Solstice Oncology Launches with $225M Series A, Licenses CTLA-4 Antibody from Harbour BioMed
- Solstice Oncology launched publicly with an oversubscribed $225 million Series A round, led by a major life-sciences investment firm with support from several other biotech investors.
- Harbour BioMed granted Solstice an exclusive ex-Greater-China license plus an equity stake to develop porustobart, a next-generation Fc-enhanced CTLA-4 antibody Harbour BioMed discovered.
- Solstice aims to move the antibody into earlier, neoadjuvant use ahead of surgery, rather than reserving it for later-line metastatic cancer.
- The approach is backed by earlier data showing porustobart plus a PD-1 inhibitor produced encouraging, durable responses in hard-to-treat MSS colorectal cancer patients without liver metastases.
- New funds will support a Phase 2 trial combining porustobart with Keytruda, plus a separate Phase 2 colon cancer study opening enrollment later this year.
• Textbook China-to-West playbook: a Western syndicate (RA Capital-led) capitalizes a new US NewCo to develop a China-originated clinical asset outside Greater China — now the default route for getting Chinese-discovered biologics into global markets. • License-plus-equity, not a straight license, is the tell: Harbour BioMed keeps upside tied to Solstice's success rather than taking cash alone, and an oversubscribed $225M Series A for a single asset signals unusually strong investor conviction. • The real strategic bet is timing — pushing porustobart into neoadjuvant use instead of crowded late-line CTLA-4/PD-1 combinations is differentiated, but also less-trodden regulatory and commercial ground. • Everything hinges on execution: the prior 'encouraging' late-line colorectal data is rationale, not proof; the coming Keytruda-combo and colon cancer Phase 2 readouts are the real test of the thesis.
Fierce Biotech Fundraising Tracker '26: Encoded finagles $275M series F; Solstice rises with $225M ↗