Abstract 348: Efficacy of triple combination treatment with trametinib, mebendazole and CD133 RNA aptamer in recalcitrant NRAS-mutant melanoma cells

Malignant melanoma is the most aggressive form of skin cancer. Although kinase inhibitors have proven to be efficient with promising clinical results, the development of drug resistance is one of the major issues in targeted therapy. CD133, also known asProminin-1, is a membrane glycoprotein studied extensively as a cell surface marker for cancer stem cells. In our previous studies, mebendazole, a repurposed broad spectrum anti-helminthic agent, inhibited the growth of NRAS mutant melanoma cells in combination with trametinib, a MEK inhibitor. However, a CD133-positive cancer stem cell population remain resistant to this targeted therapy. Use of RNA aptamers in diagnostic as well as therapeutics has been studied recently in different types of cancer cells. Drug delivery of aCD133 aptamer coupled with doxorubicin has been found to inhibit the growth of liver cancer cells. In this study, we targeted the cancer stem cells expressing CD133 with RNA aptamers, in combination with trametinib and mebendazole to sensitize the cells to the combination treatment. Patient derived melanoma cell lines, BAKP and POT, harboring BRAFWT/NRASQ61K and BRAFWT/NRASQ61R driver mutations, were co-transduced with aTet-on vector expressing CD133 and a Tet activator. The doxycycline-induced and uninduced cells were subjected to single agent treatment with 100 nM trametinib, 100 nM mebendazole or 100 nM CD133 RNA aptamer, as well as dual and triple agent combinations for 24 or 48 hours. XTT cell viability and apoptotic assays such as AnnexinV-PI flow cytometry analysis revealed that the triple combination with trametinib, mebendazole and the CD133 aptamer was the most effective in inducing apoptotic cell death, even in the doxycycline-induced CD133-overexpressing melanoma cells. Further studies will use preclinical in vivo mouse xenograft models to investigate the effects on tumor growth of CD133 RNA aptamers in combination treatments, potentially making it available for clinical trials aiming to improve patient response to therapeutics against drug-resistant melanoma cells. Citation Format: Yoga Haribabu, Raymond Chien, Ryyan Alobaidi, Li-Wei Kuo, Nusrat Islam, Cynthia M. Simbulan-Rosenthal, Dean S. Rosenthal. Efficacy of triple combination treatment with trametinib, mebendazole and CD133 RNA aptamer in recalcitrant NRAS-mutant melanoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cance