Ona's $86.6M Raise Signals a New Era for Precision Cancer Therapy

BARCELONA, Spain – June 04, 2026 – In a move that sends a clear signal about the future of oncology, Barcelona-based Ona Therapeutics announced today the closing of an oversubscribed $86.6 million Series B financing. The funding is a powerful endorsement of the company's strategy to develop a new generation of cancer therapies designed to succeed where others have failed. This capital infusion will propel Ona from a promising preclinical company into a clinical-stage entity, advancing its first-in-class antibody-drug conjugates (ADCs) into human trials for treatment-resistant breast and colorectal cancers.

The financing was co-led by new investors Columbus Venture Partners and Mérieux Equity Partners, attracting a syndicate of new and existing backers who see profound value in Ona's differentiated approach. For patients battling the most stubborn forms of cancer, this milestone represents a tangible step toward translating deep biological understanding into life-altering treatments.

Beyond the First Wave: Redefining the ADC Strategy

Antibody-drug conjugates are often described as “biological missiles,” engineered to deliver potent chemotherapy payloads directly to cancer cells while sparing healthy tissue. The field is one of the most dynamic in oncology, with blockbuster drugs like Enhertu and Kadcyla having already transformed patient outcomes. However, this success has created a crowded landscape, with many companies focusing on well-established cellular targets.

Ona Therapeutics is charting a different course. Rather than competing on familiar ground, the company is pioneering therapies that address novel targets. Its competitive edge lies in a proprietary, patient-driven discovery platform developed from its origins as a spin-off from Spain's prestigious Institute for Research in Biomedicine (IRB Barcelona) and ICREA. By analyzing real-world patient biopsies, Ona identifies unique tumor-specific antigens that are central to the biology of treatment resistance and metastasis.

This approach allows the company to build “first-in-class” ADCs. It’s a strategy focused not on creating a better version of an existing weapon, but on designing a new key for a lock that no one else has been able to open. This is precisely the kind of nuanced innovation that drives lasting value, moving beyond incremental improvements to create entirely new therapeutic possibilities.

Targeting the Toughest Cancers: ONA-255 and ONA-389

The proceeds from the Series B will primarily fuel the clinical development of Ona's two lead candidates. The first, ONA-255, is aimed at breast cancer—a disease that, despite advances, remains a formidable global challenge. According to the World Health Organization, breast cancer accounted for 2.3 million new diagnoses and 670,000 deaths globally in 2022. ONA-255 is engineered to help a population of refractory patients for whom existing treatments are no longer effective, addressing a critical unmet need.

The company’s second program, ONA-389, targets advanced colorectal cancer, another leading cause of cancer mortality worldwide. By focusing on microsatellite stable (MSS) tumors, a subtype notoriously difficult to treat with immunotherapy, ONA-389 enters a therapeutic area with few good options. The financing will advance ONA-389 toward first-in-human studies, expanding the company’s pipeline and its potential impact.

“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,” said Valerie Vanhooren, PhD, Co-Founder and Chief Executive Officer at Ona Therapeutics. “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.”

The Power of a Strategic Syndicate

The composition of the investor syndicate speaks volumes about the credibility of Ona's science. Co-lead Mérieux Equity Partners brings a legacy of deep healthcare expertise, with an innovation-focused platform designed to nurture companies like Ona from the lab to the clinic. The addition of Valérie Calenda, a seasoned scientist and investment professional from Mérieux, to Ona's board provides invaluable strategic guidance.

“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,” commented Valérie Calenda, Managing Partner at Mérieux Equity Partners.

Similarly, co-lead Columbus Venture Partners adds its experience in scaling innovative biotech ventures. “Its work on cancer resistance and metastasis addresses one of the most important challenges in oncology,” noted Jose Mesa, Partner at Columbus Venture Partners, who will also join the board. This is not just capital; it is strategic validation from experts who understand the immense scientific and clinical hurdles in oncology and believe Ona has the strategy to overcome them.

Leadership as a Cornerstone for Clinical Success

Technology alone does not bring a drug to market. Recognizing this, Ona has strategically built a leadership team with the specific experience needed to navigate the complexities of global clinical development. The appointment of Dr. Antoine Yver as Chair of the Board is particularly noteworthy. With a track record at Daiichi Sankyo and AstraZeneca, Dr. Yver was instrumental in the development of 13 landmark cancer drugs, including the revolutionary ADC, Enhertu. His direct experience in the field provides Ona with a proven playbook for success.

He is joined by other seasoned executives, including Independent Board Member Dr. Pamela Klein, who helped develop foundational therapies like Herceptin and Rituxan at Genentech, and Dr. Aleix Prat, a world-renowned breast cancer oncologist who serves as Chair of the Advisory Board and was a key figure in identifying the target for ONA-255. This combination of scientific vision and clinical execution capability positions Ona Therapeutics to effectively translate its financial resources into clinical milestones, demonstrating a mature strategy for improving lives.