Allogeneic Hematopoietic Stem Cell Transplantation for Relapsed/Refractory Acute Myeloid Leukemia: A Single-Centre Experience

Efficacy and safety of cladribine in combination with busulfan and cyclophosphamide as an intensive conditioning regimen preceding allogeneic hematopoietic stem cell transplantation in relapsed or refractory acute myeloid leukemia

BACKGROUND

Cladribine, an analogue of deoxyadenosine, is used for therapy of hematological malignancies. Cladribine-containing regimen has been recommended as a rescue therapy for relapsed or refractory (R/R) acute myeloid leukemia (AML). Its combination with busulfan plus cyclophosphamide (BuCy), as an intensive conditioning regimen prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT), requires more clinical evidence. This study aimed to explore the efficacy and safety of cladribine plus BuCy administered as an intensive conditioning regimen before allo-HSCT in R/R AML patients.

METHODS

Twenty-three R/R AML patients, who underwent cladribine plus BuCy intensive conditioning regimen before allo-HSCT, were retrospectively analyzed. The median (range) follow-up duration time of observation was 0.73 (0.08-2.69) years.

RESULTS

The median (range) returned levels of mononuclear cells were 11.5 (6.1-18.5) x 108/kg and CD34+ cells were 5.5 (3.5-9.3) x 106/kg. The median (range) time of platelet reconstitution was 13.0 (9.0-21.0) days and neutrophil reconstitution was 14.0 (11.0-26.0) days. The incidence of conditioning regimen related toxicity (CRRT) affected 69.6% of patients; all CRRT-affected patients had grade I-II symptoms, including gastrointestinal tract (39.1%), oral cavity (26.1%), liver (8.7%), and kidney (4.3%) CRRTs. The incidence of acute graft-versus-host disease (GVDH) included 30.4% among all patients with 4.3% of grade III-IV acute GVHD, and 34.8% of chronic GVHD. During the follow-up period, 4 (17.4%) patients relapsed, and 6 (26.1%) patients died (cause of death: disease relapse, n = 3; infection, n = 2; GVHD, n = 1). The 1-year and 2-year accumulating event-free survival rates were 66.3% and 53.1%, respectively. The 1-year accumulating overall survival rate was 74.7% and 2-year survival rate was 64.0%.

CONCLUSION

Cladribine plus BuCy intensive conditioning regimen before allo-HSCT exhibits favorable treatment efficacy with acceptable toxicity in R/R AML patients.

Early Allogeneic Transplantation Favorably Influences the Outcome of Pediatric Acute Myeloid Leukemia-A Retrospective Study in a Single Center Over 2 Decades

BACKGROUND

Transplantation advancements offer the potential for improving the prognosis of patients with acute myeloid leukemia (AML). Controversies surrounding indications and timing persist. We focused on identifying prognostic factors and exploring the advantages of early transplantation.

PATIENTS AND METHODS

We studied 102 pediatric patients with AML (February 1999-August 2022), using Cox regression to analyze survival and hematopoietic cell transplantation (HCT) outcomes and Kaplan-Meier curves to assess HCT timing's impact on prognosis.

RESULTS

"Treatment in First Complete Remission [CR1]: Chemotherapy" showed increased risk in multivariate and univariate Cox regression analyses, whereas "HCT during the study period" displayed divergent outcomes. Focusing on transplanted patients, "Treatment in CR1: Chemotherapy" still correlated with higher mortality risk. These findings emphasize the pivotal role of the treatment strategy adopted in CR1 on overall survival rather than HCT alone. Donor cytomegalovirus (CMV) positivity is also related to reduced mortality risk. Kaplan-Meier analysis supported superior 5-year survival rates with "HCT" compared with "chemotherapy" in CR1. In the 3-arm analysis, "HCT in CR1" demonstrated better 5-year overall survival (OS) and 5-year disease-free survival (DFS) compared with "Never HCT," whereas "HCT in CR2" had the least favorable prognosis (5-year OS: 79.2% vs 57.1% vs 50%, P = .056; 5-year DFS: 73.6% vs 55.2% vs 0%, P = .000).

CONCLUSION

Our study highlights the benefits of transplantation during CR1 on prognosis. However, when contemplating CR1 transplantation recommendations, evaluation of various factors, such as the patient's clinical state, relapse risk, transplant-related mortality, CMV status, and other pertinent considerations, is vital. Comprehensive case discussions with patients and families are demanded in optimizing treatment.

CLAG combined with total body irradiation as intensive conditioning chemotherapy prior to allogeneic hematopoietic stem cell transplantation in patients with refractory or relapsed acute myeloid leukemia

Refractory or relapsed acute myeloid leukemia (R/R AML) remains the major challenge of AML treatment. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only valid option to achieve cure, but the prognosis is still dismal. We conducted a retrospective analysis for the feasibility of CLAG regimens (cladribine, cytarabine, and granulocyte colony-stimulating factor) combined with total body irradiation (TBI) as new intensive conditioning chemotherapy prior to HSCT in R/R AML. A total of 70 patients, including 21 primary refractory and 49 relapsed AML, were analyzed. Forty-nine (70%) patients had extramedullary diseases, and 54 (77%) patients received haploidentical transplantation. Except for one who died before white blood cell engraftment, all of the 69 evaluable patients achieved measurable residual disease (MRD) negative complete remission. The 3-year overall survival (OS) and relapse-free survival (RFS) rates were 46.0% (95% confidence interval [CI], 33.5-57.7%) and 38.5% (95%CI, 26.8-50.0%). The 1-year cumulative incidences of relapse and non-relapse mortality (NRM) were 38.6% (95%CI, 27.3-49.3%) and 11.6% (95%CI: 5.4-20.3%), respectively. The presence of chronic graft-versus-host disease (cGVHD) showed a trend to be associated with a lower risk of relapse (P = 0.054) and extramedullary diseases with a higher risk of NRM (P = 0.074). Multivariate analyses identified low leukemia burden pre-HSCT (defined as bone marrow blasts ≤ 50%) and cGVHD as independent factors associated with favorable OS and RFS. In conclusion, intensive conditioning with CLAG regimens plus TBI may be an effective and well-tolerated choice for R/R AML patients undergoing allo-HSCT.