Genmab Stock Surges 29% to a Record: Cancer Combo Halves the Risk of Death

Genmab (NASDAQ: GMAB) stock surged about 29% in U.S. trading on Wednesday, October 28, 2026, after the Danish drugmaker said its experimental cancer treatment petosemtamab, combined with Merck's Keytruda, cut the risk of death by 50% in a late-stage trial of head and neck cancer patients. The shares were pacing toward their highest close and their largest single-day percentage gain on record, while Genmab's Copenhagen-listed stock rose as much as 21% toward its highest close since the company's listing in 2000.

What happened

Genmab announced positive topline results from LiGeR-HN1, a global Phase 3 trial testing petosemtamab plus pembrolizumab — the drug sold as Keytruda — against pembrolizumab alone. The patients were receiving their first treatment for PD-L1-positive recurrent or metastatic head and neck squamous cell carcinoma, a hard-to-treat cancer that has returned or spread.

At the trial's first interim analysis, reviewed by an independent data monitoring committee, the combination met both of its primary endpoints. It improved overall survival, reducing the risk of death by 50% compared with pembrolizumab alone, and it also met its objective response endpoint, which measures how many patients see their tumors shrink. Genmab said the benefit held regardless of patients' HPV status, an established risk factor in this cancer.

The key numbers

Risk of death: cut by 50%, with a hazard ratio of 0.50 (95% confidence interval 0.37 to 0.67) and a p-value below 0.0001 — a result well past the usual bar for statistical significance.

Tumor responses: the odds ratio for objective response was 3.17 (95% confidence interval 2.06 to 4.89), also with a p-value below 0.0001, meaning patients on the combination were far more likely to respond.

Safety: the combination was generally well tolerated, its profile was consistent with what is already known about each drug on its own, and no new safety signals were identified.

The drug: petosemtamab is an investigational bispecific antibody designed to target two proteins at once — EGFR and LGR5 — both involved in tumor growth.

Why the stock is blowing up

Survival results this strong are rare in head and neck cancer, and investors moved fast. U.S.-listed Genmab shares surged 29% to around $57.52, on pace for a record close and the stock's best day ever, according to Barron's. In Copenhagen, the shares jumped as much as 21%, putting them on track for their highest close since Genmab listed in 2000 and their biggest one-day gain in more than 14 years, Bloomberg reported.

Analysts also pointed to momentum across Genmab's whole pipeline. Jefferies analyst Benjamin Jackson described the result as a "hat trick" for the company, coming after recent late-stage wins for rinatabart sesutecan in ovarian cancer and epcoritamab in a type of lymphoma. Three successful Phase 3 readouts in quick succession change how investors value a pipeline: each win makes the next one look less like luck and more like a platform that works.

What Genmab says happens next

Chief Executive Jan van de Winkel framed the findings as a meaningful step toward bringing the treatment to patients. Genmab said it plans to engage with regulators globally about the results and will submit the full data for presentation at a future medical meeting. That matters because Wednesday's announcement is a topline summary: the detailed numbers — including how long the survival benefit lasts and how it breaks down across patient groups — will come later, and regulators will judge the full dataset, not the headline.

Investors will also watch Merck, whose Keytruda is the backbone of the combination and a standard of care across many cancers, and whether rival drugmakers with head and neck programs respond. For now, though, the story is Genmab's: a record share price, a possible new treatment option for a difficult cancer, and a pipeline that keeps delivering late-stage wins.

This article reports market and clinical news for information only and is not financial or medical advice.

Sources

Genmab's Phase 3 LiGeR-HN1 announcement (Business Wire) · Barron's: Genmab stock surges to record high · Bloomberg: Genmab shares hit record in Copenhagen · TradingKey: Genmab market movers, October 28

FAQ

Why did Genmab stock surge 29%?
Genmab's Phase 3 trial showed its petosemtamab combination with Keytruda cut the risk of death by 50% in head and neck cancer patients, sending the U.S.-listed shares toward a record close and their biggest daily gain on record.

What is petosemtamab?
Petosemtamab is Genmab's investigational bispecific antibody that targets EGFR and LGR5, two proteins involved in tumor growth. It is not yet approved and was tested here with pembrolizumab (Keytruda).

What did the LiGeR-HN1 trial show?
The trial met both primary endpoints at its first interim analysis: overall survival improved with a hazard ratio of 0.50, and the objective response odds ratio was 3.17, with no new safety signals.

What happens next for Genmab's cancer drug?
Genmab plans to discuss the results with regulators globally and present the full data at a future medical meeting; approval decisions will depend on that complete dataset.