Alectinib as first-line treatment for advanced ALK-positive non-small cell lung cancer in the real-world setting: preliminary analysis in a Chinese cohort

Background: Tyrosine kinase inhibitors (TKIs) have been a major advance in the treatment of anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) which have been substantiated in clinical trials. However, real-world data on first-line alectinib in a Chinese patient population are limited. Methods: We enrolled patients diagnosed with advanced ALK-positive NSCLC treated with first-line alectinib at 8 centers in China, including cases with symptomatic or active CNS metastases. Continuation of alectinib was permitted after local or gradual progression at the treating clinician's discretion. Time-to-treatment failure (TTF) was defined as the period from the start of alectinib to discontinuation for any cause including disease progression, death, adverse events and patient's preference. We defined longer EML4-ALK variants as containing EML4 fusions to at least exon 13 and shorter variants had EML4 fusions up to exon 6. Results: Of the 110 patients included, 26.4% had Eastern Cooperative Oncology Group Performance Status (ECOG) ≥2 points. The objective response rate (ORR) was 88.5% [95% confidence interval (CI): 79.9-94.3%] and median tumor shrinkage rate was 60% (range, 0-100%) in patients with target lesions. For patients with measurable central nervous system (CNS) metastases, the CNS-ORR was 92.9% (95% CI: 66.1-99.8%), additionally, 80% (8/10) of patients experienced significant improvement in CNS-related symptoms following alectinib treatment. With a median follow-up of 18.3 months, the estimated 2-year progression-free survival (PFS) rate and 2-year treatment failure-free rate were 81.1% (95% CI: 71.5-87.7%) and 81.0% (95% CI: 70.6-88.0%) respectively. Grade 3-4 adverse events occurred in 6.4% and only 2 patients (1.8%) permanently discontinued alectinib due to adverse events. Multivariate analysis indicated that patients with metastases in ≥3 distant organs and a tumor reduction rate ≤50% demonstrated more unfavorable mPFS than their counterparts. Furthermore, patients carrying longer variants showed superior mPFS to those with shorter variants (not reached vs. 24.2 months, hazard ratio =0.17, 95% CI: 0.04-0.68, P=0.004). Conclusions: Alectinib showed substantial efficacy and an excellent safety profile in a real-world setting of Chinese patients. Clinical outcomes and long-term survival still require longer follow-up. Tumors with shorter EML4 fusion variants, more extensive metastases and less reduction in tumor lesions may require more aggressive strategies.