Abstract 4547: A novel drug combination with improved therapeutic efficacy over sorafenib in multiple preclinical models of hepatocellular carcinoma

Abstract Introduction: Due to the heterogeneity of hepatocellular carcinoma (HCC), the incidence of resistance and toxicity to first-line therapy sorafenib is high. Combinations of drugs can be used to exploit synergistic effects to reduce adverse events, while improving efficacy and survival. In-vitro studies performed by our team identified irinotecan and sonidegib to have potential for synergistic therapeutic effects in combination with sorafenib. Follow up in-vivo dose optimization studies in a murine NASH induced HCC found this 3-drug combination to be more effective than sorafenib-alone at arresting tumor development and progression. In this study, we tested the in-vivo efficacy of the combination in two separate preclinical cell-line derived xenograft (CDX) models. Experimental Procedure: HCC CDX models were generated by injecting two distinct HCC cell lines, Huh7 and HepG2, subcutaneously in the flank of male NOD.Cg-PrkdcscidIL2rgtm1Wjl/SzJ (NSG) mice. Mice were administered either vehicle, sorafenib, or a 3-drug combination, and mouse tumor volumes and weights were tracked for duration of study. Mice were all euthanized at study endpoint and tissues collected for analysis, including the assessment of tumor weights, differentiation, grade, necrosis, and proliferation status. Serum collected from endpoint blood was measured for human alpha fetoprotein (AFP) and alanine transaminase (ALT) levels. Changes in protein expression of tumors were assessed by western blot analysis. Results: Huh7 and HepG2 tumors were both sensitive to sorafenib-alone treatment. However, Huh7 tumors treated with the 3-drug combination had a significant decrease in tumor volume and weight at endpoint compared to the vehicle and sorafenib-alone. HepG2 tumors treated with the combination also had a significant decrease in tumor volume and weight at endpoint compared to the vehicle. Though the difference in tumor volume and weight was not statistically significant for the combination compared to sorafenib, a trend towards decrease was observed. This was further confirmed by significantly reduced AFP levels in the combination compared to the vehicle and sorafenib in HepG2 and Huh7. Drug toxicities, measured by mouse weights and ALT levels, were not significantly different. Histological and immunohistochemical assessment of tumors showed necrosis and Ki67 staining to be significantly elevated in vehicle and sorafenib-alone compared to the 3-drug group. The targets for all three drugs present in the combination were downregulated in the combination compared to the vehicle and sorafenib-alone. Conclusion: This study provides strong evidence that a novel 3-drug combination of irinotecan, sonidegib, and low dose sorafenib can significantly reduce tumor proliferation and burden in multiple independent pre-clinical in-vivo HCC models compared to high dose sorafenib monotherapy. Citation Format: Anastasia Chambers, Sunaina Shrestha, Alexandra Ladd, Sergio Duarte, Ali Zarrinpar. A novel drug combination with improved therapeutic efficacy over sorafenib in multiple preclinical models of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4547.