Ona Therapeutics raised $86.6 million in an oversubscribed Series B to advance two antibody-drug conjugates into human testing. The Barcelona-based biotech will prioritize clinical advancement of ONA-255 in breast cancer, aiming for clinical proof of concept, while pushing ONA-389 toward first-in-human studies in colorectal cancer. The financing will be used to support investigators’ trial work and regulatory milestones through a “rapid and rigorous execution” plan, according to CEO Valerie Vanhooren. Funding came from a syndicate that included Columbus Venture Partners and Mérieux Equity Partners as co-leads, alongside new investors COFIDES and Korys and participation from existing backers. Ona’s pipeline is anchored by a patient-driven target discovery platform designed to identify tumor-specific antigens and epitopes and support targeted payload delivery through efficient internalization. The company is positioning its ADCs for “first-in-class” potential in treatment-resistant oncology indications. The raise underscores investor appetite for differentiated ADC mechanisms in solid tumors, particularly those with limited durable options and high unmet need.