Phase I/II study of JK06

Dr Nuria Kotecki, medical oncologist and medical lead of the Early Drug Development Program at the Jules Bordet Institute in Brussels, presented interim results from a phase I /II trial investigating a novel ADC directed against the oncofaetal antigen 5T4. The agent links a 5T4-targeting monoclonal antibody to an MMIE cytotoxic payload with a drug-to-antibody ratio of two. The trial uses a standard 3+3 dose-escalation design with backfill cohorts and administers treatment intravenously every three weeks.

To date, 34 patients with advanced solid tumours have been enrolled across multiple dose levels. The safety profile has been acceptable, with few high-grade treatment-related adverse events. One case of grade 5 pneumonitis occurred at a higher dose level, prompting discontinuation of that dose, but no additional severe pulmonary toxicities have been reported. Overall, adverse events have remained manageable and consistent with expectations for ADCs.

Preliminary antitumour activity has been observed at several dose levels. Among patients with NSCLC, five partial responses were recorded in a cohort of 13 patients. One partial response was also seen in a cohort of seven breast cancer patients. These findings suggest meaningful biological activity of the 5T4-targeted ADC, particularly in tumour types known to express this antigen.

Based on the combination of favourable tolerability and early signals of efficacy, the study has now moved into expansion cohorts in breast and lung cancer.