Genmab pauses enrollment in early ADC trial acquired from ProfoundBio

The study, designed to test the safety and early efficacy of the candidate known as GEN1286, was initially planned to include an estimated 214 patients with advanced solid tumors. Recruitment, however, ended after only 23 participants had joined. The trial remains open but is no longer accepting new patients, according to public clinical trial records. Genmab has confirmed the change to reporters at Endpoints News but has not shared details about the decision.

GEN1286 belongs to a new generation of antibody-drug conjugates, or ADCs. These therapies are designed to deliver toxic payloads directly to cancer cells by binding to specific targets on their surface. In this case, the drug combines two targets often implicated in tumor growth and resistance mechanisms. Such dual targeting approaches aim to improve precision but also add complexity to development.

Overlap within a growing ADC portfolio

The pause of this trial comes as Genmab expands its presence in the ADC field through multiple deals. Alongside assets from ProfoundBio, Genmab has moved to acquire Dutch biotech Merus for $8 billion in cash, with the transaction expected to close in early 2026 and with the expectation to become a global leader in the head and neck cancer fight. That overlap may have influenced internal prioritization, as companies often streamline programs that compete for the same patient populations or scientific rationale.

GEN1286 is not the first ProfoundBio-derived project to be deprioritized since the acquisition closed last year. Genmab has already discontinued other early oncology candidates like GEN1160 and GEN1107, two other ADCs, after facing challenges such as slow recruitment or unfavorable risk-benefit assessments during initial trials.

Focus shifts to late-stage opportunities

Despite these setbacks, Genmab continues to advance the centerpiece of the ProfoundBio deal: rinatabart sesutecan, a late-stage ADC aimed at gynecological cancers. That program has reached Phase 3 testing, marking a more advanced and less speculative step in development. Results from the pivotal study are expected in 2028.

This pipeline reshuffle also comes against a more challenging clinical backdrop. Last week, Genmab and partner AbbVie reported that their bispecific antibody epcoritamab did not meet its primary survival endpoint in a Phase 3 study in relapsed or refractory diffuse large B-cell lymphoma, despite positive secondary signals. The setback adds pressure on Genmab to prioritize programs with clearer late-stage paths. The company has also been recently scaling back its oncology pipeline more aggressively, including the termination in December of acasunlimab, a bispecific antibody program that had previously been partnered with BioNTech.

The decision to halt enrollment for GEN1286 reflects a broader reality in drug development: early-stage programs face intense competition for patients, capital, and strategic attention. Taken together, these moves point to a deliberate cleanup of the portfolio, as the company concentrates resources on fewer, more advanced candidates in a crowded oncology landscape.