Debiopharm ups its bispecific conjugate push

Debiopharm has upped its bet on an anti-HER2 x HER3 bispecific ADC, following a deal with SunRock Biopharma on Tuesday. The two companies have been working together on ADCs since September 2023, when they mentioned HER2 and HER3 as potential targets; now Debiopharm has exercised an option to license SunRock’s anti-HER2 x HER3 antibody SRB21, for development as an ADC known as Debio 2512. Financial terms weren’t disclosed. A look at OncologyPipeline shows only a handful of other HER2 x HER3-targeting projects, the most famous of which is Merus’s MAb Bizengri. Although this received FDA accelerated approval last December for the niche of second-line, NRG1 fusion-positive pancreatic cancer and NSCLC, Merus clearly didn’t see much value here, selling commercial rights to Partner Therapeutics for an undisclosed fee. Debiopharm might see broader use for Debio 2512: the company noted that targeting HER2 and HER3 could “overcome resistance mechanisms that limit current HER2-directed therapies”, suggesting it might be targeting the same indications as AstraZeneca and Daiichi’s HER2 ADC Enhertu, which sold $3.8bn in 2024. Debiopharm is also developing a preclinical anti-HER3 ADC, Debio 0532; however, problems with Merck and Daiichi’s similarly acting patritumab deruxtecan have cast doubt on this approach.

The HER2 x HER3 pipeline

Note: *formerly Hillstream BioPharma. Source: OncologyPipeline.