Introduction: Rivoceranib is a selective vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor with potent antitumor activity. Rivoceranib is metabolized in the liver mostly by cytochrome P450 (CYP)3A4/5, with minor contributions from CYP2D6, CYP2C9, and CYP2E1. In vitro and in vivo studies suggest rivoceranib may interact with various CYP substrates, including CYP 1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A. The purpose of study is to evaluate the effect of rivoceranib on the pharmacokinetics (PK) of various CYP substrates. Methods: This study was an open-label, 2-treatment, fixed-sequence drug-drug interaction phase 1 study evaluating the impact of multiple oral doses of 700 mg rivoceranib on the single-dose PK of CYP enzyme substrates administered in a 5+1 probe cocktail (caffeine [CYP1A2], S- and R-warfarin [CYP2C9] + vitamin K, omeprazole [CYP2C19], dextromethorphan [CYP2D6], and midazolam [CYP3A]) in healthy volunteers (N=32). On day 1, volunteers received a single dose of the 5+1 cocktail comprising 200 mg caffeine, 10 mg S- and R-warfarin with 10 mg vitamin K, 40 mg omeprazole, 30 mg dextromethorphan, and 2 mg midazolam. Blood samples were collected predose on day 1 and up to 120 hours post-dose for PK analyses of the substrates in the 5+1 cocktail. On days 6 to 15, volunteers received 700 mg rivoceranib once daily for 10 consecutive days with a single dose of the 5+1 cocktail administered on day 11. Blood samples were collected predose on day 11 and up to 120 hours post cocktail dosing (day 16) for PK analyses. Each dosing was under fasted conditions. There was a washout period of 5 days between Day 1 dosing and the first rivoceranib dose on Day 6; the 2 cocktail dosings were spaced by 10 days. Results: Rivoceranib reduced caffeine AUC0-inf by 15%, and did not change caffeine Cmax, indicating a minimal effect of rivoceranib on the PK of CYP1A2 substrates. S-warfarin and R-warfarin AUC0-inf increased by 68% and 32%, respectively, and Cmax by 19% and 15%, respectively, when co-administered with rivoceranib, indicating rivoceranib weakly inhibits CYP2C9. Rivoceranib appeared to act as a moderate inhibitor of CYP2C19, increasing omeprazole AUC0-inf 3.3-fold and increasing Cmax 2-fold. Dextromethorphan metabolism (CYP2D6) was inhibited, with a 2- to 2.7-fold increase in dextromethorphan exposure. Rivoceranib appeared to moderately inhibit midazolam metabolism by CYP3A4, with 2.4- to 2.8-fold increases in midazolam exposures. Conclusion: In the analysis, the effect of rivoceranib on the PK of CYP1A2 substrates did not appear to be clinically significant. Rivoceranib may inhibit the metabolism of CYP2C9, CYP2C19, CYP2D6, and CYP3A4 substrates, suggesting that dose adjustment of substrates of these CYP isozymes and/or cautiously monitoring patients’ adverse events may be needed when they are co-administered with rivoceranib. Citation Format: Janelle Weyer, Xianzhang Meng, Jennifer Lee, Joseph Reitano, Vinoo Urity, Cheol-Hee Park, Bill Strickland, Jan Van Tornout, Seong Jang. Evaluation of the effect of rivoceranib on the pharmacokinetics of cytochrome P450 enzyme substrates in healthy volunteers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT273.

e15122 Background: Rivoceranib is a novel oral tyrosine kinase inhibitor that potently and selectively inhibits VEGFR2. Rivoceranib is being investigated for indications targeted towards solid malignancies as either monotherapy or in combination with other anticancer therapies. Herein, we assessed the bioequivalence of a single dose of rivoceranib administered as 4 different formulations in healthy subjects. Methods: This single-center, open-label, randomized, single-dose, 4-way crossover study evaluated the bioequivalence of 4 different formulations of rivoceranib oral tablets in healthy adults. Each subject participated in 4 treatment periods, where they were randomized to 1 of 4 sequences: ABCD, BDAC, CADB, and DBAC (Formulation A = rivoceranib 250 mg tablet/clinical formulation used in the pivotal phase 3 study, Formulation B = rivoceranib 200 mg tablet/clinical formulation used in early clinical studies, Formulation C = rivoceranib 250 mg tablet/formulation to be developed for future use, Formulation D = rivoceranib 250 mg tablet/to-be-marketed formulation). Results: Of the 60 subjects enrolled, 66.7% were male, 88.3% were white, and median age was 43 years. The median plasma rivoceranib Tmax was similar following all treatments (2 hours post-dose). The 90% CIs around the geometric mean ratios (GMRs) of plasma rivoceranib AUC0-t, AUC0-inf, and Cmax for Formulation B vs. Formulation A and Formulation D vs. Formulation A were within the 80-125% reference interval, demonstrating bioequivalence between Formulation B and Formulation A as well as Formulation D and Formulation A. The 90% CIs around the GMRs of plasma rivoceranib AUC0-t, AUC0-inf, and Cmax for Formulation C vs. Formulation A were slightly outside of the 80%-125% reference interval. Conclusions: Formulations B (clinical formulation used in early clinical studies) and D (to-be-marketed formulation) were bioequivalent to Formulation A (clinical formulation used in the pivotal phase 3 study). Formulation C (formulation to be developed for future use) and Formulation A were similar, but the difference was slightly outside of the bioequivalence criteria. It remains to be evaluated whether the difference in bioavailability between Formulation C and Formulation A is clinically meaningful. Clinical trial information: NCT05287360 . [Table: see text]