[Allogeneic hematopoietic stem cell transplantation for treatment of refractory and relapsed acute myeloid leukemia: outcomes and prognostic factors]

Homoharringtonine combined with cladribine and aclarubicin (HCA) in acute myeloid leukemia: A new regimen of conventional drugs and its mechanism

Objective

The prognosis of children with refractory acute myeloid leukemia (AML) is poor. Complete remission (CR) is not always achieved with current salvage chemotherapy regimens before transplantation, and some patients have no chance of transplantation. Here, we aimed to describe a new regimen of conventional chemotherapy drugs (homoharringtonine, cladribine , and aclarubicin (HCA)) for refractory AML and its mechanism in vitro.

Methods

We retrospectively collected the clinical data of 5 children with primary refractory AML using HCA as reinduction chemotherapy, and CR rates, adverse reactions, and disease-free survival (DFS) were analyzed. The effects of homoharringtonine, cladribine, and aclarubicin alone or in combination on the proliferation of HL60 and THP1 cells were analyzed by CCK-8 assay. Furthermore, CCK-8 was used to determine the effects of HCA, alone or in combination with apoptosis inhibitors, necroptosis inhibitors, ferroptosis inhibitors, or autophagy inhibitors, on the proliferation of HL60 and THP1 cells and to screen for possible HCA-mediated death pathways in AML cells. The pathway of HCA-mediated AML cell death was further verified by Hoechst/PI staining, flow cytometry, and Western blotting.

Results

After 2 cycles of conventional chemotherapy, none of the 5 children with AML achieved CR and were then treated with the HCA regimen for two cycles, 4 of 5 achieved CR, and another child achieved CR with incomplete hematological recovery (CRi). After CR, 3 children underwent hematopoietic stem cell transplantation (HSCT), and only 2 of them received consolidation therapy. As of the last follow-up, all 5 patients had been in DFS for a range of 23 to 28 months. The inhibition rate of homoharringtonine, cladribine, and aclarubicin in combination on HL60 and THP1 cells was significantly greater than that of a single drug or a combination of two drugs. We found that inhibitors of apoptosis and necroptosis were able to inhibit HCA-mediated cell death but not ferroptosis or autophagy inhibitors. Compared with the control group, the number of apoptotic cells in the HCA group was significantly increased and could be reduced by an apoptosis inhibitor. Western blot results showed that PARP, caspase-3, and caspase-8 proteins were activated and cleaved in the HCA group, the expression of Bax was upregulated and that of Bcl-2 was downregulated. The expression of apoptosis-related proteins could be reversed by apoptosis inhibition. Compared with the control group, the expression levels of the necroptosis-related proteins RIP1, RIP3, and MLKL were downregulated in the HCA group but were not phosphorylated. The necroptosis inhibitor increased the expression of RIP1 but caused no significant changes in RIP3 and MLKL, and none were phosphorylated.

Conclusions

HCA, as a new regimen of conventional drugs, was a safe and efficacious reinduction salvage strategy in children with refractory AML before HSCT. HCA exhibits the synergistic growth inhibition of AML cells and induces cell death mainly through apoptosis.

[HLA-10/10 matched unrelated donor versus sibling donor hematopoietic stem cell transplantation for adult acute myeloid leukemia]

Objective: To evaluate the outcomes of human leukocyte antigen (HLA) matched unrelated donor hematopoietic stem cell transplantation (MUD-HSCT) for adult acute myeloid leukemia (AML) in a single center. Methods: Consecutive adult AML who received MUD-HSCT in our center from January 2008 to April 2017 were studied retrospectively, comparing with patients undergoing matched sibling donor (MSD) -HSCT in the same period. The rates of overall survival (OS) , disease free survival (DFS) , relapse, non-relapse mortality (NRM) , engraftment, acute and chronic graft-versus-host disease (aGVHD and cGVHD) were analyzed. Results: A total of 247 consecutive cases were enrolled, including 46 patients with MUD-HSCT and 201 with MSD-HSCT. All the patients experienced neutrophil engraftment except for one patient who died early in the MSD group, but the median day of engraftment was longer in the MUD group (15.0 vs 14.0, P=0.017) . The accumulative engraftment rate of platelet was comparable between the two groups (93.5%vs 98.0%, P=0.128) . The accumulative incidences of aGVHD (50.0%vs 46.3%, P=0.421) and cGVHD (37.8%vs 43.0%, P=0.581) were not statistically different between the two groups. Compared with the MSD group, the accumulative NRM rate at+36 months after transplantation was significantly higher in the MUD group (22.0%vs 10.4%, P=0.049) , while the relapse rate was not statistical difference (20.5 vs 28.3%, P=0.189) . Both the 3-year OS (61.6%vs 63.3%, P=0.867) and DFS (57.5%vs 61.6%, P=0.760) were comparable between the two groups. Four independent risk factors were confirmed by the multivariate analysis: patient age ≥45 years old, CR2 or NR before transplantation, a history of extramedullary infiltration and the occurrence of grade Ⅲ-Ⅳ aGVHD. No statistical differences were demonstrated in the survival rate between MUD-and MSD-HSCT in different subgroups. Conclusions: The outcomes, such as GVHD, relapse, OS and DFS, were comparable between MUD-and MSD-HSCT for adult AML, but higher incidence of NRM and longer time to neutrophil engraftment in the MUD group. MUD-HSCT is practical and feasible for adult AML who are lack of MSD.