IKZF1deletions Coupled with CD20 Expression Represents a Novel High-Risk Subtype in Adult B-Cell Progenitor Acute Lymphoblastic Leukemia

Genetic deletions of IKZF1 are associated with poor prognosis in B-cell acute lymphoblastic leukemia (B-ALL). Here we investigated the effect of IKZF1 deletions (IKZF1 del) plus with immunotype in adult B-ALL in PDT-ALL-2016 cohort. This cohort study involved 161 patients with B-ALL from 2016 to 2019, with detailed information about IKZF1 del and CD20 expression. Validation cohort consists N= patients from TARGET cohort. IKZF1 del was detected in 36.0% of patients with 3-year event-free survival (EFS) of 37.2±6.7% and overall survival (OS) of 51.1±7.3%, compared to IKZF1 wild-type (IKZF1 wt) with EFS 55.4±5.1% (P<0.01) and OS 74.6±4.5% (P<0.05), respectively. CD20 expression was also associated with inferior EFS than CD20-negative group (P<0.05). Furthermore, IKZF1 del coupled with CD20 expression, termed as IKZF1 del/CD20+, comprised 12.4% of patients with 3-year EFS of 25.0±9.7% compared with IKZF1 wt (P<0.05 ) and IKZF1 del/CD20- (P<0.05 ) groups, respectively. Multivariable analyses demonstrated independence of IKZF1 del/CD20+ with highest hazard ratio for EFS and OS. Furthermore, the prognostic strength of IKZF1 del/CD20+ was confirmed in TARGET validation cohort. Eighty-one patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT). Notably, neither IKZF1 del(P=0.6288), CD20 (P=0.0705) or IKZF1 del/CD20 (P=0.3410) groups were identified as poor outcome in allo-HSCT cohort. Collectively, our data demonstrate that IKZF1 del/CD20+ represents a very high-risk subtype in adult B-ALL; and particularly, allo-HSCT could overcome the poor outcome of IKZF1 del and IKZF1 del/CD20+.