Genmab Shelves Promising Cancer Drug in Bold Strategic Pivot

COPENHAGEN, DENMARK – December 29, 2025 – In a move that underscores the brutal calculus of modern drug development, Danish biotechnology giant Genmab A/S announced today its decision to discontinue all clinical development for acasunlimab, an antibody treatment that had shown an “encouraging” clinical profile in fighting solid tumors. The decision is not a reflection of failed science but rather a calculated strategic pivot to concentrate resources on what the company believes are its most valuable late-stage assets in a fiercely competitive market.

The announcement sends a clear signal to the biopharmaceutical industry: in the high-stakes race to bring transformative medicines to market, sometimes even a promising candidate isn't promising enough. Genmab will now sharpen its focus on three key programs: the already-approved EPKINLY® (epcoritamab), petosemtamab, and rinatabart sesutecan (Rina-S®).

“This strategic decision is a testament to our commitment to focus our investments and capabilities where we believe we can deliver the greatest benefit for both patients and shareholders,” said Jan van de Winkel, Ph.D., President and Chief Executive Officer of Genmab, in a statement. The company confirmed the move will not impact its full-year 2025 financial guidance, indicating the decision was a planned reallocation of resources rather than a response to an unforeseen setback.

The High Cost of an 'Encouraging' Profile

The discontinuation of acasunlimab is particularly noteworthy because the drug was far from a failing asset. Known scientifically as GEN1046, the bispecific antibody was engineered with a sophisticated dual-action mechanism, designed to simultaneously block the cancer-shielding PD-L1 pathway while activating the 4-1BB protein to stimulate a more powerful T-cell and NK-cell attack on tumors.

Its development program was well advanced. Just over a month ago, on November 25, 2024, Genmab launched a global Phase 3 trial, ABBIL1TY NSCLC-06, to test acasunlimab in combination with the blockbuster immunotherapy KEYTRUDA® (pembrolizumab) for patients with metastatic non-small cell lung cancer (NSCLC). Furthermore, a Phase 2 trial for advanced melanoma began recruiting patients in July 2025.

Earlier data had fueled optimism. Results from a Phase 2 study presented at the American Society of Clinical Oncology (ASCO) 2024 meeting showed that the acasunlimab-Keytruda combination yielded a median overall survival of 17.5 months and a 12-month overall survival rate of 69% in a similar NSCLC patient population. These figures were described by the company as encouraging and suggested the drug had clear biological activity. The therapy was also being explored for a range of other solid tumors, including endometrial, triple-negative breast, and cervical cancers.

However, developing a drug through a global Phase 3 trial is an enormously expensive undertaking, often costing hundreds of millions of dollars. The decision to halt the program, even with positive signals, reflects a disciplined assessment of the drug's ultimate market potential versus its significant development cost.

A Crowded and Competitive Battlefield

A key factor cited by Genmab for the decision was the “evolving competitive landscape.” The primary indication for acasunlimab, non-small cell lung cancer, is one of the most crowded and competitive arenas in oncology. It is dominated by well-entrenched checkpoint inhibitors like Keytruda, and dozens of companies are vying to develop the next standard of care. To succeed, a new therapy must demonstrate not just efficacy, but a substantial improvement over existing treatments to justify its adoption by physicians and reimbursement by payers.

Genmab's strategic calculation was likely complicated by a shift in its partnership with BioNTech. In August 2024, BioNTech opted to step back from its co-development of acasunlimab to prioritize its own portfolio. While the broader collaboration between the two companies remained intact, the move left Genmab with the sole financial and operational responsibility for the costly late-stage development of the drug. Faced with shouldering the entire burden, Genmab's leadership evidently concluded that the capital could be more effectively deployed elsewhere.

This pruning of the pipeline is a common, if difficult, practice in the biotech industry. Companies must constantly evaluate their assets not in a vacuum, but against the probability of clinical success, the cost of development, the competitive environment, and the potential return on investment.

Doubling Down on the Next Generation

By reallocating the substantial funds and resources once earmarked for acasunlimab, Genmab is placing a concentrated bet on a trio of assets it believes holds superior potential. The company's prioritized pipeline represents a multi-pronged approach to cancer treatment.

Leading the pack is EPKINLY® (epcoritamab), a bispecific antibody co-developed with AbbVie. Already approved in multiple markets for certain types of relapsed or refractory large B-cell lymphoma, EPKINLY provides Genmab with an existing revenue stream and a validated technological platform. Its success serves as a foundation for further expansion into other hematological malignancies.

The other prioritized assets, petosemtamab and rinatabart sesutecan (Rina-S®), represent the next wave of Genmab's innovative antibody-based therapies. Petosemtamab is an investigational antibody targeting EGFR, while Rina-S is an antibody-drug conjugate (ADC), a class of 'smart bomb' drugs that deliver potent chemotherapy directly to cancer cells. These programs are aimed at different but equally challenging cancers, and Genmab's decision signals immense confidence in their potential to become best-in-class treatments.

This strategic shift demonstrates a mature and disciplined approach to capital allocation. Rather than spreading resources across a wider range of 'good' opportunities, Genmab is channeling its considerable financial and scientific power toward a select few that it believes can be truly great, maximizing the potential for groundbreaking patient outcomes and significant shareholder returns in the years to come.