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L. De Petris
ORAL 33 - ALK (ID 145)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
ORAL33.05 - Pooled Analysis of CNS Response to Alectinib in Two Studies of Pre-Treated ALK+ NSCLC (ID 1219)
16:45 - 18:15 | Author(s): L. De Petris
The central nervous system (CNS) is a frequent site of progression in ALK+ NSCLC patients treated with crizotinib, thus good CNS efficacy is of crucial importance for new ALK inhibitors. Two recent phase II studies examined the efficacy and safety of alectinib in patients with ALK+ NSCLC who progressed after crizotinib; data from both studies were pooled to further examine the efficacy of alectinib in the CNS.
Both phase II, single-arm, multicenter studies enrolled ALK+ NSCLC patients previously treated with crizotinib. One study was conducted in North America only (NP28761; NCT01871805), the other was global (NP28673; NCT01801111). All patients received 600mg oral alectinib twice daily. A primary endpoint of both studies was objective response rate (ORR) by independent review committee (IRC) and key secondary endpoints included CNS ORR by IRC and CNS duration of response (DOR). Response was determined according to RECIST v1.1. All patients underwent imaging at baseline to assess CNS metastases.
The pooled analysis population comprised 225 patients (n=87 from NP28761 and n=138 from NP28673); baseline characteristics were similar to each study population, with most patients being non-smokers, <65 years old with ECOG performance status 0/1. Median follow-up was 27.7 weeks. Fifty patients had measurable CNS disease at baseline (MD) while a further 85 had non-measurable disease (NMD) at baseline; both groups together (M+NMD) comprised 135 patients, 60% of the overall study population. In the MD group, 34 patients (68%) had received prior radiotherapy, but 24 of them had completed that radiotherapy >6 months prior to starting alectinib. For the M+NMD group, 94 patients (70%) had received prior radiotherapy, with 55 completing this >6 months prior to starting alectinib. In the MD group, 30/50 patients had a CNS response (60.0%; 95% CI 45.2–73.6%), with 7 complete responses (CR; 14.0%) and a CNS DCR of 90.0% (78.2–96.7%). In the M+NMD group, 22 additional patients had a CR (29/135; 21.5%), giving a CNS ORR of 38.5% (30.3–47.3%), with a CNS DCR of 85.2% (78.1–90.7%). Complete responses were seen in patients with and without prior radiotherapy. Median CNS DOR after only 17% of events in both groups was 7.6 months (5.8–7.6) in the MD group (n=30) and 7.6 months (5.8–10.3) in the M+NMD group (n=52), which is similar to the systemic DOR reported in both studies (Ou et al, ASCO 2015; Gandhi et al, ASCO 2015). Tolerability was also similar to the overall study population.
Alectinib showed promising efficacy in the CNS in ALK+ NSCLC patients previously treated with crizotinib, achieving a complete response rate of 22% and a DCR of 85%, irrespective of prior radiotherapy. The CNS response was sustained for an equivalent duration to the systemic response, suggesting that alectinib could provide an effective treatment for patients with ALK+ NSCLC while actively targeting CNS metastases. The ongoing phase III clinical studies will assess the systemic and CNS efficacy of alectinib versus crizotinib as front-line therapy for ALK+ NSCLC patients.
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