Ona Therapeutics raises $86.6 M Series B to advance first-in-class ADCs into clinical development

Ona Therapeutics (“Ona”), a global biopharmaceutical company pioneering first-in-class antibody-drug conjugates (ADCs) to address treatment-resistant cancers, today announced the closing of an oversubscribed $86.6 million Series B financing. The round was co-led by new investors Columbus Venture Partners and Mérieux Equity Partners, with participation from additional investors COFIDES and Korys, alongside all existing investors Alta Life Sciences, Asabys Partners, Bpifrance, as part of the InnoBio investment strategy, CDTI through SICC Innvierte, FundPlus NV and Ysios Capital.

The proceeds will be used to advance the clinical development of Ona’s lead program, ONA-255, a first-in-class ADC initially focused on breast cancer, and to progress ONA-389, a second first-in-class ADC targeting colorectal cancer. ONA-255 is designed to address treatment-resistant tumor biology through a differentiated mechanism aimed at improving the therapeutic index compared to earlier approaches. ONA-389 will advance toward first-in-human studies, expanding Ona’s pipeline in indications with significant unmet need. Ona Therapeutics currently retains full worldwide commercial rights to all its assets. 

Valerie Vanhooren, PhD, Co-Founder and Chief Executive Officer at Ona Therapeutics, said: “The oversubscribed Series B marks an important step to advancing ONA‑255 toward clinical proof of concept in breast cancer, while progressing early clinical development activities for ONA‑389 in colorectal cancer. We are proud to have assembled a high-quality syndicate of investors who share our conviction in the differentiated science behind Ona’s novel targets and their potential to address drug resistance. Supported by a highly experienced and talented team, this financing strengthens our commitment to tackling hard-to-treat cancers through meaningful innovation and addressing the significant unmet need faced by patients with limited treatment options.”

Jose Mesa, Partner at Columbus Venture Partners, and incoming Board member at Ona Therapeutics, remarked: “At Columbus, we look for companies that combine world-class science with a clear path to clinical impact. Ona is a strong example of that. Its work on cancer resistance and metastasis addresses one of the most important challenges in oncology, and its pipeline, led by ONA-255 and followed by ONA-389, provides a compelling opportunity to build a differentiated oncology platform. We are delighted to support Valerie and the team in this next stage of growth, bringing Columbus’ experience in developing and scaling innovative oncology companies.”

Valérie Calenda, Managing Partner and Head of Innovation at Mérieux Equity Partners, and incoming Board member at Ona Therapeutics, added: “Ona exemplifies the kind of high-impact company we look to partner with: a high-quality team building a compelling and differentiated pipeline, combining deep biological insight with a highly focused development strategy. The strength of Ona’s preclinical data package behind ONA-255, the breadth of opportunity across the pipeline, and the team’s clear vision for translating novel biology into clinically meaningful therapies give us strong confidence in the Company’s long-term potential. We are excited to co-lead this financing and support Ona’s next phase of growth.”

Ona is advancing a differentiated ADC pipeline focused on cancers with high unmet medical need. Through its proprietary patient-driven target discovery platform, the Company has identified novel tumor-specific antigens and epitopes that enable highly efficient internalization and targeted payload delivery to cancer cells. This approach is designed to maximize therapeutic activity while minimizing on-target toxicities and addressing key biological mechanisms of resistance in advanced tumors.

The financing comes at a pivotal inflection point in Ona’s growth as the Company enters clinical development and begins generating initial human safety and efficacy data for ONA-255. This momentum is supported by a highly experienced clinical leadership team, including Antoine Yver, Chair of the Board, bringing deep expertise in global oncology drug development; Pamela Klein, Independent Board Member, with extensive experience advancing oncology therapeutics; Aleix Prat, a world-renowned breast cancer oncologist and Chair of the Advisory Board; and Jutta Amersdorffer, Chief Medical Officer, leading clinical strategy and execution. Together, this leadership team positions Ona strongly to deliver on key milestones and advance its innovative pipeline for patients.

In connection with the financing, Jose Mesa, Partner at Columbus Venture Partners; Valérie Calenda, Managing Partner at Mérieux Equity Partners; and Eva Van Overmeire, Senior Investment Manager at Korys, will join Ona’s Board of Directors.

For more information, please contact:

Optimum Strategic Communications
Zoe Bolt, Eleanor Cooper, Nellie Stephens
+44 (0) 203 882 9621
ona@optimumcomms.com
 

About Ona Therapeutics
Ona Therapeutics is a spin‑off from IRB Barcelona and ICREA, based at the Barcelona Science Park (PCB), and a biopharmaceutical company pioneering the development of first‑in‑class antibody‑drug conjugates (ADCs) to address treatment‑resistant cancers.

Ona applies a patient‑driven discovery platform to identify novel tumor‑specific antigens and epitopes associated with resistance biology and advanced disease. The Company’s approach integrates deep biological insight with rigorous target validation, antibody engineering, optimized payload selection, and validated linker‑payload technologies to generate precision‑engineered ADCs with the potential to enhance therapeutic activity while limiting on‑target toxicity.

Its precision-engineered ADC pipeline comprises first-in-class programs targeting aggressive and refractory cancer indications. Its lead ADC, ONA‑255, initially focused on breast cancer, is progressing toward clinical development. A second program, ONA‑389, is advancing behind it in clinical development in colorectal cancer, further strengthening the Company’s pipeline in high unmet need indications. The Company is also expanding its focus into additional aggressive cancers, including gastric and liver. For further information, visit our website here https://ona-therapeutics.com/.

About Columbus Venture Partners
Columbus Venture Partners is a Spanish venture capital firm (Valencia, 2016) specialized in biotechnology and life sciences. With over €800 million in assets under management, the firm operates a differentiated investment model and has built a strong track record in developing industrial platforms for advanced therapies. Columbus Venture Partners plays an active role in the creation and growth of more than 60% of its portfolio companies. For more information, refer to www.columbusvp.com.
 

About Mérieux Equity Partners
Mérieux Equity Partners (‘MxEP’) is an AMF-accredited investment firm specialising in the healthcare sector. With over €1.6 billion in assets under management through two dedicated strategies: Innovation and Buyout, MxEP supports companies ranging from start-ups to established leaders. 

The investment in Ona Therapeutics represents the second investment for MxEP’s Innovation fund, Mérieux Innovation 2 fund (“MI2”), following the investment in Spanish diagnostic company, deepull, in 2025. 

Based in Lyon and Paris, with a strong industrial footprint, MxEP's team of healthcare specialists and investment professionals invests in European companies with significant growth and transformation potential. By providing financial and operational resources, MxEP enables businesses to achieve their goals and create value from innovative healthcare products and services which improve patient outcomes. For more information, please visit www.merieux-partners.com.