Pooled Analysis of CNS Response to Alectinib in Two Studies of Pretreated Patients With ALK -Positive Non–Small-Cell Lung Cancer

Purpose Alectinib has shown activity in the CNS in phase I and II studies. To further evaluate this activity, we pooled efficacy and safety data from two single-arm phase II studies (NP28761 and NP28673; ClinicalTrials.gov identifiers: NCT01871805 and NCT01801111, respectively) in patients with ALK-positive non-small-cell lung cancer (NSCLC). Patients and Methods Both studies included patients with ALK-positive NSCLC who had previously received crizotinib; all patients received alectinib 600 mg twice per day. The primary end point in both studies was independent review committee (IRC)-assessed objective response rate (ORR; by Response Evaluation Criteria in Solid Tumors RECIST version 1.1). Additional end points (all by IRC) included CNS ORR (CORR), CNS disease control rate (CDCR), and CNS duration of response (CDOR). Results One hundred thirty-six patients had baseline CNS metastases (60% of the overall study populations); 50 patients (37%) had measurable CNS disease at baseline. Ninety-five patients (70%) had prior CNS radiotherapy; 55 patients completed the CNS radiotherapy more than 6 months before starting alectinib. Median follow-up time was 12.4 months (range, 0.9 to 19.7 months). For patients with baseline measurable CNS disease, IRC CORR was 64.0% (95% CI, 49.2% to 77.1%), CDCR was 90.0% (95% CI, 78.2% to 96.7%), and median CDOR was 10.8 months (95% CI, 7.6 to 14.1 months). For patients with measurable and/or nonmeasurable baseline CNS disease, IRC CORR was 42.6% (95% CI, 34.2% to 51.4%), CDCR was 85.3% (95% CI, 78.2% to 90.8%), and median CDOR was 11.1 months (95% CI, 10.3 months to not evaluable). CORR was 35.8% (95% CI, 26.2% to 46.3%) for patients with prior radiotherapy (n = 95) and 58.5% (95% CI, 42.1% to 73.7%) for patients without prior radiotherapy (n = 41). As previously reported, alectinib was well tolerated, regardless of baseline CNS disease. Conclusion Alectinib showed good efficacy against CNS metastases, in addition to systemic activity, in crizotinib-refractory ALK-positive NSCLC.