IK6 isoform with associated cytogenetic and molecular abnormalities in Chinese patients with Philadelphia chromosome-positive adult acute lymphoblastic leukemia

Philadelphia Chromosome-Positive Leukemia in the Lymphoid Lineage-Similarities and Differences with the Myeloid Lineage and Specific Vulnerabilities

Philadelphia chromosome (Ph) results from a translocation between the breakpoint cluster region (BCR) gene on chromosome 9 and ABL proto-oncogene 1 (ABL1) gene on chromosome 22. The fusion gene, BCR-ABL1, is a constitutively active tyrosine kinase which promotes development of leukemia. Depending on the breakpoint site within the BCR gene, different isoforms of BCR-ABL1 exist, with p210 and p190 being the most prevalent. P210 isoform is the hallmark of chronic myeloid leukemia (CML), while p190 isoform is expressed in majority of Ph-positive B cell acute lymphoblastic leukemia (Ph+ B-ALL) cases. The crucial component of treatment protocols of CML and Ph+ B-ALL patients are tyrosine kinase inhibitors (TKIs), drugs which target both BCR-ABL1 isoforms. While TKIs therapy is successful in great majority of CML patients, Ph+ B-ALL often relapses as a drug-resistant disease. Recently, the high-throughput genomic and proteomic analyses revealed significant differences between CML and Ph+ B-ALL. In this review we summarize recent discoveries related to differential signaling pathways mediated by different BCR-ABL1 isoforms, lineage-specific genetic lesions, and metabolic reprogramming. In particular, we emphasize the features distinguishing Ph+ B-ALL from CML and focus on potential therapeutic approaches exploiting those characteristics, which could improve the treatment of Ph+ B-ALL.

Ikaros family zinc-finger 1 mutation is an independent factor for the poor prognosis of adult B-cell acute lymphoblastic leukemia, and allogeneic hematopoietic stem cell transplantation can improve clinical outcomes

To investigate the prognosis of patients with adult B-cell acute lymphoblastic leukemia (B-ALL) with Ikaros family zinc-finger 1 (IKZF1) mutation and determine the role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in improving the clinical outcome, we detected the IKZF1 mutation and BCR-ABL fusion gene at diagnosis in the bone marrow of 164 adult patients with B-ALL, and analyzed the clinical data of these patients retrospectively. Our analysis showed that grade III-IV acute graft-versus-host disease and IKZF1 mutation in the transplantation group and age and IKZF1 mutation in the non-transplantation group were independent factors for poor prognosis by univariate and multivariate analyses.The 3-year overall survival (OS) and leukemia-free survival (LFS) rates were much lower in the IKZF1+/BCR-ABL+ subgroup than in the IKZF1+/BCR-ABL- and IKZF1-/BCR-ABL- subgroups in both the transplantation and non-transplantation groups. The 3-year OS and LFS rates were significantly higher in the transplantation group than in the non-transplantation group with IKZF1 mutation.The study demonstrated that IKZF1 mutation was an independent factor indicating the poor prognosis of adult B-ALL and much worse prognosis in the BCR-ABL+ subgroup in both non-transplantation and transplantation groups. However, allo-HSCT significantly improved the OS and LFS of patients and also their clinical outcomes.

Susceptibility of Ph-positive all to TKI therapy associated with Bcr-Abl rearrangement patterns: a retrospective analysis

Background

Tyrosine kinase inhibitors (TKIs) have demonstrated success in the treatment of acute lymphoblastic leukemia (ALL) in patients that express BCR-ABL rearrangements (Philadelphia chromosome [Ph]). The current study aimed to assess the efficacy of TKIs and prognostic factors in the treatment of adults with Ph+-ALL.

Methods

In this multicenter retrospective study, the relationship between Ph+-ALL and treatment outcomes among Chinese patients receiving TKI-containing induction/consolidation chemotherapy was examined. A total of 86 Ph+-ALL patients were included and followed for 3.85 (0.43–9.30) years. Overall survival (OS) and event-free survival (EFS) were analyzed.

Results

A total of 86 Ph+-ALL patients (40 females and 46 males; median age: 34.0 years) were enrolled, including those with BCR/ABL transcripts 190 (n = 52), 210 (n = 25), and 230 (n = 2); BCR/ABL isoform determination was not available for 7 patients. Mortality was influenced by variable BCR/ABL transcripts and TKI administration, and BCR/ABL transcripts, hematopoietic stem cell transplantation (HSCT), and TKI administration were associated with the occurrence of events. The OS rate in the TKI administration group during steady state was significantly higher compared with those patients who did not receive TKI administration (P = 0.008), the EFS rate in the TKI administration group during steady state was significantly higher compared with those patients who did not receive TKIs (P = 0.012), and also higher than those with TKI salvage administration (P = 0.004). BCR/ABL transcripts 210 showed preferable OS and EFS compared with BCR/ABL transcripts 190 and 230 (P<0.05 for each).

Conclusions

The susceptibility of Ph+-ALL to TKI associated with the patterns of BCR-ABL rearrangement is demonstrated for the first time, thus adding another risk-stratifying molecular prognostic tool for the management of patients with Ph+-ALL.