Detection of Nonreciprocal/Reciprocal ALK Translocation as Poor Predictive Marker in Patients With First-Line Crizotinib-Treated ALK-Rearranged NSCLC

Introduction: During nonreciprocal/reciprocal translocation process, 5′-anaplastic lymphoma kinase (ALK) sometimes gets retained in the genome and is detectable by next-generation sequencing; however, no study has investigated its clinical significance. Our study aimed to assess the impact of harboring 5′-ALK on the efficacy of crizotinib. Methods: A total of 150 patients with next-generation sequencing–identified ALK-rearranged NSCLC from March 2014 to July 2018 at the Hunan Cancer Hospital were enrolled in this study. The efficacy of crizotinib as first-line therapy was evaluated in 112 patients according to the retention of 5′-ALK. Results: Among the 150 patients with NSCLC, nonreciprocal/reciprocal translocation was detected in 18.7% (28 of 150), and 3′-ALK fusion alone was detected in 81.3% (122 of 150). Among the 112 patients who received first-line crizotinib, 89 had 3′-ALK fusion alone (79 echinoderm microtubule associated protein-like 4 [EML4]-ALK and 10 non–EML4-ALK), and 23 had nonreciprocal/reciprocal ALK translocation. Among the patients with nonreciprocal/reciprocal ALK translocation, three patients harbored dual concurrent 3′-ALK fusions. Patients with nonreciprocal/reciprocal ALK translocation had higher incidence of brain metastasis at baseline than those with 3′-ALK fusion alone (39.1% versus 13.4%, p = 0.028). Crizotinib-treated patients with nonreciprocal/reciprocal ALK translocation had significantly shorter median progression-free survival (PFS) compared with patients carrying 3′-ALK fusion alone (6.1 m versus 12.0 m, p = 0.001) or with EML4-ALK fusion alone (6.1 m versus 12.6 m, p = 0.001). Multivariate analysis revealed that harboring nonreciprocal/reciprocal ALK translocation was an independent predictor of worse PFS for crizotinib-treated ALK-rearranged NSCLC (p = 0.0046). Conclusions: Presence of nonreciprocal/reciprocal ALK translocation was predictive for worse PFS and greater likelihood of baseline brain metastases in patients with ALK-rearranged NSCLC who received first-line crizotinib.