Solstice Oncology secures $225M Series A to launch FDA-cleared Phase 2 CTLA-4 antibody trial

Solstice Oncology, a cancer-focused startup that emerged from stealth in February, announced a $225 million Series A financing round to fund its early-stage programs.

The capital will be used to advance porustobart, a CTLA-4 antibody acquired from China’s Harbour BioMed, which has already received an FDA investigational new drug application.

The company plans to begin a Phase 2 neoadjuvant study in advanced colon cancer, combining porustobart with Merck’s Keytruda, with patient enrollment expected to start in the fourth quarter.

Data from the trial are projected to be reported in the second half of 2027, aligning with Solstice’s goal to treat cancer earlier in the disease course.