Harbour BioMed’s partner Solstice Oncology has raised $225m in funding to advance its lead candidate, porustobart, a neoadjuvant immuno-oncology therapy.
The financing was raised in a Series A round led by RA Capital Management, with participation from Forbion, Canaan Partners and other investors.
Porustobart is a second-generation, Fc-enhanced cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody developed by Harbour BioMed.
The therapy is being investigated for use in two indications, with initial focus on treating microsatellite-stable (MSS) clinical stage II–III colon cancer in the neoadjuvant setting.
Enrolment for a Phase II trial of porustobart in combination with pembrolizumab is scheduled to begin in the fourth quarter of 2026.
The study will evaluate the effect of the combination therapy before surgery in patients with MSS colon cancer, which represents the largest subgroup of colon cancer cases and does not currently benefit from approved immunotherapies.
Harbour BioMed entered a licence and equity partnership with Solstice Oncology in February 2026.
The agreement grants Solstice exclusive rights to develop and commercialise porustobart, also known in Harbour BioMed’s pipeline as HBM4003, outside Greater China.
A Phase II clinical trial previously conducted by Harbour BioMed tested porustobart with the PD-1 inhibitor tislelizumab in patients with MSS metastatic colorectal cancer without liver metastases.
The combination yielded a 30% objective response rate, with seven out of 23 patients responding to treatment.
The median duration of response was reported at 8.4 months, and the therapy exhibited a favourable safety profile.
These results will inform further studies of porustobart in combination with PD-(L)1 inhibitors for patients at earlier disease stages.
Harbour BioMed founder, chairman and CEO Dr Jingsong Wang said: “We are pleased to see Solstice Oncology launch with strong support from leading investors and advance porustobart into the neoadjuvant setting.
“As the originator of porustobart and a partner of Solstice, we look forward to supporting the continued development of this differentiated CTLA-4 antibody and exploring its potential to benefit patients worldwide.”
In November 2025, Harbour BioMed and Evinova China formed a collaboration to implement AI and digital technologies to improve biologics development.
