Improved anti-tumor activity of fluorinated camptothecin derivatives 9-fluorocamptothecin and 7-ethyl-9-fluorocamptothecin on hepatocellular carcinoma by targeting topoisomerase I.

Primary liver cancer is one of the most common malignant cancers of the digestive system that lacks effective chemotherapeutic drugs in clinical settings. Camptothecin (CPT) and its derivatives have been approved for cancer treatment; however, their application is limited by their systemic toxicity. For lead optimization in new drug discovery stages, fluorination is an effective and robust approach to increase the bioavailability and optimize the pharmacokinetics of candidate compounds, thereby improving their efficacy. To obtain new and highly active CPT derivatives, we designed, synthesized, and evaluated two new fluorinated CPT derivatives, 9-fluorocamptothecin (A1) and 7-ethyl-9-fluorocamptothecin (A2), in this study. In vitro, A1 and A2 exhibited more robust anti-tumor activity than topotecan (TPT) in various cancer cells, particularly hepatocellular carcinoma (HCC) cells. In vivo, A1 and A2 exhibited greater anti-tumor activity than TPT in both AKT/Met induced primary HCC mouse models and implanted HepG2 cell xenografts. Acute toxicity tests revealed that A1 and A2 were not lethal and did not cause significant body weight loss at high doses. Moreover, A1 and A2 exhibited no significant toxicity in the mouse liver, heart, lung, spleen, kidney, and hematopoietic systems at therapeutic doses. Mechanistically, A1 and A2 blocked HCC cell proliferation by inhibiting the enzymatic activity of Topo I, subsequently inducing DNA damage, cell cycle arrest, and apoptosis. In summary, our results indicate that fluorination improves the anti-tumor activity of CPT while decreasing its toxicity and highlight the application potential of fluorination products A1 and A2 in clinical settings.

Anti-tumor effects and mechanism of a novel camptothecin derivative YCJ100.

AIMS: In this study, we synthesized a 10-fluorine-substitution derivative of CPT (Camptothecin) YCJ100 and evaluated its antitumor activity and systemic toxicity. MATERIALS AND METHODS: Determination of in vitro antitumor activity and mechanism of YCJ100 by the MTT assay, Molecular docking, EdU staining, Cell cycle and apoptosis determination, Western blot analysis and Topoisomerase I activity assay. The antitumor effects of YCJ100 were evaluated in primary HCC (hepatocellular carcinoma), ICC (intrahepatic cholangiocarcinoma) mouse models, and pancreatic cancer xenograft models. KEY FINDINGS: YCJ100 showed superior cytotoxic activity compared to Topotecan in SW480, SW1990, Hep3B, HepG2, A549, A2780, HeLa, and QBC cells. YCJ100 blocked the cell cycle in the G2/M phase, inhibited cell proliferation and induced apoptosis in HepG2 and SW1990 cells. Mechanistically, YCJ100 inhibited topoisomerase I activity in both a cell-free system and a cellular system, similar to the mechanism of Topotecan. YCJ100 showed significant antitumor activity and was more potent than Topotecan in primary HCC and ICC mouse models, as well as a xenograft mouse model. Additionally, YCJ100 showed only minor toxicity to the mouse hematopoietic system, liver, and kidney. These findings indicate that YCJ100 has high antitumor activity and low systemic toxicity. SIGNIFICANCE: Our findings demonstrate that YCJ100, as a Topoisomerase I inhibitor, has in vitro and in vitro antitumor activity. This study provides a new lead compound worthy of further preclinical evaluation and potential clinical development.