Ivosidenib or enasidenib combined with intensive chemotherapy in patients with newly diagnosed AML: a phase 1 study

Molecular Features and Treatment Paradigms of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a common hematologic malignancy that is considered to be a disease of aging, and traditionally has been treated with induction chemotherapy, followed by consolidation chemotherapy and/or allogenic hematopoietic stem cell transplantation. More recently, with the use of next-generation sequencing and access to molecular information, targeted molecular approaches to the treatment of AML have been adopted. Molecular targeting is gaining prominence, as AML mostly afflicts the elderly population, who often cannot tolerate traditional chemotherapy. Understanding molecular changes at the gene level is also important for accurate disease classification, risk stratification, and prognosis, allowing for more personalized medicine. Some mutations are well studied and have an established gene-specific therapy, including FLT3 and IDH1/2, while others are being investigated in clinical trials. However, data on most known mutations in AML are still minimal and therapeutic studies are in pre-clinical stages, highlighting the importance of further research and elucidation of the pathophysiology involving these genes. In this review, we aim to highlight the key molecular alterations and chromosomal changes that characterize AML, with a focus on pathophysiology, presently available treatment approaches, and future therapeutic options.

Precision medicine in AML: overcoming resistance

The development of molecularly targeted therapy for acute myeloid leukemia is progressing at an accelerated pace. Therapies targeting FLT3, IDH1, IDH2, and BCL2 have been approved in the last 5 years. As we exploit these biological vulnerabilities, various mechanisms of resistance arise. Emergence of competing clones with different genetic drivers and acquisition of constitutional mutations in the target renders therapies ineffective, and enzymatic isoform changes can lead to reappearance of the disease phenotype. Understanding the timing and circumstances of resistance origination will allow clinicians to develop combinatorial and sequential therapeutic approaches to deepen responses and improve survival. The objective of this review is to illustrate the biological underpinnings of each therapy and the landscape of resistance mechanisms and discuss strategies to overcome on- and off-target resistance.

Clinical Implications of Isocitrate Dehydrogenase Mutations and Targeted Treatment of Acute Myeloid Leukemia with Mutant Isocitrate Dehydrogenase Inhibitors-Recent Advances, Challenges and Future Prospects

Despite the better understanding of the molecular mechanisms contributing to the pathogenesis of acute myeloid leukemia (AML) and improved patient survival in recent years, AML therapy still remains a clinical challenge. For this reason, it is important to search for new therapies that will enable the achievement of remission. Recently, the Food and Drug Administration approved three mutant IDH (mIDH) inhibitors for the treatment of AML. However, the use of mIDH inhibitors in monotherapy usually leads to the development of resistance and the subsequent recurrence of the cancer, despite the initial effectiveness of the therapy. A complete understanding of the mechanisms by which IDH mutations influence the development of leukemia, as well as the processes that enable resistance to mIDH inhibitors, may significantly improve the efficacy of this therapy through the use of an appropriate synergistic approach. The aim of this literature review is to present the role of IDH1/IDH2 mutations in the pathogenesis of AML and the results of clinical trials using mIDH1/IDH2 inhibitors in AML and to discuss the challenges related to the use of mIDH1/IDH2 inhibitors in practice and future prospects related to the potential methods of overcoming resistance to these agents.

Decoding mitochondria's role in immunity and cancer therapy

The functions of mitochondria, including energy production and biomolecule synthesis, have been known for a long time. Given the rising incidence of cancer, the role of mitochondria in cancer has become increasingly popular. Activated by components released by mitochondria, various pathways interact with each other to induce immune responses to protect organisms from attack. However, mitochondria play dual roles in the progression of cancer. Abnormalities in proteins, which are the elementary structures of mitochondria, are closely linked with oncogenesis. Both the aberrant accumulation of intermediates and mutations in enzymes result in the generation and progression of cancer. Therefore, targeting mitochondria to treat cancer may be a new strategy. Several drugs aimed at inhibiting mutated enzymes and accumulated intermediates have been tested clinically. Here, we discuss the current understanding of mitochondria in cancer and the interactions between mitochondrial functions, immune responses, and oncogenesis. Furthermore, we discuss mitochondria as hopeful targets for cancer therapy, providing insights into the progression of future therapeutic strategies.

The Tricarboxylic Acid Cycle Metabolites for Cancer: Friend or Enemy

The tricarboxylic acid (TCA) cycle is capable of providing sufficient energy for the physiological activities under aerobic conditions. Although tumor metabolic reprogramming places aerobic glycolysis in a dominant position, the TCA cycle remains indispensable for tumor cells as a hub for the metabolic linkage and interconversion of glucose, lipids, and certain amino acids. TCA intermediates such as citrate, α-ketoglutarate, succinate, and fumarate are altered in tumors, and they regulate the tumor metabolism, signal transduction, and immune environment to affect tumorigenesis and tumor progression. This article provides a comprehensive review of the modifications occurring in tumor cells in relation to the intermediates of the TCA cycle, which affects tumor pathogenesis and current therapeutic strategy for therapy through targeting TCA cycle in cancer cells.

Molecularly defined sinonasal malignancies: an overview with focus on the current WHO classification and recently described provisional entities

Classification of tumors of the head and neck has evolved in recent decades including a widespread application of molecular testing in tumors of the sinonasal tract, salivary glands, and soft tissues with a predilection for the head and neck. The availability of new molecular techniques has allowed for the definition of multiple novel tumor types unique to head and neck sites. Moreover, an expanding spectrum of immunohistochemical markers specific to genetic alterations facilitates rapid identification of diagnostic molecular abnormalities. As such, it is currently possible for head and neck pathologists to benefit from a molecularly defined tumor classification while making diagnoses that are still based largely on histopathology and immunohistochemistry. This review covers the principal molecular alterations in sinonasal malignancies, such as alterations in DEK, AFF2, NUTM1, IDH1-2, and SWI/SNF genes in particular, that are important from a practical standpoint for diagnosis, prognosis, and prediction of response to treatment.

Differentiation syndrome associated with treatment with IDH2 inhibitor enasidenib: pooled analysis from clinical trials

ABSTRACT

Treatment with enasidenib, a selective mutant isocitrate dehydrogenase isoform 2 (IDH2) inhibitor, has been associated with the development of differentiation syndrome (DS) in patients with acute myeloid leukemia (AML). Studies on the incidence and clinical features of DS are limited in this setting, and diagnosis is challenging because of nonspecific symptoms. This study assessed the incidence, diagnostic criteria, risk factors, and correlation with clinical response of DS based on the pooled analysis of 4 clinical trials in patients with IDH2-mutated AML treated with enasidenib as monotherapy, or in combination with azacitidine or with chemotherapy. Across the total AML population, 67 of 643 (10.4%) had ≥1 any-grade DS event, with highest incidence in patients who received enasidenib plus azacitidine and lowest incidence in patients who received enasidenib plus chemotherapy (13/74 [17.6%] and 2/93 [2.2%]). The most common symptoms of DS were dyspnea/hypoxia (80.6%) and pulmonary infiltrate (73.1%). Median time to onset of first DS event across all studies was 32 days (range, 4-129). Most patients (88.1%) received systemic steroids for treatment of DS. Evaluation of baseline risk factors for DS identified higher levels of bone marrow blasts and lactate dehydrogenase as independent factors associated with increased grade 3 to 5 DS risk. Overall, these results suggest that DS associated with IDH inhibition is manageable, given the benefits of enasidenib treatment in IDH2-mutated AML. We further characterized enasidenib-related DS in these patients and identified risk factors, which could be used for DS management in clinical practice. These trials were registered at www.ClinicalTrials.gov as # NCT01915498, NCT02577406, NCT02677922, and NCT02632708.

AML treatment: conventional chemotherapy and emerging novel agents

Acute myeloid leukemia (AML) is driven by complex mutations and cytogenetic abnormalities with profound tumoral heterogeneity, making it challenging to treat. Ten years ago, the 5-year survival rate of patients with AML was only 29% with conventional chemotherapy and stem cell transplantation. All attempts to improve conventional therapy over the previous 40 years had failed. Now, new genomic, immunological, and molecular insights have led to a renaissance in AML therapy. Improvements to standard chemotherapy and a wave of new targeted therapies have been developed. However, how best to incorporate these advances into frontline therapy and sequence them in relapse is not firmly established. In this review, we highlight current treatments of AML, targeted agents, and pioneering attempts to synthesize these developments into a rational standard of care (SoC).

Management of isocitrate dehydrogenase 1/2 mutated acute myeloid leukemia

The emergence of next generation sequencing and widespread use of mutational profiling in acute myeloid leukemia (AML) has broadened our understanding of the heterogeneous molecular basis of the disease. Since genetic sequencing has become a standard practice, several driver mutations have been identified. Accordingly, novel targeted therapeutic agents have been developed and are now approved for the treatment of subsets of patients that carry mutations in FLT3, IDH1, and IDH2 [1, 2]. The emergence of these novel agents in AML offers patients a new modality of therapy, and shifts treatment paradigms toward individualized medicine. In this review, we outline the role of IDH mutations in malignant transformation, focus in on a novel group of targeted therapeutic agents directed toward IDH1- and IDH2-mutant AML, and explore their impact on prognosis in patients with AML.

Pyrimidine depletion enhances targeted and immune therapy combinations in acute myeloid leukemia

Acute myeloid leukemia (AML) is a fatal disease characterized by the accumulation of undifferentiated myeloblasts, and agents that promote differentiation have been effective in this disease but are not curative. Dihydroorotate dehydrogenase inhibitors (DHODHi) have the ability to promote AML differentiation and target aberrant malignant myelopoiesis. We introduce HOSU-53, a DHODHi with significant monotherapy activity, which is further enhanced when combined with other standard-of-care therapeutics. We further discovered that DHODHi modulated surface expression of CD38 and CD47, prompting the evaluation of HOSU-53 combined with anti-CD38 and anti-CD47 therapies, where we identified a compelling curative potential in an aggressive AML model with CD47 targeting. Finally, we explored using plasma dihydroorotate (DHO) levels to monitor HOSU-53 safety and found that the level of DHO accumulation could predict HOSU-53 intolerability, suggesting the clinical use of plasma DHO to determine safe DHODHi doses. Collectively, our data support the clinical translation of HOSU-53 in AML, particularly to augment immune therapies. Potent DHODHi to date have been limited by their therapeutic index; however, we introduce pharmacodynamic monitoring to predict tolerability while preserving antitumor activity. We additionally suggest that DHODHi is effective at lower doses with select immune therapies, widening the therapeutic index.

The clinical regimens and cell membrane camouflaged nanodrug delivery systems in hematologic malignancies treatment

Hematologic malignancies (HMs), also referred to as hematological or blood cancers, pose significant threats to patients as they impact the blood, bone marrow, and lymphatic system. Despite significant clinical strategies using chemotherapy, radiotherapy, stem cell transplantation, targeted molecular therapy, or immunotherapy, the five-year overall survival of patients with HMs is still low. Fortunately, recent studies demonstrate that the nanodrug delivery system holds the potential to address these challenges and foster effective anti-HMs with precise treatment. In particular, cell membrane camouflaged nanodrug offers enhanced drug targeting, reduced toxicity and side effects, and/or improved immune response to HMs. This review firstly introduces the merits and demerits of clinical strategies in HMs treatment, and then summarizes the types, advantages, and disadvantages of current nanocarriers helping drug delivery in HMs treatment. Furthermore, the types, functions, and mechanisms of cell membrane fragments that help nanodrugs specifically targeted to and accumulate in HM lesions are introduced in detail. Finally, suggestions are given about their clinical translation and future designs on the surface of nanodrugs with multiple functions to improve therapeutic efficiency for cancers.

Mitochondria inside acute myeloid leukemia cells hydrolyze ATP to resist chemotherapy

Despite early optimism, therapeutics targeting oxidative phosphorylation (OxPhos) have faced clinical setbacks, stemming from their inability to distinguish healthy from cancerous mitochondria. Herein, we describe an actionable bioenergetic mechanism unique to cancerous mitochondria inside acute myeloid leukemia (AML) cells. Unlike healthy cells which couple respiration to the synthesis of ATP, AML mitochondria were discovered to support inner membrane polarization by consuming ATP. Because matrix ATP consumption allows cells to survive bioenergetic stress, we hypothesized that AML cells may resist cell death induced by OxPhos damaging chemotherapy by reversing the ATP synthase reaction. In support of this, targeted inhibition of BCL-2 with venetoclax abolished OxPhos flux without impacting mitochondrial membrane potential. In surviving AML cells, sustained polarization of the mitochondrial inner membrane was dependent on matrix ATP consumption. Mitochondrial ATP consumption was further enhanced in AML cells made refractory to venetoclax, consequential to downregulations in both the proton-pumping respiratory complexes, as well as the endogenous F1-ATPase inhibitor ATP5IF1. In treatment-naive AML, ATP5IF1 knockdown was sufficient to drive venetoclax resistance, while ATP5IF1 overexpression impaired F1-ATPase activity and heightened sensitivity to venetoclax. Collectively, our data identify matrix ATP consumption as a cancer-cell intrinsic bioenergetic vulnerability actionable in the context of mitochondrial damaging chemotherapy.

Novel Therapeutic Targets in Acute Myeloid Leukemia (AML)

PURPOSE OF REVIEW

This review seeks to identify and describe novel genetic and protein targets and their associated therapeutics currently being used or studied in the treatment of acute myeloid leukemia (AML).

RECENT FINDINGS

Over the course of the last 5-6 years, several targeted therapies have been approved by the FDA, for the treatment of both newly diagnosed as well as relapsed/refractory AML. These novel therapeutics, as well as several others currently under investigation, have demonstrated activity in AML and have improved outcomes for many patients. Patient outcomes in AML have slowly improved over time, though for many patients, particularly elderly patients or those with relapsed/refractory disease, mortality remains very high. With the identification of several molecular/genetic drivers and protein targets and development of therapeutics which leverage those mechanisms to target leukemic cells, outcomes for patients with AML have improved and continue to improve significantly.

Comparison of clinical outcomes of several risk stratification tools in newly diagnosed AML patients: A real-world evidence in our current therapeutic era

BACKGROUND OF THE STUDY

AML classification tools have been developed to stratify the risk at AML diagnosis. There is a need to evaluate these tools in the current therapeutic era.

COHORT CHARACTERISTICS

In this retrospective study, we compared five classifiers: ELN 2017, ELN 2022, ALFA classifier, Papaemmanuil et al. classifier, and Lindsley et al. classifier, in a real-life cohort of 281 patients newly diagnosed for AML in Nice University Hospital. In our cohort median age was 68 years old, sex ratio was M/F 56%/44%, performance status was lower than 2 in 73.1% of patients, AML subtype was "De novo" in 71.5%, "secondary" in 22.4%, and "therapy-related" in 6.0% of patients. Intensive chemotherapy was used in 53.0% of patients, and non-intensive chemotherapy in 40.6% of patients. Molecular analysis was available in a large majority of patients and the main mutations found were NPM1 (22.7%), DNMT3A (17.4%), TP53 (13.1%), TET2 (12.4%), and FLT3-ITD (12.4%).

RESULTS

In our findings, the comparison of overall survival between the three prognostic groups in the global cohort was statistically significant in all classifiers: ELN 2017 p < 0.0001, ELN 2022 p < 0.0001, ALFA classifier p < 0.0001, Papaemmanuil classifier p < 0.0001, Lindsley classifier p = 0.001. ELN 2017, ELN 2022, ALFA classifier, Papaemmanuil classifier, and Lindsley classifier were calculated respectively in 99%, 99%, 89%, 90%, and 89% of patients.

CONCLUSIONS

Using Akaike's information criteria (AIC) to compare all five classifiers, ELN 2022 is the best classifier into younger and older patients and for prognosis.

Combating Acute Myeloid Leukemia via Sphingosine Kinase 1 Inhibitor-Nanomedicine Combination Therapy with Cytarabine or Venetoclax

MP-A08 is a novel sphingosine kinase 1 (SPHK1) inhibitor with activity against acute myeloid leukemia (AML). A rationally designed liposome-based encapsulation and delivery system has been shown to overcome the physicochemical challenges of MP-A08 and enable its effective delivery for improved efficacy and survival of mice engrafted with human AML in preclinical models. To establish therapies that overcome AML's heterogeneous nature, here we explored the combination of MP-A08-loaded liposomes with both the standard chemotherapy, cytarabine, and the targeted therapy, venetoclax, against human AML cell lines. Cytarabine (over the dose range of 0.1-0.5 µM) in combination with MP-A08 liposomes showed significant synergistic effects (as confirmed by the Chou-Talalay Combination Index) against the chemosensitised human AML cell lines MV4-11 and OCI-AML3. Venetoclax (over the dose range of 0.5-250 nM) in combination with MP-A08 liposomes showed significant synergistic effects against the chemosensitised human AML cell lines, particularly in venetoclax-resistant human AML cells. This strong synergistic effect is due to multiple mechanisms of action, i.e., inhibiting MCL-1 through SPHK1 inhibition, leading to ceramide accumulation, activation of protein kinase R, ATF4 upregulation, and NOXA activation, ultimately resulting in MCL-1 degradation. These combination therapies warrant further consideration and investigation in the search for a more comprehensive treatment strategy for AML.

Acute myeloid leukemia: Current understanding and management

ABSTRACT

Although relatively rare, acute myeloid leukemia (AML) is the most common type of acute leukemia in adults. AML is associated with poor 5-year overall survival and prompt treatment is critical. Classifying AML based on World Health Organization criteria is important for determining prognosis and applying a risk-adapted treatment approach. Throughout therapy, patients require comprehensive supportive care measures with blood product transfusions, antimicrobial treatment, and frequent monitoring for chemotherapy-related complications. This article provides an overview of AML and its treatments. Clinicians in all specialties must be able to recognize the early signs of AML and ensure their patients seek appropriate expert medical care with a hematologist/oncologist.

Considerations regarding maintenance therapy for acute myeloid leukemia in remission

INTRODUCTION

For most adult patients with acute myeloid leukemia, relapse is characteristic of the disease. When allotransplant in first complete remission is administered as consolidative therapy, relapse is still common, affecting 20-40% of recipients. Maintenance of remission with low-dose treatments may hold promise in preventing relapse.

AREAS COVERED

Improvements in the detection of clinical and biological variants of disease allow the practitioner to identify which patients, based on disease features, may benefit from therapy directed at residual clonal elements that might contribute to relapse. Along with improvements in methods of detecting residual disease, novel agents are under investigation as a platform in order to maintain remission and may contribute to prolonged survival. In this manuscript, we review literature available through PubMed regarding the use of maintenance therapy, described as post-remission or post-transplant treatment intended to delay or prevent relapse.

EXPERT OPINION

Although results of randomized studies are limited, a role for maintenance therapy, particularly directed at molecular targets, in distinct settings of post-remission management is recommended. We also advise that randomized studies of immune therapy along with opportunities for further evaluation of risk-agnostic interventions be a focus of cooperative groups.

Emerging and Future Targeted Therapies for Pediatric Acute Myeloid Leukemia: Targeting the Leukemia Stem Cells

Acute myeloid leukemia (AML) is a rare subtype of acute leukemia in the pediatric and adolescent population but causes disproportionate morbidity and mortality in this age group. Standard chemotherapeutic regimens for AML have changed very little in the past 3-4 decades, but the addition of targeted agents in recent years has led to improved survival in select subsets of patients as well as a better biological understanding of the disease. Currently, one key paradigm of bench-to-bedside practice in the context of adult AML is the focus on leukemia stem cell (LSC)-targeted therapies. Here, we review current and emerging immunotherapies and other targeted agents that are in clinical use for pediatric AML through the lens of what is known (and not known) about their LSC-targeting capability. Based on a growing understanding of pediatric LSC biology, we also briefly discuss potential future agents on the horizon.

Test Then Erase? Current Status and Future Opportunities for Measurable Residual Disease Testing in Acute Myeloid Leukemia

BACKGROUND

Measurable residual disease (MRD) test positivity during and after treatment in patients with acute myeloid leukemia (AML) has been associated with higher rates of relapse and worse overall survival. Current approaches for MRD testing are not standardized leading to inconsistent results and poor prognostication of disease. Pertinent studies evaluating AML MRD testing at specific times points, with various therapeutics and testing methods are presented.

SUMMARY

AML is a set of diseases with different molecular and cytogenetic characteristics and is often polyclonal with evolution over time. This genetic diversity poses a great challenge for a single AML MRD testing approach. The current ELN 2021 MRD guidelines recommend MRD testing by quantitative polymerase chain reaction in those with a validated molecular target or multiparameter flow cytometry (MFC) in all other cases. The benefit of MFC is the ability to use this method across disease subsets, at the relative expense of suboptimal sensitivity and specificity. AML MRD detection may be improved with molecular methods. Genetic characterization at AML diagnosis and relapse is now standard of care for appropriate therapeutic assignment, and future initiatives will provide the evidence to support testing in remission to direct clinical interventions.

KEY MESSAGES

The treatment options for patients with AML have expanded for specific molecular subsets such as FLT3 and IDH1/2 mutated AML, with development of novel agents for NPM1 mutated or KMT2A rearranged AML ongoing, but also due to effective venetoclax-combinations. Evidence regarding highly sensitive molecular MRD detection methods for specific molecular subgroups, in the context of these new treatment approaches, will likely shape the future of AML care.

Development of Novel Epigenetic Anti-Cancer Therapy Targeting TET Proteins

Epigenetic dysregulation, particularly alterations in DNA methylation and hydroxymethylation, plays a pivotal role in cancer initiation and progression. Ten-eleven translocation (TET) proteins catalyze the successive oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) and further oxidized methylcytosines in DNA, thereby serving as central modulators of DNA methylation-demethylation dynamics. TET loss of function is causally related to neoplastic transformation across various cell types while its genetic or pharmacological activation exhibits anti-cancer effects, making TET proteins promising targets for epigenetic cancer therapy. Here, we developed a robust cell-based screening system to identify novel TET activators and evaluated their potential as anti-cancer agents. Using a carefully curated library of 4533 compounds provided by the National Cancer Institute, Bethesda, MD, USA, we identified mitoxantrone as a potent TET agonist. Through rigorous validation employing various assays, including immunohistochemistry and dot blot studies, we demonstrated that mitoxantrone significantly elevated 5hmC levels. Notably, this elevation manifested only in wild-type (WT) but not TET-deficient mouse embryonic fibroblasts, primary bone marrow-derived macrophages, and leukemia cell lines. Furthermore, mitoxantrone-induced cell death in leukemia cell lines occurred in a TET-dependent manner, indicating the critical role of TET proteins in mediating its anti-cancer effects. Our findings highlight mitoxantrone's potential to induce tumor cell death via a novel mechanism involving the restoration of TET activity, paving the way for targeted epigenetic therapies in cancer treatment.

IDH2 mutations in acute myeloid leukemia

Advances in the treatment of acute myeloid leukemia (AML) over the last 40 years have been limited. With an improved understanding of the pathophysiology of the disease, the advent of new treatment options has enriched the armamentarium of the physician to combat the disease. Mutations of the isocitrate dehydrogenase (IDHs) genes are common in AML and occur in 20-30% of cases. These mutations lead to DNA hypermethylation, aberrant gene expression, cell proliferation, and abnormal differentiation. Targeting mutant IDH, either as monotherapy or in combination with hypomethylating agents (HMAs) or BCL-2 inhibitors, has opened new avenues of therapy for these patients.This review will outline the function of IDHs and focus on the biological effects of IDH2 mutations in AML, their prognosis and treatment options.

Characteristics and prognostic impact of IDH mutations in AML: a COG, SWOG, and ECOG analysis

Somatic mutations in isocitrate dehydrogenase (IDH) genes occur frequently in adult acute myeloid leukemia (AML) and less commonly in pediatric AML. The objective of this study was to describe the prevalence, mutational profile, and prognostic significance of IDH mutations in AML across age. Our cohort included 3141 patients aged between <1 month and 88 years treated on Children's Cancer Group/Children's Oncology Group (n = 1872), Southwest Oncology Group (n = 359), Eastern Cooperative Oncology Group (n = 397) trials, and in Beat AML (n = 333) and The Cancer Genome Atlas (n = 180) genomic characterization cohorts. We retrospectively analyzed patients in 4 age groups (age range, n): pediatric (0-17, 1744), adolescent/young adult (18-39, 444), intermediate-age (40-59, 640), older (≥60, 309). IDH mutations (IDHmut) were identified in 9.2% of the total cohort (n = 288; IDH1 [n = 123, 42.7%]; IDH2 [n = 165, 57.3%]) and were strongly correlated with increased age: 3.4% pediatric vs 21% older, P < .001. Outcomes were similar in IDHmut and IDH-wildtype (IDHWT) AML (event-free survival [EFS]: 35.6% vs 40.0%, P = .368; overall survival [OS]: 50.3% vs 55.4%, P = .196). IDH mutations frequently occurred with NPM1 (47.2%), DNMT3A (29.3%), and FLT3-internal tandem duplication (ITD) (22.4%) mutations. Patients with IDHmut AML with NPM1 mutation (IDHmut/NPM1mut) had significantly improved survival compared with the poor outcomes experienced by patients without (IDHmut/NPM1WT) (EFS: 55.1% vs 17.0%, P < .001; OS: 66.5% vs 35.2%, P < .001). DNTM3A or FLT3-ITD mutations in otherwise favorable IDHmut/NPM1mut AML led to inferior outcomes. Age group analysis demonstrated that IDH mutations did not abrogate the favorable prognostic impact of NPM1mut in patients aged <60 years; older patients had poor outcomes regardless of NPM1 status. These trials were registered at www.clinicaltrials.gov as #NCT00070174, #NCT00372593, #NCT01371981, #NCT00049517, and #NCT00085709.

Structure-Based Drug Design of Novel Triaminotriazine Derivatives as Orally Bioavailable IDH2R140Q Inhibitors with High Selectivity and Reduced hERG Inhibitory Activity for the Treatment of Acute Myeloid Leukemia

Neomorphic IDH2R140Q mutation is commonly found in acute myeloid leukemia (AML), and inhibiting its activity has been validated as an effective treatment for AML. Herein, we report a series of highly potent and selective IDH2R140Q inhibitors. Among them, compound 36 was identified as the most promising inhibitor, with an IC50 value of 29 nM and more than 490-fold selectivity over wild-type IDH2. The compound significantly suppressed D2HG production (IC50 = 10 nM) and induced differentiation in TF-1/IDH2R140Q cells. Furthermore, it showed reasonable pharmacokinetic properties with high bioavailability (F = 90.3%) and an appropriate half-life (T1/2 = 6.4 h). In vivo, oral administration of compound 36 at a dose of 25 mg/kg effectively reduced D2HG levels in the tumor of TF-1/IDH2R140Q xenograft mouse model. Besides, compound 36 displayed little effect on the hERG current. These results suggest that compound 36 has the potential to be an efficacious treatment for AML.

Ivosidenib in acute myeloid leukemia

INTRODUCTION

Traditional treatment strategies for acute myeloid leukemia (AML) have primarily relied on standard chemotherapy regimens for four decades. Indeed, the landscape of AML therapy has evolved substantially in recent years, mainly due to the introduction of hypomethylating agents and small molecules.Bcl2 inhibitor venetoclax, Fms-like tyrosine kinase 3 (FLT3) inhibitors such as midostaurin and gilteritinib, and isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) inhibitors ivosidenib and enasidenib, as well as hedgehog (HH) pathway inhibitor glasdegib represented a significant step forward in AML therapeutic armamentarium. Smoothened (SMO) inhibitor in combination with low-dose cytarabine marks a recent milestone.

AREAS COVERED

Ivosidenib, the first-in-class, selective, allosteric IDH1R132 inhibitor, showed the capability to induce in vitro differentiation of primary mIDH1 AML blasts. Clinical data highlighted its exceptional safety profile, as a standalone therapy and in combination strategy. Additionally, comprehensive studies consistently demonstrated its effectiveness, both in monotherapy and in association with chemotherapy.

EXPERT OPINION

The identified ivosidenib's strengths, including its remarkable safety record and ability to yield positive therapeutic outcomes, position it as an ideal partner for both classic chemotherapy and biological treatments, i.e. hypometilant agents and/or venetoclax. Further studies are warranted to explore strategies for overcoming the occurrence of ivosidenib resistance.

Isocitrate Dehydrogenase 1 Mutation and Ivosidenib in Patients With Acute Myeloid Leukemia: A Comprehensive Review

Acute myeloid leukemia (AML) arises from immature myeloid progenitors, resulting in a stem-cell-like proliferative state. This leads to excessive pools of immature cells that cannot function, which usually happens at the cost of the production of mature functional cells, leading to deleterious consequences. The management of AML has intensified as newer targeted therapies have come into existence owing to deeper genetic analysis of the disease and patients. Isocitrate dehydrogenase (IDH) is a cytosolic enzyme that is a part of the Krebs cycle and is extremely important in maintaining the homeostasis of the cell. It is produced by two different genes: IDH1 and IDH2. Ivosidenib has been associated with IDH1 inhibition and has been studied in numerous cancers. This review highlights the studies that have dealt with ivosidenib, an IDH1 inhibitor, in AML, the side effect profile, and the possible future course of the drug. After a scoping review of the available literature, we have identified that studies have consistently shown positive outcomes and that ivosidenib is a promising avenue for the management of AML. But it also has to be kept in mind that resistance to IDH inhibitors is on the rise, and the need to identify ways to circumvent this is to be addressed.

Maintenance therapy in acute myeloid leukemia: advances and controversies

The last decade has seen steadfast progress in drug development in acute myeloid leukemia (AML) which has moved progressively towards genomic-based therapy. With these advances, outcomes in AML have improved but remains far from satisfactory. One approach towards preventing relapse in AML is to use maintenance therapy in patients, after attaining remission. Allogeneic hematopoietic stem cell transplantation (HSCT) is an effective post-remission therapy that has been proven to reduce the risk of relapse. However, in patients who are ineligible for HSCT or have a high risk of relapse, other effective measures to prevent relapse are needed. There is also a need for post-HSCT maintenance to reduce relapse in high-risk subsets. Over the last 3 decades maintenance therapy in AML has evolved from the use of chemotherapeutic agents to more targeted therapies and better modulation of the immune system. Unfortunately, improvements in survival outcomes as a result of using these agents have not been consistently demonstrated in clinical trials. To derive the optimum benefit from maintenance therapy the time points of therapy initiation need to be defined and therapy must be selected precisely with respect to the AML genetics and risk stratification, prior treatment exposure, transplant eligibility, expected toxicity and the patient's clinical profile and desires. The far-reaching goal is to facilitate patients with AML in remission to achieve a normal quality of life while improving remission duration and overall survival. The QUAZAR trial was a welcome step towards a safe maintenance drug that is easy to administer and showed survival benefit but leaves many open issues for discussion. In this review we will discuss these issues, highlighting the development of AML maintenance therapies over the last 3 decades.

Vorasidenib in IDH1- or IDH2-Mutant Low-Grade Glioma

BACKGROUND

Isocitrate dehydrogenase (IDH)-mutant grade 2 gliomas are malignant brain tumors that cause considerable disability and premature death. Vorasidenib, an oral brain-penetrant inhibitor of mutant IDH1 and IDH2 enzymes, showed preliminary activity in IDH-mutant gliomas.

METHODS

In a double-blind, phase 3 trial, we randomly assigned patients with residual or recurrent grade 2 IDH-mutant glioma who had undergone no previous treatment other than surgery to receive either oral vorasidenib (40 mg once daily) or matched placebo in 28-day cycles. The primary end point was imaging-based progression-free survival according to blinded assessment by an independent review committee. The key secondary end point was the time to the next anticancer intervention. Crossover to vorasidenib from placebo was permitted on confirmation of imaging-based disease progression. Safety was also assessed.

RESULTS

A total of 331 patients were assigned to receive vorasidenib (168 patients) or placebo (163 patients). At a median follow-up of 14.2 months, 226 patients (68.3%) were continuing to receive vorasidenib or placebo. Progression-free survival was significantly improved in the vorasidenib group as compared with the placebo group (median progression-free survival, 27.7 months vs. 11.1 months; hazard ratio for disease progression or death, 0.39; 95% confidence interval [CI], 0.27 to 0.56; P<0.001). The time to the next intervention was significantly improved in the vorasidenib group as compared with the placebo group (hazard ratio, 0.26; 95% CI, 0.15 to 0.43; P<0.001). Adverse events of grade 3 or higher occurred in 22.8% of the patients who received vorasidenib and in 13.5% of those who received placebo. An increased alanine aminotransferase level of grade 3 or higher occurred in 9.6% of the patients who received vorasidenib and in no patients who received placebo.

CONCLUSIONS

In patients with grade 2 IDH-mutant glioma, vorasidenib significantly improved progression-free survival and delayed the time to the next intervention. (Funded by Servier; INDIGO ClinicalTrials.gov number, NCT04164901.).

Epigenetic inhibitors for cancer treatment

Epigenetics is a heritable and reversible modification that occurs independent of the alteration of primary DNA sequence but remarkably affects genetic expression. Aberrant epigenetic regulators are frequently observed in cancer progression not only influencing the behavior of tumor cells but also the tumor-associated microenvironment (TME). Increasing evidence has shown their great potential as biomarkers to predict clinical outcomes and chemoresistance. Hence, targeting the deregulated epigenetic regulators would be a compelling strategy for cancer treatment. So far, current epigenetic drugs have shown promising efficacy in both preclinical trials and clinical treatment of cancer, which encourages research discoveries on the development of novel epigenetic inhibitors either from natural compounds or artificial synthesis. However, only a few have been approved by the FDA, and more effort needs to be put into the related research. This chapter will update the applications and latest progress of epigenetic inhibitors in cancer treatment and provide prospects for the future development of epigenetic drugs.

Efficacy and safety of FDA-approved IDH inhibitors in the treatment of IDH mutated acute myeloid leukemia: a systematic review and meta-analysis

OBJECTIVE

To systematically evaluate the efficacy and safety of FDA-approved isocitrate dehydrogenase (IDH) inhibitors in the treatment of IDH-mutated acute myeloid leukemia (AML).

METHODS

We used R software to conduct a meta-analysis of prospective clinical trials of IDH inhibitors in the treatment of IDH-mutated AML published in PubMed, Embase, Clinical Trials, Cochrane Library and Web of Science from inception to November 15th, 2022.

RESULTS

A total of 1109 IDH-mutated AML patients from 10 articles (11 cohorts) were included in our meta-analysis. The CR rate, ORR rate, 2-year survival (OS) rate and 2-year event-free survival (EFS) rate of newly diagnosed IDH-mutated AML (715 patients) were 47%, 65%, 45% and 29%, respectively. The CR rate, ORR rate, 2-year OS rate, median OS and median EFS of relapsed or refractory (R/R) IDH-mutated AML (394 patients) were 21%, 40%, 15%, 8.21 months and 4.73 months, respectively. Gastrointestinal adverse events were the most frequently occurring all-grade adverse events and hematologic adverse events were the most frequently occurring ≥ grade 3 adverse events.

CONCLUSION

IDH inhibitor is a promising treatment for R/R AML patients with IDH mutations. For patients with newly diagnosed IDH-mutated AML, IDH inhibitors may not be optimal therapeutic agents due to low CR rates. The safety of IDH inhibitors is controllable, but physicians should always pay attention to and manage the differentiation syndrome adverse events caused by IDH inhibitors. The above conclusions need more large samples and high-quality RCTs in the future to verify.

Update on Small Molecule Targeted Therapies for Acute Myeloid Leukemia

OPINION STATEMENT

The search for effective therapies for the highly heterogenous disease acute myeloid leukemia (AML) has remained elusive. While cytotoxic therapies can induce complete remission and even, at times, long-term survival, this approach is associated with significant toxic effects to visceral organs and worsening of immune dysfunction and marrow suppression leading to death. Sophisticated molecular studies have revealed defects within the AML cell that can be exploited by utilizing small molecule agents to target these defects, often dubbed "target therapy." Several medications have already established new standards of care for many patients with AML, including FDA-approved agents that inhibitor IDH1, IDH2, FLT3, and BCL-2. Emerging small molecules hold additional to add to the armamentarium of AML treatment options including MCL-1 inhibitors, TP53 inhibitors, menin inhibitors, and E-selectin antagonists. Moreover, the increasing options also mean that future combinations of these agents need to be explored, including with cytotoxic drugs and other newer emerging strategies such as immunotherapies for AML. Recent investigations continue to show that overcoming many of the challenges of treating AML finally is on the horizon.

An Overview of Targeted Therapies in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most aggressive adult leukemia, characterized by clonal differentiation arrest of progenitor or precursor hematopoietic cells. Intense preclinical and clinical research has led to regulatory approval of several targeted therapeutics, administered either as single agents or as combination therapies. However, the majority of patients still face a poor prognosis and disease relapse frequently occurs due to selection of therapy-resistant clones. Hence, more effective novel therapies, most likely as innovative, rational combination therapies, are urgently needed. Chromosomal aberrations, gene mutations, and epigenetic alterations drive AML pathogenesis but concurrently provide vulnerabilities to specifically target leukemic cells. Other molecules, either aberrantly active and/or overexpressed in leukemic stem cells, may also be leveraged for therapeutic benefit. This concise review of targeted therapies for AML treatment, which are either approved or are being actively investigated in clinical trials or recent preclinical studies, provides a flavor of the direction of travel, but also highlights the current challenges in AML treatment.

Venetoclax combined with daunorubicin and cytarabine (2 + 6) as induction treatment in adults with newly diagnosed acute myeloid leukemia: a phase 2, multicenter, single-arm trial

BACKGROUND

Venetoclax (Ven) combined with intensive chemotherapy was proven effective in the management of acute myeloid leukemia (AML). However, the severe and prolonged myelosuppression remains a concern to worry about. To explore more appropriate combination regimens, we designed Ven combining daunorubicin and cytarabine (DA 2 + 6) regimen as induction therapy, aimed to evaluate the effectiveness and safety in adults de novo AML.

METHODS

A phase 2 clinical trial was performed in 10 Chinese hospitals to investigate Ven combined with daunorubicin and cytarabine (DA 2 + 6) in patients with AML. The primary endpoints were overall response rate (ORR), comprising of complete remission (CR), complete remission with incomplete blood cell count recovery (CRi), and partial response (PR). Secondary endpoints included measurable residual disease (MRD) of bone marrow assessed by flow cytometry, overall survival (OS), event-free survival (EFS), disease-free survival (DFS), and the safety of regimens. This study is a currently ongoing trial listed on the Chinese Clinical Trial Registry as ChiCTR2200061524.

RESULTS

Overall, 42 patients were enrolled from January 2022 to November 2022; 54.8% (23/42) were male, and the median age was 40 (range, 16-60) years. The ORR after one cycle of induction was 92.9% (95% confidence interval [CI], 91.6-94.1; 39/42) with a composite complete response rate (CR + CRi) 90.5% (95% CI, 89.3-91.6, CR 37/42, CRi 1/42). Moreover, 87.9% (29/33) of the CR patients with undetectable MRD (95% CI, 84.9-90.8). Grade 3 or worse adverse effects included neutropenia (100%), thrombocytopenia (100%), febrile neutropenia (90.5%), and one mortality. The median neutrophil and platelet recovery times were 13 (5-26) and 12 (8-26) days, respectively. Until Jan 30, 2023, the estimated 12-month OS, EFS, and DFS rates were 83.1% (95% CI, 78.8-87.4), 82.7% (95% CI, 79.4-86.1), and 92.0% (95% CI, 89.8-94.3), respectively.

CONCLUSION

Ven with DA (2 + 6) is a highly effective and safe induction therapy for adults with newly diagnosed AML. To the best of our knowledge, this induction therapy has the shortest myelosuppressive period but has similar efficacy to previous studies.

Older Adults With Newly Diagnosed AML: Hot Topics for the Practicing Clinician

Over the past decade, our understanding of AML pathogenesis and pathophysiology has improved significantly with mutational profiling. This has led to translational advances in therapeutic options, as there have been 10 new US Food and Drug Administration (FDA) approvals for AML therapies since 2017, half of which target specific driver mutations in FLT3, IDH1, or IDH2. These new agents have expanded the therapeutic armamentarium for AML, particularly for patients who are considered ineligible for intensive chemotherapy with anthracycline- and cytarabine-containing regimens. These new treatment options are relevant because the median age at diagnosis is 68 years, and outcomes for patients older than 60 years have historically been dismal. However, the optimal approach to incorporating novel agents into frontline regimens remains a clinical challenge, particularly with regard to sequencing of therapies, considering the role of allogeneic hematopoietic stem cell transplantation and managing toxicities.

Efficacy and tolerability of isocitrate dehydrogenase inhibitors in patients with acute myeloid leukemia: A systematic review of clinical trials

BACKGROUND

Acute myeloid leukemia (AML) is a hematological malignancy due to anomalous differentiation and proliferation of hematopoietic stem cells with myeloid blast buildup. Induction chemotherapy is considered the first line of treatment in most patients with AML. However, targeted therapy in the form of FLT-3, IDH, BCL-2, and immune checkpoint inhibitors, can be considered as the first line depending on their molecular profile, resistance to chemotherapy, comorbidities, etc. This review aims to assess the tolerability and efficacy of isocitrate dehydrogenase (IDH) inhibitors in AML.

METHODS

We searched Medline, WOS, Embase, and clinicaltrials.gov. PRISMA guidelines were followed in this systematic review. 3327 articles were screened, and 9 clinical trials (N = 1119) were included.

RESULTS

In randomized clinical trials (RCTs), objective response (OR) was reported in 63-74% of the patients with IDH inhibitors + azacitidine as compared to 19-36 % of the patients with azacitidine monotherapy in newly diagnosed (ND) medically unfit patients. Survival rates were significantly improved with the use of ivosidenib. OR was reported in 39.1-46 % of the patients who relapsed/refractory to chemotherapy. ≥Grade 3 IDH differentiation syndrome and QT prolongation were reported in 3.9-10 % and 2-10 % of the patients, respectively.

CONCLUSION

IDH inhibitors (ivosidenib for IDH-1 and enasidenib for IDH-2) are safe and effective in treating ND medically unfit or relapsed refractory patients with IDH mutation. However, no survival benefit was reported with enasidenib. More randomized multicenter double-blinded clinical studies are needed to confirm these results and compare them with other targeting agents.

Prediction of survival with lower intensity therapy among older patients with acute myeloid leukemia

BACKGROUND

The aim of this study was to develop a prognostic model for survival in older/unfit patients with newly diagnosed acute myeloid leukemia (AML) who were treated with lower-intensity chemotherapy regimens.

METHODS

The authors reviewed all older/unfit patients with newly diagnosed AML who received lower-intensity chemotherapy from 2000 until 2020 at their institution. A total of 1462 patients were included. They were divided (3:1 basis) into a training (n = 1088) and a validation group (n = 374).

RESULTS

In the training cohort of 1088 patients (median age, 72 years), the multivariate analysis identified 11 consistent independent adverse factors associated with survival: older age, therapy-related myeloid neoplasm, existence of previous myelodysplastic syndrome or myeloproliferative neoplasms, poor performance status, pulmonary comorbidity, anemia, thrombocytopenia, elevated lactate dehydrogenase, cytogenetic abnormalities, and the presence of infection at diagnosis, and therapy not containing venetoclax. The 3-year survival rates were 52%, 24%, 10%, and 1% in favorable, intermediate, poor, and very poor risk, respectively. This survival model was validated in an independent cohort. In a subset of patients in whom molecular mutation profiles were performed in more recent times, adding the mutation profiles after accounting for the effects of previous factors identified IDH2 (favorable), NPM1 (favorable), and TP53 (unfavorable) mutations as molecular prognostic factors.

CONCLUSION

The proposed survival model with lower-intensity chemotherapy in older/unfit patients with newly diagnosed AML may help to advise patients on their expected outcome, to propose different strategies in first complete remission, and to compare the results of different existing or future investigational therapies.

PLAIN LANGUAGE SUMMARY

Lower intensity therapy can be considered for older patients to avoid severe toxicities and adverse events. However, survival prediction in AML was commonly developed in patients who received intensive chemotherapy. In this study, we have proposed a survival model to guide therapeutic approach in older patients who received lower-intensity therapy.

Amsacrine-based induction therapy in AML patients with cardiac comorbidities: a retrospective single-center analysis

Intensive chemotherapy is the backbone of induction treatment in patients with acute myeloid leukemia (AML). However, AML patients with concomitant cardiac disease may not be eligible for anthracycline-based therapies. In a small cohort of patients, we have previously shown that anthracycline-free, amsacrine-based chemotherapy TAA (thioguanine, cytarabine, amsacrine) may be as effective as cytarabine/daunorubicin for induction therapy in these patients. In this systematic retrospective single-center analysis, we documented the outcome of 31 patients with significant cardiac comorbidities including coronary heart disease or cardiomyopathy receiving TAA as induction chemotherapy. Median (range) ejection fraction (EF) was 48% (30-67%) in this cohort. Patients with EF below 30% were considered unfit for intensive induction therapy. Event-free survival (EFS), overall survival (OS), and relapse-free survival (RFS) were 1.61, 5.46, and 13.6 months respectively. Poor outcome was primarily related to a high early mortality rate within the first 30 days of therapy, mainly caused by infectious complications. TAA cannot be recommended as a substitute of standard induction for AML patients with significant concomitant cardiac disease. In the era of novel agents, alternative strategies (e.g., hypomethylating agents plus venetoclax) should be considered when anthracycline-based regimens are not suitable.

Recent advances in targeted therapies in acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. While survival for younger patients over the last several decades has improved nearly sixfold with the optimization of intensive induction chemotherapy and allogeneic stem cell transplantation (alloHSCT), this effect has been largely mitigated in older and less fit patients as well as those with adverse-risk disease characteristics. However, the last 10 years has been marked by major advances in the molecular profiling of AML characterized by a deeper understanding of disease pathobiology and therapeutic vulnerabilities. In this regard, the classification of AML subtypes has recently evolved from a morphologic to a molecular and genetic basis, reflected by recent updates from the World Health Organization and the new International Consensus Classification system. After years of stagnation in new drug approvals for AML, there has been a rapid expansion of the armamentarium against this disease since 2017. Low-intensity induction therapy with hypomethylating agents and venetoclax has substantially improved outcomes, including in those previously considered to have a poor prognosis. Furthermore, targeted oral therapies against driver mutations in AML have been added to the repertoire. But with an accelerated increase in treatment options, several questions arise such as how to best sequence therapy, how to combine therapies, and if there is a role for maintenance therapy in those who achieve remission and cannot undergo alloHSCT. Moreover, certain subtypes of AML, such as those with TP53 mutations, still have dismal outcomes despite these recent advances, underscoring an ongoing unmet need and opportunity for translational advances. In this review, we will discuss recent updates in the classification and risk stratification of AML, explore the literature regarding low-intensity and novel oral combination therapies, and briefly highlight investigative agents currently in early clinical development for high-risk disease subtypes.

The occurrence of thrombosis during intensive chemotherapy treatment for acute myeloid leukemia patients does not impact on long-term survival

Venous thromboembolism (VTE) is frequently seen in acute myeloid leukemia (AML) patients and presents a significant clinical challenge. The association of VTE during intensive chemotherapy with risk models such as the Medical Research Council (MRC) cytogenetic-based assessment and the European LeukemiaNet (ELN) 2017 molecular risk model have not been rigorously evaluated. Additionally, there is a paucity of data pertaining to the long-term prognostic impact of VTE in AML patients. We performed an analysis of baseline parameters of AML patients diagnosed with VTE during intensive chemotherapy and compared them with patients without VTE. The analyzed cohort consisted of 335 newly diagnosed AML patients with a median age of 55 years. Thirty-five patients (11%) were classified as MRC favorable risk, 219 (66%) patients as intermediate risk, 58 patients (17%) as adverse risk. Per ELN 2017, 132 patients (40%) had favorable risk disease, 122 patients (36%) intermediate risk, and 80 patients (24%) had adverse risk. VTE was seen in 33 patients (9.9%), occurring mostly during induction (70%), and required catheter removal in 9 patients (28%). Baseline clinical, laboratory, molecular, and ELN 2017 parameters were not significantly different groups. However, MRC intermediate-risk group patients were significantly more likely to experience thrombosis compared to favorable risk and adverse risk patients (12.8% versus 5.7% and 1.7%, respectively; p = 0.049). Median overall survival was not significantly impacted by the diagnosis of thrombosis (3.7 years versus 2.2 years; p = 0.47). VTE is tightly associated with temporal and cytogenetic parameters in AML but does not significantly impact on long-term outcomes.

Molecularly Targeted Therapy in Acute Myeloid Leukemia: Current Treatment Landscape and Mechanisms of Response and Resistance

Treatment for acute myeloid leukemia (AML) has evolved rapidly over the last decade as improved understanding of cytogenetic and molecular drivers of leukemogenesis refined survival prognostication and enabled development of targeted therapeutics. Molecularly targeted therapies are now approved for the treatment of FLT3 and IDH1/2-mutated AML and additional molecularly and cellularly targeted therapeutics are in development for defined patient subgroups. Alongside these welcome therapeutic advancements, increased understanding of leukemic biology and treatment resistance has resulted in clinical trials investigating combinations of cytotoxic, cellular, and molecularly targeted therapeutics resulting in improved response and survival outcomes in patients with AML. Herein, we comprehensively review the current landscape of IDH and FLT3 inhibitors in clinical practice for the treatment of AML, highlight known resistance mechanisms, and discuss new cellular or molecularly targeted therapies currently under investigation in ongoing early phase clinical trials.

Targeting Measurable Residual Disease (MRD) in Acute Myeloid Leukemia (AML): Moving beyond Prognostication

Measurable residual disease (MRD) assessment in acute myeloid leukemia (AML) has an established role in disease prognostication, particularly in guiding decisions for hematopoietic cell transplantation in first remission. Serial MRD assessment is now routinely recommended in the evaluation of treatment response and monitoring in AML by the European LeukemiaNet. The key question remains, however, if MRD in AML is clinically actionable or "does MRD merely portend fate"? With a series of new drug approvals since 2017, we now have more targeted and less toxic therapeutic options for the potential application of MRD-directed therapy. Recent approval of NPM1 MRD as a regulatory endpoint is also foreseen to drastically transform the clinical trial landscape such as biomarker-driven adaptive design. In this article, we will review (1) the emerging molecular MRD markers (such as non-DTA mutations, IDH1/2, and FLT3-ITD); (2) the impact of novel therapeutics on MRD endpoints; and (3) how MRD might be used as a predictive biomarker to guide therapy in AML beyond its prognostic role, which is the focus of two large collaborative trials: AMLM26 INTERCEPT (ACTRN12621000439842) and MyeloMATCH (NCT05564390).

Acute myeloid leukemia: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Acute myeloid leukemia (AML) is a frequently fatal bone marrow stem cell cancer characterized by unbridled proliferation of malignant marrow stem cells with associated infection, anemia, and bleeding. An improved understanding of pathophysiology, improvements in measurement technology and at least 10 recently approved therapies have led to revamping the diagnostic, prognostic, and therapeutic landscape of AML.

DIAGNOSIS

One updated and one new classification system were published in 2022, both emphasizing the integration of molecular analysis into daily practice. Differences between the International Consensus Classification and major revisions from the previous 2016 WHO system provide both challenges and opportunities for care and clinical research.

RISK ASSESSMENT AND MONITORING

The European Leukemia Net 2022 risk classification integrates knowledge from novel molecular findings and recent trial results, as well as emphasizing dynamic risk based on serial measurable residual disease assessment. However, how to leverage our burgeoning ability to measure a small number of potentially malignant myeloid cells into therapeutic decision making is controversial.

RISK ADAPTED THERAPY

The diagnostic and therapeutic complexity plus the availability of newly approved agents requires a nuanced therapeutic algorithm which should integrate patient goals of care, comorbidities, and disease characteristics including the specific mutational profile of the patient's AML. The framework we suggest only represents the beginning of the discussion.

An overview of novel therapies in advanced clinical testing for acute myeloid leukemia

INTRODUCTION

The past decade has seen a sea change in the AML landscape with vastly improved cognizance of molecular pathogenesis, clonal evolution, and importance of measurable residual disease. Since 2017, the therapeutic armamentarium of AML has considerably expanded with the approval of midostaurin, enasidenib, ivosidenib, gilteritinib, and venetoclax in combination with hypomethylating agents and others. Nevertheless, relapse and treatment refractoriness remain the insurmountable challenges in AML therapy. This has galvanized the leukemic research community leading to the discovery and development of agents that specifically target gene mutations, molecularly agnostic therapies that exploit immune environment, apoptotic pathways, leukemic cell surface antigens and so forth.

AREAS COVERED

This article provides an overview of the pathophysiology of AML in the context of non-cellular immune and molecularly targeted and agnostic therapies that are in clinical trial development in AML.

EXPERT OPINION

Ever growing understanding of the molecular pathogenesis and metabolomics in AML has allowed the researchers to identify targets directed at specific genes and metabolic pathways. As a result, AML therapy is constantly evolving and so are the escape mechanisms leading to disease relapse. Therefore, it is of paramount importance to sequentially evaluate the patient during AML treatment and intervene at the right time.

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.

Update on current treatments for adult acute myeloid leukemia: to treat acute myeloid leukemia intensively or non-intensively? That is the question

For several decades, the treatment for acute myeloid leukemia (AML) has been a dichotomous choice between intensive chemotherapy strategies with curative intent and non-intensive options including supportive care. Patients' age and fitness, as well as comorbidities, primarily influenced this choice. However, the therapeutic armamentarium is evolving, so that there are highly effective and increasingly specific drugs, fitting the mutational profile of a patient's leukemia. There is now a spectrum of treatment options that are less intense and can be administered in an outpatient setting and to a substantial extent are equally or even more effective than standard intensive therapy. We are, therefore, witnessing a radical change in the treatment landscape of AML. In this review, we examine the current treatment options for patients with AML, considering the molecular spectrum of the disease on the background of patient-related factors.

The Cup Runneth Over: Treatment Strategies for Newly Diagnosed Acute Myeloid Leukemia

Since 2017, the number of agents for acute myeloid leukemia (AML) has rapidly expanded. Given the increased therapeutic options, better identification of high-risk subsets of AML and more refined approaches to patient fitness assessment, the decisions surrounding selection of intensive chemotherapy versus lower-intensity treatment have grown increasingly more nuanced. In this review, we present available data for both standard and investigational approaches in the initial treatment of AML using an intensive chemotherapy backbone or a lower-intensity approach. We summarize management strategies in newly diagnosed secondary AML, considerations around allogeneic stem-cell transplantation, and the role of maintenance therapy. Finally, we highlight important areas of future investigation and novel agents that may hold promise in combination with standard therapies.

New drugs before, during, and after hematopoietic stem cell transplantation for patients with acute myeloid leukemia

The treatment of acute myeloid leukemia (AML) has evolved over the past few years with the advent of next-generation sequencing. Targeted therapies alone or in combination with low-dose or high-intensity chemotherapy have improved the outcome of patients with AML treated in the frontline and relapsed/refractory settings. Despite these advances, allogeneic stem cell transplantation (allo-HCT) remains essential as consolidation therapy following frontline treatment in intermediate-and adverse-risk and relapsed/refractory disease. However, many patients relapse, with limited treatment options, hence the need for post-transplant strategies to mitigate relapse risk. Maintenance therapy following allo-HCT was developed for this specific purpose and can exploit either a direct anti-leukemia effect and/or enhance the bona fide graft-versus-leukemia effect without increasing the risk of graft-versus-host disease. In this paper, we summarize novel therapies for AML before, during, and after allo-HCT and review ongoing studies.

Distinct and opposite effects of leukemogenic Idh and Tet2 mutations in hematopoietic stem and progenitor cells

Mutations in IDH1, IDH2, and TET2 are recurrently observed in myeloid neoplasms. IDH1 and IDH2 encode isocitrate dehydrogenase isoforms, which normally catalyze the conversion of isocitrate to α-ketoglutarate (α-KG). Oncogenic IDH1/2 mutations confer neomorphic activity, leading to the production of D-2-hydroxyglutarate (D-2-HG), a potent inhibitor of α-KG-dependent enzymes which include the TET methylcytosine dioxygenases. Given their mutual exclusivity in myeloid neoplasms, IDH1, IDH2, and TET2 mutations may converge on a common oncogenic mechanism. Contrary to this expectation, we observed that they have distinct, and even opposite, effects on hematopoietic stem and progenitor cells in genetically engineered mice. Epigenetic and single-cell transcriptomic analyses revealed that Idh2^R172K and Tet2 loss-of-function have divergent consequences on the expression and activity of key hematopoietic and leukemogenic regulators. Notably, chromatin accessibility and transcriptional deregulation in Idh2^R172K cells were partially disconnected from DNA methylation alterations. These results highlight unanticipated divergent effects of IDH1/2 and TET2 mutations, providing support for the optimization of genotype-specific therapies.

Mechanisms of myeloid leukemogenesis: Current perspectives and therapeutic objectives

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic neoplasm which results in clonal proliferation of abnormally differentiated hematopoietic cells. In this review, mechanisms contributing to myeloid leukemogenesis are summarized, highlighting aberrations of epigenetics, transcription factors, signal transduction, cell cycling, and the bone marrow microenvironment. The mechanisms contributing to AML are detailed to spotlight recent findings that convey clinical impact. The applications of current and prospective therapeutic targets are accentuated in addition to reviews of treatment paradigms stratified for each characteristic molecular lesion - with a focus on exploring novel treatment approaches and combinations to improve outcomes in AML.