Evolving Therapies in Acute Myeloid Leukemia: Progress at Last?

Current and Emerging Techniques for Diagnosis and MRD Detection in AML: A Comprehensive Narrative Review

Acute myeloid leukemia (AML) comprises a group of hematologic neoplasms characterized by abnormal differentiation and proliferation of myeloid progenitor cells. AML is associated with poor outcome due to the lack of efficient therapies and early diagnostic tools. The current gold standard diagnostic tools are based on bone marrow biopsy. These biopsies, apart from being very invasive, painful, and costly, have low sensitivity. Despite the progress uncovering the molecular pathogenesis of AML, the development of novel detection strategies is still poorly explored. This is particularly important for patients that check the criteria for complete remission after treatment, since they can relapse through the persistence of some leukemic stem cells. This condition, recently named as measurable residual disease (MRD), has severe consequences for disease progression. Hence, an early and accurate diagnosis of MRD would allow an appropriate therapy to be tailored, improving a patient's prognosis. Many novel techniques with high potential in disease prevention and early detection are being explored. Among them, microfluidics has flourished in recent years due to its ability at processing complex samples as well as its demonstrated capacity to isolate rare cells from biological fluids. In parallel, surface-enhanced Raman scattering (SERS) spectroscopy has shown outstanding sensitivity and capability for multiplex quantitative detection of disease biomarkers. Together, these technologies can allow early and cost-effective disease detection as well as contribute to monitoring the efficiency of treatments. In this review, we aim to provide a comprehensive overview of AML disease, the conventional techniques currently used for its diagnosis, classification (recently updated in September 2022), and treatment selection, and we also aim to present how novel technologies can be applied to improve the detection and monitoring of MRD.

Combined use of interferon alpha-1b, interleukin-2, and thalidomide to reverse the AML1-ETO fusion gene in acute myeloid leukemia

This study aims to explore the effect of the ITI (interferon alpha-1b, thalidomide, and interleukin-2) regimen on the AML1-ETO fusion gene in patients with t(8;21) acute myeloid leukemia (AML) who were in hematologic remission but positive for the AML1-ETO fusion gene. From September 2014 to November 2020; 20 patients with AML (15 from The Affiliated Cancer Hospital of Zhengzhou University, 4 from The First Affiliated Hospital; and College of Clinical Medicine of Henan University of Science and Technology, and 1 from Anyang District Hospital) with hematological remission but AML1-ETO fusion gene positivity were treated with different doses of the ITI regimen to monitor changes in AML1-ETO fusion gene levels. Twenty patients were treated with a routine dose of the ITI regimen, including 13 males and 7 females. The median patient age was 38 (14–70 years). The fusion gene was negative in 10 patients after 1 (0.5 ~ 8.6) month, significantly decreased in 4 patients after 2.8 (1 ~ 6) months, increased in 4 patients, and unchanged in 2 patients. The 4 patients with elevated levels of the fusion gene were treated with an increased dose of the ITI regimen, and all four patients became negative, for a total effective rate of 90%. The ITI regimen reduces AML1-ETO fusion gene levels in patients with AML who are in hematologic remission but are fusion gene–positive. Improvement was observed in patients’ response to a higher dose administration, and patients tolerated the treatment well.

[Therapeutic effect of combined use of interferon alpha-1b, interleukin-2 and thalidomide on reversing minimal residual disease in acute myeloid leukemia]

Objective: To explore the effect of combination regimen of interferon alpha-1b, interleukin-2 and thalidomide (ITI regimen) on minimal residual disease (MRD) in patients with acute myeloid leukemia (AML) who were in hematologic remission but MRD-positive. Methods: Eighteen patients (17 from Tumor Hospital of Zhengzhou University and 1 from the First People's Hospital of Pingdingshan City) with AML admitted from July 2016 to June 2018, who were in hematologic remission but MRD-positive were treated with different doses of ITI regimen, and the MRD levels were monitored. Results: Among 18 patients who received a conventional dose of ITI regimen for 1 to 2 months, 7 patients had undetectable MRD, 3 had significant decrease in MRD levels, 3 had elevated MRD level and had hematologic recurrence. Three patients with elevated MRD level received a higher dose of ITI regimen, 2 of them turned to MRD negative and the other 1 patient had decreased MRD level. The total response rate was 72.2%, and the response rate in patients with MRD > 1.0% was 57.1% (4/7) , and that of patients with MRD < 1.0% was 81.8% (9/11) , respectively. Conclusion: The ITI regimen can reduce the MRD level of patient with AML who are in hematologic remission but MRD-positive. The therapeutic effect could be improved by a higher dose administration of ITI regimen, and therapeutic effect may be negatively correlated with MRD level before treatment.

Evaluating measurable residual disease in acute myeloid leukemia

Mounting evidence indicates that the presence of measurable ("minimal") residual disease (MRD), defined as posttherapy persistence of leukemic cells at levels below morphologic detection, is a strong, independent prognostic marker of increased risk of relapse and shorter survival in patients with acute myeloid leukemia (AML) and can be used to refine risk-stratification and treatment response assessment. Because of the association between MRD and relapse risk, it has been postulated that testing for MRD posttreatment may help guide postremission treatment strategies by identifying high-risk patients who might benefit from preemptive treatment. This strategy, which remains to be formally tested, may be particularly attractive with availability of agents that could be used to specifically eradicate MRD. This review examines current methods of MRD detection, challenges to adopting MRD testing in routine clinical practice, and recent recommendations for MRD testing in AML issued by the European LeukemiaNet MRD Working Party. Inclusion of MRD as an end point in future randomized clinical trials will provide the data needed to move toward standardizing MRD assays and may provide a more accurate assessment of therapeutic efficacy than current morphologic measures.

Improved outcome for AML patients over the years 2000-2014

Few recent studies from registries have reported an improvement in overall survival of younger patients with acute myeloid leukemia (AML). However, reasons for this improvement are not defined. We analyzed the therapeutic course and outcome of 976 patients treated by intensive chemotherapy between 2000 and 2014. The number of patients receiving allogeneic stem cell transplantation in first or second response significantly increased over time whereas autologous transplantation was progressively abandoned. In the 513 younger patients, there were no differences in first complete response, induction failure, incidence of relapse, or non-relapse mortality over time. The period of time was significantly associated with a better overall survival especially in 2010–2014. The 2010–2014 period effect was still significant in multivariate analysis and was independent of allogeneic stem cell transplantation. In the 463 older patients, there was a significant interaction between the period and leukocytosis in multivariate analysis meaning that the 2010–2014 period had only an impact in patients with white blood cell count >50 giga/L for response and overall survival. Progresses have been made in each phase of the therapeutic course of younger AML patients resulting in survival improvement. In older patients, the outcome of hyperleukocytic patients has significantly improved in 2010–2014.

Erythroleukemia-historical perspectives and recent advances in diagnosis and management

Acute erythroleukemia is a rare form of acute myeloid leukemia recognized by its distinct phenotypic attribute of erythroblastic proliferation. After a century of its descriptive history, many diagnostic, prognostic, and therapeutic implications relating to this unique leukemia subset remain uncertain. The rarity of the disease and the simultaneous involvement of its associated myeloid compartment have complicated in vitro studies of human erythroleukemia cell lines. Although murine and cell line erythroleukemia models have provided valuable insights into pathophysiology, translation of these concepts into treatment are not forthcoming. Integration of knowledge gained through a careful study of these models with more recent data emerging from molecular characterization will help elucidate key mechanistic pathways and provide a much needed framework that accounts for erythroid lineage-specific attributes. In this article, we discuss the evolving diagnostic concept of erythroleukemia, translational aspects of its pathophysiology, and promising therapeutic targets through an appraisal of the current literature.

Treated secondary acute myeloid leukemia: a distinct high-risk subset of AML with adverse prognosis

Secondary acute myeloid leukemia (s-AML) includes therapy-related AML and AML evolving from antecedent hematological disorder (AHD). s-AML arising after treating AHD likely represents a prognostically distinct, high-risk disease category. In this study, treated s-AML (ts-AML) was defined by: (1) prior diagnosis of myelodysplasia, myeloproliferative neoplasm, or aplastic anemia and (2) at least 1 therapy for that diagnosis. ts-AML was categorized by age (< or ≥60 years), and each cohort assessed for response rates and overall survival (OS) on various treatment regimens. Survival outcomes were compared against other high-risk prognostic subsets. Results showed that complete response and 8-week mortality rates were 32% and 27% in the younger, and 24% and 19% in the older age groups, respectively. There was a significant OS difference within s-AML based on prior treatment of AHD (ie, ts-AML vs s-AML with untreated AHD, 4.2 vs 9.2 months; P < .001). Survival in ts-AML was poor across both cohorts (younger and older, 5 and 4.7 months, respectively). In younger AML, survival was significantly inferior in ts-AML when compared with deletion 5/7, TP53, 3q abnormality, and therapy-related AML groups (median, 5 vs 7.9, 7.8, 7.9, and 11.2 months, respectively; P < .01). Additional adverse karyotype within ts-AML was associated with even worse outcomes (OS range, 1.6-2.8 months). ts-AML represents a very high-risk category, even in younger AML patients. s-AML should be further classified to describe ts-AML, an entity less responsive to currently applied treatment approaches. Future AML trial designs should accommodate ts-AML as a distinct subgroup.