Abstract 4359: Comprehensive pharmacokinetics of Re-phenformin as an anticancer agent for pancreatic cancer therapy in mice: a comparative study with phenformin

Abstract Re-phenformin (Re-(CO)3-phenformin, Re-phen (MW=476.07)), a derivative of phenformin (MW= 206.24), was previously synthesized, purified, and characterized to explore its anticancer potential in comparison to phenformin, a biguanide medication. It has demonstrated enhanced in vitro anticancer efficacy compared to phenformin with significantly lower IC50 values in MiaPaca-2 (0.75 mM) and Kras* cells (0.410 mM) versus phenformin (4.02 mM and 2.36 mM, respectively). The primary aim of this study is to compare the pharmacokinetic (PK) characteristics of Re-phenformin, with phenformin to evaluate their PK parameters. We conducted a PK study in healthy male FVB mice, administering equimolar intravenous doses of Re-phenformin (25 mg/kg, n = 5) and phenformin (12.69 mg/kg, n = 4) using a Saline: Ethanol: Cremophor EL (8:1:1) vehicle. Blood samples were collected at six time points (0.33-24 hours), and organs were harvested at 24 hours post-dose. Quantification was performed using a validated LC-MS/MS method with a Kinetex® 1.7 µm XB-C18 column (LLOQ: 0.25 ng/mL) following liquid-liquid extraction of 10 µL blood spiked with 10 µL internal standard (D5-phenformin) and 200 µL acetonitrile (0.1% formic acid). The mixture underwent vortexing, sonication, centrifugation, and reconstitution in 100 µL mobile phase (ACN: water, 35:65, with 0.1% formic acid). The method yielded 93.91% recovery (CV = 2.10%, N=3) and minimal matrix effects (86.38%-90.96%). The PK profiles of Re-phen and phenformin were modeled using a two-compartment model in Phoenix® WinNonlin (version 8.0) for comparison. Statistical significance was evaluated using a two-tailed unpaired t-test at p <0.05. Re-phen showed smaller systemic exposure (AUC = 15.9 hr.µg/mL, p = 0.02*) and lower peak concentration (Cmax = 5.3 µg/mL, p = 0.0062**) than phenformin (AUC = 40.2 hr·µg/mL, Cmax = 30.4 µg/mL). Despite its faster clearance rate (CL = 1.7 L/hr/kg vs. 0.3 L/hr/kg, p = 0.0019**), Re-phen exhibited a prolonged half-life (11.1 hours vs. 7.8 hours), primarily attributed to its significantly larger volume of distribution (Vss = 17.1 L/kg vs. 1.3 L/kg, p < 0.001 ****). These findings highlight distinct distribution and elimination differences between the two compounds. Ongoing co-modeling aims to elucidate the in vivo conversion of Re-phen to phenformin and their PK interplay. This first PK comparison in healthy mice extends previous research and supports further evaluation in an orthotopic PDAC model to explore therapeutic potential in pancreatic cancer. Citation Format: Amir Mohammad Gholizadeh, Fatima Dagher, Chiyi Xiong, Chun Li, Diana S-L Chow. Comprehensive pharmacokinetics of Re-phenformin as an anticancer agent for pancreatic cancer therapy in mice: a comparative study with phenformin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4359.