Abstract LB184: CF10 displays improved activity relative to 5-FU in a mouse CRLM model under conditions of physiological folate

Abstract At least 25% of colorectal cancer (CRC) patients develop liver metastases (CRLM) and chemotherapeutic regimens based on the fluoropyrimidine (FP) drug 5-fluorouracil (5-FU) are widely used for CRLM treatment. While 5-FU-based regimens provide a survival advantage in CRLM treatment, long-term survival is uncommon. The primary molecular target of FPs is thymidylate synthase (TS). We demonstrated that a nanoscale FP polymer, CF10, displayed greater potency than expected based on FP content in part through more direct conversion to the TS-inhibitory metabolite, FdUMP. CF10 has shown encouraging pre-clinical efficacy in multiple CRC models. In this study, we tested CF10 for potency advantages relative to 5-FU and trifluorothymidine (TFT, the FP component of TAS-102), in CRC cell lines in the Broad Institute PRISM screen and in CRC cells cultured under conditions of human-like folate levels. We confirm a general potency advantage for CF10 relative to 5-FU and TFT and demonstrate that this potency advantage is retained in CRC cells cultured with human-like folate levels and is enhanced by LV co-treatment to a similar extent as 5-FU. Our results confirm CF10 development proceeding as a CF10/LV combination. Mechanistically, CF10 cytotoxicity closely correlates with poisons of DNA topoisomerase 1 (Top1) in the PRISM screen relative to 5-FU and TFT. A TS/Top1 dual targeting cytotoxic mechanism for CF10/LV was confirmed by TS activity assay, and immunofluorescence detection of Top1cc. CF10/LV activated the ATR/Chk1 pathway consistent with enhanced replication stress and induced apoptosis. In vivo studies confirm CF10/LV is well-tolerated in mice adapted to human-like folate levels. CF10 and CF10/LV eradicated liver metastasis in a CRLM model without scarring or weight loss displaying therapeutic advantages relative to legacy FPs. Our pre-clinical data support an early-phase clinical trial for CF10 for treating liver-metastatic CRC. Citation Format: William H. Gmeiner, Charles Okechukwu, Xue Ma, Wencheng Li, Ralph D'Agostino, Matthew G. Rees, Melissa M. Ronan, Jennifer A. Roth. CF10 displays improved activity relative to 5-FU in a mouse CRLM model under conditions of physiological folate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB184.