Ona Therapeutics, a Barcelona-based biotech developing first-in-class antibody drug conjugates for advanced and treatment-refractory cancers, has raised $86.6 million in Series B funding. The round was co-led by Columbus Venture Partners and Mérieux Equity Partners, with participation from existing investors including Asabys Partners, Ysios Capital, and Alta Life Sciences, plus new backers such as Bpifrance. Ona's ADCs target novel tumor-specific antigens identified from real-world refractory patient samples to address cancers that progress after multiple lines of therapy. The capital will advance ONA-255 into clinical proof-of-concept studies in HR+/HER2- breast cancer and ONA-389 to first-in-human trials in colorectal cancer.
ADC Market Accelerates Clinical Push
The timing aligns with surging interest in next-generation ADCs for solid tumors. Recent sector activity includes multiple large financings and acquisitions that validate differentiated platforms targeting resistance mechanisms. Ona's patient-derived biology approach, which sources targets from how standard-of-care alters cancer at the molecular level, fills a gap left by traditional tumor antigen strategies.
Resistance Biology Limits Current Options
Patients with advanced solid tumors such as HR+/HER2- breast cancer and microsatellite stable colorectal cancer often exhaust approved therapies, leaving few options. Standard monoclonal antibodies frequently fail to deliver sufficient payload in resistant disease settings. Ona selects targets with high expression in metastatic-initiating cells but minimal presence in healthy tissue to improve therapeutic index.
Patient-Derived Targets Drive Differentiation
Ona builds precision-engineered ADCs customized for optimized pharmacokinetics and tolerability. Its pipeline includes ONA-255 and ONA-389 as wholly owned programs plus a dual-payload candidate and an anti-CD36 monoclonal antibody. This contrasts with payload-focused competitors by emphasizing metastatic cell biology discovered through academic partnerships at IRB Barcelona.
"If we can tackle those cells responsible for resistance, you can have a deeper response and you can give these patients a longer quality of life." — Valerie Vanhooren, CEO
European Syndicate Backs Clinical Transition
New co-leads Columbus Venture Partners and Mérieux Equity Partners bring clinical-stage oncology expertise and board-level support. Existing Spanish life sciences investors continued participation, signaling conviction in the metastasis-focused platform. The oversubscribed round follows the appointment of Dr. Antoine Yver, former leader on Enhertu development, as Board Chair.
ADC Sector Expands to $28B by 2035
The antibody-drug conjugate market stands at $18.69 billion in 2026 and is projected to reach $28.41 billion by 2035, growing at 28.88% CAGR. per Mordor Intelligence. Structural drivers include demand for precision agents in metastatic disease and regulatory tailwinds for breakthrough designations. Recent M&A activity, such as Gilead's acquisition of Tubulis, highlights exit potential for innovative European ADC assets.
Leadership Adds Enhertu Expertise
Dr. Antoine Yver joined as Chair in October 2025 after a career spanning Daiichi Sankyo, AstraZeneca, and J&J with 13 approved oncology therapies. His experience guiding Enhertu development directly supports Ona's clinical timelines, with ONA-255 IND-enabling studies underway and first-in-human entry planned for early 2026.
What's Next
With $86.6 million in hand, Ona plans to deliver clinical proof-of-concept data for ONA-255 in third-line breast cancer and initiate first-in-human studies for ONA-389 in colorectal cancer while expanding its dual-payload and anti-CD36 programs.