Biopharmaceutical company Harbour BioMed (HKEX: 02142) reported on Wednesday that its partner company Solstice Oncology has launched with a USD225m Series A financing led by RA Capital Management, with participation from Canaan Partners, Forbion and other investors. Solstice will use the funding to advance porustobart, a second-generation Fc-enhanced CTLA-4 antibody, in the neoadjuvant setting.

Solstice is developing porustobart across two clinical indications, beginning with microsatellite-stable clinical stage II-III colon cancer. A Phase 2 trial evaluating porustobart in combination with pembrolizumab is expected to open for enrolment in early Q4 2026.

Porustobart was discovered and developed by Harbour BioMed and licensed exclusively to Solstice for development and commercialisation outside Greater China in February 2026. In a Harbour BioMed Phase 2 study, the treatment combination achieved a 30% objective response rate in late-line MSS metastatic colorectal cancer patients without liver metastases, with a median duration of response of 8.4 months.

The results support further evaluation of porustobart with PD-(L)1 blockade and in earlier lines of treatment, including the neoadjuvant setting.