All is not lost in accelerated phase/blast crisis and after tyrosine kinase inhibitors fail in chronic myeloid leukaemia: a retrospective study of allogeneic stem cell transplant outcomes in Australia and New Zealand

Case report: CD38-directed CAR-T cell therapy: A novel immunotherapy targeting CD38- positive blasts overcomes TKI and chemotherapy resistance of myeloid chronic myeloid leukemia in blastic phase

Resistance to tyrosine kinase inhibitor (TKI) is a tough problem in the treatment of chronic myeloid leukemia in blastic phase (CML-BP), which was often associated with acquired mutations in the kinase domain and not eliminating the leukemic stem cells. The efficacy of TKI or combination with chemotherapy in CML-BP remains unsatisfactory. Chimeric antigen receptor T (CAR-T) cell immunotherapy may overcome TKI and chemotherapy resistance. However, lack of ideal targetable antigens is a major obstacle for treating patients with myeloid malignancies. CD38 is known to be expressed on most (acute myeloid leukemia) AML cells, and its lack of expression on hematopoietic stem cells renders it as a potential therapeutic target for myeloid CML-BP. We develop a CD38-directed CAR-T cell therapy for AML, and two patients with myeloid CML-BP were enrolled (NCT04351022). Two patients, harboring E255K and T315I mutation in the ABL kinase domain, respectively, were resistant to multiple TKIs (imatinib, dasatinib, nilotinib, and ponatinib) and intensive chemotherapy. The blasts in the bone marrow of two patients exhibited high expression of CD38. After tumor reduction chemotherapy and lymphodepletion chemotherapy, 1 × 10⁷ CAR-T-38 cells per kilogram of body weight were administered. They achieved minimal residual disease-negative and BCR::ABL1-negative complete remission and experienced grade II cytokine release syndrome manifesting as fever. Our data highlighted that CAR-T-38 cell therapy may overcome TKI and chemotherapy resistance in patients with myeloid CML-BP.

Combined chronic myeloid leukaemia and chronic lymphocytic leukaemia in five patients, including one with 17p deletion

We report a series of five Australian cases of chronic lymphocytic leukaemia (CLL) occurring concurrently with chronic myeloid leukaemia (CML). Patient management including therapies and response together with clinical progress was obtained from medical records and laboratory information systems. Prior to CML diagnosis, all five had a preceding diagnosis of CLL. Three had received prior fludarabine. All received tyrosine kinase inhibitors (TKI). None required subsequent therapy for CLL. One patient had 17p deletion CLL and another patient had normal CLL cytogenetics. All currently have satisfactory blood counts with quantitative polymerase chain reaction for CML showing molecular response. All remain alive. Thus, such cases can be successfully managed by treating each haematological disorder in the usual manner. The control achieved in CML with the TKI enables satisfactory marrow function to recover in patients with concomitant CLL. The role for allograft in patients with dual malignancies is uncertain and needs to be individualised depending on control of each malignancy.

Efficacy of allogeneic hematopoietic cell transplantation in patients with chronic phase CML resistant or intolerant to tyrosine kinase inhibitors

Approximately 15-20% of chronic myeloid leukemia (CML) patients fail tyrosine kinase inhibitor (TKI) therapy secondary to resistance or intolerance. In the pre-TKI era, front-line allogeneic hematopoietic cell transplantation (allo-HCT) represented the standard approach for patients with chronic phase-CML (CP-CML) who were deemed fit to tolerate the procedure and had a human leukocyte antigen compatible donor available. Currently, CP-CML patients are eligible for allo-HCT only if they fail more than one TKI and/or are intolerant to the drug. We performed a systematic review/meta-analysis of the available literature to assess the evidence regarding allo-HCT efficacy in CP-CML patients. Data from eligible studies were extracted in relation to benefits (overall survival [OS], progression-free survival, disease-free survival [DFS], complete remission [CR], and molecular response [MR]) and harms (nonrelapse mortality [NRM], relapse, and acute and chronic graft-versus-host disease), and stratified by age into adult and pediatric groups. For adult allo-HCT recipients, the pooled OS, DFS, CR and, MR were 84% [95% confidence interval (CI) 59-99%], 66% (95% CI 59-73%), 56% (95% CI 30-80%), and 88% (95% CI 62-98%), respectively. Pooled NRM and relapse were 20% (95% CI 15-26%) and 19% (95% CI 10-28%), respectively. For the pediatric group, the OS rate was reported in one study and was 91% (95% CI 72-99%). Our results suggest that allo-HCT is an effective treatment for TKI-resistant or TKI-intolerant CP-CML. Post-transplant strategies are still needed to further mitigate the risk of relapse.

Prognostic factors and survival outcomes in patients with chronic myeloid leukemia in blast phase in the tyrosine kinase inhibitor era: Cohort study of 477 patients

BACKGROUND

Outcomes in patients with chronic myeloid leukemia in blast phase (CML-BP) are historically dismal. Herein, the authors sought to analyze the characteristics, prognostic factors, and survival outcomes in patients with CML-BP in the tyrosine kinase inhibitor (TKI) era.

METHODS

A total of 477 patients with CML-BP were treated with a TKI at some point during the course of their CML. Cox proportional hazard models identified characteristics that were predictive of survival. Overall survival and failure-free survival were assessed. Optimal cutoff points for specific parameters were identified using classification and regression tree (CART) analysis.

RESULTS

The median age of the patients was 53 years (range, 16-84 years) and 64% were male. Approximately 80% of patients initially were diagnosed in the chronic phase of CML at a median of 41 months (range, 0.7-298 months) before transformation to CML-BP. De novo CML-BP occurred in 71 patients. Approximately 72% of patients received TKI therapy before CML-BP. The initial therapy for CML-BP included a TKI alone (35%), a TKI with chemotherapy (46%), and non-TKI therapies (19%). The median overall survival was 12 months and the median failure-free survival was 5 months. In multivariate analysis, myeloid immunophenotype, prior TKI, age ≥58 years, lactate dehydrogenase level ≥1227 IU/L, platelet count < 102 K/μL, no history of stem cell transplantation, transition to BP from chronic phase/accelerated phase, and the presence of chromosome 15 aberrations predicted for a significantly increased risk of death. Achievement of major hematologic response and/or complete cytogenetic response to first-line treatment was found to be predictive of better survival. The combination of a TKI with intensive chemotherapy followed by stem cell transplantation appeared to confer the best outcome.

CONCLUSIONS

Patients with CML-BP continue to pose a therapeutic challenge, have dismal outcomes, and require newer treatment approaches. Cancer 2017;123:4391-402. © 2017 American Cancer Society.