ASCO 2025: OnCusp Shares Positive Phase Ia Data for CUSP06 in Ovarian Cancer

OnCusp Therapeutics has reported encouraging Phase Ia results for its antibody-drug conjugate (ADC), CUSP06, in patients with platinum-resistant/refractory ovarian cancer and other solid tumors. Presented at ASCO 2025, the trial evaluated safety, tolerability, pharmacokinetics, and preliminary efficacy. As of May 13, 37 participants received doses ranging from 1.6–5.6 mg/kg every three weeks, with a median of four prior treatment lines.

In heavily pretreated high-grade serous ovarian cancer (HGSOC) patients, the overall response rate (ORR) was 36% (9 of 25), including five confirmed responses. Some dosing cohorts showed ORRs up to 50%, with a 92% clinical benefit rate and 45% CA-125 response in GCIG-evaluable HGSOC patients. CUSP06 was well-tolerated, with manageable hematologic toxicity.

These findings support continued development in Phase Ib trials targeting CDH6-positive tumors. The FDA granted Fast Track designation for CUSP06 in platinum-resistant ovarian cancer following IND clearance in 2023.

10-06-2025