US-based OnCusp Therapeutics has reported initial Phase Ia data from its ongoing multicentre dose escalation and expansion Phase I trial of the cadherin-6 (CDH6)-directed antibody-drug conjugate (ADC), CUSP06, in individuals with platinum-refractory/resistant ovarian cancer and other advanced solid tumours.
The company announced the data at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting held in Chicago, Illinois.
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By GlobalDataThis open-label, first-in-human trial’s primary goal is to evaluate the tolerability, safety, preliminary efficacy, and pharmacokinetics of the ADC.
The Phase Ia segment aims to establish the recommended doses for expansion, while Phase Ib will further evaluate the efficacy and safety in selected tumour types.
OnCusp noted that as of 13 May, data for 37 subjects who were given the ADC every three weeks at doses ranging from 1.6 to 5.6 mg/kg are available.
These individuals had undergone a median of four previous therapy lines. Notably, promising efficacy was said to be observed in those with heavily pretreated platinum-resistant high-grade serous ovarian cancer (HGSOC), without pre-selecting for CDH6.
The overall response rate (ORR) in HGSOC was 36%, with nine out of 25 patients showing responses, including five confirmed responses.
Additionally, 50% ORR was observed in specific dosing cohorts. The clinical benefit rate was reported at 92%, and CA-125 responses were observed in 45% of Gynecologic Cancer InterGroup (GCIG)-evaluable HGSOC subjects.
CUSP06 claims to have demonstrated a well-tolerated safety profile, with manageable haematologic toxicities as the widespread treatment-related adverse events.
These Phase Ia efficacy and safety outcomes support the continued investigation of the ADC in platinum-resistant HGSOC and other tumours which are CDH6-positive, in the Phase Ib expansion cohorts.
OnCusp Therapeutics CEO and co-founder Dr Bing Yuan said: “We are excited by the early results, especially in platinum-resistant HGSOC, which demonstrated promising activity in a heavily pretreated population without requiring CDH6 biomarker selection.”
CUSP06 secured fast-track designation from the US Food and Drug Administration (FDA) for the treatment of platinum-resistant ovarian cancer, following the investigational new drug (IND) clearance for the Phase I trial, in August 2023.
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