Tyrosine kinase inhibitors of anaplastic lymphoma kinase (ALK-TKIs) including alectinib have been the standard therapy against ALK fusion gene-positive non-small cell lung cancers (NSCLCs). Many ALK fusion variants have been identified in NSCLCs, and the predominant variants are echinoderm microtubule-associated protein-like 4-ALK (EML4-ALK) variant 1 (V1), V2 and V3a/b. However, there have been conflicting reports on the clinical responses of these variants to ALK-TKIs, and there are few reports on other less common ALK variants. To examine the influence of ALK variants on the efficacy of ALK-TKIs, we analyzed the sensitivity to alectinib of eight types of ALK variant: three major variants (V1, V2 and V3a) and five less common variants (V4; kinesin family member 5-ALK; kinesin light chain 1-ALK; striatin, calmodulin-binding protein-ALK; and tropomyosin-receptor kinase fused gene-ALK). Analysis was done by cell-free kinase assays using the recombinant proteins and by cell, growth assays using murine Ba/F3 cells expressing ALK variants. The kinase activity of each recombinant protein was significantly inhibited by alectinib. Intracellular ALK phosphorylation levels and its downstream signaling mediators, STAT3 and ERK, were suppressed by alectinib in each ALK variant-expressing Ba/F3 cell. Each cellular proliferation was markedly inhibited by alectinib treatment. There was no significant difference in the IC50 values between cells, with a <3.6-fold difference in responsiveness. In conclusion, these eight ALK variants had similar sensitivity to alectinib in vitro, indicating that it may not be possible to predict the response to alectinib just by determination of the ALK variant type in ALK fusion-positive NSCLCs.

中文翻译：

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八种 ALK 融合变体对 ALK 转化细胞中艾乐替尼的敏感性。

包括艾乐替尼在内的间变性淋巴瘤激酶 (ALK-TKI) 的酪氨酸激酶抑制剂已成为 ALK 融合基因阳性非小细胞肺癌 (NSCLC) 的标准疗法。已在 NSCLC 中鉴定出许多 ALK 融合变体，主要变体是棘皮动物微管相关蛋白样 4-ALK (EML4-ALK) 变体 1 (V1)、V2 和 V3a/b。然而，关于这些变异体对 ALK-TKIs 的临床反应的报道相互矛盾，并且很少有关于其他不太常见的 ALK 变异体的报道。为了检查 ALK 变体对 ALK-TKI 疗效的影响，我们分析了八种 ALK 变体对艾乐替尼的敏感性：三种主要变体（V1、V2 和 V3a）和五种不太常见的变体（V4；驱动蛋白家族成员 5 -ALK；驱动蛋白轻链 1-ALK；纹状蛋白，钙调蛋白结合蛋白-ALK；和原肌球蛋白受体激酶融合基因-ALK）。使用重组蛋白通过无细胞激酶测定和使用表达 ALK 变体的鼠 Ba/F3 细胞通过细胞生长测定进行分析。艾乐替尼显着抑制了每种重组蛋白的激酶活性。在每个表达 ALK 变体的 Ba/F3 细胞中，艾乐替尼抑制细胞内 ALK 磷酸化水平及其下游信号传导介质 STAT3 和 ERK。艾乐替尼治疗显着抑制了每种细胞增殖。细胞之间的 IC50 值没有显着差异，反应性差异小于 3.6 倍。总之，这八种 ALK 变体在体外对艾乐替尼具有相似的敏感性，