The decrease in CD26⁺ SCs correlates with clinical responses in CML. (A) The percentage of CD26⁺ SC (CD34⁺/CD38⁻ cells) in patients with CML at diagnosis (n = 21) and at the time of complete cytogenetic response (CCyR) and/or MMR after treatment (imatinib n = 17, nilotinib n = 2, dasatinib n = 2) are shown. (B) Left panel: The percentage of CD26⁺ SC (CD34⁺/CD38⁻ cells) in patients with CML at diagnosis (n = 35), those who had <10% BCR/ABL1 during the first year of therapy (n = 46; imatinib n = 38, nilotinib n = 7, dasatinib n = 1), and patients with >10% BCR/ABL1 in the follow-up (n = 14; imatinib n = 4, nilotinib n = 2, dasatinib n = 1, multiple therapies n = 7) are shown. (B) Right panel: The percentage of CD26⁺ SC (CD34⁺/CD38⁻ cells) in patients with CML at diagnosis (n = 35), patients with CCyR without MMR (n = 10), patients with MMR (n = 36), and patients with fully relapsed or resistant CML (n = 14) are shown. (C) BCR/ABL1 mRNA levels in sorted CD34⁺/CD38⁻/CD26⁺ and CD34⁺/CD38⁻/CD26⁻ SC in a patient with CML after 3 months of treatment with imatinib (400 mg/day). (D) Percentage of CD26⁺ SC (CD34⁺/CD38⁻ cells) and BCR/ABL1 mRNA levels (according to IS) in a patient with CML who had developed resistance against imatinib and nilotinib. The figure shows 3 different time points.