Alectinib (ALK TKI) shows bigger PFS edge in low tumor burden ALK+ NSCLC

A pooled individual patient-level analysis of the randomized Phase III ALEX (NCT02075840) and J-ALEX (JapicCTI-132316) trials compared first-line alectinib (a next-generation ALK tyrosine kinase inhibitor with CNS activity) vs crizotinib (first-gen ALK/MET/ROS1 TKI) in ALK-positive advanced NSCLC (n=500; alectinib n=249, crizotinib n=251; median follow-up 17.1 months). Overall, alectinib improved PFS vs crizotinib (HR 0.41, 95%CI 0.31–0.55; p<0.001) without a statistically significant OS difference at this cutoff (HR 0.80, 95%CI 0.50–1.28; p=0.353); tumor burden (RECIST target lesion sum above vs below median) was prognostic for both PFS (multivariate HR 1.66, p<0.001) and OS (HR 2.24, p<0.001) and predictive for treatment effect (PFS interaction p=0.002), with alectinib’s PFS benefit larger in low tumor burden (HR 0.25) than high tumor burden (HR 0.52). BMI>25kg/m² was not associated with PFS (HR 0.92; p=0.375) but correlated with longer OS (HR 0.50; p=0.025) and did not modify treatment effect; as external anchoring, crizotinib’s historical first-line mPFS is ~10.9 months, whereas mature ALEX updates report alectinib mPFS ~34.8 months vs 10.9 months for crizotinib—this pooled HR 0.41 is directionally consistent with that established SOC shift away from crizotinib.