Abstract 9061 pooled data from two clinical trials. 129 patients had biopsies done after Crizotinib but before Alectinib. Plasma samples were available for all 272 patients at baseline and for about 50% at progression.
At baseline 13 functional ALK mutations were identified (5 previously unreported). At progression 3 new mutations were seen. At least 7 baseline mutations had median PFS greater than 3 months suggesting Alectinib was active against them. Mutations I1171S/N ans G1202R may occur during treatment.
As for liquid biopsy, “Tumor DNA in plasma may be a non-invasive way to monitor resistance mutations”.