Genmab Tops Europe's Market: Stock Jumps 13% as Its Cancer Drug Posts 28-Month Survival Data

Genmab stock: the short answer

Genmab shares jumped 13.7% on Monday, October 26, 2026, to the top of Europe's STOXX 600 index, after the Danish biotech reported updated Phase 2 data for its experimental cancer antibody petosemtamab at the ESMO Congress 2026 in Madrid. In head and neck cancer, patients on petosemtamab plus pembrolizumab reached a median overall survival of 28.2 months. In metastatic colorectal cancer, response rates reached 75% in first-line treatment. The stock closed in Copenhagen at 2,981 Danish kroner, up 12.6% on the day.

What happened

Genmab, the Copenhagen-based antibody specialist listed in Denmark and on Nasdaq under the ticker GMAB, used the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid to release two sets of updated Phase 2 results for petosemtamab — an investigational bispecific antibody that targets two proteins, EGFR and LGR5, found on cancer cells.

The headline dataset covered first-line treatment of recurrent or metastatic PD-L1-positive head and neck squamous cell carcinoma. Among 43 efficacy-evaluable patients treated with petosemtamab plus pembrolizumab (sold as Keytruda), the median overall survival was 28.2 months — more than two years. The overall response rate was 63%, the complete response rate was 19%, and median progression-free survival was 9.0 months. With a median follow-up of 25.5 months, an estimated 55% of responders were still responding at 24 months, and the company reported no Grade 5 adverse events and no treatment-related deaths. Responses were seen across HPV-positive and HPV-negative disease and across PD-L1 expression levels.

The second dataset, in metastatic colorectal cancer, combined petosemtamab with standard FOLFOX or FOLFIRI chemotherapy. Confirmed and unconfirmed objective response rates were 75% in first-line patients and 67% in second-line patients, rising to 81% among first-line patients with left-sided tumors. Disease control rates were 95% in the first-line setting and 93% in the second line.

Why the stock is blowing up

Three things landed on the same morning. First, the data itself: a median survival past two years in a hard-to-treat head and neck cancer population is the kind of number that moves a biotech's valuation, because it supports the Phase 3 program already under way. Second, the market context: Reuters reported that Genmab jumped 13.7% to lead the entire STOXX 600 as European shares recovered 0.4%, helped by easing oil prices and upbeat corporate updates at the start of a week packed with ECB and Federal Reserve decisions. Third, Wall Street piled in — JPMorgan raised Genmab from neutral to overweight, and options traders bought roughly 12,591 call contracts, about 403% above the stock's typical call volume, according to MarketBeat.

The Copenhagen shares touched 3,047 kroner intraday before closing at 2,981 kroner, up from a previous close of 2,648 kroner. The move caps a strong run: the stock is up roughly 47% year to date.

Key facts

• Company: Genmab A/S, headquartered in Copenhagen, Denmark; listed in Copenhagen and on Nasdaq as GMAB.
• Drug: Petosemtamab, an investigational IgG1 bispecific antibody targeting EGFR and LGR5. It is not yet approved in any market.
• Head and neck data: Median overall survival 28.2 months; overall response rate 63%; complete response rate 19%; median progression-free survival 9.0 months (n=43, petosemtamab plus pembrolizumab).
• Colorectal data: Response rates of 75% (first line) and 67% (second line) with chemotherapy; 81% in first-line left-sided tumors; disease control 95% and 93%.
• Market reaction: Shares up 13.7% intraday to top the STOXX 600 (Reuters); Copenhagen close 2,981 kroner, +12.6%.
• Analyst move: JPMorgan upgraded Genmab to overweight from neutral.

What happens next

The number investors now circle is the Phase 3 readout. Genmab's global Phase 3 program in first-line head and neck cancer is ongoing, with topline data anticipated later this year, and global Phase 3 trials in colorectal cancer are also under way. Phase 2 results, however encouraging, do not guarantee Phase 3 success or regulatory approval — that confirmatory step is where the investment case will be proved or broken. This post reports the data and the market reaction only; it is not investment advice, and nothing here is a recommendation to buy, sell, or hold any security.

Sources

• Reuters — European stocks rebound as investors eye ECB, Fed meetings (Genmab +13.7%, top of STOXX 600)
• Genmab via Business Wire — Updated Phase 2 data: 28.2-month median overall survival
• TipRanks / The Fly — Genmab announces updated Phase 2 data on petosemtamab
• GlobeNewswire — Petosemtamab colorectal cancer Phase 2 results (75% / 67% response rates)
• MarketBeat — JPMorgan upgrade and Genmab call-option activity

FAQ

Why did Genmab stock jump on October 26, 2026?

Genmab reported updated Phase 2 results for petosemtamab at ESMO 2026 — 28.2 months of median overall survival in head and neck cancer and response rates up to 75% in colorectal cancer — and the shares rose 13.7% to lead Europe's STOXX 600.

What is petosemtamab?

Petosemtamab is Genmab's investigational bispecific antibody targeting EGFR and LGR5. It is being tested with pembrolizumab in head and neck cancer and with chemotherapy in colorectal cancer, and it is not yet approved anywhere.

When will Genmab's Phase 3 results arrive?

Genmab says topline data from its Phase 3 program in first-line head and neck cancer are anticipated later this year, with global Phase 3 colorectal trials also ongoing.

Where does Genmab trade?

Genmab is headquartered in Copenhagen, Denmark. Its shares trade in Copenhagen and in the United States on Nasdaq under the ticker GMAB; the Copenhagen shares closed October 26 at 2,981 kroner, up 12.6%.