Efficacy of Alectinib in Patients with ALK-Positive NSCLC and Symptomatic or Large CNS Metastases

Abstract

Background: Central nervous system (CNS) metastases represent a significant source of morbidity and mortality for patients with ALK tyrosine kinase gene (ALK)-positive NSCLC. Alectinib has demonstrated robust CNS activity in both crizotinib-naive and crizotinib-resistant settings. However, the CNS efficacy of alectinib has not been established in patients with untreated symptomatic, large CNS metastases.

Methods: In this retrospective study, patients were eligible if they had advanced ALK-positive NSCLC with large (defined as ≥1 cm) or symptomatic CNS metastases and received alectinib. Medical records and radiographic imaging were reviewed to determine treatment outcomes. CNS efficacy was assessed per the modified Response Evaluation Criteria in Solid Tumors version 1.1.

Results: Of the 19 patients, 15 (79%) had measurable CNS disease at baseline and were evaluable for response. The CNS objective response rate in these patients was 73.3% (95% confidence interval [CI]: 44.9%-92.2%), the CNS disease control rate was 100.0% (95% CI: 78.2%-100.0%), and the median CNS duration of response was 19.3 months (95% CI: 14.3 months-not evaluable). In 18 evaluable patients with measurable and/or nonmeasurable baseline CNS disease, the CNS objective response rate was 72.2% (95% CI: 46.5%-90.3%), the CNS disease control rate was 100.0% (95% CI: 81.5%-100.0%), and the median CNS duration of response was 17.1 months (95% CI: 14.3 months-not evaluable). All eight patients with symptoms attributable to CNS metastases had clinical improvement upon starting alectinib therapy. Six patients (32%) eventually required salvage brain radiotherapy.

Conclusions: Alectinib demonstrated meaningful CNS efficacy in patients with ALK-positive NSCLC with untreated symptomatic or large brain metastases.

Keywords: ALK; Alectinib; Brain metastases; Central nervous system; NSCLC.