Ona Therapeutics bags $86.6m Series B for stealth ADC push

The company said the proceeds will support the development of its ADC pipeline, led by ONA-255, which is advancing toward clinical testing. While the target of ONA-255 has not been publicly disclosed, Ona has described the programme as a first-in-class ADC. Ona’s pipeline also includes ONA-389, another oncology programme emerging from the company’s target discovery platform. The secrecy around the target suggests Ona is still protecting the competitive positioning of a programme that sits in one of the hottest areas of oncology drug development.

ADCs combine the targeting specificity of monoclonal antibodies with highly potent cytotoxic drugs. The antibody binds to a protein on the surface of cancer cells and is internalised, allowing the attached payload to be released inside the cell. As highlighted in recent reviews of the field, the effectiveness of an ADC depends not only on target selection but also on the interplay between antibody, linker and payload. Advances in linker stability, payload chemistry and conjugation technologies have helped transform ADCs from a relatively niche modality into one of the fastest-growing areas of oncology drug development, particularly in solid tumours.

For Ona, the financing marks a transition from target discovery and preclinical research into clinical execution. The company was founded in Barcelona in 2019 as a spin-off from IRB Barcelona and ICREA, building on research from the laboratory of Salvador Aznar Benitah. Ona was established to translate insights from metastasis biology into therapies aimed at preventing or treating cancer spread, which remains the leading cause of cancer-related death.

The company’s most advanced publicly known programme before its ADC focus was ONA-01, a monoclonal antibody targeting CD36. Research from the founding laboratory identified CD36 as a key regulator of metastasis in several tumour types, and preclinical studies suggested that blocking the receptor could impair metastatic dissemination.

The new Series B follows a €30m Series A financing announced in 2020, which was intended to advance Ona’s metastasis-focused therapeutic strategy. Since then, the company has increasingly aligned its development plans with ADCs.