BioNTech ends work on Genmab-partnered bispecific antibody acasunlimab

BioNTech may still claim that the bispecific antibody acasunlimab has an “encouraging” clinical profile, but the mRNA leader has opted to end its involvement and allow partner Genmab to go solo for phase 3 trials.

Acasunlimab is a PD-L1x4-1BB bispecific antibody designed to produce an anti-tumor response by activating a receptor called 4-1BB on T cells and natural killer cells.

BioNTech and Genmab had been evaluating the candidate in three clinical trials, including a phase 2 study as both a monotherapy and in combination with Merck & Co.’s PD-1 inhibitor Keytruda in patients with non-small cell lung cancer (NSCLC) who have failed on standard-of-care treatment with immune checkpoint inhibitors.

But while BioNTech claimed this morning that the emerging clinical profile of the drug is encouraging, it used its second-quarter earnings results to announce that it has opted not to go any further with the development of the candidate “for reasons relating to portfolio strategy.”

It’s not the end of the road for acasunlimab, however, with Genmab quick out of the gate to state that it plans to launch a phase 3 trial in the second half of this year.

Both companies also stressed that their overall relationship is unaffected by today’s decision. In 2022, BioNTech and Genmab expanded their existing partnership to encompass the development of monospecific antibody candidates to address malignant solid tumors. The first candidate from this upsized collaboration to enter the clinic was the CD27 antibody dubbed GEN1053/BNT313.

“Genmab’s partnership with BioNTech is a highly successful one,” Genmab’s CEO Jan van de Winkel, Ph.D., said in the company’s own release this morning.

“Genmab is exceptionally well-positioned to maximize the potential of acasunlimab, and we are confident about the prospect of taking acasunlimab into late-stage development as our second wholly owned Genmab asset in addition to Rina-S,” van de Winkel added. “We look forward to our continued partnership with BioNTech on other pipeline programs.”

The CEO also pointed out that acasunlimab’s “potential to impact patients with metastatic non-small cell lung cancer” had been demonstrated by “promising initial results” presented at the 2024 American Society of Clinical Oncology Meeting in June.

BioNTech had seemed fully on board the acasunlimab train when those results were announced, touting a 12-month overall survival rate of 69% in patients with previously treated PD-L1-positive metastatic NSCLC who received a combination of acasunlimab and Keytruda.

“Most patients with [metatstatic] NSCLC have limited treatment options following progression on first-line checkpoint inhibitor therapy,” BioNTech Chief Medical Officer Özlem Türeci, M.D., said at the time. “The data of our phase 2 trial show that the combination of acasunlimab with PDL1-blockade may be a suitable approach in this heavily pretreated patient population.”