The 2010 and 2017 editions of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults are widely recognized among physicians and investigators. There have been major advances in our understanding of AML, including new knowledge about the molecular pathogenesis of AML, leading to an update of the disease classification, technological progress in genomic diagnostics and assessment of measurable residual disease, and the successful development of new therapeutic agents, such as FLT3, IDH1, IDH2, and BCL2 inhibitors. These advances have prompted this update that includes a revised ELN genetic risk classification, revised response criteria, and treatment recommendations.

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

Progress in the understanding of the biology and therapy of acute myeloid leukemia (AML) is occurring rapidly. Since 2017, nine agents have been approved for various indications in AML. These included several targeted therapies like venetoclax, FLT3 inhibitors, IDH inhibitors, and others. The management of AML is complicated, highlighting the need for expertise in order to deliver optimal therapy and achieve optimal outcomes. The multiple subentities in AML require very different therapies. In this review, we summarize the important pathophysiologies driving AML, review current therapies in standard practice, and address present and future research directions.

Effective treatment options are limited for patients with acute myeloid leukemia (AML) who cannot tolerate intensive chemotherapy. Adults age ≥18 years with newly diagnosed AML ineligible for intensive chemotherapy were enrolled in this international phase 3 randomized double-blind placebo-controlled trial. Patients (N = 211) were randomized 2:1 to venetoclax (n = 143) or placebo (n = 68) in 28-day cycles, plus low-dose cytarabine (LDAC) on days 1 to 10. Primary end point was overall survival (OS); secondary end points included response rate, transfusion independence, and event-free survival. Median age was 76 years (range, 36-93 years), 38% had secondary AML, and 20% had received prior hypomethylating agent treatment. Planned primary analysis showed a 25% reduction in risk of death with venetoclax plus LDAC vs LDAC alone (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.52-1.07; P = .11), although not statistically significant; median OS was 7.2 vs 4.1 months, respectively. Unplanned analysis with additional 6-month follow-up demonstrated median OS of 8.4 months for the venetoclax arm (HR, 0.70; 95% CI, 0.50-0.98; P = .04). Complete remission (CR) plus CR with incomplete blood count recovery rates were 48% and 13% for venetoclax plus LDAC and LDAC alone, respectively. Key grade ≥3 adverse events (venetoclax vs LDAC alone) were febrile neutropenia (32% vs 29%), neutropenia (47% vs 16%), and thrombocytopenia (45% vs 37%). Venetoclax plus LDAC demonstrates clinically meaningful improvement in remission rate and OS vs LDAC alone, with a manageable safety profile. Results confirm venetoclax plus LDAC as an important frontline treatment for AML patients unfit for intensive chemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT03069352.

The BCL-2 inhibitor venetoclax combined with hypomethylating agents or low-dose cytarabine represents an important new therapy for older or unfit patients with acute myeloid leukemia (AML). We analyzed 81 patients receiving these venetoclax-based combinations to identify molecular correlates of durable remission, response followed by relapse (adaptive resistance), or refractory disease (primary resistance). High response rates and durable remissions were typically associated with NPM1 or IDH2 mutations, with prolonged molecular remissions prevalent for NPM1 mutations. Primary and adaptive resistance to venetoclax-based combinations was most commonly characterized by acquisition or enrichment of clones activating signaling pathways such as FLT3 or RAS or biallelically perturbing TP53. Single-cell studies highlighted the polyclonal nature of intratumoral resistance mechanisms in some cases. Among cases that were primary refractory, we identified heterogeneous and sometimes divergent interval changes in leukemic clones within a single cycle of therapy, highlighting the dynamic and rapid occurrence of therapeutic selection in AML. In functional studies, FLT3 internal tandem duplication gain or TP53 loss conferred cross-resistance to both venetoclax and cytotoxic-based therapies. Collectively, we highlight molecular determinants of outcome with clinical relevance to patients with AML receiving venetoclax-based combination therapies.

Patients with CML treated with TKI can have a life expectancy comparable to that of the general population. Due to the extended duration of TKI administration, treatment discontinuation has been increasingly sought. Medical records of 100 patients with CML who were in MR4.5 and discontinued their TKI outside clinical trials were reviewed. After a median follow-up of 30 months (range, 5–112 months) after discontinuation, 35% and 17% lost MR4.5 and major molecular response (MMR), respectively. Only six patients lost MMR 12 months or more after discontinuation. Loss of MR4.5 was observed in 29% and 7% of patients with sustained MR4.5 duration of more than 2 and 6 years before discontinuation, respectively. By univariate analysis, there was a higher risk of loss of MR4.5 for patients who were treated for less than 87 months, received second or subsequent line TKI, never received interferon, or those with sustained MR4.5 for less than 6 years. By multivariate analysis, sustained MR4.5 for 6 years or more was the only significant predictor for durable response. Overall, 30% of patients who discontinued while in MR4.5 were retreated with 93% regaining MR4.5 at a median of 5 months. These results demonstrate that under proper conditions, treatment discontinuation is feasible outside of clinical trial setting. MR4.5 duration of 6 years or more before discontinuation is associated with very low risk of loss of MR4.5.