Since the duration of response to imatinib has been shown to be depending on the type of detected mutations in GIST patients and, in particular, individuals harboring deletions at codons 557/558 showed a significantly shorter PFS than point mutations [31], we have performed a multivariate analysis for PFS in order to correlate the type of KIT exon 11 mutation detected in our population cohort (Table 2), levels of plasma immune checkpoints and other clinical factors. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.