Genmab Acquires Merus in $8 Billion Deal, Bolstering Oncology Pipeline

Danish antibody specialist Genmab has agreed to acquire Netherlands-based biotechnology company Merus for $8 billion, marking a significant move in the pharmaceutical industry's ongoing consolidation trend. The deal, announced on September 29, 2025, centers around Merus' promising bispecific antibody petosemtamab, which has shown potential in treating head and neck cancer.

Deal Details and Strategic Implications

Genmab will pay $97 per share in cash for Merus, representing a 41% premium to the biotech's closing price on Friday. The acquisition aligns with Genmab's long-term strategy to shift towards a wholly-owned model and accelerate its evolution into a global biotechnology leader.

Jan van de Winkel, CEO of Genmab, stated, "The proposed acquisition of Merus clearly aligns with our long-term strategy. It has the potential to significantly accelerate our evolution into a global biotechnology leader by providing durable growth for the company well into the next decade."

The transaction is expected to close in the first quarter of 2026, subject to regulatory clearances and approval from at least 80% of Merus shareholders.

Petosemtamab: A Potential Game-Changer in Cancer Treatment

At the heart of the acquisition is petosemtamab, Merus' bispecific antibody targeting EGFR and LGR5. The drug has demonstrated promising results in clinical trials for head and neck squamous cell carcinoma:

• In a Phase II trial, petosemtamab combined with Merck's Keytruda achieved a 79% overall survival rate at 12 months.
• The regimen elicited an overall response rate of 63% and a median progression-free survival rate of 9 months.

These results have led analysts to describe petosemtamab as having a "best-in-disease profile" for head and neck cancer, with William Blair analysts suggesting it could unlock a "potential blockbuster market opportunity" for Genmab.

Genmab projects that petosemtamab could generate $1 billion in annual sales by 2029, with multi-billion-dollar annual revenue potential thereafter. The company aims to bring the drug to market by 2027, pending successful completion of ongoing Phase III trials expected to read out next year.

Impact on the Pharmaceutical Landscape

The Genmab-Merus deal is seen as a positive sign for the wider biopharma industry, potentially spurring broader M&A activity. BMO Capital Markets analysts noted, "We are encouraged by news of M&A discussions following lagging M&A activity over the last few years," referencing this deal alongside Pfizer's recent $4.9 billion Metsera takeover.

For Genmab, the acquisition adds to its growing portfolio of antibody drugs, which includes partnerships on successful therapies such as Darzalex (multiple myeloma), Tivdak (cervical cancer), and Epkinly (lymphoma). The addition of petosemtamab strengthens Genmab's late-stage pipeline, bringing the total number of wholly-owned programs with potential market entry by 2027 to four.

As the pharmaceutical industry continues to evolve, this acquisition underscores the growing interest in innovative cancer therapies and the strategic importance of building robust, wholly-owned pipelines in the competitive oncology space.