PFS and OS curves of ISM patients, grouped according to the proposed scoring systems, for the discovery and/or the validation patient cohorts. Scoring systems for PFS (A,C,E) and OS (B,D,F) are based on (1) the combination of sβ2M levels at diagnosis (score 1 when ≥ 2.5 µg/mL), and/or the KIT D816V VAF in BM (score 1 when ≥1%), and/or pathogenic variants in the A/R/D gene panel with VAF ≥ 30% (score 1 when ≥1 mutation with VAF ≥ 30% in any of these 3 genes) (A,C,E) and (2) pathogenic variants in the A/R/D gene panel with VAF ≥ 30% (score 1 if there was a mutation in any of these 3 genes with VAF ≥ 30%) (B,D,F). Please note that all patients who scored 1 in (A) had multilineage involvement of BM hematopoiesis by the KIT mutation with sβ2M levels < 2.5 µg/mL. NR, not reached.