<p>Alectinib is a highly selective and potent ALK and RET tyrosine kinase inhibitor.In nonclinicalstudies, inhibition of ALK tyrosine kinase activity led to blockage of downstream signaling pathways including STAT 3 and PI3K/AKT and inducedtumor cell death (apoptosis).<br />
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Alectinib demonstratedin vitroand in vivoactivity against mutant forms of the ALK enzyme, including mutations responsible forresistance to crizotinib.The major metabolite of alectinib (M4) has shown similar in vitropotency and activity.<br />
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Based on nonclinicaldata, alectinib is not a substrate of p-glycoprotein (P-gp) or breast cancer resistance protein (BCRP), which are both efflux transporters in the blood brain barrier, and is therefore able to distribute into and be retained within the central nervous system. Alectinibinducedtumor regressionin nonclinicalmousexenograft models, including antitumor activity in the brain, and prolonged survival inintracranial tumor animal models.</p>