Ona Therapeutics raises $86.6m Series B to bring ADCs into clinic
Ona Therapeutics has closed an oversubscribed $86.6 million Series B financing to fund the clinical development of two first-in-class antibody-drug conjugates (ADCs), marking the Barcelona-based spin-out's transition from preclinical to clinical-stage company.
The round was co-led by Columbus Venture Partners and Mérieux Equity Partners, both new investors, with participation from COFIDES and Korys. All existing investors — Alta Life Sciences, Asabys Partners, Bpifrance (via its InnoBio strategy), CDTI through SICC Innvierte, FundPlus NV and Ysios Capital — also participated. Three incoming board seats have been allocated to Columbus, Mérieux, and Korys.
The pipeline
Proceeds are earmarked for two programmes. ONA-255, the lead asset, is directed at treatment-resistant breast cancer and is advancing toward clinical proof-of-concept studies; the company positions it as designed to improve the therapeutic index relative to earlier ADC approaches by targeting novel tumour-specific antigens identified through a proprietary patient-driven discovery platform. ONA-389, targeting colorectal cancer, will move toward first-in-human studies. Ona said it retains full worldwide commercial rights to both assets.
Valerie Vanhooren, co-founder and chief executive, said the financing reflects investor "conviction in the differentiated science behind Ona's novel targets and their potential to address drug resistance." Jose Mesa, partner at Columbus Venture Partners and an incoming board member, described the company's focus on cancer resistance and metastasis as "one of the most important challenges in oncology."
Ona was founded as a spin-off from IRB Barcelona and ICREA and is headquartered at the Barcelona Science Park. The clinical leadership team includes Antoine Yver as chair, Jutta Amersdorffer as chief medical officer, and Aleix Prat — a breast cancer oncologist — as chair of the advisory board.
Market context
The ADC sector has attracted substantial capital and deal-making activity in recent years, driven by the clinical and commercial success of agents such as trastuzumab deruxtecan in HER2-positive breast and lung cancers. That success has prompted a wave of next-generation programmes seeking to improve on tolerability, payload potency, and breadth of target coverage. Ona's emphasis on novel tumour-specific antigens and resistance biology is a differentiated angle in a crowded field; however, first-in-class claims at the preclinical stage require validation in human studies before investors and clinicians can assess competitive positioning with confidence.
The financing also reflects continuing appetite among European venture capital for oncology platforms, with French investor Mérieux Equity Partners — which manages over €1.6 billion in assets — making this its second investment from its MI2 Innovation fund. Columbus Venture Partners, a Valencia-based firm with more than €800 million under management, brings active portfolio-building experience in advanced therapies. The round's oversubscription suggests the syndicate was assembled with room to grow, though Ona has not disclosed a post-money valuation.
Key near-term milestones to watch include the initiation of the ONA-255 Phase 1/2 study, first safety and tolerability data in breast cancer patients, and a first-in-human filing timeline for ONA-389. Ona has also flagged expansion into gastric and liver cancers as longer-term pipeline ambitions, though no candidates or timelines were disclosed in this release.