Background: INV-1120 is a highly selective, orally available inhibitor of PGE2-EP4, an immunosuppressive mediator in the TME. Objectives of this Phase I study in Chinese patients was to assess safety and pharmacokinetics and define a RP2D of INV-1120. Methods: Escalation was based on a 3+3 sequential design starting @ 60mg QD po as guided by the FIH trial in a Western population. DLT evaluation period was 4 weeks. Efficacy (RECIST 1.1) was evaluated every 8 weeks. Blood samples were collected for pharmacokinetics. Results: 9 patients were enrolled and treated with INV-1120 in 3 dose cohorts (60, 100, 150mg, n=3 each). All 9 patients had CRC. All 9 patients were evaluable for activity. Stable disease was observed in 3 of 9 (33.3%) patients. The median PFS (95% CI) was 55.0 days (range: 42.0-NE). The plasma exposure increased from 60 mg to 100 mg. Maximum concentrations were achieved approximately 2 hours post dose. The half-life was approximately 5-16 hours. No accumulation was noted after multiple doses. The PK profiles were similar to that in a Western population [NCT04443088, presented @ SITC 2022]. Conclusions: Single agent INV-1120 was generally well tolerated in the Chinese population and showed preliminary signs of antitumor activity in terms of stable disease. Data from this trial were in line with data in a Western population [NCT04443088, presented @ SITC 2022] and warrant further Global development. Due to the combined findings of this study and the above-mentioned sister study, the doses of 60, 100 and/or 150mg QD are proposed for further exploration in combination trials.Clinical trial information: ChiCTR20211872. Clinical trial information: CTR20211872.

No DLTs were observed and the escalation was concluded at 150mg QD primarily due to saturation pharmacokinetics. All 9 patients had ≥1 TEAE. No ≥ Grade 3 were reported. Related TEAEs occurred in 7 patients (77.8 %) with no ≥Grade 3 related TEAEs.