How I treat refractory and early relapsed acute myeloid leukemia

Rhein exerts anti-multidrug resistance in acute myeloid leukemia via targeting FTO to inhibit AKT/mTOR

Chemotherapy failure and resistance are the leading causes of mortality in patients with acute myeloid leukemia (AML). However, the role of m6A demethylase FTO and its inhibitor rhein in AML and AML drug resistance is unclear. Therefore, this study aimed to investigate the antileukemic effect of rhein on AML and explore its potential mechanisms underlying drug resistance. Bone marrow fluid was collected to assess FTO expression in AML. The Cell Counting Kit 8 reagent was used to assess cell viability. Migration assays were conducted to assess the cell migration capacity. Flow cytometry was used to determine the apoptotic effects of rhein and western blot analysis was used to detect protein expression. Online SynergyFinder software was used to calculate the drug synergy scores. The in-vivo antileukemic effect of rhein was assessed in an AML xenograft mouse model. We analyzed different types of AML bone marrow specimens to confirm that FTO is overexpressed in AML, particularly in cases of multidrug resistance. Subsequently, we conducted in-vivo and in-vitro investigations to explore the pharmacological activity and mechanism of rhein in AML and AML with multidrug resistance. The findings demonstrated that rhein effectively suppressed the proliferation and migration of AML cells in a time- and dose-dependent manner and induced apoptosis. Rhein targets FTO, inhibits the AKT/mTOR pathway, and exhibits synergistic antitumor effects when combined with azacitidine. This study elucidates the significant role of FTO and its inhibitor rhein in AML and AML with multidrug resistance, providing new insights for overcoming multidrug resistance in AML.

Allogeneic Stem Cell Transplantation in Refractory Acute Myeloid Leukaemia

Refractory acute myeloid leukaemia is very difficult to treat and represents an unmet clinical need. In recent years, new drugs and combinations of drugs have been tested in this category, with encouraging results. However, all treated patients relapsed and died from the disease. The only curative option is allogeneic transplantation through a graft from a healthy donor immune system. Using myeloablative conditioning regimens, the median overall survival regimens is 19%. Several so-called sequential induction chemotherapies followed by allogeneic transplantation conditioned by reduced intensity regimens have been developed, improving the overall survival to 25-57%. In the allogeneic transplantation field, continuous improvements in practices, particularly regarding graft versus host disease prevention, infection prevention, and treatment, have allowed us to observe improvements in survival rates. This is true mainly for patients in complete remission before transplantation and less so for refractory patients. However, full myeloablative regimens are toxic and carry a high risk of treatment-related mortality. In this review, we describe the results obtained with the different modalities used in more recent retrospective and prospective studies. Based on these findings, we speculate how allogeneic stem cell transplantation could be modified to maximise its therapeutic effect on refractory acute myeloid leukaemia.

Integrated Analysis of Single-Cell RNA-Seq and Bulk RNA-Seq Unravels the Molecular Feature of Tumor-Associated Macrophage of Acute Myeloid Leukemia

Background

The association between acute myeloid leukemia (AML) and macrophage remains to be deeply explored.

Methods

Gene expression profiles and clinical variable characteristics of AML patients were collected from TCGA, GEO, and TARGET databases. Consensus clustering was employed to construct the macrophage-related clusters. The macrophage-related index (MRI) was constructed using the LASSO and multivariate Cox analysis. The GSE71014 and TARGET datasets were utilized as external validation sets. Single-cell sequencing data for AML (GSE116256) was adopted to analyze modeled gene expression levels in cells.

Results

Two macrophage-related clusters with different prognostic and immune infiltration characteristics were constructed in AML. Cluster B had a poorer prognosis, more cancer-promoting pathway enrichment, and an immunosuppressive microenvironment. Relied on the MRI, patients of different groups showed different levels of immune infiltration, different mutations, and prognoses. LGALS1 and BCL2A1 may play roles in promoting cancer in AML, while ELANE may have a significant effect on suppressing cancer.

Conclusion

Macrophage-related genes (MRGs) had significant impacts on the occurrence and progression of AML. MRI may better evaluate the prognosis and immune features of AML patients.

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.

Exploring the Potential of siRNA Delivery in Acute Myeloid Leukemia for Therapeutic Silencing

We investigated the feasibility of using siRNA therapy for acute myeloid leukemia (AML) by developing macromolecular carriers that facilitated intracellular delivery of siRNA. The carriers were derived from low-molecular-weight (<2 kDa) polyethyleneimine (PEI) and modified with a range of aliphatic lipids. We identified linoleic acid and lauric acid-modified PEI as optimal carriers for siRNA delivery to AML cell lines KG1 and KG1a, as well as AML patient-derived mononuclear cells. As they have been proven to be potent targets in the treatment of AML, we examined the silencing of BCL2L12 and survivin and showed how it leads to the decrease in proliferation of KG1 and stem-cell-like KG1a cells. By optimizing the transfection schedule, we were able to enhance the effect of the siRNAs on proliferation over a period of 10 days. We additionally showed that with proper modifications of PEI, other genes, including MAP2K3, CDC20, and SOD-1, could be targeted to decrease the proliferation of AML cells. Our studies demonstrated the versatility of siRNA delivery with modified PEI to elicit an effect in leukemic cells that are difficult to transfect, offering an alternative to conventional drugs for more precise and targeted treatment options.

LILRB3 Modulates Acute Myeloid Leukemia Progression and Acts as an Effective Target for CAR T-cell Therapy

Identifying novel cell surface receptors that regulate leukemia cell differentiation and can be targeted to inhibit cellular proliferation is crucial to improve current treatment modalities in acute myeloid leukemia (AML), especially for relapsed or chemotherapy-refractory leukemia. Leukocyte immunoglobulin-like receptor type B (LILRB) is an immunomodulatory receptor originally found to be expressed in myeloid cells. In this study, we found that LILRB receptors can be induced under inflammatory stimuli and chemotherapy treatment conditions. Blockade of LILRB3 inhibited leukemia cell proliferation and leukemia progression. In addition, treatment with LILRB3 blocking antibodies upregulated myeloid lineage differentiation transcription factors, including PU.1, C/EBP family, and IRF, whereas phosphorylation of proliferation regulators, for example, AKT, cyclin D1, and retinoblastoma protein, was decreased. Conversely, transcriptomic analysis showed LILRB3 activation by agonist antibodies may enhance leukemia survival through upregulation of cholesterol metabolism, which has been shown to promote leukemia cell survival. Moreover, LILRB3-targeted CAR T cells exhibited potent antitumor effects both in vitro and in vivo. Taken together, our results suggest that LILRB3 is a potentially potent target for multiple treatment modalities in AML.

SIGNIFICANCE

LILRB3 regulates differentiation and proliferation in acute myeloid leukemia and can be targeted with monoclonal antibodies and CAR T cells to suppress leukemia growth.

Chidamide, Decitabine, Cytarabine, Aclarubicin, and Granulocyte Colony-stimulating Factor Therapy for Patients with Relapsed/Refractory Acute Myeloid Leukemia: A Retrospective Study from a Single-Center

OBJECTIVE

Preclinical evidence and clinical trials have suggested synergistic effects of epigenetic modifiers in combination with cytotoxic agents for the treatment of leukemia. However, their efficacy in patients with relapsed/refractory acute myeloid leukemia (R/R AML) remains unclear.

METHODS

Clinical data of R/R AML patients who received a CDCAG regimen (chidamide, decitabine, cytarabine, aclarubicin, and granulocyte colony-stimulating factor) from July 1, 2018 to October 31, 2021 at our center were retrospectively assessed, and the safety and efficacy of the CDCAG regimen were evaluated. Patients were followed up until November 30, 2021, with a median follow-up of 21.6 months (95% CI: 10.0-33.2 months).

RESULTS

A total of 67 patients were enrolled. Two patients died within 3 weeks after the initiation, and therefore only 65 patients underwent the assement for clinical response and survival. It was found that 56.9% patients achieved complete remission with a median overall survival (OS) of 9.6 months. The median OS of responders was 25.9 months, while that of non-responders was 5.0 months (P<0.0001). Patients with gene mutations had a superior overall response rate (ORR) (80.4% vs. 45.5%, P=0.043) compared to those without gene mutations. The presence of DNA methyltransferase 3 A (DNMT3A), ten-eleven translocation-2 (TET2), and isocitrate dehydrogenase 1/2 (IDH1/2) mutations did not affect the response rate (88.2% vs. 68.9%, P=0.220) and reflected a better OS (not attained vs. 9.0 months, P=0.05). The most common non-hematologic adverse events were pulmonary infection (73.1%), followed by febrile neutropenia (23.9%) and sepsis (19.4%).

CONCLUSIONS

The CDCAG regimen was effective and well-tolerated in R/R AML patients, increasing the potential for allogeneic hematopoietic stem cell transplantation. Moreover, patients with DNMT3A, TET2, and IDH1/2 mutations might benefit from this regimen.

Venetoclax combined with hypomethylating agents and the CAG regimen in relapsed/refractory AML: a single-center clinical trial

Objective

This study aimed to evaluate the efficacy and safety of venetoclax in combination with hypomethylating agents and CAG (VEN-DCAG) regimens in patients with relapsed/refractory acute myeloid leukemia (R/R AML).

Methods

The treatment response was analyzed by retrospective methods in R/R AML patients treated with the VEN-DCAG regimen at our institution. This included, but was not limited to, CR/CRi (complete remission/complete remission with incomplete hematologic recovery) rate, measurable residual disease (MRD) negative rate, and overall survival (OS).

Results

20 patients with R/R AML were recruited, with a median age of 40 years (10-70), 11 of whom were male (55%), and a median follow-up of 10.4 months (0.7-21.8). The overall response rate (ORR) after receiving 1 course of VEN-DCAG was 90% (18/20), with 17 (85%) CR/CRi (10 MRD-CR), 1 (5%) PR, and 2 (10%) NR. Subsequently, 12 patients (7 MRD-CR, 4 MRD+CR, 1 NR) were treated with the VEN-DCAG regimen, and 3 MRD+CR patients turned negative, and 13 patients finally achieved MRD-CR. Among them, 7 patients were in the relapse group, all achieving CR/CRi (6 MRD-CR), and 13 patients in the refractory group, with 10 CR/CRi (7 MRD-CR). The ORR for patients in the relapse and refractory groups was 100% (7/7) and 84.6% (11/13), respectively. Further, all patients experienced adverse events (AEs) of varying degrees of severity, with hematologic AEs primarily consisting of myelosuppression, while non-hematologic AEs were more common in the form of fever, gastrointestinal distress, and infections. 11 patients were followed up with bridging allogeneic hematopoietic stem cell transplantation (allo-HSCT) therapy. At the last follow-up, 11 patients (7 MRD-CR, 4 MRD+CR) who received allo-HSCT, 1 (MRD+CR) died, and 9 patients (6 MRD-CR, 1 PR, 2 NR) who did not receive allo-HSCT, 5 (2 MRD-CR, 1 PR, 2 NR) died as well.

Conclusion

The VEN-DCAG regimen may be an effective treatment option for R/R AML patients, with high ORR and MRD negative remission rates in both the relapsed and refractory groups. It is recommend that patients should be bridged to allo-HSCT as soon as possible after induction to CR by the VEN-DCAG regimen, which can lead to a significant long-term survival benefit.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2300075985.

STAT5 promotes PD-L1 expression by facilitating histone lactylation to drive immunosuppression in acute myeloid leukemia

Immunotherapy is a revolutionized therapeutic strategy for tumor treatment attributing to the rapid development of genomics and immunology, and immune checkpoint inhibitors have successfully achieved responses in numbers of tumor types, including hematopoietic malignancy. However, acute myeloid leukemia (AML) is a heterogeneous disease and there is still a lack of systematic demonstration to apply immunotherapy in AML based on PD-1/PD-L1 blockage. Thus, the identification of molecules that drive tumor immunosuppression and stratify patients according to the benefit from immune checkpoint inhibitors is urgently needed. Here, we reported that STAT5 was highly expressed in the AML cohort and activated the promoter of glycolytic genes to promote glycolysis in AML cells. As a result, the increased-lactate accumulation promoted E3BP nuclear translocation and facilitated histone lactylation, ultimately inducing PD-L1 transcription. Immune checkpoint inhibitor could block the interaction of PD-1/PD-L1 and reactive CD8+ T cells in the microenvironment when co-culture with STAT5 constitutively activated AML cells. Clinically, lactate accumulation in bone marrow was positively correlated with STAT5 as well as PD-L1 expression in newly diagnosed AML patients. Therefore, we have illustrated a STAT5-lactate-PD-L1 network in AML progression, which demonstrates that AML patients with STAT5 induced-exuberant glycolysis and lactate accumulation may be benefited from PD-1/PD-L-1-based immunotherapy.

Effectiveness of chemotherapy using bortezomib combined with homoharringtonine and cytarabine in refractory or relapsed acute myeloid leukemia: a phase II, multicenter, prospective clinical trial

Background

Refractory/relapsed acute myeloid leukemia (R/R AML) has unsatisfactory outcomes even after allogeneic hematopoietic stem cell transplantation. Long-term survival is mainly influenced by complete remission (CR) rates after induction therapies.

Objectives

To investigate CR/CR with incomplete hematologic recovery (CRi) rates and adverse events with a new induction therapy (bortezomib, homoharringtonine, and cytarabine [BHA]) for patients with R/R AML.

Methods

We enrolled 21 patients with R/R AML (median age, 42 [range, 30-62] years), who received BHA for remission induction (bortezomib, 1.3 mg/m2/day on days 1 and 4; homoharringtonine, 4 mg/m2/day for 5 days, and cytarabine, 1.5 g/m2/day for 5 days). CR and adverse events were assessed.

Results

After one course of BHA, the CR/CRi and partial remission rates were 38.1% and 14.3%, respectively, with an overall response rate (ORR) of 52.4% in 21 patients. 9 of 21 patients harbored FLT3-ITD or FLT3-TKD mutations, and achieved either CR/CRi or ORR of 66.7% (P=0.03) by comparison with that in R/R AML without FLT3 mutation. After induction therapy, consolidation chemotherapy or allogeneic hematopoietic stem cell transplantation led to a one-year overall survival of 27.8% in all patients. One-year relapse-free survival was 50% in 8 patients who had achieved CR/CRi after one course of BHA. During induction, non-hematologic adverse events (grade 3/4) commonly were infection (90.5%), hypokalemia (14.4%), hypocalcemia (14.3%), and mucositis (9.5%). In patients achieving CR, the median time to neutrophil count >0.5×109/L and time to platelet count >20×109/L were 15 (13-17) days and 13 (13-18) days, respectively.

Conclusion

BHA chemotherapy regimen was safe and tolerable to serve as an induction therapy for R/R AML, particularly with FLT3 mutation. The higher CR/CRi rate will give a clue to determine a potentialeffectiveness of BHA for AML patients carrying FLT3 mutation in a further investigation.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2000029841.

Role of Intracellular Drug Disposition in the Response of Acute Myeloid Leukemia to Cytarabine and Idarubicin Induction Chemotherapy

Despite its often low efficacy and high toxicity, the standard treatment for acute myeloid leukemia (AML) is induction chemotherapy with cytarabine and idarubicin. Here, we have investigated the role of transporters and drug-metabolizing enzymes in this poor outcome. The expression levels (RT-qPCR) of potentially responsible genes in blasts collected at diagnosis were related to the subsequent response to two-cycle induction chemotherapy. The high expression of uptake carriers (ENT2), export ATP-binding cassette (ABC) pumps (MDR1), and enzymes (DCK, 5-NT, and CDA) in the blasts was associated with a lower response. Moreover, the sensitivity to cytarabine in AML cell lines was associated with ENT2 expression, whereas the expression of ABC pumps and enzymes was reduced. No ability of any AML cell line to export idarubicin through the ABC pumps, MDR1 and MRP, was found. The exposure of AML cells to cytarabine or idarubicin upregulated the detoxifying enzymes (5-NT and DCK). In AML patients, 5-NT and DCK expression was associated with the lack of response to induction chemotherapy (high sensitivity and specificity). In conclusion, in the blasts of AML patients, the reduction of the intracellular concentration of the active metabolite of cytarabine, mainly due to the increased expression of inactivating enzymes, can determine the response to induction chemotherapy.

A Panorama of Immune Fighters Armored with CARs in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a devastating disease. Intensive chemotherapy is the mainstay of treatment but results in debilitating toxicities. Moreover, many treated patients will eventually require hematopoietic stem cell transplantation (HSCT) for disease control, which is the only potentially curative but challenging option. Ultimately, a subset of patients will relapse or have refractory disease, posing a huge challenge to further therapeutic decisions. Targeted immunotherapies hold promise for relapsed/refractory (r/r) malignancies by directing the immune system against cancer. Chimeric antigen receptors (CARs) are important components of targeted immunotherapy. Indeed, CAR-T cells have achieved unprecedented success against r/r CD19+ malignancies. However, CAR-T cells have only achieved modest outcomes in clinical studies on r/r AML. Natural killer (NK) cells have innate anti-AML functionality and can be engineered with CARs to improve their antitumor response. CAR-NKs are associated with lower toxicities than CAR-T cells; however, their clinical efficacy against AML has not been extensively investigated. In this review, we cite the results from clinical studies of CAR-T cells in AML and describe their limitations and safety concerns. Moreover, we depict the clinical and preclinical landscape of CAR used in alternative immune cell platforms with a specific focus on CAR-NKs, providing insight into the future optimization of AML.

Mediastinal Mass as an Initial Presentation of Acute Myeloid Leukemia in a Young Man

A 29-year-old male, hemodynamically stable, presented with chest pain radiating to the interscapular region, with no fever, cough, dyspnea, or other constitutional symptoms. He had right cervical lymphadenopathy on physical examination. Investigations revealed a 3.1 cm anterior mediastinal nodular mass, peripheral immature blood cells, and thrombocytopenia. Bone marrow core biopsy findings were consistent with acute myeloid leukemia (AML). The mediastinal mass was resected via robotic-assisted thoracoscopic surgery. Histopathology revealed involvement of the mediastinal adipose tissue with myeloid sarcoma. Molecular testing showed TP53 mutation, signifying a poor prognosis. The patient failed several lines of therapy and expired. This case demonstrates an atypical presentation of AML and emphasizes the criticality of early detection in individuals who do not exhibit the usual symptoms associated with the disease. The presence of immature cell lines in peripheral blood should prompt an investigation to determine bone marrow involvement in an otherwise healthy young adult.

Venetoclax Combined with Azacitidine and Homoharringtonine in Relapsed/Refractory AML: A Multicenter, Phase 2 Trial

BACKGROUND

Relapsed or refractory acute myeloid leukemia (R/R AML) has a dismal prognosis. The aim of this study was to investigate the activity and tolerability of venetoclax combined with azacitidine plus homoharringtonine (VAH) regimen for R/R AML.

METHODS

This phase 2 trial was done at ten hospitals in China. Eligible patients were R/R AML (aged 18-65 years) with an Eastern Cooperative Oncology Group performance status of 0-2. Patients received venetoclax (100 mg on day 1, 200 mg on day 2, and 400 mg on days 3-14) and azacitidine (75 mg/m² on days 1-7) and homoharringtonine (1 mg/m² on days 1-7). The primary endpoint was composite complete remission rate [CRc, complete response (CR) plus complete response with incomplete blood count recovery (CRi)] after 2 cycles of treatment. The secondary endpoints include safety and survival.

RESULTS

Between May 27, 2020, and June 16, 2021, we enrolled 96 patients with R/R AML, including 37 primary refractory AML and 59 relapsed AML (16 relapsed after chemotherapy and 43 after allo-HSCT). The CRc rate was 70.8% (95% CI 60.8-79.2). In the patients with CRc, measurable residual disease (MRD)-negative was attained in 58.8% of CRc patients. Accordingly, overall response rate (ORR, CRc plus partial remission (PR)) was 78.1% (95% CI 68.6-85.4). At a median follow-up of 14.7 months (95% CI 6.6-22.8) for all patients, median overall survival (OS) was 22.1 months (95% CI 12.7-Not estimated), and event-free survival (EFS) was 14.3 months (95% CI 7.0-Not estimated). The 1-year OS was 61.5% (95% CI 51.0-70.4), and EFS was 51.0% (95% CI 40.7-60.5). The most common grade 3-4 adverse events were febrile neutropenia (37.4%), sepsis (11.4%), and pneumonia (21.9%).

CONCLUSIONS

VAH is a promising and well-tolerated regimen in R/R AML, with high CRc and encouraging survival. Further randomized studies are needed to be explored. Trial registration clinicaltrials.gov identifier: NCT04424147.

Unraveling the therapeutic potential of natural products in the prevention and treatment of leukemia

Leukemia is a heterogeneous group of hematological malignancies distinguished by differentiation blockage and uncontrolled proliferation of myeloid or lymphoid progenitor cells in the bone marrow (BM) and peripheral blood (PB). There are various types of leukemia in which intensive chemotherapy regimens or hematopoietic stem cell transplantation (HSCT) are now the most common treatments associated with severe side effects and multi-drug resistance in leukemia cells. Therefore, it is crucial to develop novel therapeutic approaches with adequate therapeutic efficacy and selectively eliminate leukemic cells to improve the consequences of leukemia. Medicinal plants have been utilized for ages to treat multiple disorders due to their diverse bioactive compounds. Plant-derived products have been used as therapeutic medication to prevent and treat many types of cancer. Over the last two decades, 50 % of all anticancer drugs approved worldwide are from natural products and their derivatives. Therefore this study aims to review natural products such as polyphenols, alkaloids, terpenoids, nitrogen-containing, and organosulfur compounds as antileukemic agents. Current investigations have identified natural products efficiently destroy leukemia cells through diverse mechanisms of action by inhibiting proliferation, reactive oxygen species production, inducing cell cycle arrest, and apoptosis in both in vitro, in vivo, and clinical studies. Current investigations have identified natural products as suitable promising chemotherapeutic and chemopreventive agents. It played an essential role in drug development and emerged as a possible source of biologically active metabolites for therapeutic interventions, especially in leukemia. DATA AVAILABILITY: Data will be made available on request.

Genetic characteristics predict response to venetoclax plus hypomethylating agents in relapsed or refractory acute myeloid leukemia

BACKGROUND

The heterogeneity of relapsed or refractory (R/R) acute myeloid leukemia (AML) leads to no response to venetoclax (VEN)-based therapy in more than half of the patients. Genetic characteristics are considered important predictors for response to treatment in adults with AML. However, the association of genetic characteristics with outcomes receiving VEN-based therapy is incompletely understood in R/R AML.

OBJECTIVE

To evaluate the efficacy of VEN combined with hypomethylating agents (HMA) and identify the potential genetic predictors of response in R/R AML.

METHODS

A total of 150 R/R AML patients treated with VEN combined with HMA were enrolled in this retrospective study. Outcomes of the response and overall survival (OS) were analyzed. The predictors of response and OS were analyzed by logistic regression or Cox proportional hazards model.

RESULTS

With a median of two (range, 1-4) cycles of therapy, the overall response rate was 56.2%, including 22.0% complete remission (CR), 21.3% CR with incomplete hematologic recovery, 2.0% morphologic leukemia-free state, and 10.7% partial remission, in which 25 patients achieved measurable residual disease (MRD)-negative response. With a median follow-up of 11.2 [95% confidence interval (CI), 7.2-14.8] months, 1- and 2-year OS were 46.9% (95% CI, 37.8%-58.1%) and 38.9% (95% CI, 28.7%-52.9%), respectively. Adverse cytogenetics and European Leukemia Net (ELN) risk predicted inferior response to VEN-based therapy. Mutations in IDH1/2, NPM1, ASXL1, and chromatin-cohesin genes predicted superior response to VEN-based therapy, whereas mutations in active signaling genes such as FLT3-ITD and K/NRAS predicted inferior response.

CONCLUSION

VEN combined with HMA was effective with R/R AML patients, and the response to treatment was associated with genetic characteristics.

Dipeptidylpeptidase 4 promotes survival and stemness of acute myeloid leukemia stem cells

Leukemic-stem-cell-specific targeting may improve the survival of patients with acute myeloid leukemia (AML) by avoiding the ablative effects of standard regimens on normal hematopoiesis. Herein, we perform an unbiased screening of compounds targeting cell surface proteins and identify clinically used DPP4 inhibitors as strong suppressors of AML development in both murine AML models and primary human AML cells xenograft model. We find in retrovirus-induced AML mouse models that DPP4-deficient AML cell-transplanted mice exhibit delay and reversal of AML development, whereas deletion of DPP4 has no significant effect on normal hematopoiesis. DPP4 activates and sustains survival of AML stem cells that are critical for AML development in both human and animal models via binding with Src kinase and activation of nuclear factor κB (NF-κB) signaling. Thus, inhibition of DPP4 is a potential therapeutic strategy against AML development through suppression of survival and stemness of AML cells.

Single-cell analysis reveals the chemotherapy-induced cellular reprogramming and novel therapeutic targets in relapsed/refractory acute myeloid leukemia

Chemoresistance and relapse are the leading cause of AML-related deaths. Utilizing single-cell RNA sequencing (scRNA-seq), we dissected the cellular states of bone marrow samples from primary refractory or short-term relapsed AML patients and defined the transcriptional intratumoral heterogeneity. We found that compared to proliferating stem/progenitor-like cells (PSPs), a subpopulation of quiescent stem-like cells (QSCs) were involved in the chemoresistance and poor outcomes of AML. By performing longitudinal scRNA-seq analyses, we demonstrated that PSPs were reprogrammed to obtain a QSC-like expression pattern during chemotherapy in refractory AML patients, characterized by the upregulation of CD52 and LGALS1 expression. Flow cytometric analysis further confirmed that the preexisting CD99⁺CD49d⁺CD52⁺Galectin-1⁺ (QSCs) cells at diagnosis were associated with chemoresistance, and these cells were further enriched in the residual AML cells of refractory patients. Interaction of CD52-SIGLEC10 between QSCs and monocytes may contribute to immune evading and poor outcomes. Furthermore, we identified that LGALS1 was a promising target for chemoresistant AML, and LGALS1 inhibitor could help eliminate QSCs and enhance the chemotherapy in patient-derived primary AML cells, cell lines, and AML xenograft models. Our results will facilitate a better understanding of the AML chemoresistance mechanism and the development of novel therapeutic strategies for relapsed/refractory AML patients.

Experimental drugs in clinical trials for acute myeloid leukemia: innovations, trends, and opportunities

INTRODUCTION

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by many cytogenetic and molecular alterations. Due to better knowledge of the molecular basis of AML, many targeted therapies have been introduced and registered, e.g. FMS-like tyrosine kinase 3 inhibitors, isocitrate dehydrogenase 1/2 mutation inhibitors, and Bcl-2 inhibitor. Despite that, the cure for AML remains an unmet clinical need in most patients.

AREAS COVERED

The review aims to present new, not yet registered drugs for AML. We searched the English literature for articles concerning AML, targeted drugs, menin inhibitors, DOT1L, BET, IDH inhibitors, FLT3, hedgehog inhibitors, Polo-like kinase inhibitors, RNA splicing, and immune therapies via PubMed. Publications from January 2000 to August 2022 were scrutinized. Additional relevant publications were obtained by reviewing the references from the chosen articles and Google search. Conference proceedings from the previous 5 years of The American Society of Hematology, the European Hematology Association, and the American Society of Clinical Oncology were searched manually. Additional relevant publications were obtained by reviewing the references.

EXPERT OPINION

For several years, the therapeutic approach in AML has become more individualized. Novel groups of drugs give hope for greater curability. High response rates have agents that restore the activity of the p53 protein. In addition, agents that work independently of a particular mutation seem promising for AML without any known mutation.

GARP-mediated active TGF-β1 induces bone marrow NK cell dysfunction in AML patients with early relapse post-allo-HSCT

Relapse is a leading cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). However, the underlying mechanisms remain poorly understood. Natural killer (NK) cells play a crucial role in tumor surveillance and cancer immunotherapy, and NK cell dysfunction has been observed in various tumors. Here, we performed ex vivo experiments to systematically characterize the mechanisms underlying the dysfunction of bone marrow-derived NK (BMNK) cells isolated from AML patients experiencing early relapse after allo-HSCT. We demonstrated that higher levels of active transforming growth factor β1 (TGF-β1) were associated with impaired effector function of BMNK cells in these AML patients. TGF-β1 activation was induced by the overexpression of glycoprotein A repetitions predominant on the surface of CD4+ T cells. Active TGF-β1 significantly suppressed mTORC1 activity, mitochondrial oxidative phosphorylation, the proliferation, and cytotoxicity of BMNK cells. Furthermore, pretreatment with the clinical stage TGF-β1 pathway inhibitor, galunisertib, significantly restored mTORC1 activity, mitochondrial homeostasis, and cytotoxicity. Importantly, the blockade of the TGF-β1 signaling improved the antitumor activity of NK cells in a leukemia xenograft mouse model. Thus, our findings reveal a mechanism explaining BMNK cell dysfunction and suggest that targeted inhibition of TGF-β1 signaling may represent a potential therapeutic intervention to improve outcomes in AML patients undergoing allo-HSCT or NK cell-based immunotherapy.

Resistance Mechanism of Acute Myeloid Leukemia Cells Against Daunorubicin and Cytarabine: A Literature Review

Acute myeloid leukemia (AML) is a hematological malignancy commonly found in adult patients. Low overall survival and resistance to therapy are the main issues in AML. The first line of treatment for AML chemotherapy is the induction phase, namely, the phase to induce remission by administering a combination of daunorubicin (DNR) for three days followed by administration of cytarabine (Ara-C) with continuous infusion for seven days, which is referred to as "3 + 7." Such induction therapy has been the standard therapy for AML for the last four decades. This review article is made to discuss daunorubicin and cytarabine from their chemical structure, pharmacodynamics, pharmacokinetics, and mechanisms of resistance in AML.

Activation of orphan receptor GPR132 induces cell differentiation in acute myeloid leukemia

Blocked cellular differentiation is a critical pathologic hallmark of acute myeloid leukemia (AML). Here, we showed that genetic activation of the orphan GPCR GPR132 significantly induced cell differentiation of AML both in vitro and in vivo, indicating that GPR132 is a potential trigger of myeloid differentiation. To explore the therapeutic potential of GPR132 signaling, we screened and validated a natural product 8-gingerol (8GL) as a GPR132 agonist. Notably, GPR132 activation by 8GL promoted differentiation and reduced colony formation in human AML cell lines with diverse genetic profiles. Mechanistic studies revealed that 8GL treatment inhibits the activation of the mammalian target of rapamycin (mTOR), a regulator of AML cell differentiation blockade, via activating GPR132-G_s-PKA pathway. We further showed that the combination of 8GL and an mTOR inhibitor synergistically elicited AML cell differentiation in vitro. Importantly, 8GL alone or in combination with an mTOR inhibitor remarkably impaired tumor growth and extended mouse survival in an AML xenograft model accompanied by enhanced cell differentiation. Notably, genetic or pharmacological activation of GPR132 triggered the differentiation of human primary AML cells. In summary, this study demonstrated that activation of orphan GPR132 represents a potential strategy for inducing myeloid differentiation in AML patients.

Longitudinal Outcome over Two Decades of Unrelated Allogeneic Stem Cell Transplantation for Relapsed/Refractory Acute Myeloid Leukemia: An ALWP/EBMT Analysis

PURPOSE

We evaluated outcomes of unrelated transplantation for primary refractory/relapsed (ref/rel) acute myeloid leukemia (AML), comparing two cohorts according to the year of transplant, 2000-2009 and 2010-2019.

PATIENTS AND METHODS

Multivariable analyses were performed using the Cox proportional-hazards regression model.

RESULTS

3,430 patients were included; 876 underwent a transplant between 2000-2009 and 2554 in 2010-2019. Median follow-up was 8.7 (95% CI, 7.8-9.4) and 3.4 (95% CI, 3.1-3.6) years (P < 0.001). Median age was 52 (18-77) and 56 (18-79) years (P > 0.0001); 45.5% and 55.5% had refractory AML while 54.5% and 44.5% had relapsed AML. Conditioning was myeloablative in 60% and 52%, respectively. Neutrophil recovery and day 100 incidence of acute and 2-year incidence of chronic graft-versus-host disease (GvHD) were similar between the two periods. Two-year relapse incidence was higher for patients undergoing transplant in the 2000-2009 period versus those undergoing transplant in 2010-2019: 50.2% versus 45.1% (HR, 0.85; 95% CI, 0.74-0.97; P = 0. 002). Leukemia-free survival; overall survival; and GvHD-free, relapse-free survival were lower for the 2000-2009 period: 26% versus 32.1% (HR, 0.87; 95% CI, 0.78-0.97; P = 0.01), 32.1% versus 38.1% (HR, 0.86; 95% CI, 0.77-0.96; P = 0.01), and 21.5% versus 25.3% (HR, 0.89; 95% CI, 0.81-0.99; P = 0.03), respectively. Two-year nonrelapse mortality was not significantly different (23.8% vs. 23.7%; HR, 0.91; 95% CI, 0.76-1.11; P = 0.34).

CONCLUSIONS

Outcome of unrelated transplantation for patients with ref/rel AML has improved in the last two decades, rescuing about one third of the patients. See related commentary by Adrianzen-Herrera and Shastri, p. 4167.

Updates on the Management of Acute Myeloid Leukemia

Acute myeloid leukemia is a heterogeneous disease defined by a large spectrum of genetic aberrations that are potential therapeutic targets. New targeted therapies have changed the landscape for a disease with poor outcomes. They are more effective than standard chemotherapy with a good safety profile. For "fit patients" in first-line, the combination of gemtuzumab ozogamicin or midostaurin with intensive chemotherapy or Vyxeos is now considered the "standard of care" for selected patients. On the other hand, for "unfit patients", azacitidine-venetoclax has been consolidated as a frontline treatment, while other combinations with magrolimab or ivosidenib are in development. Nevertheless, global survival results, especially in relapsed or refractory patients, remain unfavorable. New immunotherapies or targeted therapies, such as Menin inhibitors or sabatolimab, represent an opportunity in this situation. Future directions will probably come from combinations of different targeted therapies ("triplets") and maintenance strategies guided by measurable residual disease.

Isocitrate dehydrogenase 2 inhibitor enasidenib synergizes daunorubicin cytotoxicity by targeting aldo-keto reductase 1C3 and ATP-binding cassette transporters

Targeting mutations that trigger acute myeloid leukaemia (AML) has emerged as a refined therapeutic approach in recent years. Enasidenib (Idhifa) is the first selective inhibitor of mutated forms of isocitrate dehydrogenase 2 (IDH2) approved against relapsed/refractory AML. In addition to its use as monotherapy, a combination trial of enasidenib with standard intensive induction therapy (daunorubicin + cytarabine) is being evaluated. This study aimed to decipher enasidenib off-target molecular mechanisms involved in anthracycline resistance, such as reduction by carbonyl reducing enzymes (CREs) and drug efflux by ATP-binding cassette (ABC) transporters. We analysed the effect of enasidenib on daunorubicin (Daun) reduction by several recombinant CREs and different human cell lines expressing aldo-keto reductase 1C3 (AKR1C3) exogenously (HCT116) or endogenously (A549 and KG1a). Additionally, A431 cell models overexpressing ABCB1, ABCG2, or ABCC1 were employed to evaluate enasidenib modulation of Daun efflux. Furthermore, the potential synergism of enasidenib over Daun cytotoxicity was quantified amongst all the cell models. Enasidenib selectively inhibited AKR1C3-mediated inactivation of Daun in vitro and in cell lines expressing AKR1C3, as well as its extrusion by ABCB1, ABCG2, and ABCC1 transporters, thus synergizing Daun cytotoxicity to overcome resistance. This work provides in vitro evidence on enasidenib-mediated targeting of the anthracycline resistance actors AKR1C3 and ABC transporters under clinically achievable concentrations. Our findings may encourage its combination with intensive chemotherapy and even suggest that the effectiveness of enasidenib as monotherapy against AML could lie beyond the targeting of mIDH2.

[Variables associated with hematological remission and survival in patients with acute myeloid leukemia after induction failure and relapse]

Objective: This study aimed to explore variables associated with remission rate and survival in patients with acute myeloid leukemia (AML) after induction failure and relapse. Methods: Data of 373 consecutive patients with AML were analyzed after induction failure and relapse. Binary logistics and the Cox model regression were used to identify variables associated with remission rate and outcomes. Results: In patients with AML after induction failure and relapse, the total CR+CRi rates were 50.6% and 40.3%, respectively; among those who achieved CR/CRi, the 3-year RFS rates were 34.4% and 30.4%, respectively, and the 3-year overall survival rates were 40.1% and 31.6%, respectively. In the multivariate analyses, using CLAG or FLAG regimen as a re-induction chemotherapy regimen, age <39 years and SWOG low-risk were significantly associated with higher remission rates in patients with induction failure. Male, secondary AML, SWOG high-risk, the interval from the first remission to relapse within 12 months, and bone marrow blasts ≥20% at the time of relapse were significantly associated with lower remission rates in relapsed patients. Transplantation was significantly associated with prolonged relapse-free survival and overall survival in patients achieving hematologic remission; the SWOG low-risk group was significantly associated with longer overall survival in those with induction failure; and achieving CR (not CRi) or having female gender was associated with longer RFS or overall survival in relapsed patients. Conclusion: Reinduction chemotherapy regimen, age, gender, SWOG risk, secondary AML, the interval from the first remission to relapse, and bone marrow blast percentage at the time of relapse were significantly associated with remission rates in the patients with AML after induction failure and relapse. Transplantation, SWOG low-risk, achieving CR, or female gender were associated with longer survivals in those achieving remission.

The Landscape of Exosome-Derived Non-Coding RNA in Leukemia

Leukemia is a group of life-threatening hematological malignancies which is currently incurable and often accompanied by drug resistance or disease relapse. Understanding the pathogenesis of leukemia and finding specific therapeutic targets and biomarkers is of great importance to improve the clinical efficacy of leukemia. Exosome-derived ncRNAs have been demonstrated as critical components of intercellular communication and function as key facilitators in the leukemia biological process. This review outlines the current investigations of exosomal ncRNAs (including miRNA, circRNA, and lncRNA) as important mediators of leukemia and potential therapeutic targets and biomarkers for leukemia treatment. Moreover, we generally analyze the prospects and challenges for exosomal ncRNAs from the aspects of research and clinical application.

Multi-omics reveals mitochondrial metabolism proteins susceptible for drug discovery in AML

Acute myeloid leukemia (AML) is a devastating cancer affecting the hematopoietic system. Previous research has relied on RNA sequencing and microarray techniques to study the downstream effects of genomic alterations. While these studies have proven efficacious, they fail to capture the changes that occur at the proteomic level. To interrogate the effect of protein expression alterations in AML, we performed a quantitative mass spectrometry in parallel with RNAseq analysis using AML mouse models. These combined results identified 34 proteins whose expression was upregulated in AML tumors, but strikingly, were unaltered at the transcriptional level. Here we focus on mitochondrial electron transfer proteins ETFA and ETFB. Silencing of ETFA and ETFB led to increased mitochondrial activity, mitochondrial stress, and apoptosis in AML cells, but had little to no effect on normal human CD34+ cells. These studies identify a set of proteins that have not previously been associated with leukemia and may ultimately serve as potential targets for therapeutic manipulation to hinder AML progression and help contribute to our understanding of the disease.

Myeloablative conditioning with thiotepa-busulfan-fludarabine does not improve the outcome of patients transplanted with active leukemia: final results of the GITMO prospective trial GANDALF-01

The outcome of refractory/relapsed (R/R) acute leukemias is still dismal and their treatment represents an unmet clinical need. However, allogeneic transplantation (allo-HSCT) remains the only potentially curative approach in this setting. A prospective study (GANDALF-01, NCT01814488; EUDRACT:2012-004008-37) on transplantation with alternative donors had been run by GITMO using a homogeneous myeloablative conditioning regimen with busulfan, thiotepa and fludarabine while GVHD prophylaxis was stratified by donor type. The study enrolled 101 patients; 90 found an alternative donor and 87 ultimately underwent allo-HSCT. Two-year overall survival of the entire and of the transplant population (primary endpoint) were 19% and 22%, without significant differences according to disease, donor type and disease history (relapsed vs refractory patients). Two-year progression-free survival was 19% and 17% respectively. The cumulative incidences of relapse and non-relapse mortality were 49% and 33% at two years. Acute grade II-IV and chronic GVHD occurred in 23 and 10 patients. Dose intensification with a myeloablative two-alkylating regimen as sole strategy for transplanting R/R acute leukemia does seem neither to improve the outcome nor to control disease relapse. A pre-planned relapse prevention should be included in the transplant strategy in this patient population.

[Efficacy and safety of IAC regimen for relapse/refractory acute myeloid leukemia: a prospective randomized controlled study]

Objective: To evaluate the efficacy and toxicity profiles of idarubicin, cytarabine, and cyclophosphamide (IAC) in relapse/refractory acute myeloid leukemia (AML) . Methods: This study was a prospective, randomized controlled clinical trial with the registration number NCT02937662. The patients were randomly divided into two groups. The experimental group was treated with an IAC regimen, and the regimen of the control group was selected by doctors according to medication experience. After salvage chemotherapy, allogeneic hematopoietic stem cell transplantation (allo-HSCT) was conducted as far as possible according to the situation of the patients. We aimed to observe the efficacy, safety, and toxicity of the IAC regimen in relapse/refractory AML and to explore which is the better regimen. Results: Forty-two patients were enrolled in the clinical trial, with a median age of 36 years (IAC group, 22 cases and control groups, 20 cases) . ①The objective response rate was 71.4% in the IAC group and 40.0% in the control group (P=0.062) ; the complete remission (CR) rate was 66.7% in the IAC group and 40.0% in the control group (P=0.121) . The median follow-up time of surviving patients was 10.5 (range:1.7-32.8) months; the median overall survival (OS) was 14.1 (range: 0.6-49.1) months in the IAC group and 9.9 (range: 2.0-53.8) months in the control group (P=0.305) . The 1-year OS was 54.5% (95%CI 33.7%-75.3%) in the IAC group and 48.2% (95%CI 25.9%-70.5%) in the control group (P=0.305) , with no significant difference between these two regimens. ②The main hematologic adverse events (AEs) were anemia, thrombocytopenia, and neutropenia. The incidence of grade 3-4 hematologic AEs in the two groups was 100% (22/22) in the IAC group and 95% (19/20) in the control group. The median time of neutropenia after chemotherapy in the IAC group and control group was 20 (IQR: 8-30) and 14 (IQR: 5-50) days, respectively (P=0.023) . ③The CR rate of the early relapse (relapse within 12 months) group was 46.7% and that of the late relapse (relapse after 12 months) group was 72.7% (P=0.17) . The median OS time of early recurrence was 9.9 (range:1.7-53.8) months, and that of late recurrence patients was 19.3 (range: 0.6-40.8) months (P=0.420) , with no significant differences between the two groups. The 1-year OS rates were 45.3% (95%CI 27.2%-63.3%) and 66.7% (95%CI 40.0%-93.4%) , respectively (P=0.420) . Survival analysis showed that the 1-year OS rates of the hematopoietic stem cell transplantation group and non-hematopoietic stem cell transplantation group were 87.5% (95%CI 71.2%-100%) and 6.3% (95%CI 5.7%-18.3%) , respectively. The OS rate of the hematopoietic stem cell transplantation group was significantly higher than that of the non-hematopoietic stem cell transplantation group (P<0.001) . Conclusion: The IAC regimen is a well-tolerated and effective regimen in relapsed/refractory AML; this regimen had similar efficacy and safety with the regimen selected according to the doctor's experience for treating relapsed/refractory AML. For relapsed/refractory patients with AML, allogeneic hematopoietic stem cell transplantation should be attempted as soon as possible to achieve long-term survival.

Mechanisms of Resistance to Targeted Therapies for Relapsed or Refractory Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive disease of clonal hematopoiesis with a high rate of relapse and refractory disease despite intensive therapy. Traditionally, relapsed or refractory AML has increased therapeutic resistance and poor long-term survival. In recent years, advancements in the mechanistic understanding of leukemogenesis have allowed for the development of targeted therapies. These therapies offer novel alternatives to intensive chemotherapy and have prolonged survival in relapsed or refractory AML. Unfortunately, a significant portion of patients do not respond to these therapies and relapse occurs in most patients who initially responded. This review focuses on the mechanisms of resistance to targeted therapies in relapsed or refractory AML.

A retrospective comparison of salvage intensive chemotherapy versus venetoclax-combined regimen in patients with relapsed/refractory acute myeloid leukemia (AML)

Background:

Evidence that a venetoclax (VEN)-combined regimen is effective in relapsed/refractory acute myeloid leukemia (R/R AML) is emerging. However, it is unknown how VEN-combined low intensity treatment compares to intensive chemotherapy (IC) in medically fit patients with R/R AML.

Methods:

We compared AML patients who received IC (n = 89) to those who received a VEN in combination with hypomethylating agents or low dose cytarabine (VEN combination) (n = 54) as their first- or second-line salvage after failing anthracycline-containing intensive chemotherapy.

Results:

The median age was 49 years, and significantly more patients in the VEN combination group were in their second salvage and had received prior stem cell transplantation (SCT). Overall response rates including CR, CRi, and MLFS were comparable (44.0% for IC vs. 59.3% for VEN combination, p = 0.081), but VEN combination group compared to IC group tended to show lower treatment related mortality. The rate of bridging to SCT was the same (68.5%), but the percentage of SCT at blast clearance was significantly higher in the VEN-combined group (62.3% vs. 86.5%, p = 0.010). After median follow-up periods of 22.5 (IC) and 11.3 months (VEN combination), the median overall survival was 8.9 (95% CI, 5.4-12.4) and 12.4 months (95% CI, 9.5-15.2) (p = 0.724), respectively.

Conclusion:

VEN combination provides a comparable anti-leukemic response and survival to salvage IC, and provide a bridge to SCT with better disease control in medically-fit patients with R/R AML.

Chemotherapy or Allogeneic Stem Cell Transplantation as Salvage Therapy for Patients with Refractory Acute Myeloid Leukemia: A Multicenter Analysis

Introduction

The overall outcome of patients with refractory AML (rAML) remains poor. Though allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered as the only curative therapy, it is routinely recommended only for patients after remission with salvage chemotherapy.

Objective

In this study, we evaluated the impact of salvage chemotherapy or allo-HSCT on the overall outcome in rAML.

Methods

We collected the clinical data of 220 patients from 4 medical centers and performed retrospective analysis of prognosis factors, including salvage chemotherapy, intensity of chemotherapy, and allo-HSCT.

Results

A total of 29 patients received allo-HSCT directly without salvage chemotherapy, 26 patients achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) after transplantation and 4-year leukemia-free survival (LFS) and overall survival (OS) were 45.0 ± 10.7 and 51.0 ± 10.6%, respectively. Another 191 patients received salvage chemotherapy and 81 (42.2%) achieved CR or CRi. Thirty-four patients among them underwent subsequent allo-HSCT with 4-year LFS and OS of 46.0 ± 8.8 and 46.2 ± 9.0%. The 4-year LFS and OS in 26 patients who failed to obtain CR or CRi but received allo-HSCT with active disease were 32.9 ± 10.0 and 36.9 ± 10.8%, respectively. For patients who received salvage chemotherapy but not allo-HSCT, few of them became long-term survivors. In multivariate analysis, salvage chemotherapy and the intensity of chemotherapy failed to have significant impact on both OS and LFS. Allo-HSCT was the only prognostic factor for improved OS and LFS in multivariate analysis.

Conclusions

These results indicate the benefit of allo-HSCT in patients with rAML and direct allo-HSCT without salvage chemotherapy could be treatment option.

Palliative cytoreduction with low dose intravenous melphalan in patients with acute myeloid leukemia refractory to prior treatment

BACKGROUND

Hyperproliferative crises with hyperleukocytosis occur frequently in the disease course of refractory or relapsed acute myeloid leukemia (AML). Palliative cytoreduction aims to control blast count in order to avoid life-threatening complications and preserve quality of life in patients unfit for intensive treatment. In our center, low-dose intravenous melphalan is sometimes used with this intent.

METHODS

We performed a retrospective analysis of patients with AML who were treated with low-dose intravenous melphalan (15-30 mg/m²) in a palliative setting.

RESULTS

Thirty patients with AML who received low-dose melphalan (15-25 mg/m²) were identified. In total, 63 administrations of low-dose melphalan were counted. A clear cytoreductive effect (>50%) was seen within a few days in 78% of melphalan administrations. The median duration of response after an individual dose was 17 days (interquartile range [IQR] 10-26). The median overall survival was 29 days (IQR 16-73). Most common side effects were worsening pancytopenia with neutropenic fever and an increase in transfusion dependency and tumor lysis syndrome.

CONCLUSION

Intravenous low-dose melphalan is effective, quick and safe as palliative cytoreductive therapy in patients with hyperproliferative AML. It can be considered in palliative care of patients refractory to prior treatment with preserving acceptable quality of life. Our small retrospective cohort is the first to report the use of low-dose intravenous melphalan as palliative cytoreductive treatment in this population.

Allogeneic Stem Cell Transplantation with Sequential Melphalan-Based Conditioning in AML: Residual Morphological Blast Count Determines the Risk of Relapse

Introduction

Allogeneic hematopoietic cell transplantation (HCT) during chemotherapy-induced aplasia may offer long-term survival in acute myeloid leukemia (AML) with otherwise poor prognosis including ELN adverse risk, relapsed or refractory disease. However, the value of residual morphologic disease prior HCT in this context has not been conclusively settled until yet. Therefore, we aimed to investigate variables predicting outcome in this unique setting of sequential conditioning therapy, with a focus on pretreatment morphologic blast count. In contrast to the most popular FLAMSA-RIC protocol, we used a melphalan-based conditioning regimen during aplasia.

Methods

We retrospectively analyzed data from 173 AML patients who underwent a sequential melphalan-based conditioning therapy between 2003 and 2015 at our centre. All patients participated either in the prospective Phase 2 BRIDGE trial (NCT01295307), the Phase 3 AML2003 study (NCT00180102) or were treated according to this protocol and underwent allogeneic HCT after melphalan-based conditioning in treatment-induced aplasia.

Results

Median bone marrow blast count prior to conditioning was 10% (range, 0–96%). Four year probabilities of EFS and OS were 34% (95% CI, 28–43%) and 43% (95% CI, 36–52%), respectively. In multivariate analysis, blast count >20% was associated with worse EFS (HR = 1.93; p = 0.009) and OS (HR = 1.80; p = 0.026). This effect was not significant anymore for HCT during 1st line therapy.

Conclusion

Allogeneic HCT in aplasia with a melphalan-based conditioning regimen has the potential to cure a subset of adverse risk AML patients, even with persistent morphological disease prior HCT. However, a high pre-transplant blast count still indicates patients with a dismal prognosis, especially in the relapsed patient group, for whom post-transplant strategies should be considered to further optimize post HCT outcome.

European LeukemiaNet-defined primary refractory acute myeloid leukemia: the value of allogeneic hematopoietic stem cell transplant and overall response

We sought to appraise the value of overall response and salvage chemotherapy, inclusive of allogeneic hematopoietic stem cell transplant (AHSCT), in primary refractory acute myeloid leukemia (prAML). For establishing consistency in clinical practice, the 2017 European LeukemiaNet (ELN) defines prAML as failure to attain CR after at least 2 courses of intensive induction chemotherapy. Among 60 consecutive patients (median age 63 years) correspondent with ELN-criteria for prAML, salvage was documented in 48 cases, 30/48 (63%) being administered intensive chemotherapy regimens and 2/48 consolidated with AHSCT as first line salvage. 13/48 (27%) attained response: CR, 7/13 (54%), CRi, 2/13 (15%), MLFS, 4/13 (31%). The CR/CRi rate was 9/48 (19%), with CR rate of 7/48 (15%). On univariate analysis, intermediate-risk karyotype was the only predictor of response (44% vs 17% in unfavorable karyotype; P = 0.04). Administration of any higher-dose (>1 g/m²) cytarabine intensive induction (P = 0.50), intensive salvage chemotherapy (P = 0.72), targeted salvage (FLT3 or IDH inhibitors) (P = 0.42), greater than 1 salvage regimen (P = 0.89), age < 60 years (P = 0.30), and de novo AML (P = 0.10) did not enhance response achievement, nor a survival advantage. AHSCT was performed in 12 patients with (n = 8) or without (n = 4) CR/CRi/MLFS. 1/2/5-year overall survival (OS) rates were 63%/38%/33% in patients who received AHSCT (n = 12) vs 27%/0%/0% in those who achieved CR/CRi/MLFS but were not transplanted (n = 5), vs 14%/0%/0% who were neither transplanted nor achieved CR/CRi/MLFS (n = 43; P < 0.001); the median OS was 18.6, 12.6 and 5.6 months, respectively. Although CR/CRi/MLFS bridged to AHSCT (n = 8), appeared to manifest a longer median OS (20 months), vs (13.4 months) for those with no response consolidated with AHSCT (n = 4), the difference was not significant P = 0.47. We conclude AHSCT as indispensable for securing long-term survival in prAML (p = 0.03 on multivariate analysis), irrespective of response achievement.

Nrf2 overexpression increases the resistance of acute myeloid leukemia to cytarabine by inhibiting replication factor C4

Drug resistance is a key factor in the treatment failure of acute myeloid leukemia (AML). Nuclear factor E2-related factor 2 (Nrf2) plays a crucial role in tumor chemotherapy resistance. However, the potential mechanism of Nrf2 regulating DNA mismatch repair (MMR) pathway to mediate gene-instability drug resistance in AML is still unclear. Here, it was found that Nrf2 expression was closely related to the disease progression of AML as well as highly expressed in AML patients with poor prognostic gene mutations. Meanwhile, it was also found that the expression of Nrf2 was significantly negatively correlated with DNA MMR gene replication factor C4 (RFC4) in AML. CHIP analysis combined with luciferase reporter gene results further showed that Nrf2 may inhibit the expression of RFC4 by its interaction with the RFC4 promoter. In vitro and vivo experiments showed that the overexpression of Nrf2 decreased the killing effect of chemotherapy drug cytarabine (Ara-C) on leukemia cells and inhibited the expression of RFC4. Mechanistically, The result that Nrf2-RFC4 axis mediated AML genetic instability drug resistance might be received by activating the JNK/NF-κB signaling pathway. Taken together, these findings may provide a new idea for improving AML drug resistance.

What to use to treat AML: the role of emerging therapies

The development and approval of novel substances have resulted in substantial improvements in the treatment of acute myeloid leukemia (AML). In the current era of novel treatment options, genetic and molecular testing at the time of diagnosis and relapse becomes increasingly relevant. Midostaurin in combination with intensive chemotherapy is the standard of care as upfront therapy in younger AML patients with mutated fms-related tyrosine kinase 3 (FLT3). Gilteritinib, a second- generation FLT3 inhibitor, represents a key drug for relapsed/refractory (R/R) FLT3-mutated AML patients. Targeted therapy has also been developed for patients with mutated isocitrate dehydrogenase 1 (IDH1) and IDH2. The US Food and Drug Administration (FDA) approved ivosidenib as a monotherapy for newly diagnosed older adult IDH1-mutated patients and enasidenib for R/R IDH2-mutated AML patients. CPX-351, a liposomal formulation of daunorubicin and cytarabine, has become an important upfront treatment strategy for fit patients with therapy-related AML or AML with myelodysplasia-related changes that are generally challenging to treat. The antibody drug conjugate gemtuzumab ozogamicin was approved in combination with intensive therapy for patients with newly diagnosed (FDA/European Medicines Agency [EMA]) as well as R/R CD33+ AML. The combination of venetoclax, an oral selective B-cell leukemia/lymphoma-2 inhibitor, with hypomethylating agents or low-dose AraC (LDAC) has changed the treatment landscape and prognosis for older adult patients very favorably. The addition of glasdegib, a small-molecule hedgehog inhibitor, to LDAC is another example of novel options in older patients. Further substances have shown promising results in early clinical trials.

Analysis of efficacy, safety and prognostic factors of DAC-HAA treatment in Chinese pediatric patients with refractory or relapsed acute myeloid leukemia

Hematopoietic stem cell transplantation (HSCT) is generally considered as the only effective treatment for children with relapsed/refractory (R/R) acute myeloid leukemia (AML). Achieving remission prior to HSCT affects the efficacy of the procedure and patient survival; therefore, induction therapy in children with R/R AML prior to HSCT is very important. The aim of the present study was to evaluate the clinical efficacy, prognosis and safety of 5-aza-2-deoxycytidine (DAC) combined with homoharringtonine + cytarabine + aclarubicin (HAA regimen) in the treatment of pediatric R/R AML. A total of 53 pediatric patients with R/R AML, aged 1-14 years, were treated with DAC-HAA. The overall response rate was 83.1%, with a complete remission rate of 77.4% and a partial remission rate of 5.7%. In conclusion, DAC-HAA therapy for children with R/R AML was found to be associated with a high remission rate, a short period of bone marrow suppression and a good safety profile. Therefore, DAC-HAA may be of value as a transitional regimen prior to HSCT and is worthy of clinical consideration.

The changing landscape for patients with relapsed/refractory acute myeloid leukaemia

PURPOSE OF REVIEW

The treatment of patients with relapsed or refractory (R/R) acute myeloid leukaemia (AML) has been an unequal challenge for many decades. Although significant progress has been made in the discovery of the mechanisms underlying the molecular pathogenesis of the disease, more than 50% of AML patients still die, mostly from relapsed disease. Currently, the only potential curative option for patients with R/R AML remains allogeneic bone marrow transplantation in second complete remission, which is far being easy to achieve, mainly for patients with primary induction failure or older than 65 years. The purpose of this review is to discuss recent advances in the management of patients with R/R AML, with particular emphasis to new therapeutic options that are replacing conventional salvage chemotherapy.

RECENT FINDINGS

The development of new agents selectively targeting molecular abnormalities offer more effective and less toxic alternative to chemotherapy, potentially useful as a bridge to allogeneic stem cell transplantation in second complete remission.

SUMMARY

The recent approval of new drugs for R/R is transforming the paradigm of care we have relied on for the past 50 years. Ongoing clinical trials will tell us how bright is the future for R/R AML patients.

Outcome of patients with relapsed or refractory acute myeloid leukemia treated with Mito-FLAG salvage chemotherapy

PURPOSE

Curative intended treatment is challenging in patients with relapsed or refractory acute myeloid leukemia (r/r AML) and associated with a dismal prognosis for long-term survival. Despite novel treatment options, the majority of patients are treated with chemotherapy-based regimens. Although widely used, little data exist on the combination of fludarabine, cytarabine, granulocyte colony stimulating factor (FLAG) and mitoxantrone as salvage strategy for r/r AML.

MATERIALS AND METHODS

Sixty-six patients receiving Mito-FLAG for r/r AML treated at a German tertiary care center between 2009 and 2019 were analyzed with regard to response rates, survival and safety profile.

RESULTS

Overall response rate was 75.8% with 56.1% of patients achieving complete remission (CR) and 19.7% partial remission (PR). After a median follow-up of 54 months, median overall survival (OS) was 13 months. Patients transitioned to allogeneic hematopoietic stem cell transplantation (alloHSCT) (75.8%) showed a significant improvement in OS with a median OS of 17 (95% CI 8.5-25.4) months vs 3 (95% CI 1.7-4.3) months (p < 0.001). 30- and 60-day mortality rates for all patients after the initial cycle of Mito-FLAG were 4.5% and 7.6%, respectively.

CONCLUSION

The Mito-FLAG salvage protocol represents an effective and feasible treatment regimen for r/r AML. Importantly, a high rate of transition to successful alloHSCT with the aim of long-term disease-free survival has been shown.

A Retrospective Observation of Treatment Outcomes Using Decitabine-Combined Standard Conditioning Regimens Before Transplantation in Patients With Relapsed or Refractory Acute Myeloid Leukemia

Hypomethylating agents, decitabine (DAC) and azacitidine, can act as prophylactic and pre-emptive approaches after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and a non-intensive bridging approach before allo-HSCT. However, they are rarely used as a part of conditioning regimens in patients with relapsed or refractory acute myeloid leukemia (AML). This retrospectively study included a total of 65 patients (median, 37; range, 13–63) with relapsed or refractory AML who were treated by allo-HSCT after myeloablative conditioning regimens without or with DAC (high-dose DAC schedule, 75 mg/m² on day −9 and 50 mg/m² on day −8; low-dose DAC schedule, 25 mg/m²/day on day −10 to −8). DAC exerted no impact on hematopoietic reconstitution. However, patients who were treated with the high-dose DAC schedule had significantly higher incidence of overall survival (OS, 50.0%) and leukemia-free survival (LFS, 35.0%), and lower incidence of relapse (41.1%) and grade II–IV acute graft versus host disease (aGVHD, 10.0%) at 3 years, when compared with those treated with standard conditioning regimens or with the low-dose DAC schedule. In conclusion, high-dose DAC combined with standard conditioning regimens before allo-HSCT is feasible and efficient and might improve outcomes of patients with relapsed or refractory AML, which provides a potential approach to treat these patients.

MRD abnormal expression predict poor outcomes for refractory or relapsed acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation

We retrospectively analyzed data from 197 patients with refractory or relapsed acute myeloid leukemia (r/rAML) who underwent allo‐HCT between January 2013 and February 2020 in our center (patients with promyelocytic leukemia were excluded). Of all patients, 86 achieved a complete morphological remission (CR) before transplant, while 111 failed to do so (NR). In the CR group, 32 patients displayed minimal residual disease (MRD‐positive). According to their immunophenotype pre‐HCT, we divided the MRD‐positive group and NR group into three subgroups: MRD 0+ group (without any antigen abnormal expression of CD7+, CD56+, CD38−, or HLA‐DR−) 28 patients, MRD 1+ group (with one abnormal antigen expression of CD7+, CD56+, CD38−, or HLA‐DR−) 63 patients, MRD 2+ group (with two or more abnormal antigens expression of CD7+, CD56+, CD38‐, or HLA‐DR‐) 52 patients. 3‐year estimates of disease‐free survival (DFS) for MRD 0+, MRD 1+ and MRD 2+ patients were 59.5 ± 9.5%, 29.9 ± 6.1%, and 9.4 ± 5.1%, and 3‐year estimates of overall survival (OS) were 59.5 ± 9.5%, 34.5 ± 6.3%, and 14.5 ± 10.8%, respectively. Multivariate analysis adjusted for genetic risk, blast cell level, secondary disease, age, sex, and donor relationship pre‐HCT, the hazard ratios of abnormal expression of CD7+, CD56+, HLA‐DR−, and CD38^‐ were 6.69 (range 2.08–21.52; p = 0.001) for DFS, 2.24 (range 1.21–4.14; p = 0.010) for OS, and 7.18 (range 2.23–23.10; p = 0.001) for relapse compared with CD7−, CD56−, HLA‐DR+, and CD38+ patients. Our finding suggested that abnormal expression of CD7+, CD56+, HLA‐DR−, and CD38− is associated with poor outcomes, and the more number of abnormal antigens expression predict worse outcomes.

Management Approach to Acute Myeloid Leukemia Leveraging the Available Resources in View of the Latest Evidence: Consensus of the Saudi Society of Blood and Marrow Transplantation

Acute myeloid leukemia (AML) is the most prevalent acute leukemia in adults and is responsible for the majority of cancer-related mortality. In Saudi Arabia, leukemia is ranked the fifth most prevalent type of malignancy in adults. Our aim is to review existing epidemiologic data in Saudi Arabia and develop consensus guidelines for management of AML.

FLAMSA-Busulfan-Melphalan as a Sequential Conditioning Regimen in HLA-Matched or Haploidentical Hematopoietic Stem Cell Transplantation for High-Risk Myeloid Diseases

Given the poor prognosis of relapsed/refractory myeloid malignancies, the concept of sequential conditioning before allogeneic hematopoietic stem cell transplantation (allo-HSCT) has proven to be an effective approach. We sought to evaluate a sequential scheme combining fludarabine, amsacrine, and cytarabine (FLAMSA) for cytoreduction, followed by reduced-intensity conditioning with busulfan and melphalan (FLAMSA-BuMel), which was designed to be suitable for both HLA-matched and haploidentical HSCT. This single-center retrospective study included 36 adult patients with high-risk myeloid malignancies who underwent allo-HSCT from HLA-matched (n = 19) or haploidentical (n = 17) donors. Along with the standard prophylaxis for graft-versus-host disease (GVHD), patients with a haploidentical donor received post-transplantation high-dose cyclophosphamide. A post-transplantation consolidation treatment with low-dose 5-azacytidine and prophylactic donor lymphocyte infusions was provided whenever possible. Thirty patients (83%) achieved complete remission on day +30. With a median follow-up of 30.0 months, the 2-year overall survival was 89% in the HLA-matched group versus 34% in the haploidentical group (P = .0018). The 2-year disease-free survival in these 2 groups was 68% and 34%, respectively (P = .013). At 2 years, the probability of relapse was 32% and 20%, respectively, and nonrelapse mortality was 0% and 58%, respectively (P = .0003). The leading cause of death was relapse in the HLA-matched group (3 of 19) and hemorrhagic events (5 of 17) in the haploidentical group, favored by significantly delayed platelet reconstitution and a severe GVHD context. These data confirm the feasibility of FLAMSA-BuMel as a sequential conditioning in allo-HSCT for high-risk myeloid malignancies. The use of bone marrow as the preferred graft source might reduce the incidence of acute GVHD and nonrelapse mortality in the haploidentical transplantation setting.

Treatment for Relapsed/Refractory Acute Myeloid Leukemia

Patients with relapsed or refractory (r/r) acute myeloid leukemia (AML) have a poor prognosis and treatment remains challenging. For the majority of r/r patients, allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment approach. Salvage therapy is given in order to reduce the leukemia load prior to transplantation. Patients achieving complete remission prior to allogeneic HSCT have a more favorable outcome. Intensive salvage regimens commonly consist of an anthracycline and high-dose cytarabine backbone. Donor lymphocyte infusions have shown efficacy in patients relapsing after allogeneic HSCT. For patients who cannot be intensively treated (eg, elderly AML patients), outcome is generally very poor and combinations with novel agents are currently under investigation. Mutational analysis should be repeated at the time of relapse to identify aberrations that can be targeted with new agents. For r/r AML patients with mutated fms-related tyrosine kinase 3 (FLT3), gilteritinib has shown superior results to intensive salvage regimens. The US Food and Drug Administration (FDA) and European Medicines Agency (EMA) approved gilteritinib for FLT3 mutated r/r AML patients. Ivosidenib and enasidenib, inhibitors for mutated isocitrate dehydrogenase (IDH) 1 and 2, respectively, have received approval for IDH1/IDH2 mutated r/r AML by the FDA (not EMA). APR-246 restores the function of mutated TP53 and early study results are promising. Other agents targeting CD47, menin, neural-precursor-cell-expressed developmentally down-regulated 8, as well as bispecific antibodies or chimeric antigen receptor T cells are under investigation. Further trials are needed to understand how to best combine novel agents with each other or with chemotherapy.

MicroRNA-363-3p promote the development of acute myeloid leukemia with RUNX1 mutation by targeting SPRYD4 and FNDC3B

BACKGROUND

Runt-related transcription factor 1 (RUNX1) is one of the most frequently mutated genes in most of hematological malignancies, especially in acute myeloid leukemia. In the present study, we aimed to identify the key genes and microRNAs based on acute myeloid leukemia with RUNX1 mutation. The newly finding targeted genes and microRNA associated with RUNX1 may benefit to the clinical treatment in acute myeloid leukemia.

MATERIAL/METHODS

The gene and miRNA expression data sets relating to RUNX1 mutation and wild-type adult acute myeloid leukemia (AML) patients were downloaded from The Cancer Genome Atlas database. Differentially expressed miRNAs and differentially expressed genes (DEGs) were identified by edgeR of R platform. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed by Metascape and Gene set enrichment analysis. The protein-protein interaction network and miRNA-mRNA regulatory network were performed by Search Tool for the Retrieval of Interacting Genes database and Cytoscape software.

RESULTS

A total of 27 differentially expressed miRNAs (25 upregulated and 2 downregulated) and 561 DEGs (429 upregulated and 132 downregulated) were identified. Five miRNAs (miR-151b, miR-151a-5p, let-7a-2-3p, miR-363-3p, miR-20b-5p) had prognostic significance in AML. The gene ontology analysis showed that upregulated DEGs suggested significant enrichment in MHC class II protein complex, extracellular structure organization, blood vessel development, cell morphogenesis involved in differentiation, embryonic morphogenesis, regulation of cell adhesion, and so on. Similarly, the downregulated DEGs were mainly enriched in secretory granule lumen, extracellular structure organization. In the gene set enrichment analysis of Kyoto Encyclopedia of Genes and Genomes pathways, the RUNX1 mutation was associated with adherent junction, WNT signaling pathway, JAK-STAT signaling pathway, pathways in cancer, cell adhesion molecules CAMs, MAPK signaling pathway. Eleven genes (PPBP, APP, CCR5, HLA-DRB1, GNAI1, APLNR, P2RY14, C3AR1, HTR1F, CXCL12, GNG11) were simultaneously identified by hub gene analysis and module analysis. MicroRNA-363-3p may promote the development of RUNX1 mutation AML, targeting SPRYD4 and FNDC3B. In addition, the RUNX1 mutation rates in patient were obviously correlated with age, white blood cell, FAB type, risk(cyto), and risk(molecular) (P < .05).

CONCLUSION

Our findings have indicated that multiple genes and microRNAs may play a crucial role in RUNX1 mutation AML. MicroRNA-363-3p may promote the development of RUNX1 mutation AML by targeting SPRYD4 and FNDC3B.