Alectinib Resistance in ALK-Rearranged Lung Cancer by Dual Salvage Signaling in a Clinically Paired Resistance Model

The mechanisms responsible for the development of resistance to alectinib, a second-generation anaplastic lymphoma kinase (ALK) inhibitor, are still unclear, and few cell lines are currently available for investigating ALK-rearranged lung cancer. To identify the mechanisms underlying acquired resistance to alectinib, two patient-derived cell lines were established from an alectinib-naïve ALK-rearranged lung cancer and then after development of alectinib resistance. The properties acquired during treatments were detected by comparisons of the two cell lines, and then functional analyses were performed. Coactivation of c-Src and MET was identified after the development of alectinib resistance. Combinatorial therapy against Src and MET significantly restored alectinib sensitivity in vitro (17.2-fold). Increased apoptosis, reduction of tumor volume, and inhibition of MAPK and PI3K/AKT signaling molecules for proliferation and survival were observed when the three kinases (Src, MET, and ALK) were inhibited. A patient-derived xenograft from the alectinib-resistant cells indicated that combination therapy with a saracatinib and crizotinib significantly decreased tumor size in vivo. To confirm the generality, a conventional alectinib-resistant cell line model (H2228-AR1S) was established from NCI-H2228 cells (EML4-ALK variant 3a/b). In H2228-AR1S, combination inhibition of Src and MET also restored alectinib sensitivity. These data reveal that dual salvage signaling from MET and Src is a potential therapeutic target in alectinib-resistant patients.

Implications: This study demonstrates the feasibility to elucidate personalized drug-resistance mechanisms from individual patient samples.