Abstract 754: Selective ALK inhibitor alectinib (CH5424802/RO5424802) with potent antitumor activity in models of crizotinib resistance, including intracranial metastases

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Purpose: EML4-ALK has been implicated as a driver oncogene and a therapeutic target in non-small cell lung cancer (NSCLC). The clinical efficacy of the ALK inhibitor crizotinib has been demonstrated in ALK fusion-positive NSCLC; however, resistance to crizotinib certainly occurs through ALK secondary mutations in clinical use. In addition, brain metastases are frequent sites of initial failure in patients because crizotinib has poor penetration of the central nervous system. This study aimed to clarify the efficacy of ALK inhibitor alectinib (CH5424802/RO5424802) in models of crizotinib-resistant ALK mutant tumors and intracranial tumors. Experimental Design: The antitumor activity of alectinib was evaluated in subcutaneous xenograft tumor models of Ba/F3 cells expressing mutated EML4-ALK, and in intracranial tumor implantation models of EML4-ALK-positive NSCLC NCI-H2228. Results: Alectinib had kinase inhibitory activity against some ALK mutations, including G1269A, and blocked tumor growth driven by a mutant of EML4-ALK in vitro and in vivo. In intracranial tumor implantation mouse models, alectinib resulted in regression of NCI-H2228 tumor in brain and provided a survival benefit. Alectinib is not a substrate for P-glycoprotein efflux transporter in vitro and showed a high brain-to-plasma ratio in rat. Additionally, alectinib led to tumor size reduction in the subcutaneous NCI-H2228 xenograft tumor that had failed to regress fully during treatment with crizotinib. Conclusions: Alectinib was effective against most EML4-ALK mutations and showed potent efficacy against intracranial ALK-positive tumor. Thus, alectinib might provide therapeutic opportunities for crizotinib-treated patients with ALK secondary mutations and brain metastases. Citation Format: Tatsushi Kodama, Toshiyuki Tsukaguchi, Masami Hasegawa, Miyuki Yoshida, Kenji Takanashi, Osamu Kondoh, Hiroshi Sakamoto. Selective ALK inhibitor alectinib (CH5424802/RO5424802) with potent antitumor activity in models of crizotinib resistance, including intracranial metastases. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 754. doi:10.1158/1538-7445.AM2014-754