Proposal and clinical application of molecular genetic risk scoring system, "MRplus", for BCR-ABL1 negative pediatric B-cell acute lymphoblastic leukemia- report from a single centre

Clinical and Prognostic Impact of Copy Number Alterations and Associated Risk Profiles in a Cohort of Pediatric B-cell Precursor Acute Lymphoblastic Leukemia Cases Treated Under ICiCLe Protocol

Copy number alteration (CNA) status and CNA risk profiles of IKZF1^plus, UK-ALL CNA risk groups and MRplus scores, were evaluated for clinical and prognostic impact in a cohort of 493 B-cell acute lymphoblastic leukemia cases diagnosed and treated under the Indian Collaborative Childhood Leukemia group (ICiCLe) protocol trial. Overall CNA frequency was 59% with 60% of cases showing 2-loci deletion. CDKN2A/B deletion was most common CNA (36.3%), while IKZF1 deletion and IKZF1^plus profile were noted in 19.5% and 13.4% of cases, respectively. IKZF1 deletions and other CNA risk profiles were significantly associated with poor (PR)/high risk (HR) clinical and genetic profile parameters (P < 0.001). In addition, the 3-year OS, event-free survival (EFS) was significantly poor with high relapse rate (RR) of 38.6%, 46.5%, and 35.2% for IKZF1 deletions, IKZF1^plus profiles, and UK-ALL CNA-intermediate risk (IR)+PR risk groups, respectively (P < 0.001). Integrated evaluation of UK-ALL CNA risk profile with ICiCLe trial risk stratification groups revealed a worse overall survival, EFS, and RR of 63.3%, 43.2%, and 35.2% for CNA-IR+PR profile compared to CNA-good risk profile (81.3%, 65.0%, and 21.0%; P < 0.001). Hence, routine CNA testing in our setting is must to identify standard risk and IR cases likely to benefit from HR treatment.

Allogeneic hematopoietic stem cell transplantation overcome the poor prognosis of patients with IKZF1plus CD20-a very high-risk subtype in B-cell acute lymphoblastic leukemia

Genetic deletions of IKZF1 (IKZF1^del) and IKZF1^del plus other mutations (IKZF1^plus) have been identified in B-cell acute lymphoblastic leukemia (B-ALL) with a poor prognosis. Herein, we investigated the combination of IKZF1^del and CD20 immunotypes in adult patients with B-ALL in the PDT-ALL-2016 cohort. This study cohort consisted of 161 patients with B-ALL with detailed information on IKZF1^del and CD20 expression. The independent cohort included 196 patients from the TARGET dataset. IKZF1^del was detected in 36.0% of patients with 3-year event-free survival (EFS) of 37.1 ± 6.7% and overall survival (OS) of 51.5 ± 7.3%, compared to IKZF1 wild-type (IKZF1^wt) with an EFS 55.3 ± 5.1% (P = 0.011) and OS 74.4 ± 4.5% (P = 0.013), respectively. CD20-positive (CD20⁺) was associated with inferior EFS compared to the CD20-negative (CD20^-) group (P = 0.020). Furthermore, IKZF1^del coupled with CD20+, IKZF1^del/CD20⁺, comprised 12.4% of patients with a 3-year EFS of 25.0 ± 9.7%, compared with IKZF1^wt/CD20^- (P ≤ 0.001) and IKZF1^del/CD20^- (P = 0.047) groups. Multivariable analyses demonstrated the independence of IKZF1^del/CD20⁺, with the highest predicted hazard ratio for EFS and OS. Furthermore, the prognostic panel of IKZF1^del/CD20⁺ was confirmed in the TARGET cohort. Notably, neither the IKZF1^del, CD20⁺, or IKZF1^del/CD20⁺ groups were identified to have poor outcomes in the cohort of allogeneic hematopoietic stem cell transplantation (n = 81).Collectively, our data define IKZF1^del/CD20⁺ as a very high-risk subtype in B-ALL, and allo-HSCT could abrogate the poor outcome of both IKZF1^del and IKZF1^del/CD20⁺ subsets.

Prognostic significance of copy number variation in B-cell acute lymphoblastic leukemia

Copy number variations (CNVs) are widespread in both pediatric and adult cases of B-cell acute lymphoblastic leukemia (B-ALL); however, their clinical significance remains unclear. This review primarily discusses the most prevalent CNVs in B-ALL to elucidate their clinical value and further personalized management of this population. The discovery of the molecular mechanism of gene deletion and the development of targeted drugs will further enhance the clinical prognosis of B-ALL.

[Prognostic significance of IKZF1 gene deletions in patients with B-cell acute lymphoblastic leukemia]

Objective: This study aimed to investigate the prognostic significance of IKZF1 gene deletion in patients with acute B lymphoblastic leukemia (B-ALL) . Methods: The clinical data of 142 patients with B-ALL diagnosed in Nanfang Hospital between March 2016 and September 2019 were analyzed. Results: IKZF1 deletion was found in 36.0% of the 142 patients with B-ALL, whereas exon 4-7 deletion was found in 44.0% . White blood cell counts were higher in patients with the IKZF1 deletion (52.0% and 28.3% , P=0.005) ; these patients also experienced worse effects of mid-term induction therapy (40.0% and 70.7% , P<0.001) and had a higher proportion of Philadelphia chromosome-positive (52.0% and 21.7% , respectively, P<0.001) . Univariate analysis revealed that the 3-year overall survival rate (OS) and event-free survival rate (EFS) in the IKZF1 deletion group were significantly lower than the IKZF1 wild-type group [ (37.1±7.3) % vs (54.7±5.4) % , (51.8±7.9) % vs (73.9±4.7) % ; P=0.025, 0.013, respectively]. Multivariable analysis showed that harboring IKZF1 deletion was an adverse factor of EFS and OS (HR=1.744, 2.036; P=0.022, 0.020, respectively) . Furthermore, the IKZF1 deletion/chemotherapy group had significantly lower 3-year OS, EFS, and disease-free survival rates than other subgroups. In the IKZF1 deletion cohort, allo-hematopoietic stem cell transplantation (HSCT) significantly improved OS and EFS compared to non-allo-HSCT[ (67.9±10.4) % vs (31.9±11.0) % , (46.6±10.5) % vs (26.7±9.7) % ; P=0.005, 0.026, respectively]. Conclusion: Pediatric-inspired chemotherapy was unable to completely reverse the negative effect of IKZF1 deletion on prognosis. Pediatric-inspired regimen therapy combined with allo-HSCT, in contrast, significantly improved the overall prognosis of IKZF1 deletion B-ALL.