P1, N=125, Recruiting, Daiichi Sankyo, Inc. | Trial completion date: Nov 2023 --> Feb 2026 | Trial primary completion date: Nov 2023 --> Feb 2026

19 patients with platinum-resistant/refractory ovarian cancer were evaluated across 8 dose levels (0.2 to 2.4 mg/kg IV every 3 weeks, 21 day cycles) (data cutoff 01APR2023). Most pts had ≥ 3 prior treatment lines in the metastatic setting. The most common treatment-related adverse events were Gr1 peripheral neuropathy (n=3), Gr1/2 fatigue (n=2), and Gr1 nausea (n=2).

Conclusions In participants with heavily-pretreated CLDN6-expressing ovarian cancer, the novel TORL-1-23 ADC has a favorable safety/tolerability profile and encouraging antitumor activity in a phase 1 dose finding study. Further evaluation in ovarian cancer and other CLDN6+ cancers is warranted.

TORL-1-23 has a favorable safety/tolerability profile and PK characteristics with preliminary antitumor activity in pts with heavily-pretreated CLDN6-expressing ovarian and testicular cancers. Doses above the historic MTD for MMAE containing ADCs may be explored given the safety/tolerability and PK data observed up to 2.4 mg/kg. Dose finding is ongoing to identify the MTD and optimal doses for subsequent development.

Patient-derived xenograft models were also created through intracranial injection of multiple ATRT patient cell lines, and ongoing work will evaluate locoregional administration of CLDN6-directed CAR T cells in orthotopic xenograft models to test in vivo efficacy. This work highlights the potential for targeting CLDN6 via CAR T cell therapy in patients with ATRT as a novel therapeutic strategy for these devastating tumors.