Danish biotech Genmab has seen its shares double in three months after a string of major cancer drug trial successes, giving fresh momentum to its push to take greater control of the medicines it develops and sells.
Shares in the roughly $35 billion company surged 48% last week, including a 29% jump in a single session after strong results for petosemtamab, its experimental head and neck cancer treatment. The announcement marked Genmab's third successful Phase 3 trial in October, following positive results for treatments targeting ovarian cancer and lymphoma.
After nearly three decades spent building Genmab into one of Europe's prominent biotechnology companies, CEO Jan van de Winkel told CNBC on Friday the breakthroughs marked "a completely new era."
Historically, Genmab made money from royalties from drugs it helped develop, including Johnson & Johnson's multiple myeloma treatment Darzalex and Novartis' Kesimpta. Van de Winkel said Johnson & Johnson is expected to generate $16.5 billion to $16.9 billion in Darzalex sales this year, with Genmab receiving royalties of up to 20%.
Genmab is now using that financial firepower to build a business that keeps a much larger share of the revenue from its own treatments.
Cancer breakthroughs
The biggest market reaction followed Genmab's Oct. 28 announcement that petosemtamab, combined with Merck's Keytruda, reduced the risk of death by 50% compared with Keytruda alone in a Phase 3 trial of patients with recurrent or metastatic head and neck cancer.
The combination also significantly improved response rates and showed no new safety signals, according to Genmab.
Van de Winkel told CNBC the combination "could potentially set a completely new standard" of care although he declined to say whether the survival data might hold up as the data mature, citing still unpublished full data.
Days earlier, Genmab reported that its medicine Rina-S reduced the risk of disease progression or death by 71% and the risk of death by 57% versus chemotherapy in a Phase 3 ovarian cancer trial.
Barclays analysts said the results exceeded investor expectations and suggested Rina-S could offer an alternative for patients ineligible for AbbVie's competing treatment Elahere, or whose cancer had progressed after receiving it. They cautioned, however, that cross-trial comparisons are limited.
A third late-stage October win came from Epkinly, co-developed with AbbVie, which reduced the risk of disease progression or death by 51% when combined with standard chemotherapy in previously untreated diffuse large B-cell lymphoma.
Analysts see significant commercial potential for petosemtamab, including beyond its initial target market.
Jefferies analysts said the drug could generate $3.5 billion in peak annual global sales treating recurrent or metastatic head and neck cancer, and estimated an expansion into locally advanced disease could add another $3.5 billion, an opportunity they believe investors have yet to fully appreciate.
Declining to give specific numbers, van de Winkel said he expects petosemtamab to become a "multi-billion dollar drug."
Genmab is due to report third-quarter earnings on Nov. 5.
Antibody specialist
Genmab has built its business around antibody-based medicines, including so-called bispecific antibodies such as petosemtamab, which can bind to two different targets on cancer cells simultaneously.
Petosemtamab targets the proteins EGFR and LGR5, and is designed to both disrupt signals that help cancer cells grow and to encourage the immune system to attack the tumor.
Van de Winkel said Genmab's expertise in antibodies and their interaction with the immune system has also helped it spot promising medicines developed by others. It acquired petosemtamab through an $8 billion purchase of Merus in 2025 and Rina-S through a $1.8 billion acquisition of ProfoundBio in 2024.
Those deals are also central to Genmab's changing business model.
It fully owns petosemtamab and Rina-S, while splitting the commercial economics of Epkinly equally with AbbVie, much larger shares than with Johnson & Johnson and Novartis.
"From now on I'm going to increasingly hold on to ownership of these new medicines," Van de Winkel said.
Genmab now has 15 Phase 3 trials across its three lead compounds.
"The model is beginning to be validated and click together," he said. "I think the market gets it at this point finally."
The Merus deal underscored the scale of the bet. Genmab borrowed $5.5 billion to help fund the purchase, relying on its royalty income as a financial backstop if petosemtamab failed.
A new chapter
Owning more of its medicines also means taking on more of the work of selling them. Van de Winkel said the company already has much of the necessary infrastructure in place, having built up commercial capabilities around existing treatments including Epkinly and Tivdak, co-developed with Pfizer.
The company is expanding its sales presence in Europe and seeking to reach more cancer patients through community healthcare, beyond specialist hospitals, in the U.S.
Van de Winkel said he wants Genmab's majority-owned medicines to reach around 500,000 patients by the 2030s, up from fewer than 30,000 today.
He also acknowledged potential interest from larger drugmakers, saying Genmab was likely "high up on the radar screen," but stressed that his ambition remained to build an independent European biotech.
Greater ownership, however, also means bearing more of the cost and risk of clinical trials, regulatory approvals and commercialization.
Van de Winkel acknowledged that geopolitical shifts and drug-pricing pressures could complicate expansion plans and change the order in which Genmab launches medicines in different markets.
