A phase I dose-escalation and expansion study of RMX1002, a selective E-type prostanoid receptor 4 antagonist, as monotherapy and in combination with anti-PD-1 antibody in advanced solid tumors

作者：Dan Liu, Jifang Gong, Jian Zhang, Yongqian Shu, Hao Wu, Tianshu Liu, Yanhua Xu, Lijia Zhang, Min Li, Xichun Hu, Lin Shen · 发表于：Investigational New Drugs · 年份：2025 · DOI：10.1007/s10637-025-01512-z · 被引用次数：2 · 研究领域：Angiogenesis and VEGF in Cancer、Nanoplatforms for cancer theranostics、Photodynamic Therapy Research Studies

RMX1002 (grapiprant) is a selective E-type prostanoid receptor 4 (EP4) antagonist and a promising candidate for cancer therapy, potentially enhancing anti-tumor immune responses. This study aimed to evaluate the safety, pharmacokinetics, pharmacodynamics, and efficacy of RMX1002 as monotherapy and in combination with anti-PD-1 antibody toripalimab for advanced solid tumors. This multicenter, phase I trial enrolled patients with histologically or cytologically confirmed advanced solid tumors. This study included three phases: Ia (dose-escalation of RMX1002 monotherapy from 200 to 650 mg BID), Ib (dose-escalation from 500 to 650 mg BID in combination with toripalimab), and Ic (dose-expansion of 500 mg BID with toripalimab). Safety, pharmacokinetics, pharmacodynamics, and efficacy were assessed. A total of 45 patients were enrolled (17 in phase Ia, 12 in phase Ib, and 16 in phase Ic). No dose-limiting toxicity was reported, and the MTD was not reached. Overall, 21 patients experienced RMX1002-related adverse events with CTCAE grade ≥ 3. Pharmacokinetics revealed rapid absorption of RMX1002 with the maximum concentration (C max ) reached within 2 to 5 h, and dose-dependent increases in C max and area under the concentration-time curve. The increase in urinary metabolite of PGE2 suggested the inhibition of EP4 signaling pathway. The best response was stable disease, reported in 64.7%, 28.6%, and 18.8% of patients in phase Ia, Ib, and Ic, respectively. RMX1002 was well tolerated an...