Abstract 295: Efficacy of MCL1 inhibitor S63845 in small cell lung cancer

Lung cancer is the leading cause of cancer death. Small cell lung cancer (SCLC) is a histologic subtype of lung cancer and the proportion of SCLC is approximately 15%. New molecular targeted drugs and immune checkpoint inhibitors are successfully effective for non-small cell lung cancer. However, treatment of SCLC has not been improved over recent decades. It is important to explore new treatment strategies of SCLC. MCL1 is a member of the BCL-2 family, which regulates apoptosis. Targeting MCL1 represents a potential breakthrough of cancer treatment. We tested S63845, a MCL1 inhibitor, in four SCLC cell lines (DMS114, DMS53, SW1271, and NCI-H69) and, in addition, one patient derived SCLC cell (KTOR201). S63845 had greater efficacy in two of five SCLC cells (DMS114 and KTOR201). These two SCLC cells had higher expression of MCL1 and lower expression of BCL-XL, which is another member of the BCL-2 family. The other three SCLC cells (DMS53, SW1271 and NCI-H69) were resistant to S63845 and had a higher expression of BCL-XL or lower expression of MCL1. These data suggested that S63845 might be a powerful treatment of SCLC as a new therapeutic strategy. It is possible that the expressions of MCL1 and other members of the BCL-2 family predict the sensitivity of S63845. Citation Format: Yuto Yasuda, Hiroaki Ozasa, Takahiro Tsuji, Takashi Nomizo, Tomoko Funazo, Hironori Yoshida, Yuichi Sakamori, Toyohiro Hirai, Young Hak Kim. Efficacy of MCL1 inhibitor S63845 in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 295.