Abstract 1271: ABCC11 is involved in resistance to alectinib
Authors: Funazo Tomoko Yamamoto , Ozasa Hiroaki , Tsuji Takahiro , Furugaki Koh , Yoshimura Yasushi , Ajimizu Hitomi , Yasuda Yuto , Nomizo Takashi , Sakamori Yuichi , Yoshida Hironori , Kim Young Hak , Hirai Toyohiro 
Published: August 2019

Abstract
Non-small cell lung cancer is known to have a poor prognosis. One reason for this is resistance to anticancer drugs. Various mechanisms for resistance to anticancer drugs have been reported. Herein we focus on ABCC11, an adenosine triphosphate (ATP)-binding cassette transporter. ABCC11 is ubiquitously expressed in various adult human tissues, including liver, lung, and kidney, and confers drug resistance to some cytotoxic agents such as 5-fluorouracil (5-FU), pemetrexed, and methotrexate. However, the association between ABCC11 and resistance to molecularly-targeted therapeutic drugs is still unknown. We hypothesized that alectinib, a molecularly-targeted therapeutic agent for anaplastic lymphoma kinase (ALK)-rearranged lung cancer, was a substrate for ABCC11. To evaluate the expression of ABCC11 in alectinib-resistant cells, an alectinib-resistant cell line model (AR1S) was established by exposing NCI-H2228, an ALK-rearranged cell line, to alectinib for 3 months. Patient-derived cell lines that were sensitive or resistant to alectinib were also established from a treatment-naïve patient (KTOR-1), and after disease progression (KTOR-1 RE). The protein expression of ABCC11 was increased in both alectinib-resistant cell lines (AR1S and KTOR-1 RE), compared to naïve cell lines (H2228 and KTOR-1). To investigate the role of ABCC11 in alectinib resistance, ABCC11 overexpression cell lines (OE-A and OE-B) were established by introducing an ABCC11 expression construct into H2228. A negative control cell line (mock) was established by introducing the control empty vector into H2228. The gene expression of ABCC11 in OE-A and OE-B was higher than that in mock (133-fold increase, P &lt; 0.0001 and 109-fold increase, P &lt; 0.0001 respectively), and the protein expression of ABCC11 was also higher in OE-A and OE-B. The IC50 for alectinib was higher in OE-A (8.0 times) and OE-B (10.8 times) compared to mock. ABCC11 was knocked down using siRNA in AR1S to evaluate alectinib susceptibility. Knockdown of ABCC11 improved the IC50 for alectinib, compared with a negative control (0.299-fold decrease). Next, the tumor responses to alectinib in OE-A and OE-B were evaluated in vivo. Xenograft models of OE-A, OE-B, and mock on BALB/nu mice were administered daily alectinib (8 mg/kg/day) or vehicle for 10 days. In mice administered alectinib (N = 6-7), the tumor shrinkage rate of OE-A (−23.6%) and OE-B (−34.3%) was significantly lower than that of mock (−76.8%). There results have provided the first of preclinical evidence that ABCC11 is involved in resistance to alectinib.
Citation Format: Tomoko Yamamoto Funazo, Hiroaki Ozasa, Takahiro Tsuji, Koh Furugaki, Yasushi Yoshimura, Hitomi Ajimizu, Yuto Yasuda, Takashi Nomizo, Yuichi Sakamori, Hironori Yoshida, Young Hak Kim, Toyohiro Hirai. ABCC11 is involved in resistance to alectinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1271.