acquisition announcement, Merus CEO Bill Lundberg called Genmab a “leader in antibody therapeutics,” adding that the Danish pharma “has the right vision and experience” to take its star asset petosemtamab forward.
Petosemtamab is a bispecific antibody designed to target the EGFR and LGR5 proteins, a mechanism that activates the immune system’s anti-cancer activity. In May, the biotech announced that petosemtamab aced a Phase II trial in head-and-neck squamous cell carcinoma, hitting a 79% overall survival rate at 12 months when used with Merck’s Keytruda. The regimen also elicited an overall response rate of 63% and a median progression-free survival rate of 9 months.
Reacting to the readout, William Blair analysts at the time said petosemtamab had a “best-in-disease profile” for the indication, unlocking a “potential blockbuster market opportunity” for Merus. Leerink analysts were similarly bullish on petosemtamab, noting that its combination with Keytruda could “become the standard of care” in this disease.
Genmab’s acquisition of Merus also reads positively for the wider biopharma industry, according to BMO on Monday. “We are encouraged by news of M&A discussions following lagging M&A activity over the last few years,” the analysts said, pointing particularly to Pfizer’s $4.9 billion Metsera takeover last week.
These deals, they added, “could start to spur broader M&A in the sector.”