Effective treatment of acute promyelocytic leukemia with all-trans-retinoic acid, arsenic trioxide, and gemtuzumab ozogamicin

Therapeutic horizon of acute myeloid leukemia: Success, optimism, and challenges

Focused research in acute myeloid leukemia (AML) biology and treatment has led to the identification of new therapeutic targets and several new drug approvals over the last decade. Progressive improvements in response and survival have mirrored these improvements in treatment options. Traditionally adverse subtypes such as FLT3-internal tandem duplication-positive AML now have better outcomes with potent FLT3 inhibitors, and menin inhibitors in KMT2A-rearranged and other MEIS/HOX-dependent leukemias hold promise toward improving outcomes. More patients with AML are now able to undergo a consolidative allogeneic hematopoietic stem cell transplantation (HSCT), and the rates of nonrelapse mortality with or without HSCT have also decreased. Comprehensive genomic interrogation of AML has elucidated mechanisms of response and resistance to treatments, which has enabled more precise decision algorithms and better prognostication. Deep levels of measurable residual disease assessment in some AML subsets hold the potential to dynamically modify treatment on the basis of these responses. Improving frontline intensive and low-intensity therapies, by incorporating venetoclax and other targeted agents, is the most important intervention to improve AML outcomes. Despite these developments, a sizeable percentage of AML, such as AML with TP53 or MECOM aberrations, postmyeloproliferative neoplasm AML, and so forth, remains as subsets without significant improvement in outcomes and no targeted options. Evolving strategies with natural killer cell-based approaches, novel antibody-drug conjugates, bispecific T-cell engagers, and engineered chimeric antigen receptor T-cell therapies are being evaluated, and may fill the therapeutic vacuum for some of the high-risk AML subtypes.

How I treat acute myeloid leukemia with differentiation therapy

ABSTRACT

An increasing number of acute myeloid leukemia (AML) therapeutics have been developed, not as cytotoxic therapies but rather as targeted agents able to restore the aberrant and leukemogenic "block" in normal differentiation. All-trans retinoic acid and arsenic trioxide are classic examples of differentiating agents for treatment of acute promyelocytic leukemia (APL); newer therapies functioning through differentiation include isocitrate dehydrogenase 1 and 2 inhibitors, FMS-like tyrosine kinase 3 inhibitors, and menin inhibitors. The terminal differentiation of leukemic blasts via differentiating-agent therapy can lead to a constellation of signs and symptoms, originally referred to as "retinoic acid syndrome" and now termed "differentiation syndrome" (DS), characterized predominantly by systemic inflammatory response system-like features of dyspnea, pulmonary infiltrates, pleural and pericardial effusions, unexplained fevers, hypotension, edema, and renal insufficiency. DS in patients with newly diagnosed APL is generally straightforward to identify; however, DS in patients with multiply relapsed AML can be more challenging to diagnose, due to nonspecific signs and symptoms that can be mistakenly attributed to infectious etiologies or the underlying refractory leukemia itself. Prompt consideration of DS, rapid initiation of systemic corticosteroids, and early cytoreduction in the setting of concomitant hyperleukocytosis are essential for optimal management.

Long-term follow-up of a phase 2 study of all-trans retinoic acid, arsenic trioxide, and gemtuzumab ozogamicin in acute promyelocytic leukemia

BACKGROUND

All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) combinations have produced excellent outcomes in patients with standard-risk acute promyelocytic leukemia (APL). Herein, the authors update their long-term results with the regimen of ATO-ATRA and gemtuzumab ozogamicin (GO) in standard-risk and high-risk APL.

METHODS

This was a phase 2 trial of patients with newly diagnosed APL. Induction comprised ATRA 45 mg/m2 and ATO 0.15 mg/kg daily. GO 6-9 mg/m2 was added for high-risk patients and for standard-risk patients who developed leukocytosis >10 × 109/L. Consolidation consisted of four courses of ATO-ATRA, with GO for patients who had PML::RARA persistence.

RESULTS

One hundred forty-six patients (median age, 53.0 years; range, 19.3-83.9 years) were treated, including 106 patients (72.6%) with standard-risk APL and 40 (27.4%) with high-risk APL. GO was administered to 68 standard-risk patients (64.2%) for leukocytosis. The complete remission rate was 93.8% (95% confidence interval [CI], 92.2%-98.5%). Negative measurable residual disease status was achieved in 97.1% of patients who attained complete remission. At a median follow-up of 61.8 months (95% CI, 4.7-128.4 months), the 5-year event-free survival, disease-free survival, and overall survival rates were 92.4% (95% CI, 87.9%-97.1%), 93.6% (95% CI, 89.5%-97.8%), and 93.1% (95% CI, 88.9%-97.7%), respectively. Induction mortality was 2.7%. The most common severe adverse events were elevated transaminases in 41.0% of patients and infection in 13.7%. There were no cases of veno-occlusive disease.

CONCLUSIONS

The combination of ATO-ATRA and GO was curative in 94% of patients who had APL with a favorable safety profile (ClinicalTrials.gov identifier NCT01409161).

Acute myeloid leukemia management and research in 2025

The first 5 decades of research in acute myeloid leukemia (AML) were dominated by the cytarabine plus anthracyclines backbone, with advances in strategies including allogeneic hematopoietic stem cell transplantation, high-dose cytarabine, supportive care measures, and targeted therapies for the subset of patients with acute promyelocytic leukemia. Since 2017, a turning point in AML research, 12 agents have received regulatory approval for AML in the United States: venetoclax (BCL2 inhibitor); gemtuzumab ozogamicin (CD33 antibody-drug conjugate); midostaurin, gilteritinib, and quizartinib (fms-like tyrosine kinase 3 inhibitors); ivosidenib, olutasidenib, and enasidenib (isocitrate dehydrogenase 1 and 2 inhibitors); oral azacitidine (a partially absorbable formulation); CPX351 (liposomal encapsulation of cytarabine:daunorubicin at a molar ratio of 5:1); glasdegib (hedgehog inhibitor); and recently revumenib (menin inhibitor; approved November 2024). Oral decitabine-cedazuridine, which is approved as a bioequivalent alternative to parenteral hypomethylating agents in myelodysplastic syndrome, can be used for the same purpose in AML. Menin inhibitors, CD123 antibody-drug conjugates, and other antibodies targeting CD123, CD33, and other surface markers are showing promising results. Herein, the authors review the frontline and later line therapies in AML and discuss important research directions.

Acute Promyelocytic Leukemia in the Real World: Understanding Outcome Differences and How We Can Improve Them

The advent of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has revolutionized the treatment of acute promyelocytic leukemia (APL), resulting in excellent rates of remission and long-term survival. However, real-world outcomes often fall short of those observed in clinical trials due to various factors related to patient demographics and clinical practices. This review examines APL treatment outcomes in real-world settings and highlights the phenomenon of APL clusters. Clinical trials frequently exclude older patients and individuals with significant comorbidities, yet these groups represent a substantial portion of patients in clinical practice. Early mortality remains high in real-world settings, compounded by delayed diagnosis and treatment initiation, as well as the inexperience of some community providers and limited resources of their centers in managing APL and its associated complications. High rates of disease and induction-related complications further exacerbate early mortality. Continuous education and collaboration between community healthcare centers and expert institutions are essential, and international partnerships between resource-limited settings and expert centers can improve global APL outcomes. Ongoing monitoring for measurable residual disease (MRD) recurrence and long-term treatment toxicity, coupled with comprehensive patient evaluations, and experienced management, can enhance long-term outcomes. The clustered incidence of APL, while frequently reported, remains poorly understood. Regular reporting of these clusters could provide valuable insights into disease pathology and aid in developing predictive models for APL incidence, which would guide future resource allocation.

Chemotherapy-free approaches to newly-diagnosed acute promyelocytic leukaemia: is oral-arsenic trioxide/all-trans retinoic acid/ascorbic acid the answer?

INTRODUCTION

Acute promyelocytic leukemia (APL) is a distinct form of acute myeloid leukemia characterized by the presence of t(15;17)(q24;21) and the PML:RARA gene fusion. Frontline use of intravenous arsenic trioxide (i.v.-ATO) and all-trans retinoic acid (ATRA) has vastly improved cure rates in APL. Researchers in Hong Kong invented the oral formulation of ATO (oral-ATO) and have confirmed a bioavailability comparable to i.v.-ATO. A plethora of studies have confirmed the safety and efficacy of oral-ATO-based regimens in the frontline and relapsed setting.

AREAS COVERED

Aspects on the development of oral-ATO-based regimens for APL in the frontline and relapsed setting are discussed. The short-term and long-term safety and efficacy of oral-ATO-based regimens are discussed. The frontline use of oral-ATO in combination with ATRA and ascorbic acid (AAA) induction in a 'chemotherapy-free' is highlighted.

EXPERT OPINION

Current and ongoing data on the use of oral-ATO-based regimens in APL support the use of oral-ATO as an alternative to i.v.-ATO allowing a more convenient and economical approach to the management of APL.

MRD in Acute Leukemias: Lessons Learned from Acute Promyelocytic Leukemia

Introduction: Advances in molecular biology, polymerase chain reaction (PCR), and next-generation sequencing (NGS) have transformed the concept of minimal residual disease (MRD) from a philosophical idea into a measurable reality. Current Treatment Paradigms and Lessons Learned from APL: Acute promyelocytic leukemia (APL) leads the way in this transformation, initially using PCR to detect MRD in patients in remission, and more recently, aiming to eliminate it entirely with modern treatment strategies. Along the way, we have gained valuable insights that, when applied to other forms of acute leukemia, hold the potential to significantly improve the outcomes of these challenging diseases. Does the BM Microenvironment Play a Role in MRD?: In this review, we explore the current use of MRD in the management of acute leukemia and delve into the biological processes that contribute to MRD persistence, including its overlap with leukemia stem cells and the role of the bone marrow microenvironment.

Current status and research directions in acute myeloid leukemia

The understanding of the molecular pathobiology of acute myeloid leukemia (AML) has spurred the identification of therapeutic targets and the development of corresponding novel targeted therapies. Since 2017, twelve agents have been approved for the treatment of AML subsets: the BCL2 inhibitor venetoclax; the CD33 antibody drug conjugate gemtuzumab ozogamicin; three FLT3 inhibitors (midostaurin, gilteritinib, quizartinib); three IDH inhibitors (ivosidenib and olutasidenib targeting IDH1 mutations; enasidenib targeting IDH2 mutations); two oral hypomethylating agents (oral poorly absorbable azacitidine; fully absorbable decitabine-cedazuridine [latter approved as an alternative to parenteral hypomethylating agents in myelodysplastic syndrome and chronic myelomonocytic leukemia but commonly used in AML]); and CPX-351 (encapsulated liposomal 5:1 molar ratio of cytarabine and daunorubicin), and glasdegib (hedgehog inhibitor). Other targeted therapies (menin inhibitors, CD123 antibody-drug conjugates) are showing promising results. To achieve optimal results in such a rare and heterogeneous entity as AML requires expertise, familiarity with this rare cancer, and the access to, and delivery of disparate therapies under rigorous supportive care conditions. In this review, we update the standard-of-care and investigational therapies and outline promising current and future research directions.

Breaking Boundaries: Immunotherapy for Myeloid Malignancies

Immunotherapy has revolutionized the treatment of myeloid oncologic diseases, particularly for patients resistant to chemotherapy or ineligible for allogeneic stem cell transplantation due to age or fitness constraints. As our understanding of the immunopathogenesis of myeloid malignancies expands, so too do the treatment options available to patients. Immunotherapy in myeloid malignancies, however, faces numerous challenges due to the dynamic nature of the disease, immune dysregulation, and the development of immune evasion mechanisms. This review outlines the progress made in the field of immunotherapy for myeloid malignancies, addresses its challenges, and provides insights into future directions in the field.

Acute Promyelocytic Leukemia: Review of Complications Related to All-Trans Retinoic Acid and Arsenic Trioxide Therapy

The hallmark of acute promyelocytic leukemia (APL) is the presence of the characteristic fusion transcript of the promyelocytic leukemia gene with the retinoic acid receptor α gene (PML::RARA). The PML::RARA fusion is a molecular target for all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Therapies based on ATRA plus ATO have excellent outcomes in terms of complete remission rates, overall survival, and achievement of deep and durable molecular responses with a very low incidence of relapse. However, although the combination of ATRA and ATO has lower hematologic toxicity than standard chemotherapy, its use is associated with a spectrum of distinctive toxicities, such as differentiation syndrome, liver toxicity, QT interval prolongation, and neurotoxicity. Rigorous monitoring of patients' clinical evolution is indispensable for identifying and addressing each complication. The objective is to maintain an equilibrium between treatment-induced adverse events and therapeutic efficacy. This paper focused on non-hematologic complications associated with the combination of ATRA and ATO. Additionally, we discuss late-onset complications of this therapy. In summary, the majority of treatment-related adverse events are manageable, self-limiting, and reversible. More so, there seems to be a lower incidence rate of secondary neoplasms compared to standard chemotherapy. However, further research is required to assess how the ATRA plus ATO regimen affects the emergence of additional comorbidities.

Research progress on arsenic, arsenic-containing medicinal materials, and arsenic-containing preparations: clinical application, pharmacological effects, and toxicity

Introduction: The toxicity of arsenic is widely recognized globally, mainly harming human health by polluting water, soil, and food. However, its formulations can also be used for the clinical treatment of diseases such as leukemia and tumors. Arsenic has been used as a drug in China for over 2,400 years, with examples such as the arsenic-containing drug realgar mentioned in Shennong's Herbal Classic. We have reviewed references on arsenic over the past thirty years and found that research has mainly focused on clinical, pharmacological, and toxicological aspects. Results and Discussion: The finding showed that in clinical practice, arsenic trioxide is mainly used in combination with all-trans retinoic acid (ATRA) at a dose of 10 mg/d for the treatment of acute promyelocytic leukemia (APL); realgar can be used to treat acute promyelocytic leukemia, myelodysplastic syndrome, and lymphoma. In terms of pharmacology, arsenic mainly exerts anti-tumor effects. The dosage range of the action is 0.01-80 μmol/L, and the concentration of arsenic in most studies does not exceed 20 μmol/L. The pharmacological effects of realgar include antiviral activity, inhibition of overactivated lactate dehydrogenase, and resistance to malaria parasites. In terms of toxicity, arsenic is toxic to multiple systems in a dose-dependent manner. For example, 5 μmol/L sodium arsenite can induce liver oxidative damage and promote the expression of pro-inflammatory factors, and 15 μmol/L sodium arsenite induces myocardial injury; when the concentration is higher, it is more likely to cause toxic damage.

Acute kidney injury in acute promyelocytic leukemia: a possible adverse effect of high dose arsenic trioxide in obese patients

Arsenic trioxide (ATO)-based regimens are standard in acute promyelocytic leukemia (APL). ATO-related nephrotoxicity has not been reported. We reviewed APL patients treated with ATO to identify cases of acute kidney injury (AKI). Clinically significant cases were characterized. Multivariate analysis was performed to identify predictors of idiopathic, clinically significant AKI. One hundred and eight patients were included. ATO dose was 0.15 mg/kg/day using actual body weight with no dose cap. Thirty-one (28.7%) AKI cases were identified, 10 (32.3%) clinically significant. Six were idiopathic; five required dialysis. The proportion with significant, idiopathic AKI was 15.8% in patients receiving >15mg ATO versus 0% in those receiving ≤15mg (p = 0.001). On multivariate analysis, only ATO dose was a significant predictor of clinically significant AKI (odds ratio of 1.91, 95%CI, 1.19-3.07, p = 0.007). High-dose ATO may be associated with significant nephrotoxicity. We recommend that ATO dose be capped at 15 mg to minimize toxicity for this curable disease.

Acute leukemias and complicated lymphomas: pearls to optimize management when patients stay local

Hematologic malignancies often present acutely with a constellation of infectious complications, pancytopenia, tumor lysis, and renal dysfunction. Acute leukemias and aggressive lymphomas often require hospitalization for rapid diagnostic evaluation, urgent management of complicating presentations, and timely management of intensive systemic therapies. There is an emerging paradigm whereby complex cancer care can be safely and effectively provided in the community, where the majority of cancer is treated. A substantive and effective network between local oncologists and their academic counterparts will enhance care for the patient, advance research, and help bring complicated therapies to local centers, thereby improving access. Here we present several cases that highlight a collaborative approach to complicated hematologic malignancies in the community.

Measurable residual disease monitoring in patients with acute myeloid leukemia treated with lower-intensity therapy: Roadmap from an ELN-DAVID expert panel

With the availability of effective targeted agents, significant changes have occurred in the management of patients with acute myeloid leukemia (AML) over the past several years, particularly for those considered unfit for intensive chemotherapy. While testing for measurable residual disease (MRD) is now routinely performed in patients treated with intensive chemotherapy to refine prognosis and, possibly, inform treatment decision-making, its value in the context of lower-intensity regimens is unclear. As such regimens have gained in popularity and can be associated with higher response rates, the need to better define the role of MRD assessment and the appropriate time points and assays used for this purpose has increased. This report outlines a roadmap for MRD testing in patients with AML treated with lower-intensity regimens. Experts from the European LeukemiaNet (ELN)-DAVID AML MRD working group reviewed all available data to propose a framework for MRD testing in future trials and clinical practice. A Delphi poll served to optimize consensus. Establishment of uniform standards for MRD assessments in lower-intensity regimens used in treating patients with AML is clinically relevant and important for optimizing testing and, ultimately, improving treatment outcomes of these patients.

Differentiation Syndrome in Acute Leukemia: APL and Beyond

Differentiation syndrome (DS) is a frequent and potentially life-threatening clinical syndrome first recognized with the advent of targeted therapeutics for acute promyelocytic leukemia (APL). DS was subsequently observed more broadly with targeted therapeutics for acute myeloid leukemia (AML). DS is typically characterized by fever, dyspnea, hypotension, weight gain, pleural or pericardial effusions, and acute renal failure. The incidence in patients with APL ranges from 2 to 37%, with the wide variation likely attributed to different diagnostic criteria, use of prophylactic treatment, and different treatment regimens. Treatment with corticosteroids +/- cytoreductive therapy should commence as soon as DS is suspected to reduce DS-related morbidity and mortality. The targeted anti-leukemic therapy should be discontinued in patients with severe DS. Here, we discuss the pathogenesis of DS, clinical presentations, diagnostic criteria, management strategies, and implementation of prospective tracking on clinical trials.

Immunotherapy for Acute Myeloid Leukemia: Current Trends, Challenges, and Strategies

BACKGROUND

In the past decade, there have been significant breakthroughs in immunotherapies for B-cell lymphoid malignancies and multiple myeloma, but progress has been much less for acute myeloid leukemia (AML). Nevertheless, challenge begets innovation and several therapeutic strategies are under investigation.

SUMMARY

In this review, we review the state of the art in AML immunotherapy including CD33- and CD123-targeted agents, immune checkpoint inhibition, and adoptive cell therapy strategies. We also share conceptual frameworks for approaching the growing catalog of investigational AML immunotherapies and propose future directions for the field.

KEY MESSAGES

Immunotherapies for AML face significant challenges but novel strategies are in development.

The Coagulopathy of Acute Promyelocytic Leukemia: An Updated Review of Pathophysiology, Risk Stratification, and Clinical Management

Acute promyelocytic leukemia (APL) has a well-established mechanism and a long-term prognosis that exceeds that of any other acute leukemia. These improving outcomes are due, in part, to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), two targeted and highly active agents in this disease. However, there remains a considerable morbidity and mortality risk in APL secondary to clinically significant hemorrhagic and/or thrombotic events. Prevention and treatment of these coagulopathic complications remain significant impediments to further progress in optimizing outcomes for patients with APL. Moreover, the relative rarity of APL hinders adequately powered randomized controlled trials for evaluating APL coagulopathy management strategies. This review draws from peer-reviewed works falling between initial descriptions of APL in 1957 and work published prior to January 2023 and provides an updated overview of the pathophysiology of hemorrhagic and thrombotic complications in APL, outlines risk stratification parameters, and compiles current clinical best practices. An improved understanding of the pathophysiologic mechanisms driving hemorrhage and thrombosis along with the completion of well-designed trials of management strategies will assist clinicians in developing interventions that mitigate these devastating complications in an otherwise largely curable disease.

Combination Effect of Deferoxamine and Arsenic Trioxide on Viability and Vitality of APL Like Cell Line

Background

Arsenic trioxide is an activist agent in the treatment of acute promyelocytic leukemia (APL), which acts alone, but has an adverse effect on patients. Moreover, deferoxamine has antiproliferative activity and induces leukopenia. In order to enhance antileukemic effectiveness and to reduce the dosage of arsenic trioxide, the combination effect of it with deferoxamine (DFO) was evaluated on the APL cell line (NB4).

Methods

In this experimental study, to investigate the cytotoxic effects of ATO/DFO in acute promyelocytic leukemia, the NB4 cell line (provided by Pasteur Institute of Iran) was treated with different doses and then at 24, 48, and 72 hrs intervals, the percentage of survival, cell count, metabolic activity and apoptosis induction were investigated respectively. Also, hTERT gene expression was analyzed by the RT-PCR method.

Results

We found that DFO alone and in combination with ATO has cytotoxic and antiproliferative effects, and reduces viability and cell metabolic activity in the NB4 cell line in a dose and time-dependent manner. In addition, this combination causes an increase in apoptosis, up-regulation of Caspase-3, and down-regulation of hTERT genes in cells.

Conclusion

Combined ATO/ DFO treatment cooperatively decreased the mRNA levels of the hTERT and increased the mRNA levels of Caspase-3 in a time-dependent manner compared to DFO alone.

Treating low- and intermediate-risk acute promyelocytic leukemia with and without chemotherapy: A comparison in a tertiary care center

Background

Acute promyelocytic leukemia (APL) comprises approximately 10% of acute myeloid leukemia (AML) cases.

Material and Methods

Both options of treatment (ATRA-ATO and ATRA-chemotherapy) were discussed with patients with low- and intermediate-risk APL, pros and cons explained in details, and treatment regimen selected after getting informed written consent.

Results

Total 71 patients were included in the study; among these patients, 3 were negative for both FISH for t (15,17) and RT-PCR for promyelocytic leukemia retinoic acid receptor alpha, and 36 patients with APL had white blood cell count at diagnosis >10 × 109/l. Total 30 patients with newly diagnosed as low- and intermediate-risk-APL fulfilled all inclusion criteria, treated and followed for a minimum period of 2 years up to June, 2016. Fifteen patients liked to be treated with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), while rest of the 15 patients preferred treatment with ATRA and chemotherapy.

Conclusion

Combination of ATRA and ATO is equally effective, less toxic, and more feasible in comparison to ATRA and chemotherapy for patients with low- and intermediate-risk APL and is a viable option for this subset of patients, especially in countries with limited resources.

Antibody-drug conjugate [ADC] treatment of leukaemia

Three ADCs: Mylotarg, Besponda and Lumoxiti have improved overall survival and event=free survival as well as reduced relapse in 3 types of Leukaemia: AML, ALL and HCL, respectively. Lessons from these three SOC successful ADCs should guide other new ADCs in addressing the ADC-related off target toxicity due to the cytotoxic payload that limits their therapeutic index by using the successful approach of administrating lower doses in a fractionated regimen over time in separate days of the cycle to reduce the severity and frequency of the ADC-related serious toxicities that include ocular damage, long-term peripheral neuropathy and hepatic toxicity etc.

North American Blastic Plasmacytoid Dendritic Cell Neoplasm Consortium: position on standards of care and areas of need

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with historically poor outcomes and no worldwide consensus treatment approach. Unique among most hematologic malignancies for its frequent cutaneous involvement, BPDCN can also invade other extramedullary compartments, including the central nervous system. Generally affecting older adults, many patients are unfit to receive intensive chemotherapy, and although hematopoietic stem cell transplantation is preferred for younger, fit individuals, not all are eligible. One recent therapeutic breakthrough is that all BPDCNs express CD123 (IL3Rα) and that this accessible surface marker can be pharmacologically targeted. The first-in-class agent for BPDCN, tagraxofusp, which targets CD123, was approved in December 2018 in the United States for patients with BPDCN aged ≥2 years. Despite favorable response rates in the frontline setting, many patients still relapse in the setting of monotherapy, and outcomes in patients with relapsed/refractory BPDCN remain dismal. Therefore, novel approaches targeting both CD123 and other targets are actively being investigated. To begin to formally address the state of the field, we formed a new collaborative initiative, the North American BPDCN Consortium (NABC). This group of experts, which includes a multidisciplinary panel of hematologists/oncologists, hematopoietic stem cell transplant physicians, pathologists, dermatologists, and pediatric oncologists, was tasked with defining the current standard of care in the field and identifying the most important research questions and future directions in BPDCN. The position findings of the NABC's inaugural meetings are presented herein.

Moving toward individualized target-based therapies in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease at the genetic level. The field of AML therapy is increasingly shifting away from uniform approaches based solely on intensive chemotherapy (such as '7 + 3') toward personalized therapy. The treatment of AML can now be individualized based on patient characteristics and cytogenetic/molecular disease features. In this review, we provide a comprehensive updated summary of personalized, target-directed therapy in AML. We first discuss the selection of intensive versus low-intensity treatment approaches based on the patient's age and/or comorbidities. We follow with a detailed review of specific molecularly defined AML subtypes that benefit from the addition of targeted agents. In this context, we highlight the urgent need for novel therapies in tumor protein p53 (TP53)-mutated AML. We then propose approaches to optimize AML therapy in patients without directly actionable mutations. We conclude with a discussion on the emerging role of using measurable residual disease to modify therapy based on the quality of response.

The emerging scenario of immunotherapy for T-cell Acute Lymphoblastic Leukemia: advances, challenges and future perspectives

T-cell acute lymphoblastic leukemia (T-ALL) is a challenging pediatric and adult haematologic disease still associated with an unsatisfactory cure rate. Unlike B-ALL, the availability of novel therapeutic options to definitively improve the life expectancy for relapsed/resistant patients is poor. Indeed, the shared expression of surface targets among normal and neoplastic T-cells still limits the efficacy and may induce fratricide effects, hampering the use of innovative immunotherapeutic strategies. However, novel monoclonal antibodies, bispecific T-cell engagers (BTCEs), and chimeric antigen receptors (CAR) T-cells recently showed encouraging results and some of them are in an advanced stage of pre-clinical development or are currently under investigation in clinical trials. Here, we review this exciting scenario focusing on most relevant advances, challenges, and perspectives of the emerging landscape of immunotherapy of T-cell malignancies.

A novel network pharmacology approach for leukaemia differentiation therapy using Mogrify®

Acute myeloid leukaemia (AML) is a rapidly fatal blood cancer that is characterised by the accumulation of immature myeloid cells in the blood and bone marrow as a result of blocked differentiation. Methods which identify master transcriptional regulators of AML subtype-specific leukaemia cell states and their combinations could be critical for discovering novel differentiation-inducing therapies. In this proof-of-concept study, we demonstrate a novel utility of the Mogrify® algorithm in identifying combinations of transcription factors (TFs) and drugs, which recapitulate granulocytic differentiation of the NB4 acute promyelocytic leukaemia (APL) cell line, using two different approaches. In the first approach, Connectivity Map (CMAP) analysis of these TFs and their target networks outperformed standard approaches, retrieving ATRA as the top hit. We identify dimaprit and mebendazole as a drug combination which induces myeloid differentiation. In the second approach, we show that genetic manipulation of specific Mogrify®-identified TFs (MYC and IRF1) leads to co-operative induction of APL differentiation, as does pharmacological targeting of these TFs using currently available compounds. We also show that loss of IRF1 blunts ATRA-mediated differentiation, and that MYC represses IRF1 expression through recruitment of PML-RARα, the driver fusion oncoprotein in APL, to the IRF1 promoter. Finally, we demonstrate that these drug combinations can also induce differentiation of primary patient-derived APL cells, and highlight the potential of targeting MYC and IRF1 in high-risk APL. Thus, these results suggest that Mogrify® could be used for drug discovery or repositioning in leukaemia differentiation therapy for other subtypes of leukaemia or cancers.

Evolving of treatment paradigms and challenges in acute promyelocytic leukaemia: A real-world analysis of 1105 patients over the last three decades

Although acute promyelocytic leukaemia (APL) is a highly curable disease, challenges of early death (ED) and relapse still exist, and real-world data are scarce in the ATRA plus ATO era. A total of 1105 APL patients from 1990 to 2020 were enrolled and categorized into three treatment periods, namely ATRA, ATRA plus ATO, and risk-adapted therapy. The early death (ED) rate was 20.2%, 10.1%, and 7.0%, respectively, in three periods, while there was no significant decline in the 7-day death rate. Consistently, the overall survival (OS) and disease-free survival (DFS) of APL patients markedly improved over time. Despite the last two periods exhibiting similar DFS, the chemotherapy load was substantially lower in Period 3. Notably, leveraging older age and higher WBC count (especially > 50 × 10⁹/L), we could identify a small group of extremely high-risk patients who had a very high ED rate and poor prognosis, while those with NRAS mutations and higher WBC tended to relapse, both representing obstacles to curing all patients. In conclusion, the evolvement of treatment paradigms can reduce the ED rate, improve clinical outcomes, and spare patients the toxicity of chemotherapy. Special care and innovative agents are warranted for the particularly high-risk APL.

The rs1001179 SNP and CpG methylation regulate catalase expression in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is an incurable disease characterized by an extremely variable clinical course. We have recently shown that high catalase (CAT) expression identifies patients with an aggressive clinical course. Elucidating mechanisms regulating CAT expression in CLL is preeminent to understand disease mechanisms and develop strategies for improving its clinical management. In this study, we investigated the role of the CAT promoter rs1001179 single nucleotide polymorphism (SNP) and of the CpG Island II methylation encompassing this SNP in the regulation of CAT expression in CLL. Leukemic cells harboring the rs1001179 SNP T allele exhibited a significantly higher CAT expression compared with cells bearing the CC genotype. CAT promoter harboring the T -but not C- allele was accessible to ETS-1 and GR-β transcription factors. Moreover, CLL cells exhibited lower methylation levels than normal B cells, in line with the higher CAT mRNA and protein expressed by CLL in comparison with normal B cells. Methylation levels at specific CpG sites negatively correlated with CAT levels in CLL cells. Inhibition of methyltransferase activity induced a significant increase in CAT levels, thus functionally validating the role of CpG methylation in regulating CAT expression in CLL. Finally, the CT/TT genotypes were associated with lower methylation and higher CAT levels, suggesting that the rs1001179 T allele and CpG methylation may interact in regulating CAT expression in CLL. This study identifies genetic and epigenetic mechanisms underlying differential expression of CAT, which could be of crucial relevance for the development of therapies targeting redox regulatory pathways in CLL.

Role of Prophylactic Steroids in Differentiation Syndrome

Acute promyelocytic leukemia (APML) is defined as a balanced chromosomal translocation between chromosomes 15 and 17 t(15;17)(q24;q21), which results in the formation of promyelocytic leukemia-retinoic acid receptor-alpha (PML-RARA) fusion protein. A widespread recommendation for APML treatment is combined all-trans retinoic acid (ATRA)/arsenic trioxide (ATO) therapy. Differentiation syndrome (DS), or retinoic acid syndrome, is one of the well-known complications of APML treated with ATRA or ATO. The presenting symptoms of APML-induced DS are diverse, and rare symptoms are easily misdiagnosed. However, unexplained fever, dyspnea, weight gain > 5 kg, leukocytosis, acute renal failure, and a chest radiograph demonstrating pleural or pericardial effusion are the most common manifestations of DS. Early recognition and prompt initiation of corticosteroids are key factors in the management of DS. As soon as ATRA/ATO therapy is started, prophylactic treatment with steroids has been recommended to minimize the severity of DS. It is proposed that ATRA/ATO should be stopped or held once the signs and symptoms of DS develop. This case report describes a 45-year-old male who was diagnosed with APML after he developed episodes of hematuria and nose bleeding at home. The patient was also given an empiric steroid along with ATRA/ATO to lessen the intensity of DS. Our study suggests that early initiation of prophylactic steroid treatment can improve the prognosis and mortality of patients with APML-induced DS.

Value of measurable residual disease monitoring in patients with acute promyelocytic leukemia in the era of frontline 'chemotherapy-free' therapy

Acute promyelocytic leukemia (APL) is characterized by the chromosomal translocation t(15;17) and the resulting gene PML-RARA, used for measurable residual disease (MRD) monitoring. Despite highly effective therapy for APL, MRD monitoring practices are not fully established. We aimed to assess the value of MRD monitoring by RT-qPCR in patients with APL treated with ATRA and arsenic trioxide +/- GO. We reviewed 223 patients with APL treated with this regimen. RT-qPCR for PML-RARA was measured every 3 months, and at 12, 18, and 24 months after therapy. Seven patients relapsed. Time to relapse was 7.9-12.4 months in 6 patients, and one patient relapsed after 79.5 months. These data show that MRD monitoring may be important for the detection of relapse in patients treated with this regimen within one year after completing therapy, however, since late molecular relapse is rare, our data suggest a low value of MRD monitoring beyond that first year.

The cure of leukemia through the optimist's prism

Progress is occurring at a dizzying rate across all leukemias. Since the authors' review of the topic in Cancer in 2018, numerous discoveries have been made that have improved the therapy and outcomes of several leukemia subsets. Hairy cell leukemia is potentially curable with a single course of cladribine followed by rituximab (10-year survival, ≥90%). Acute promyelocytic leukemia is curable at a rate of 80% to 90% with a nonchemotherapy regimen of all-trans retinoic acid and arsenic trioxide. The cure rate for core-binding factor acute myeloid leukemia (AML) is ≥75% with fludarabine, high-dose cytarabine, and gemtuzumab ozogamicin. Survival for patients with chronic myeloid leukemia is close to that for an age-matched normal population with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Chronic lymphocytic leukemia, a previously incurable disease, may now be potentially curable with a finite duration of therapy with Bruton tyrosine kinase inhibitors and venetoclax. The estimated 5-year survival rate for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) exceeds 70% with intensive chemotherapy and ponatinib, a third-generation BCR-ABL1 TKI, and more recent nonchemotherapy regimens using dasatinib or ponatinib with blinatumomab are producing outstanding results. Survival in both younger and older patients with ALL has improved with the addition of antibodies targeting CD20, CD19 (blinatumomab), and CD22 (inotuzumab) to chemotherapy. Several recent drug discoveries (venetoclax, FLT3 and IDH inhibitors, and oral hypomethylating agents) are also improving outcomes for younger and older patients with AML and for those with higher risk myelodysplastic syndrome.

Early Death and Survival of Patients With Acute Promyelocytic Leukemia in ATRA Plus Arsenic Era: A Population-Based Study

Most randomized trials for acute promyelocytic leukemia (APL) have investigated highly selected patients under idealized conditions, and the findings need to be validated in the real world. We conducted a population-based study of all APL patients in Zhejiang Province, China, with a total population of 82 million people, to assess the generalization of all-trans retinoic acid (ATRA) and arsenic as front-line treatment. The outcomes of APL patients were also analyzed. Between January 2015 and December 2019, 1,233 eligible patients were included in the final analysis. The rate of ATRA and arsenic as front-line treatment increased steadily from 66.2% in 2015 to 83.3% in 2019, with no difference among the size of the center (≥5 or <5 patients per year, p = 0.12) or age (≥60 or <60 years, p = 0.35). The early death (ED) rate, defined as death within 30 days after diagnosis, was 8.2%, and the 3-year overall survival (OS) was 87.9% in the whole patient population. Age (≥60 years) and white blood cell count (>10 × 10⁹/L) were independent risk factors for ED and OS in the multivariate analysis. This population-based study showed that ATRA and arsenic as front-line treatment are widely used under real-world conditions and yield a low ED rate and a high survival rate, which mimic the results from clinical trials, thereby supporting the wider application of APL guidelines in the future.

Assessment of Arsenic Trioxide and All-trans Retinoic Acid for the Treatment of Pediatric Acute Promyelocytic Leukemia: A Report From the Children's Oncology Group AAML1331 Trial

Importance

All-trans retinoic acid (ATRA) and arsenic trioxide therapy without the use of maintenance therapy has been found to be beneficial for the treatment of adults with standard-risk acute promyelocytic leukemia (APL). However, it is unclear whether similar regimens are safe and beneficial for the treatment of high-risk APL or pediatric patients with standard-risk APL.

Objective

To assess whether treatment with an ATRA and arsenic trioxide-based regimen is safe and allows for the elimination or substantial reduction of chemotherapy use among pediatric patients with standard-risk or high-risk APL, respectively.

Design, Setting, and Participants

The Children's Oncology Group AAML1331 study is a nonrandomized, noninferiority trial that examined survival outcomes among 154 pediatric patients with APL compared with a historical control group of patients with APL from the AAML0631 study. Patients aged 1 to 21 years were enrolled at 85 pediatric oncology centers (members of the Children's Oncology Group) in Australia, Canada, and the US from June 29, 2015, to May 7, 2019, with follow-up until October 31, 2020. All patients had newly diagnosed APL and were stratified into standard-risk APL (white blood cell count <10 000/μL) and high-risk APL (white blood cell count ≥10 000/μL) cohorts.

Interventions

All patients received ATRA and arsenic trioxide continuously during induction therapy and intermittently during 4 consolidation cycles. Patients with high-risk APL received 4 doses of idarubicin during induction therapy only. The duration of therapy was approximately 9 months, and no maintenance therapy was administered.

Main Outcomes and Measures

Event-free survival (EFS) at 2 years after diagnosis.

Results

Among 154 patients (median age, 14.4 years [range, 1.1-21.7 years]; 81 male participants [52.6%]) included in the analysis, 98 patients (63.6%) had standard-risk APL, and 56 patients (36.4%) had high-risk APL. The median follow-up duration was 24.7 months (range, 0-49.5 months) for patients with standard-risk APL and 22.8 months (range, 0-47.7 months) for patients with high-risk APL. Patients with standard-risk APL had a 2-year EFS rate of 98.0% and an overall survival rate of 99.0%; adverse events included 1 early death during induction therapy and 1 relapse. Patients with high-risk APL had a 2-year EFS rate of 96.4% and an overall survival rate of 100%; adverse events included 2 relapses and 0 deaths. These outcomes met predefined noninferiority criteria (noninferiority margin of 10% among those with standard-risk APL and 14.5% among those with high-risk APL).

Conclusions and Relevance

In this nonrandomized, noninferiority trial, pediatric patients with standard-risk APL who received treatment with a chemotherapy-free ATRA and arsenic trioxide regimen experienced positive outcomes. Patients with high-risk APL also had positive outcomes when treated with a novel ATRA and arsenic trioxide-based regimen that included 4 doses of idarubicin during induction therapy only and no maintenance therapy. The 2-year EFS estimates were noninferior to the historical comparator group, and advantages of the regimen included shorter treatment duration, lower exposure to anthracycline and intrathecal chemotherapy, and fewer days hospitalized.

Trial Registration

ClinicalTrials.gov Identifier: NCT02339740.

Arsenic Combined With All-Trans Retinoic Acid for Pediatric Acute Promyelocytic Leukemia: Report From the CCLG-APL2016 Protocol Study

PURPOSE

Arsenic combined with all-trans retinoic acid (ATRA) is the standard of care for adult acute promyelocytic leukemia (APL). However, the safety and effectiveness of this treatment in pediatric patients with APL have not been reported on the basis of larger sample sizes.

METHODS

We conducted a multicenter trial at 38 hospitals in China. Patients with newly diagnosed APL were stratified into two risk groups according to baseline WBC count and FLT3-ITD mutation. ATRA plus arsenic trioxide or oral arsenic without chemotherapy were administered to the standard-risk group, whereas ATRA, arsenic trioxide, or oral arsenic plus reduced-dose anthracycline were administered to the high-risk group. Primary end points were event-free survival and overall survival at 2 years.

RESULTS

We enrolled 193 patients with APL. After a median follow-up of 28.9 months, the 2-year overall survival rate was 99% (95% CI, 97 to 100) in the standard-risk group and 95% (95% CI, 90 to 100) in the high-risk group (P = .088). The 2-year event-free survival was 97% (95% CI, 93 to 100) in the standard-risk group and 90% (95% CI, 83 to 96) in the high-risk group (P = .252). The plasma levels of arsenic were significantly elevated after treatment, with a stable effective level ranging from 42.9 to 63.2 ng/mL during treatment. In addition, plasma, urine, hair, and nail arsenic levels rapidly decreased to normal 6 months after the end of treatment.

CONCLUSION

Arsenic combined with ATRA is effective and safe in pediatric patients with APL, although long-term follow-up is still needed.

KDM5A suppresses PML-RARα target gene expression and APL differentiation through repressing H3K4me2

Epigenetic abnormalities are frequently involved in the initiation and progression of cancers, including acute myeloid leukemia (AML). A subtype of AML, acute promyelocytic leukemia (APL), is mainly driven by a specific oncogenic fusion event of promyelocytic leukemia-RA receptor fusion oncoprotein (PML-RARα). PML-RARα was reported as a transcription repressor through the interaction with nuclear receptor corepressor and histone deacetylase complexes leading to the mis-suppression of its target genes and differentiation blockage. Although previous studies were mainly focused on the connection of histone acetylation, it is still largely unknown whether alternative epigenetics mechanisms are involved in APL progression. KDM5A is a demethylase of histone H3 lysine 4 di- and tri-methylations (H3K4me2/3) and a transcription corepressor. Here, we found that the loss of KDM5A led to APL NB4 cell differentiation and retarded growth. Mechanistically, through epigenomics and transcriptomics analyses, KDM5A binding was detected in 1889 genes, with the majority of the binding events at promoter regions. KDM5A suppressed the expression of 621 genes, including 42 PML-RARα target genes, primarily by controlling the H3K4me2 in the promoters and 5' end intragenic regions. In addition, a recently reported pan-KDM5 inhibitor, CPI-455, on its own could phenocopy the differentiation effects as KDM5A loss in NB4 cells. CPI-455 treatment or KDM5A knockout could greatly sensitize NB4 cells to all-trans retinoic acid-induced differentiation. Our findings indicate that KDM5A contributed to the differentiation blockage in the APL cell line NB4, and inhibition of KDM5A could greatly potentiate NB4 differentiation.

High Risk Acute Promyelocytic Leukemia - An Enigma for Hematologists: Optimizing Treatment with APML-4 Protocol

Management of Acute Promyelocytic Leukemia (APML) has improved drastically after the introduction of ATRA (All-trans-retinoic acid) and Arsenic trioxide (ATO). The use of APML-4 protocol has shown its effectiveness in Australian population. We know that high-risk APML represents a subset with poor outcomes. There is scarcity of literature reporting outcomes of high-risk APML from India. We present a 5-year retrospective analysis of the safety and efficacy of APML-4 protocol in our 28 high-risk patients. Of 28 patients, there were 8(28.5%) early deaths; all 20 patients (100%) who were alive achieved hematologic complete remission post-induction and molecular complete remission post-consolidation. The 5-year disease free survival, failure free survival (FFS) and overall survival were 100%, 69% and 69% respectively. Factors affecting FFS were age > 45 years (p = 0.008), baseline ECOG-PS > 1 (p < 0.0001), and grade 3-4 differentiation syndrome (p = 0.008). APML-4 protocol in high-risk patients is capable of achieving excellent disease control with less toxicities. While early induction deaths in high-risk APML still remain an issue, protocol modifications (for steroid and anthracyclines) are important considering high frequency of infections at baseline and during induction therapy in our population.

Acute Myeloid Leukemia: Historical Perspective and Progress in Research and Therapy Over 5 Decades

With the Food and Drug Administration approval of 9 agents for different acute myeloid leukemia (AML) indications, the prognosis and management of AML is evolving rapidly. Herein, we review the important milestones in the history of AML research and therapy, discuss insights regarding prognostic assessment and prediction of treatment outcome, detail practical supportive care measures, and summarize the current treatment landscape and areas of evolving research.

Browsing the oldest antioxidant enzyme: catalase and its multiple regulation in cancer

Aerobic organisms possess numerous antioxidant enzymatic families, including catalases, superoxide dismutases (SODs), peroxiredoxins (PRDXs), and glutathione peroxidases (GPXs), which work cooperatively to protect cells from an excess of reactive oxygen species (ROS) derived from endogenous metabolism or external microenvironment. Catalase, as well as other antioxidant enzymes, plays an important dichotomous role in cancer. Therefore, therapies aimed at either reverting the increased or further escalating catalase levels could be effective, depending on the metabolic landscape and on the redox status of cancer cells. This dichotomous role of catalase in cancers highlights the importance to deepen comprehensively the role and the regulation of this crucial antioxidant enzyme. The present review highlights the role of catalase in cancer and provides a comprehensive description of the molecular mechanisms associated with the multiple levels of catalase regulation.

Drug treatment options for acute promyelocytic leukemia

INTRODUCTION

Until the late 1980s, acute promyelocytic leukemia (APL) was the most rapidly fatal leukemia; however, nowadays, it is a curable disease with survival rates exceeding 90-95%. The improvement of APL outcome is mainly due to two agents, which target the typical translocation t(15;17) and its fusion transcript PML-RARα responsible for initiating and maintaining the disease: all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). The story of APL represents a pioneering model for the development of precision medicine and curative chemotherapy-free approaches for acute leukemia.

AREA COVERED

The authors examine the major advances in the treatment of patients with APL focusing on three different eras: 1) the pre-ATRA era; 2) the ATRA era; 3) the ATO era.

EXPERT OPINION

The combination of ATRA and ATO is effective and curative for the majority of APL patients. It has been approved for low/intermediate risk cases while an experimental trial with a minimal addition of chemotherapy for high-risk ones is ongoing. Disease relapse is infrequent and can be cured with ATRA-ATO rechallenging, with or without subsequent transplantation depending on the interval between complete remission and relapse. New therapeutic landscapes contemplate the use of an oral chemo-free ATRA-ATO combination, implementing treatment as outpatient care, thus increasing quality of life and decreasing medical costs.

Updates on targeted therapies for acute myeloid leukaemia

In the past few years research in the underlying pathogenic mechanisms of acute myeloid leukaemia (AML) has led to remarkable advances in our understanding of the disease. Cytogenetic and molecular aberrations are the most important factors in determining response to chemotherapy as well as long-term outcome, but beyond prognostication are potential therapeutic targets. Our increased understanding of the pathogenesis of AML facilitated by next-generation sequencing has spurred the development of new compounds in the treatment of AML, particularly the creation of small molecules that target the disease on a molecular level. Many of the hopeful predictions outlined in our AML review of 2018 are now therapeutic realities: gemtuzumab ozogamicin, venetoclax, FLT3 inhibitors (midostaurin, gilteritinib), IDH inhibitors (ivosidenib, enasidenib), CPX-351, glasdegib, oral decitabine, and oral azacitidine. Others may soon be (quizartinib, APR246 magrolimab, menin inhibitors). The wealth of positive data allows reconsideration of what might soon be new standards of care in younger and older patients with AML. In this review we give an overview of recently approved therapies in AML and address present and future research directions.

Arsenic trioxide in pediatric cancer - a case series and review of literature

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

Health-related quality of life in patients with acute promyelocytic leukemia: a systematic literature review

Introduction: Remarkable advances have been made in acute promyelocytic leukemia (APL) research over the past decades and many patients can now also be cured without traditional chemotherapy. Therefore, the assessment of health-related quality of life (HRQoL) and other types of patient-reported outcomes (PROs) is highly relevant in the current APL treatment landscape.Areas covered: A systematic literature review was performed to identify APL studies assessing HRQoL that were published over the last 15 years. Eligible studies were evaluated on a predetermined data extraction form including information on the study design, PRO measure used, as well patient characteristics and summary of HRQoL findings. For descriptive purposes, selected studies were grouped and discussed based on the type of treatment: standard chemotherapy only versus those also including more recent targeted arsenic trioxide (ATO)-based strategies.Expert opinion: Inclusion of HRQoL in APL research was important to better understand the benefit-risk profile of intravenous ATO compared to traditional chemotherapy. While some information on HRQoL and symptoms in APL survivors treated with standard chemotherapy is available, the long-term effects of ATO therapy on patients' HRQoL are largely unknown. Additionally, future studies are needed to evaluate the potential advantages of oral ATO over intravenous administration.

Acute promyelocytic leukemia current treatment algorithms

In 1957, Hillestad et al. defined acute promyelocytic leukemia (APL) for the first time in the literature as a distinct type of acute myeloid leukemia (AML) with a “rapid downhill course” characterized with a severe bleeding tendency. APL, accounting for 10–15% of the newly diagnosed AML cases, results from a balanced translocation, t(15;17) (q22;q12-21), which leads to the fusion of the promyelocytic leukemia (PML) gene with the retinoic acid receptor alpha (RARA) gene. The PML–RARA fusion oncoprotein induces leukemia by blocking normal myeloid differentiation. Before using anthracyclines in APL therapy in 1973, no effective treatment was available. In the mid-1980s, all-trans retinoic acid (ATRA) monotherapy was used with high response rates, but response durations were short. Later, the development of ATRA, chemotherapy, and arsenic trioxide combinations turned APL into a highly curable malignancy. In this review, we summarize the evolution of APL therapy, focusing on key milestones that led to the standard-of-care APL therapy available today and discuss treatment algorithms and management tips to minimize induction mortality.

CD33 Expression and Gentuzumab Ozogamicin in Acute Myeloid Leukemia: Two Sides of the Same Coin

Simple Summary

Roughly 85–90% of adult and pediatric acute myeloid leukemia (AML) are CD33-positive. Gemtuzumab ozogamicin (GO), a humanized murine IgG4 anti-CD33 antibody, is the first target therapy approved in AML therapeutic scenario. This review focuses on current biological information and clinical data from several studies investigating the use of GO in patients with AML. Over the years, flow cytometry, cytogenetics, molecular techniques, and genotyping studies of CD33 SNPs have provided a comprehensive analysis of promising biomarkers for GO responses and have potentially helped to identify subgroups of patients that may benefit from GO addition to standard chemotherapies. Increased understanding of molecular mutations, altered intracellular pathways, and their potential relationship with CD33 expression may open new therapeutic landscapes based on combinatorial regimens in an AML scenario.

Abstract

Acute myeloid leukemia (AML), the most frequent acute leukemia in adults, has been historically treated with infusional cytarabine (ara-c) + daunorubicin (3 + 7) for at least 40 years. The first “target therapy” to be introduced was the monoclonal anti-CD33 gemtuzumab ozogamicin (GO) in 2004. Unfortunately, in 2010 it was voluntarily withdrawn from the market both for safety reasons related to potential liver toxicity and veno-occlusive disease (VOD) and because clinical studies failed to confirm the clinical benefit during induction and maintenance. Seven years later, GO was re-approved based on new data, including insights into its mechanism of action on its target receptor CD33 expressed on myeloid cells. The present review focuses on current biological information and clinical data from several studies investigating GO. Cytogenetic, molecular, and immunophenotypic data are now able to predict the potential positive advantages of GO, with the exception of high-risk AML patients who do not seem to benefit. GO can be considered a ‘repurposed drug’ that could be beneficial for some patients with AML, mostly in combination with new drugs already approved or currently in testing.

Arsenic trioxide replacing or reducing chemotherapy in consolidation therapy for acute promyelocytic leukemia (APL2012 trial)

As all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) are widely accepted in treating acute promyelocytic leukemia (APL), deescalating toxicity becomes a research hotspot. Here, we evaluated whether chemotherapy could be replaced or reduced by ATO in APL patients at different risks. After achieving complete remission with ATRA-ATO-based induction therapy, patients were randomized (1:1) into ATO and non-ATO groups for consolidation: ATRA-ATO versus ATRA-anthracycline for low-/intermediate-risk patients, or ATRA-ATO-anthracycline versus ATRA-anthracycline-cytarabine for high-risk patients. The primary end point was to assess disease-free survival (DFS) at 3 y by a noninferiority margin of -5%; 855 patients were enrolled with a median follow-up of 54.9 mo, and 658 of 755 patients could be evaluated at 3 y. In the ATO group, 96.1% (319/332) achieved 3-y DFS, compared to 92.6% (302/326) in the non-ATO group. The difference was 3.45% (95% CI -0.07 to 6.97), confirming noninferiority (P < 0.001). Using the Kaplan-Meier method, the estimated 7-y DFS was 95.7% (95% CI 93.6 to 97.9) in ATO and 92.6% (95% CI 89.8 to 95.4) in non-ATO groups (P = 0.066). Concerning secondary end points, the 7-y cumulative incidence of relapse (CIR) was significantly lower in ATO (2.2% [95% CI 1.1 to 4.2]) than in non-ATO group (6.1% [95% CI 3.9 to 9.5], P = 0.011). In addition, grade 3 to 4 hematological toxicities were significantly reduced in the ATO group during consolidation. Hence, ATRA-ATO in both chemotherapy-replacing and -reducing settings in consolidation is not inferior to ATRA-chemotherapy (https://www.clinicaltrials.gov/, NCT01987297).

De novo acute myeloid leukemia: A population-based study of outcome in the United States based on the Surveillance, Epidemiology, and End Results (SEER) database, 1980 to 2017

BACKGROUND

Several important treatment and supportive care strategies have been implemented over the past 4 decades in the management of acute myeloid leukemia (AML).

METHODS

The authors identified 29,107 patients who were diagnosed with de novo AML between 1980 and 2017 in the National Cancer Institute's Surveillance, Epidemiology, and End Results database. Patients were categorized into 5 age groups (ages birth to 14, 15-39, 40-59, 60-69, and ≥70 years) and 4 calendar periods (1980-1989, 1990-1999, 2000-2009, and 2010-2017). The outcomes of patients who had AML within these categories were analyzed.

RESULTS

The overall 5-year survival rates in patients with AML were 9%, 15%, 22%, and 28% in the decades 1980 to 1989, 1990 to 1999, 2000 to 2009, and 2010 to 2017, respectively. Among patients aged 15 to 39 years, the 5-year survival rates were 24%, 41%, 52%, and 63%, respectively; among those aged ≥70 years, the 5-year survival rates were 1%, 2%, 3%, and 5%, respectively. Four-week mortality was surprising high among adults and older patients (range, 20%-45%), even in modern times. Overall, survival continued to improve over the calendar periods and was best in the period from 2010 to 2017. Survival improvement was noticeable across all age groups except patients aged ≥70 years, in whom the estimated 5-year survival rate remained 5% even during the period from 2010 to 2017.

CONCLUSIONS

The outcomes of patients with AML showed incremental improvement over time in a population-based study of the Surveillance, Epidemiology, and End Results data. The introduction since 2017 of targeted therapies among older patients and optimizations in supportive care hopefully will continue to improve outcomes in AML, particularly among older patients.

Acute Promyelocytic Leukemia: A Long-Term Retrospective Study in Mexico

Background

The present retrospective study reviewed acute promyelocytic leukemia (APL) cases recorded in Mexico between January 2007 and January 2017. The primary objective of the study was to evaluate overall survival (OS) in Mexican patients with APL. Secondary objective was to evaluate the impact of induction treatment with different anthracyclines on OS, event-free survival (EFS) and complications in this patient population.

Methods

The medical charts of patients referred to medical institutions in Mexico from January 2007 through January 2017 for the treatment of suspected APL were reviewed retrospectively. Patients aged 15 - 75 years, in whom the diagnosis of APL was confirmed, who had an Eastern Cooperative Group performance status of 0 - 2, and who were eligible for combined treatment with intensive chemotherapy and all-trans retinoic acid (ATRA), were included in the study. Study participants received induction and consolidation treatment with ATRA plus either daunorubicin or idarubicin, followed by 2 years of single-agent ATRA as maintenance therapy. Patients who were unable to pay for ATRA treatment received anthracycline-based induction and consolidation, with methotrexate plus mercaptopurine as maintenance therapy.

Results

A total of 360 patients from 21 public and private hospitals were included in the study. The median age of the population was 37 years, and 51% were male. Of the 360 patients, 205 (57%) vs. 155 (43%) received daunorubicin vs. idarubicin as induction treatment for APL. ATRA was administered to 201 (98%) patients in the daunorubicin group vs. 138 (89%) in the idarubicin group (P = 0.001), and was initiated at diagnosis in 92% vs. 73% of recipients, respectively (P = 0.0001). At 150 months, OS and EFS for the entire population were 84% and 79%, respectively. Both OS (90% vs. 76%, P = 0.003) and EFS (85% vs. 72%, P = 0.001) were significantly prolonged in daunorubicin vs. idarubicin recipients. Rates of complications were similar in the two groups.

Conclusions

As arsenic trioxide (ATO) is not currently available in Mexico, anthracycline plus ATRA is the mainstay of treatment for APL here. Our results confirm the efficacy of this strategy, with high OS and EFS rates being observed 12.5 years after diagnosis.

A phase 2 study of ATRA, arsenic trioxide, and gemtuzumab ozogamicin in patients with high-risk APL (SWOG 0535)

High-risk acute promyelocytic leukemia (APL) remains a therapeutic challenge, with higher associated rates of early mortality and relapse than standard-risk APL. All-trans retinoic acid (ATRA) plus arsenic trioxide (ATO) is a well-established treatment for patients with standard-risk APL, but it is not well defined for those with high-risk APL. In a prior study of patients with high-risk APL, the addition of gemtuzumab ozogamicin (GO) to ATO plus ATRA suggested benefit. The SWOG Cancer Research Network conducted a phase 2 study to confirm the efficacy and safety of the combination of ATRA plus ATO plus GO in treating high-risk APL patients. The primary end points were 3-year event-free survival (EFS) and early (6-week) death rates associated with this combination. Seventy patients were treated. With a median follow-up of 3.4 years, the 3-year EFS and overall survival estimates were 78% (95% confidence interval [CI], 67%-86%) and 86% (95% CI, 75%-92%), respectively. Overall, 86% of patients achieved complete response. The 6-week mortality rate was 11%. The most common treatment-emergent toxicities during the induction phase included febrile neutropenia, aspartate aminotransferase/alanine aminotransferase elevation, hyperglycemia, hypoxia, headache, and prolonged QT interval corrected for heart rate. Retinoic acid syndrome occurred in 9% of patients. Approximately 37% of patients did not complete all planned courses of postremission therapy. The combination of ATRA plus ATO plus GO in high-risk APL patients was effective and generally well tolerated, suggesting an opportunity to offer a chemotherapy-free induction platform for patients with this disease. This trial was registered at www.clinicaltrials.gov as #NCT00551460.