(A) KIT secondary mutation detection significantly increased upon disease progression. (B) Representative subclonal evolution showing increased allele frequency in subpopulations with a KIT exon 13 V654A mutation, in parallel to primary clonal KIT exon 11 mutations. ABP, ATP-BP; AL, activation loop; BL, baseline; EOT, end-of-treatment; FC, fold change; VAF, variable allele frequency.