Abstract 5489: Synergistic activity of SCD1 blockade in combination with tyrosine kinase inhibitors lenvatinib and cabozantinib in hepatocellular carcinoma (HCC)

Abstract Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Tyrosine kinase inhibitors (TKIs) are approved as a first-line treatment for unresectable HCC. Lenvatinib and cabozantinib are two of the most used TKIs, but the therapeutic duration is limited due to the development of drug resistance. Therefore, understanding the mechanisms of resistance and combining TKIs with other drugs antagonizing resistance should lead to antitumor synergy, eliminating drug resistance. It turns out that the simultaneous use of TKIs together with an inhibitor of stearoyl-CoA desaturase 1 (SCD1) prevents the development of drug resistance, leading to a durable response. SCD1 is the enzyme responsible for de novo fatty acid (FAs) synthesis, converting saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs). MUFAs are an alternative energy source to glucose, integral to cellular membranes, and prevent endoplasmic reticulum (ER) stress and other signaling pathways. In our laboratory, we developed a novel, highly specific SCD1 inhibitor - SSI-4. We have tested the biological activity of SSI-4 against different HCC cell lines and patient-derived xenografts (PDX) mouse models. Of the twelve tested HCC cell lines, four were highly sensitive to SSI-4 (IC50 1-50 nM). Other cell lines showed moderate or no sensitivity to SSI-4. We tested the concomitant use of SSI-4 with lenvatinib and cabozantinib, tyrosine kinase inhibitors (TKIs) FDA-approved for HCC, in HCC cell lines in vitro and using HCC PDX in vivo mouse models. Our studies showed that the combination of the SCD1 inhibitor with both lenvatinib and cabozantinib showed a highly synergistic effect and no development of drug resistance i.e. durable response versus single TKI therapy. Ongoing mechanistic studies are examining whether known molecular targets of tested TKI’s such as VEGFR1, 2, and 3, PDGFRα, FGFR, KIT, and RET dominate in HCC drug resistance to lenvatinib and cabozantinib, and how the use of SSI-4 overcomes the phenomenon of resistance. Citation Format: Justyna J. Gleba, Aylin Alasonyalilar-Demirer, Matthew L. Pawlush, Ahmet Bilgili, Peyton G. Hickman, Kabir Mody, Lewis R. Roberts, Steven R. Alberts, Mark J. Truty, Tushar C. Patel, Han W. Tun, John A. Copland. Synergistic activity of SCD1 blockade in combination with tyrosine kinase inhibitors lenvatinib and cabozantinib in hepatocellular carcinoma (HCC). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5489.