Genmab Halts Clinical Development of Acasunlimab After Portfolio Review, Shifts Focus to Late-Stage Oncology Pipeline

Genmab A/S has announced that it will discontinue clinical development of its investigational cancer therapy acasunlimab after a strategic portfolio review. The decision was confirmed in a company press release issued December 29, 2025.

The Copenhagen-based biotechnology firm said the move reflects a deliberate shift in focus toward what it considers the highest-impact programs in its late-stage pipeline, in light of an increasingly competitive landscape for oncology treatments. According to the announcement, the clinical profile of acasunlimab seen so far was described as encouraging, but Genmab concluded that it must dedicate resources to assets with greater potential to benefit patients and shareholders.

Acasunlimab, also known by its research designation GEN1046, is an investigational bispecific antibody that targets the immune checkpoints PD-L1 and 4-1BB. The therapy was designed to stimulate anti-tumor immune responses by engaging and activating T cells and natural killer cells through 4-1BB only in the presence of PD-L1 on tumor cells. Bispecific antibodies like acasunlimab aim to improve the precision and potency of immune modulation in cancer therapy.

The program saw earlier partnership involvement from BioNTech, which exited the collaboration in 2024, leaving Genmab to assume sole responsibility for further development. At that time, Genmab initiated plans for late-stage clinical trials, including studies in non-small cell lung cancer.

In its update, Genmab framed the decision as part of a comprehensive portfolio prioritization strategy. The company cited an evolving competitive landscape and the need to focus its capital and operational capacity on therapies it believes have the strongest potential to deliver meaningful clinical benefit.

Genmab’s leadership emphasized that although data from acasunlimab were promising, the momentum and prospects of other late-stage assets like EPKINLY (Epcoritamab), Petosemtamab, and rinatabart sesutecan (Rina-S) justify reallocating resources. These programs, spanning different mechanisms and cancer indications, are positioned as core to Genmab’s late-stage oncology strategy.

At the time of the announcement, Genmab underlined that the discontinuation of acasunlimab would not affect its full-year 2025 financial guidance. That reassurance may be aimed at maintaining investor confidence as the company funnels attention toward other high-priority assets.

Genmab’s stock moving lower in response to the news. This suggests that while the decision aligns with strategic priorities, it also signals the inherent risks biotech firms face when adjusting development plans.

Genmab has several late-stage programs advancing in oncology and other areas of high unmet need. EPKINLY, a T-cell engager targeting CD20, has shown clinical activity in lymphomas. Petosemtamab is being developed for head and neck cancers, and Rinatabart Sesutecan (Rina-S) is under investigation in ovarian and endometrial cancers. The company’s broader pipeline includes antibody-based therapies and next-generation modalities that reflect its core expertise in engineered immune therapies.