A Spanish biotech banks $87M to make differentiated ADCs

An article from Emerging biotech A Spanish biotech banks $87M to make differentiated ADCs Ona Therapeutics, a Barcelona-based drugmaker, is developing next-generation drugs it says could help patients with advanced forms of breast and colorectal cancers. Published June 4, 2026 Gwendolyn Wu Senior Reporter Share Copy link Email LinkedIn X/Twitter Facebook Print License Add us on Google Barcelona-based biotechnology startup Ona Therapeutics announced Thursday it raised an $86.6 million Series B round to launch a pair of antibody-drug conjugates into clinical development for breast and colorectal cancers. Antibody-drug conjugates, or ADCs, are now a pillar of cancer care. More than 20 are approved for different tumor types, and some are now working their way into earlier treatment lines, where they might be able to supplant traditional chemotherapy. AstraZeneca and Daiichi Sankyo’s Enhertu, for example, is now a multibillion-dollar seller available in multiple breast cancer settings. Many others that are available or in development are aiming for similarly expansive use. Newer biotechs aiming to break into the field are trying to improve the technology in one way or another. Some are working with proprietary “linkers” that connect an ADC’s targeting molecule to its toxic payload. Others are delivering different types of tumor-killing molecules, or simultaneously homing in on multiple targets. Ona is instead focusing on new targets it believes can help address drug resistance, a strategy CEO Valerie Vanhooren says might be able to help those who haven’t responded to other therapies. Vanhooren’s team initially looked to monoclonal antibodies to find these kinds of drugs, but found they weren’t potent enough to eliminate the treatment-resistant tumors they hoped to pursue. Ona then turned to ADCs instead, specifically searching for targets expressed in cancer cells but “barely” detectable in healthy tissue, she said. “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,” Vanhooren told BioPharma Dive. The biotech is initially developing its lead asset, dubbed ONA-255, in the third-line setting in breast cancers that are hormone receptor-positive but negative for the protein HER2. These slow-growing tumors make up more than 70% of metastatic breast cancer cases. And while patients can get different types of hormone therapies and targeted medications called CDK 4/6 inhibitors to slow progression and hold disease in check, there are few drug options afterwards. “There are not novel targets and not novel treatments there,” Vanhooren said. Ona hasn’t disclosed the target for ONA-255. But it’s same one a second preclinical prospect, a colorectal cancer treatment called ONA-389, homes in on. The company expects to advance its first drug into human studies in the near future, but didn’t give an estimated timeframe. “[Ona’s] work on cancer resistance and metastasis addresses one of the most important challenges in oncology,” said Jose Mesa, a partner at Columbus Venture Partners, in a statement. Columbus co-led the Series B round with Mérieux Equity Partners, and they were joined by eight other investment firms. Ona launched with €30 million, or about $34 million, in a Series A round announced in 2020. Among its board members are Antoine Yver, a former AstraZeneca and Daiichi Sankyo executive who helped develop Enhertu, and Pamela Klein, a veteran of Genentech who led development of cancer drugs like Herceptin and Rituxan. Add us on Google Share Copy link Email LinkedIn X/Twitter Facebook Print purchase licensing rights Filed Under: Biotech