Low-dose interleukin-2 immunotherapy does not improve outcome of patients age 60 years and older with acute myeloid leukemia in first complete remission: Cancer and Leukemia Group B Study 9720

Novel insights into immune cells modulation of tumor resistance

Tumor resistance poses a significant challenge to effective cancer treatment, making it imperative to explore new therapeutic strategies. Recent studies have highlighted the profound involvement of immune cells in the development of tumor resistance. Within the tumor microenvironment, macrophages undergo polarization into the M2 phenotype, thus promoting the emergence of drug-resistant tumors. Neutrophils contribute to tumor resistance by forming extracellular traps. While T cells and natural killer (NK) cells exert their impact through direct cytotoxicity against tumor cells. Additionally, dendritic cells (DCs) have been implicated in preventing tumor drug resistance by stimulating T cell activation. In this review, we provide a comprehensive summary of the current knowledge regarding immune cell-mediated modulation of tumor resistance at the molecular level, with a particular focus on macrophages, neutrophils, DCs, T cells, and NK cells. The targeting of immune cell modulation exhibits considerable potential for addressing drug resistance, and an in-depth understanding of the molecular interactions between immune cells and tumor cells holds promise for the development of innovative therapies. Furthermore, we explore the clinical implications of these immune cells in the treatment of drug-resistant tumors. This review emphasizes the exploration of novel approaches that harness the functional capabilities of immune cells to effectively overcome drug-resistant tumors.

Maintenance Therapy in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) poses significant challenges due to its high relapse rates despite initial successful induction chemotherapy. Maintenance therapy aims to prevent disease recurrence, particularly in high-risk patients. This review explores current maintenance treatments, their impacts on patient outcomes, and ongoing studies shaping the treatment landscape for AML. Hypomethylating agents like azacitidine and decitabine have shown promise in improving relapse-free and overall survival, particularly in older patients with AML ineligible for transplantation. Combination regimens involving azacitidine and venetoclax have demonstrated encouraging outcomes post-hematopoietic stem cell transplantation. Targeted therapies, particularly FLT3 inhibitors like midostaurin and quizartinib, have shown significant benefits in improving survival outcomes, especially in FLT3-mutated AML cases. Gilteritinib and sorafenib also exhibit the potential to reduce relapse rates post-transplant. Isocitrate dehydrogenase inhibitors, including ivosidenib and enasidenib, present novel options for postchemotherapy and posttransplantation maintenance. Immunotherapies, such as Wilms tumor 1 peptide-based vaccines and checkpoint inhibitors, are being explored, although results vary. Despite ongoing research, the role of maintenance chemotherapy remains uncertain, with inconsistent outcomes across trials. The approval of oral azacitidine represents a significant advancement, emphasizing the need for further investigation into personalized maintenance approaches. In conclusion, the evolving landscape of maintenance therapy and integrating targeted therapies in AML offers promising avenues for improving patient outcomes.

Optimal Post-Remission Consolidation Therapy in Patients with AML

BACKGROUND

Despite recent advances, 40-85% of patients with acute myeloid leukaemia (AML) achieve complete remission after intensive chemotherapy. However, without optimal treatment after remission, the risk of relapse remains high.

SUMMARY

A variable number of consolidation cycles consisting of intermediate doses of cytarabine are the most commonly used regimens in low-intermediate-risk AML, while patients at higher risk of relapse should consolidate response by proceeding to HSCT. Different post-consolidation (maintenance therapies) have demonstrated their benefit in prolonging relapse-free survival, and others are still under investigation. Careful consideration should be given to which patients benefit most from each of these interventions, considering that the risk of relapse is dynamic.

KEY MESSAGES

Patients consolidated with chemotherapy should receive either 2 courses of HDAC or no more than 3-4 cycles of IDAC with dose reduction in patients over 60 years. Patients with mutated FLT3 AML benefit from post-consolidation maintenance with FLT3 inhibitors, and selected patients not fit for adequate consolidation may benefit from CC-468 maintenance. Patients at higher risk of relapse should proceed to allogeneic SCT as soon as possible, opting for a more intensive conditioning in patients younger than 55 years. However, autologous HSCT may still have role in favourable-risk MRD-negative AML. Multiple treatment options targeting MRD are emerging, either as definitive treatment or as a bridge to allogeneic transplantation, and are likely to become increasingly relevant.

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.

Outcomes of Older Adults With AML Treated in Community Versus Academic Centers: An Analysis of Alliance Trials

PURPOSE

Clinical trials are important for managing older patients with AML. We investigated differences in outcomes of older patients with AML on the basis of whether patients participated in intensive chemotherapy trials at community versus academic cancer centers.

METHODS

We used data from the Alliance for Clinical Trials in Oncology phase III trials that enrolled patients age ≥ 60 years with newly diagnosed AML between 1998 and 2002 in the Cancer and Leukemia Group B (CALGB) 9720 trial and between 2004 and 2006 in the CALGB 10201 trial. Centers funded by the NCI Community Oncology Research Program were identified as community cancer centers; others were designated as academic cancer centers. Logistic regression models and Cox proportional hazards models were used to compare 1-month mortality and overall survival (OS) by center type.

RESULTS

Seventeen percent of the 1,170 patients were enrolled in clinical trials in community cancer centers. The study results demonstrated comparable rates of grade ≥3 adverse events (97% v 93%), 1-month mortality (19.1% v 16.1%), and OS (43.9% v 35.7% at 1 year) between community versus academic cancer centers, respectively. After adjusting for covariates, 1-month mortality (odds ratio, 1.40; 95% CI, 0.92 to 2.12; P = .11) and OS (hazard ratio, 1.04; 95% CI, 0.88 to 1.22; P = .67) were not statistically different among patients treated in community versus academic cancer centers.

CONCLUSION

An older patient population, who have complex health care needs, can be successfully treated on intensive chemotherapy trials in select community cancer centers with outcomes comparable with that achieved at academic cancer centers.

SOHO State of the Art Updates and Next Questions |The Role of Maintenance Therapy in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive disease predominantly affecting the elderly population. Although, up to 65% of patients with AML achieve a complete remission with standard induction chemotherapy, the majority of patients will relapse and succumb to the disease. Although maintenance therapy is a component of standard management for various hematological malignancies, such as acute lymphoblastic leukemia (ALL), acute promyelocytic leukemia (APL) or multiple myeloma, past studies investigating the role of maintenance therapy in AML were unable to demonstrate an advantage in overall survival, and therefore, it has not been an established practice in the treatment of AML. For patients, who are not candidates for stem cell transplant, effective AML maintenance therapies are needed in order to reduce the risk of relapse. Over the past decades, many investigators have examined the role of various maintenance strategies in AML; with the intention to prolong remission and overall survival. This review will provide an overview of prior and ongoing approaches and strategies to maintenance therapy for AML.

Design of the VIALE-M phase III trial of venetoclax and oral azacitidine maintenance therapy in acute myeloid leukemia

Prevention of relapse is a major therapeutic challenge and an unmet need for patients with acute myeloid leukemia (AML). Venetoclax is a highly selective, potent, oral BCL-2 inhibitor that induces apoptosis in AML cells. When combined with azacitidine, it leads to prolonged overall survival and rapid, durable remissions in treatment-naive AML patients ineligible for intensive chemotherapy. VIALE-M is a randomized, double-blind, two-arm study to evaluate the safety and efficacy of venetoclax in combination with oral azacitidine (CC-486) as maintenance therapy in patients in complete remission with incomplete blood count recovery after intensive induction and consolidation therapies. The primary end point is relapse-free survival. Secondary outcomes include overall survival, minimal residual disease conversion and improvement in quality-of-life.

Trial registration number: NCT04102020 ( ClinicalTrials.gov )

Natural killer cells and acute myeloid leukemia: promises and challenges

Acute myeloid leukemia (AML) is considered as one of the most malignant conditions of the bone marrow. Over the past few decades, despite substantial progresses in the management of AML, relapse remission remains a major problem. Natural killer cells (NK cells) are known as a unique component of the innate immune system. Due to swift tumor detection, distinct cytotoxic action, and extensive immune interaction, NK cells have been used in various cancer settings for decades. It has been a growing knowledge of therapeutic magnitudes ranging from adoptive NK cell transfer to chimeric antigen receptor NK cells, aiming to achieve better therapeutic responses in patients with AML. In this article, the potentials of NK cells for treatment of AML are highlighted, and challenges for such therapeutic methods are discussed. In addition, the clinical application of NK cells, mainly in patients with AML, is pictured according to the existing evidence.

Autologous hematopoietic stem cell transplantation followed by interleukin-2 for adult acute myeloid leukemia patients with favorable or intermediate risk after complete remission

High-dose chemotherapy followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) is generally the optimal option for patients with acute myeloid leukemia (AML). However, for favorable- and intermediate-risk patients, the regimen remains less understood due to graft versus host disease (GVHD) and increased non-relapsed mortality (NRM) caused by allo-HSCT. Additionally, the benefit of maintenance therapy has not yet been conclusively proven. Here, we conducted a retrospective study on the long-term outcome of AML patients with favorable or intermediate risk who underwent autologous hematopoietic stem cell transplantation (auto-HSCT) followed by interleukin-2 (IL-2) subcutaneous injection as maintenance therapy. A total of 49 patients from 2007 to 2019 were included in our study. They all received a daunorubicin + cytarabine regimen as induction chemotherapy followed by four to six cycles of consolidation therapy with medium- or high-dose cytarabine. Once patients achieved complete remission (CR1), they started receiving auto-HSCT followed by IL-2 injections. The results showed that no patients stopped receiving IL-2 injections on account of adverse side effects, and the 5-year overall survival (OS) and leukemia-free survival (LFS) rates were 85.6 ± 5.0% and 78.5 ± 6.1%, respectively. The multivariate analysis also suggested that age, gender, initial white blood cell (WBC) count, AML subtype, cytogenetic risk, and conditioning regimen did not affect the prognosis. In conclusion, auto-HSCT followed by IL-2 injection is an effective treatment that can improve the prognosis of AML for patients with favorable or intermediate risk.

OUP accepted manuscript

As in younger patients, allogeneic stem cell transplantation (alloHSCT) offers the best chance for durable remission in older patients (≥60 years) with acute myeloid leukemia (AML). However, defining the best treatment strategy (and in particular, whether or not to proceed to alloHSCT) for elderly patients with AML remains a difficult decision for the hematologist, since potential toxicity of conditioning regimens, risks of graft-versus-host disease, impaired immune reconstitution and the need for prolonged immunosuppression may be of major concern in these vulnerable patients with complex needs. Hopefully, significant progress has been made over the past decade in alloHSCT for elderly patients and current evidence suggests that chronological age per se (between 60 and 75) is not a reliable predictor of outcome after alloHSCT. Here, we review the current state of alloHSCT in elderly patients with AML and also discuss the different approaches currently being investigated to improve both accessibility to as well as success of alloHSCT in these patients.

Tipifarnib as maintenance therapy did not improve disease-free survival in patients with acute myelogenous leukemia at high risk of relapse: Results of the phase III randomized E2902 trial

PURPOSE

Despite the achievement of complete remission with chemotherapy in patients with acute myeloid leukemia (AML), relapse is common and the majority of patients will die of their disease. Patients who achieve a remission after refractory or relapsed disease as well as elderly patients have a very high rate of relapse even if they achieve a complete remission. A phase 3 randomized ECOG-ACRIN-led intergroup study was conducted to determine whether post-remission therapy with the farnesyl transferase inhibitor, tipifarnib (R115777), improved the disease-free survival (DFS) of adult patients with AML in complete remission (CR), at high risk for relapse.

PATIENTS AND METHODS

Adult patients with AML in remission after salvage therapy and/or over age 60 in first remission were enrolled in this study. They were randomly assigned to treatment with tipifarnib or observation (control). The primary objective was to compare the disease-free survival (DFS) between the two arms based on intention to treat, which includes all randomized patients.

RESULTS

One hundred and forty-four patients were enrolled on the study. Median DFS was 8.9 vs 5.3 months, for tipifarnib vs observation (one-sided p = 0.026) and did not cross the pre-specified boundary to call the study positive. For the 134 eligible patients, median DFS was 10.8 vs 5.3 months for those randomized to tipifarnib vs observation (one-sided p = 0.008). Moreover in an ad hoc evaluation of all women (n = 71) median DFS was 12.1 vs 3.9 months for tipifarnib vs observation (one-sided p = 0.0004) while median OS was 26.5 vs 8.4 months respectively (one-sided p = 0.001).

CONCLUSION

This study was not able to demonstrate a benefit to tipifarnib as maintenance therapy in patients with AML in remission. While subsets of patients may indeed benefit, additional studies would be needed to elucidate that benefit which is unlikely given that other seemingly better options have since become available.

Efficacy and safety of Wilms' tumor 1 helper peptide OCV-501 in elderly patients with acute myeloid leukemia: a multicenter, randomized, double-blind, placebo-controlled phase 2 trial

PURPOSE

Complete remission (CR) of acute myeloid leukemia (AML) in elderly patients has a short duration, and there is no suitable post-remission therapy. We explored the role of the Wilms' tumor 1 helper peptide OCV-501 to prevent recurrence after remission.

METHODS

This placebo-controlled phase 2 study was designed to evaluate accurately the efficacy and immunogenicity of OCV-501 in elderly AML patients. Elderly AML patients who achieved first CR were randomly allocated to receive either OCV-501 (N = 69) or placebo (N = 65) once a week for eight weeks and then every two weeks until week 104. The primary endpoint was disease-free survival (DFS).

RESULTS

Nineteen (27.5%) patients in the OCV-501 group and 23 (35.4%) patients in the placebo group completed the study without relapse. The median DFS in the OCV-501 and placebo groups was 12.1 and 8.4 months, respectively (p = 0.7671, hazard ratio [95% confidence interval]: 0.933 [0.590, 1.477]). The major drug adverse reactions were injection-site reactions. Although treatment with OCV-501 did not prolong DFS for elderly AML patients, post hoc analysis found that immune responders to OCV-501 whose specific IgG was > 10,000 ng/mL (N = 16) and whose WT1-specific interferon-γ response was > 10 pg/mL (N = 26) had significantly longer overall survival compared with placebo.

CONCLUSIONS

The placebo-controlled design of this study and quantitative immunological monitoring provides new insight into the relationship between peptide-induced immune responses and survival, suggesting future perspectives for cancer immunotherapy.

Maintenance therapies in acute myeloid leukemia: the renaissance of an old therapeutic concept

PURPOSE OF REVIEW

Disease relapse remains the major cause of death in patients with acute myeloid leukemia (AML) and is driven by the persistence of leukemic cells following induction chemotherapy or allogeneic hematopoietic cell transplant (allo-HCT). Maintenance therapies to extend the duration of remission and to improve survival have been proposed for several years with mixed results but have experienced a renaissance recently.

RECENT FINDINGS

The oral hypomethylating agent CC-486 has been the first agent to show an overall survival (OS) benefit compared with observation in AML patients in remission following intensive chemotherapy who are not proceeding to allo-HCT. In the realm of postallo-HCT maintenance therapy, the FLT3 inhibitor sorafenib has yielded superior results in terms of OS and relapse-free survival in randomized trials compared with observation. Several open questions remain regarding patient selection, timing, duration and safety of maintenance therapies. Various targeted agents are currently tested in clinical trials and could potentially enable an even more individualized therapeutic approach.

SUMMARY

Maintenance therapies following intensive chemotherapy or allo-HCT offer a new therapeutic paradigm for an increasing number of AML patients and have been shown to result in an OS benefit in selected patients.

A precision medicine classification for treatment of acute myeloid leukemia in older patients

Background

Older patients (≥ 60 years) with acute myeloid leukemia (AML) often have multiple, sequentially acquired, somatic mutations that drive leukemogenesis and are associated with poor outcome. Beat AML is a Leukemia and Lymphoma Society-sponsored, multicenter umbrella study that algorithmically segregates AML patients based upon cytogenetic and dominant molecular abnormalities (variant allele frequencies (VAF) ≥ 0.2) into different cohorts to select for targeted therapies. During the conception of the Beat AML design, a historical dataset was needed to help in the design of the genomic algorithm for patient assignment and serve as the basis for the statistical design of individual genomic treatment substudies for the Beat AML study.

Methods

We classified 563 newly diagnosed older AML patients treated with standard intensive chemotherapy on trials conducted by Cancer and Leukemia Group B based on the same genomic algorithm and assessed clinical outcomes.

Results

Our classification identified core-binding factor and NPM1-mutated/FLT3-ITD-negative groups as having the best outcomes, with 30-day early death (ED) rates of 0 and 20%, respectively, and median overall survival (OS) of > 1 year and 3-year OS rates of ≥ 20%. All other genomic groups had ED rates of 17–42%, median OS ≤ 1 year and 3-year OS rates of ≤ 15%.

Conclusions

By classifying patients through this genomic algorithm, outcomes were poor and not unexpected from a non-algorithmic, non-dominant VAF approach. The exception is 30-day ED rate typically is not available for intensive induction for individual genomic groups and therefore difficult to compare outcomes with targeted therapeutics. This Alliance data supported the use of this algorithm for patient assignment at the initiation of the Beat AML study. This outcome data was also used for statistical design for Beat AML substudies for individual genomic groups to determine goals for improvement from intensive induction and hopefully lead to more rapid approval of new therapies.

Trial registration ClinicalTrials.gov Identifiers: NCT00048958 (CALGB 8461), NCT00900224 (CALGB 20202), NCT00003190 (CALGB 9720), NCT00085124 (CALGB 10201), NCT00742625 (CALGB 10502), NCT01420926 (CALGB 11002), NCT00039377 (CALGB 10801), and NCT01253070 (CALGB 11001).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01110-5.

Targeted and cytotoxic therapies as maintenance treatment for non-transplant eligible patients with acute myeloid leukemia

In the recent years, there have been multiple approvals by the Food and Drug Administration (FDA) for therapeutics for acute myeloid leukemia (AML). The role of maintenance therapy in AML has been rather unrealized mostly due to lack of efficacy and increased toxicity of classical chemotherapy agents. Many clinical trials have demonstrated a disease-free survival benefit for various therapeutics in the maintenance setting for patients with AML who are ineligible for stem cell transplant. Notably, oral hypomethylating agent therapy has recently shown an overall survival and disease-free survival benefit in the maintenance setting for AML. In this review, we summarize the relevant data on maintenance therapy with a specific focus on cytotoxic antimetabolite chemotherapeutics, hypomethylating agents, targeted agents, and immunotherapeutics. We discuss our approach to maintenance therapy in AML in 2021 and propose a measurable residual disease (MRD)-adapted, personalized approach based on the best available evidence.

Efficacy and safety of chemotherapy combined with different doses of IL-2 maintenance therapies for acute myeloid leukemia: A protocol for a Bayesian network meta-analysis

BACKGROUND

Acute myeloid leukemia (AML) is the most common malignant tumor of the hematopoietic system, which seriously threatens the lives of patients. Most AML patients have acute onset, severe condition, and poor prognosis. The present study aimed to comprehensively evaluate the effectiveness and safety of chemotherapy combined with different doses of interleukin-2 (IL-2) maintenance treatments in AML by Bayesian network meta-analysis (NMA).

METHODS

From its inception until October 2021, we will search PubMed, Cochrane Library, CNKI, Embase, and other databases to comprehensively collect randomized controlled trials (RCTs) of chemotherapy combined with different doses of IL-2 maintenance therapies for AML. Two independent researchers will complete the literature screening and data extraction according to the inclusion and exclusion criteria, and then independently conduct a bias risk assessment of all the evidence. Bayesian NMA was used to evaluate all the evidence comprehensively. Use STATA16.0 and WinBUGS1.4.3 software to process and analyze all data, and classify the quality of evidence in NMA according to grading of recommendations assessment, development, and evaluation .

RESULTS

The study will evaluate the efficacy and safety of chemotherapy combined with different doses of IL-2 maintenance therapies for AML.

CONCLUSION

The study will provide a basis for the efficacy and safety of chemotherapy combined with different doses of IL-2 maintenance therapies for AML. We hope that this study can provide meaningful support for clinicians and patients.

PROTOCOL REGISTRATION NUMBER

INPLASY202140106.

ETHICAL APPROVAL

Since the study is based on published or registered RCTs, ethical approval and patient informed consent are abandoned.

Maintenance Therapy in AML

Recent advances in therapeutics coupled with steady improvements in supportive care for patients with acute myeloid leukemia (AML) have led to improved outcomes. Despite these advances, even in patients that achieve a complete remission with initial therapy high rates of relapse remain a clinical dilemma. For decades, investigators have attempted strategies of maintenance therapy to prolong both remission duration and overall survival in patients with AML. These approaches have included cytotoxic chemotherapy, immunotherapy, hypomethylating agents, and targeted small molecule therapy. Overall, the evidence in favor of maintenance therapy is limited. Recent strategies, especially with hypomethylating agents have begun to show promise as maintenance therapy in improving clinical outcomes. Ongoing and future studies will continue to elucidate the true role for maintenance therapy options in patients with AML. In this review we summarize prior and ongoing maintenance therapy approaches in AML and highlight some of the most promising strategies.

Natural killer cell-based immunotherapy for acute myeloid leukemia

Despite considerable progress has been achieved in the treatment of acute myeloid leukemia over the past decades, relapse remains a major problem. Novel therapeutic options aimed at attaining minimal residual disease-negative complete remission are expected to reduce the incidence of relapse and prolong survival. Natural killer cell-based immunotherapy is put forward as an option to tackle the unmet clinical needs. There have been an increasing number of therapeutic dimensions ranging from adoptive NK cell transfer, chimeric antigen receptor-modified NK cells, antibodies, cytokines to immunomodulatory drugs. In this review, we will summarize different forms of NK cell-based immunotherapy for AML based on preclinical investigations and clinical trials.

Mutational landscape and clinical outcome of patients with de novo acute myeloid leukemia and rearrangements involving 11q23/KMT2A

Balanced rearrangements involving the KMT2A gene, located at 11q23, are among the most frequent chromosome aberrations in acute myeloid leukemia (AML). Because of numerous fusion partners, the mutational landscape and prognostic impact of specific 11q23/KMT2A rearrangements are not fully understood. We analyzed clinical features of 172 adults with AML and recurrent 11q23/KMT2A rearrangements, 141 of whom had outcome data available. We compared outcomes of these patients with outcomes of 1,097 patients without an 11q23/KMT2A rearrangement categorized according to the 2017 European LeukemiaNet (ELN) classification. Using targeted next-generation sequencing, we investigated the mutational status of 81 leukemia/cancer-associated genes in 96 patients with 11q23/KMT2A rearrangements with material for molecular studies available. Patients with 11q23/KMT2A rearrangements had a low number of additional gene mutations (median, 1; range 0 to 6), which involved the RAS pathway (KRAS, NRAS, and PTPN11) in 32% of patients. KRAS mutations occurred more often in patients with t(6;11)(q27;q23)/KMT2A-AFDN compared with patients with the other 11q23/KMT2A subsets. Specific gene mutations were too infrequent in patients with specific 11q23/KMT2A rearrangements to assess their associations with outcomes. We demonstrate that younger (age <60 y) patients with t(9;11)(p22;q23)/KMT2A-MLLT3 had better outcomes than patients with other 11q23/KMT2A rearrangements and those without 11q23/KMT2A rearrangements classified in the 2017 ELN intermediate-risk group. Conversely, outcomes of older patients (age ≥60 y) with t(9;11)(p22;q23) were poor and comparable to those of the ELN adverse-risk group patients. Our study shows that patients with an 11q23/KMT2A rearrangement have distinct mutational patterns and outcomes depending on the fusion partner.

Natural Killer Cells in Myeloid Malignancies: Immune Surveillance, NK Cell Dysfunction, and Pharmacological Opportunities to Bolster the Endogenous NK Cells

Natural killer (NK) cells are large granular lymphocytes involved in our defense against certain virus-infected and malignant cells. In contrast to T cells, NK cells elicit rapid anti-tumor responses based on signals from activating and inhibitory cell surface receptors. They also lyse target cells via antibody-dependent cellular cytotoxicity, a critical mode of action of several therapeutic antibodies used to treat cancer. A body of evidence shows that NK cells can exhibit potent anti-tumor activity against chronic myeloid leukemia (CML), acute myeloid leukemia (AML), and myelodysplastic syndromes (MDS). However, disease-associated mechanisms often restrain the proper functions of endogenous NK cells, leading to inadequate tumor control and risk for disease progression. Although allogeneic NK cells can prevent leukemia relapse in certain settings of stem cell transplantation, not all patients are eligible for this type of therapy. Moreover, remissions induced by adoptively infused NK cells are only transient and require subsequent therapy to maintain durable responses. Hence, new strategies are needed to trigger full and durable anti-leukemia responses by NK cells in patients with myeloid malignancies. To achieve this, we need to better understand the interplay between the malignant cells, their microenvironment, and the NK cells. This review focuses on mechanisms that are involved in suppressing NK cells in patients with myeloid leukemia and MDS, and means to restore their full anti-tumor potential. It also discusses novel molecular targets and approaches, such as bi- and tri-specific antibodies and immune checkpoint inhibitors, to redirect and/or unleash the NK cells against the leukemic cells.

Clinical and molecular characterization of patients with acute myeloid leukemia and sole trisomies of chromosomes 4, 8, 11, 13 or 21

Sole trisomies of chromosomes 4, 8, 11, 13 and 21 account for 89-95% of all sole trisomies in adult AML patients. We analyzed clinical and molecular characteristics of 138 de novo AML patients with sole +4, +8, +11, +13 or +21, and compared them with AML patients with those trisomies occurring in addition to other chromosome abnormalities (non-sole trisomy) and with cytogenetically normal AML (CN-AML) patients. Mutations in methylation-related genes were most commonly observed within each sole trisomy group (+4, 55%; +8, 58%; +11, 71%; +13, 71%; +21, 75% of patients). Patients with sole trisomies, excluding +4, also had frequent mutations in spliceosome genes (+8, 43%; +11, 65%; +13, 65%; +21, 45% of patients). In contrast, +4 patients frequently had mutations in transcription factor genes (44%) and NPM1 (36%). While 48% of patients with sole trisomies harbored mutations in a spliceosome gene, spliceosome mutations were observed in only 24% of non-sole trisomy (n = 131, P < 0.001) and 19% of CN-AML patients (n = 716, P < 0.001). Our data suggest that mutations affecting methylation-related genes are a molecular hallmark of sole trisomies. Mutations in spliceosome genes were also commonly observed in many sole trisomy patients and represent a novel finding in this cytogenetic subgroup.

Mutations associated with a 17-gene leukemia stem cell score and the score's prognostic relevance in the context of the European LeukemiaNet classification of acute myeloid leukemia

Leukemia stem cells (LSC) are more resistant to standard chemotherapy and their persistence during remission can cause relapse, which is still one of the major clinical challenges in the treatment of acute myeloid leukemia (AML). A better understanding of the mutational patterns and the prognostic impact of molecular markers associated with stemness could lead to better clinical management and improve patients’ outcomes. We applied a previously described 17-gene expression score comprising genes differently expressed between LSC and leukemic bulk blasts, for 934 adult patients with de novo AML, and studied associations of the 17-gene LSC score with clinical data and mutation status of 81 genes recurrently mutated in cancer and leukemia. We found that patients with a high 17-gene score were older and had more mutations. The 17-gene score was found to have a prognostic impact in both younger (aged <60 years) and older (aged ≥60 years) patients with AML. We also analyzed the 17-gene LSC score in the context of the 2017 European LeukemiaNet genetic-risk classification and found that for younger patients the score refined the classification, and identified patients currently classified in the European LeukemiaNet Favorable-risk category who had a worse outcome.

Genetic Characterization and Prognostic Relevance of Acquired Uniparental Disomies in Cytogenetically Normal Acute Myeloid Leukemia

PURPOSE

Uniparental disomy (UPD) is a way cancer cells duplicate a mutated gene, causing loss of heterozygosity (LOH). Patients with cytogenetically normal acute myeloid leukemia (CN-AML) do not have microscopically detectable chromosome abnormalities, but can harbor UPDs. We examined the prognostic significance of UPDs and frequency of LOH in patients with CN-AML.Experimental Design: We examined the frequency and prognostic significance of UPDs in a set of 425 adult patients with de novo CN-AML who were previously sequenced for 81 genes typically mutated in cancer. Associations of UPDs with outcome were analyzed in the 315 patients with CN-AML younger than 60 years.

RESULTS

We detected 127 UPDs in 109 patients. Most UPDs were large and typically encompassed all or most of the affected chromosome arm. The most common UPDs occurred on chromosome arms 13q (7.5% of patients), 6p (2.8%), and 11p (2.8%). Many UPDs significantly cooccurred with mutations in genes they encompassed, including 13q UPD with FLT3-internal tandem duplication (FLT3-ITD; P < 0.001), and 11p UPD with WT1 mutations (P = 0.02). Among patients younger than 60 years, UPD of 11p was associated with longer overall survival (OS) and 13q UPD with shorter disease-free survival (DFS) and OS. In multivariable models that accounted for known prognostic markers, including FLT3-ITD and WT1 mutations, UPD of 13q maintained association with shorter DFS, and UPD of 11p maintained association with longer OS.

CONCLUSIONS

LOH mediated by UPD is a recurrent feature of CN-AML. Detection of UPDs of 13q and 11p might be useful for genetic risk stratification of patients with CN-AML.

Complex karyotype in de novo acute myeloid leukemia: typical and atypical subtypes differ molecularly and clinically

Complex karyotype (CK) with ≥ 3 abnormalities is detected in 10-12% of patients with acute myeloid leukemia (AML) and associated with poor prognosis. The most common unbalanced abnormalities found in CK result in loss of material from the 5q, 7q, and/or 17p chromosome arms. The presence of 5q, 7q, and/or 17p abnormalities denotes typical CK and their absence denotes atypical CK. Since molecular features of CK-AML are not well characterized, we investigated mutational status of 81 leukemia/cancer-associated genes in 160 clinically well-characterized patients. They included 136 patients with ≥ 3 exclusively unbalanced chromosome abnormalities, 96 of whom had a typical CK and 40 atypical CK, and 24 patients with ≥ 1 balanced abnormality in addition to ≥ 2 unbalanced ones. Patients with atypical CK-AML differed from those with typical CK-AML: they carried TP53 mutations less often (P < 0.001) and more often PHF6 (P = 0.008), FLT3-TKD (P = 0.02), MED12 (P = 0.02), and NPM1 (P = 0.02) mutations. They were younger (P = 0.007), had higher WBC (P = 0.001) and percentages of marrow (P < 0.001) and blood (P = 0.006) blasts, higher complete remission rates (P = 0.02), and longer overall survival (P < 0.001), thus indicating that atypical and typical CK-AMLs constitute distinct disease subtypes. We also identified smaller patient subsets within both typical and atypical CK-AML that differed molecularly and clinically.

Ten-year outcome of patients with acute myeloid leukemia not treated with allogeneic transplantation in first complete remission

The probability that adult patients with de novo acute myeloid leukemia (AML) receiving intensive chemotherapy in the absence of allogeneic hematopoietic stem cell transplantation (Allo-HCT) in first complete remission (CR1) will be disease-free at 10 years after diagnosis, a long-term surrogate of cure, is unknown. To address this question, we examined 2551 AML patients (1607 aged <60 years, and 944 aged ≥60 years) enrolled in Cancer and Leukemia Group B treatment protocols and the cytogenetics companion protocol 8461 between 1983 and 2004. At 10 years, 267 (16.6%) of patients aged <60 years and 23 (2.4%) of those aged ≥60 years were alive and disease-free. This disease-free AML group consisted predominantly of patients with core-binding factor AML with t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22) and those with a normal karyotype. Occurrences of AML beyond 10 years were infrequent and associated with cytogenetic findings different from those at diagnosis. These data provide evidence that the frequency of long-term cure of AML is low among younger and especially older patients in the absence of Allo-HCT in CR1. In older patients not appropriate for Allo-HCT, these data provide further justification for early use of alternative treatments outside of intensive chemotherapy.

Azacitidine maintenance after intensive chemotherapy improves DFS in older AML patients

The prevention of relapse is the major therapeutic challenge in older patients with acute myeloid leukemia (AML) who have obtained a complete remission (CR) on intensive chemotherapy. In this randomized phase 3 study (HOVON97) in older patients (≥60 years) with AML or myelodysplastic syndrome with refractory anemia with excess of blasts, in CR/CR with incomplete hematologic recovery (CRi) after at least 2 cycles of intensive chemotherapy, we assessed the value of azacitidine as postremission therapy with respect to disease-free survival (DFS; primary end point) and overall survival (OS; secondary end point). In total, 116 eligible patients were randomly (1:1) assigned to either observation (N = 60) or azacitidine maintenance (N = 56; 50 mg/m2, subcutaneously, days 1-5, every 4 weeks) until relapse, for a maximum of 12 cycles. Fifty-five patients received at least 1 cycle of azacitidine, 46 at least 4 cycles, and 35 at least 12 cycles. The maintenance treatment with azacitidine was feasible. DFS was significantly better for the azacitidine treatment group (logrank; P = .04), as well as after adjustment for poor-risk cytogenetic abnormalities at diagnosis and platelet count at randomization (as surrogate for CR vs CRi; Cox regression; hazard ratio, 0.62; 95% confidence interval, 0.41-0.95; P = .026). The 12-month DFS was estimated at 64% for the azacitidine group and 42% for the control group. OS did not differ between treatment groups, with and without censoring for allogeneic hematopoietic cell transplantation. Rescue treatment was used more often in the observation group (n = 32) than in the azacitidine maintenance group (n = 9). We conclude that azacitidine maintenance after CR/CRi after intensive chemotherapy is feasible and significantly improves DFS. The study is registered with The Netherlands Trial Registry (NTR1810) and EudraCT (2008-001290-15).

Maintenance Therapy With Interleukin-2 for Childhood AML: Results of ELAM02 Phase III Randomized Trial

Despite significant progress in the treatment of pediatric acute myeloblastic leukemia (AML), relapse remains the commonest cause of death. Randomized ELAM02 trial questioned if maintenance therapy with interleukin-2 (IL2), for 1 year, improves disease-free survival (DFS). Patients aged 0 to 18 years, with newly diagnosed AML (excluding patients with acute promyelocytic leukemia or down syndrome AML) were enrolled. They received 1 course of induction treatment (cytarabine and mitoxantrone) and 3 courses of consolidation treatment (high-dose cytarabine in courses 1 and 3). According to the cytogenetics risk, patients not undergoing hematopoietic stem cell transplantation, still in complete remission (CR) after the third course of consolidation treatment, were eligible for randomization to 1 year of maintenance therapy with monthly courses of IL2 or no maintenance treatment. There were 438 evaluable patients, 154 of whom were randomized to the IL2/no maintenance groups. Relapse occurred in 28 patients from the IL2+ group and 29 patients in the IL2- group. Survival was similar in the 2 groups, with a 4-year DFS of 62% without IL2 and 66% with IL2 (P = 0.75). In the CBF population, 4-year DFS was 55% without IL2 and 78% with IL2 (P = 0.07). No deaths from toxicity or excess of serious adverse events related to IL2 treatment were recorded. Prolonged IL2 for maintenance therapy after intensive chemotherapy is feasible and safe in pediatric AML patients in their first CR. Such treatment did not improve DFS in this study, but a positive trend was observed in favor of IL2 maintenance therapy among core binding factor acute myeloblastic leukemia.

Allogeneic Hematopoietic Stem Cell Transplantation for Older Patients With Acute Myeloid Leukemia

OPINION STATEMENT

Acute myelogenous leukemia (AML) in the elderly is complex and has a poor prognosis, often characterized by higher risk cytogenetic and molecular features compared to that in younger patients. Rates of transplant have been limited by concern related to non-relapse mortality, as older patients have historically been considered medically unfit for the transplantation process. Reduced-intensity conditioning (RIC) for hematopoietic stem cell transplantation (HSCT) has been shown to provide similar efficacy to myeloablative methods, with decreased non-relapse mortality in the elderly and improved efficacy over non-transplant approaches with cytotoxic chemotherapy alone. Targeted non-cytotoxic and modified cytotoxic agents have emerged to further improve transplant outcomes for older AML patients. Validated comorbidity indices are useful tools to assess an individual's fitness for undergoing HSCT rather than chronological age alone. We believe HSCT is the primary curative treatment approach for many older AML patients, taking into account risk and comorbidities, particularly given the tendency of leukemia in this population to harbor an unfavorable disease profile. We use RIC and advocate for the addition of targeted agents if applicable. With continuing data in support of transplant for older AML patients, we anticipate that transplant rates in this population will continue to rise.

NF1 mutations are recurrent in adult acute myeloid leukemia and confer poor outcome

Targeted mutation assessment of 81 genes in 1,021 adults with de novo acute myeloid leukemia (AML) identified recurrent mutations in the neurofibromin 1 (NF1) gene in 52 (5.1%) patients, including 36 (5.2%) younger and 16 (4.8%) older patients, which suggests NF1 belongs to the 20 most frequently mutated genes in adult AML. NF1 mutations were found throughout the gene, and comprised missense, frame-shift and nonsense mutations. One mutation hotspot, at amino acid threonine 676 (Thr676), was found in 27% of AML patients with NF1 mutations. NF1-mutated patients belonged more often to the adverse European LeukemiaNet (ELN) risk category than NF1 wild-type patients. Among patients aged <60 years, the presence of NF1 Thr676 mutations was associated with lower complete remission (CR) rates (P=0.04) and shorter overall survival (OS; P=0.01), as was the presence of any NF1 mutation in patients in the adverse ELN risk category (CR, P=0.05; OS, P<0.001). CR rates were also lower in NF1-mutated patients aged ≥60 years compared with NF1 wild-type patients (P=0.001). In summary, our findings provide novel insights into the frequency of NF1 mutations in AML, and are suggestive of an adverse prognostic impact in patients treated with standard chemotherapy.

The antiviral effects of acteoside and the underlying IFN-γ-inducing action

There are many herbal teas that are found in nature that may be effective at treating the symptoms and also shortening the duration of viral infections. When combating viral infections, T lymphocytes are an indispensable part of human acquired immunity. However, studies on the use of natural products in stimulating lymphocyte-mediated interferon-gamma (IFN-γ) production are very limited. In this study, we found that acteoside, a natural phenylpropanoid glycoside from Kuding Tea, enhanced IFN-γ production in mouse lymphocytes in a dose-dependent manner, particularly in the CD4+ and CD8+ subsets of T lymphocytes. To this end, we suggest that the antiviral activity of acteoside was highly correlated to its inducing ability of IFN-γ production. Mechanistically, the activation of T-bet enhanced the promoter of IFN-γ and subsequently resulted in an increased IFN-γ production in T cells. Collectively, we have found a natural product with the capacity to selectively enhance mouse T cell IFN-γ production. Given the role of IFN-γ in the immune system, further studies to clarify the role of acteoside in inducing IFN-γ and prevention of viral infection are needed.

Maintenance therapy with histamine plus IL-2 induces a striking expansion of two CD56bright NK cell subpopulations in patients with acute myeloid leukemia and supports their activation

Histamine dihydrochloride (HDC) plus IL-2 has been proposed as a novel maintenance-immunotherapy in acute myeloid leukemia (AML). We analyzed the immunophenotype and function of natural killer (NK) cells in blood of AML patients treated after chemotherapy with HDC plus IL-2. The treatment caused a striking expansion of CD56brightCD16neg and CD56brightCD16low NK cell subpopulations. A reduced NK cell fraction recovered and high proportions of cells expressed the activating receptors NKG2D, NKp30, and NKp46. Concomitantly, KIR-expressing NK cells were reduced and NK cells with inhibitory NKG2A/CD94 receptors increased beyond normal levels. In addition, the immunotherapy-induced NK cells exhibited high capacity to produce IFN-γ and to degranulate. Furthermore, we provide evidence from subsequent in vitro studies that this is caused in part by direct effects of IL-2 on the CD56bright cells. IL-2 specifically induced proliferation of both CD56bright subpopulations, but not of CD56dim cells. It further preserved the expression of activating receptors and the capacity to produce IFN-γ and to degranulate. These data suggest that therapy with HDC plus IL-2 supports the reconstitution of a deficient NK cell fraction through the specific amplification of CD56bright NK cells giving rise to a functional NK cell compartment with high potential to combat leukemic disease.

Role of regulatory T cells in acute myeloid leukemia patients undergoing relapse-preventive immunotherapy

Regulatory T cells (T_regs) have been proposed to dampen functions of anti-neoplastic immune cells and thus promote cancer progression. In a phase IV trial (Re:Mission Trial, NCT01347996, http://www.clinicaltrials.gov) 84 patients (age 18–79) with acute myeloid leukemia (AML) in first complete remission (CR) received ten consecutive 3-week cycles of immunotherapy with histamine dihydrochloride (HDC) and low-dose interleukin-2 (IL-2) to prevent relapse of leukemia in the post-consolidation phase. This study aimed at defining the features, function and dynamics of Foxp3⁺CD25^highCD4⁺ T_regs during immunotherapy and to determine the potential impact of T_regs on relapse risk and survival. We observed a pronounced increase in T_reg counts in peripheral blood during initial cycles of HDC/IL-2. The accumulating T_regs resembled thymic-derived natural T_regs (nT_regs), showed augmented expression of CTLA-4 and suppressed the cell cycle proliferation of conventional T cells ex vivo. Relapse of AML was not prognosticated by T_reg counts at onset of treatment or after the first cycle of immunotherapy. However, the magnitude of T_reg induction was diminished in subsequent treatment cycles. Exploratory analyses implied that a reduced expansion of T_regs in later treatment cycles and a short T_reg telomere length were significantly associated with a favorable clinical outcome. Our results suggest that immunotherapy with HDC/IL-2 in AML entails induction of immunosuppressive T_regs that may be targeted for improved anti-leukemic efficiency.

Prognostic and biological significance of the proangiogenic factor EGFL7 in acute myeloid leukemia

Epithelial growth factor-like 7 (EGFL7) is a protein that is secreted by endothelial cells and plays an important role in angiogenesis. Although EGFL7 is aberrantly overexpressed in solid tumors, its role in leukemia has not been evaluated. Here, we report that levels of both EGFL7 mRNA and EGFL7 protein are increased in blasts of patients with acute myeloid leukemia (AML) compared with normal bone marrow cells. High EGFL7 mRNA expression associates with lower complete remission rates, and shorter event-free and overall survival in older (age ≥60 y) and younger (age <60 y) patients with cytogenetically normal AML. We further show that AML blasts secrete EGFL7 protein and that higher levels of EGFL7 protein are found in the sera from AML patients than in sera from healthy controls. Treatment of patient AML blasts with recombinant EGFL7 in vitro leads to increases in leukemic blast cell growth and levels of phosphorylated AKT. EGFL7 blockade with an anti-EGFL7 antibody reduced the growth potential and viability of AML cells. Our findings demonstrate that increased EGFL7 expression and secretion is an autocrine mechanism supporting growth of leukemic blasts in patients with AML.

The mutational oncoprint of recurrent cytogenetic abnormalities in adult patients with de novo acute myeloid leukemia

Recurrent chromosomal abnormalities and gene mutations detected at the time of diagnosis of acute myeloid leukemia (AML) are associated with particular disease features, treatment response and survival of AML patients, and are used to denote specific disease entities in the World Health Organization classification of myeloid neoplasms and acute leukemia. However, large studies that integrate cytogenetic and comprehensive mutational information are scarce. We created a comprehensive oncoprint of mutations associated with recurrent cytogenetic findings by combining the information on mutational patterns of 80 cancer- and leukemia-associated genes with cytogenetic findings in 1603 adult patients with de novo AML. We show unique differences in the mutational profiles among major cytogenetic subsets, identify novel associations between recurrent cytogenetic abnormalities and both specific gene mutations and gene functional groups, and reveal differences in cytogenetic and mutational features between patients younger than 60 years and those aged 60 years or older. The identified associations between cytogenetic and molecular genetic data may help guide mutation testing in AML, and result in more focused application of targeted therapy in patients with de novo AML.

Dynamics of myeloid cell populations during relapse-preventive immunotherapy in acute myeloid leukemia

Relapse of leukemia in the postchemotherapy phase contributes to the poor prognosis and survival in patients with acute myeloid leukemia (AML). In an international phase IV trial (ClinicalTrials.gov; NCT01347996), 84 patients with AML in first complete remission who had not undergone transplantation received immunotherapy with histamine dihydrochloride (HDC) and low-dose IL-2 with the aim of preventing relapse. The dynamics of myeloid cell counts and expression of activation markers was assessed before and after cycles of immunotherapy and correlated with clinical outcome in terms of relapse risk and survival. During cycles, a pronounced increase in blood eosinophil counts was observed along with a reduction in monocyte and neutrophil counts. A strong reduction of blood monocyte counts during the first HDC/IL-2 treatment cycle predicted leukemia-free survival. The HDC component of the immunotherapy exerts agonist activity at histamine type 2 receptors (H2Rs) that are expressed by myeloid cells. It was observed that the density of H₂ R expression in blood monocytes increased during cycles of immunotherapy and that high monocyte H₂R expression implied reduced relapse risk and improved overall survival. Several other activation markers, including HLA-DR, CD86, and CD40, were induced in monocytes and dendritic cells during immunotherapy but did not predict clinical outcome. In addition, expression of HLA-ABC increased in all myeloid populations during therapy. A low expression of HLA-ABC was associated with reduced relapse risk. These results suggest that aspects of myeloid cell biology may impact clinical benefit of relapse-preventive immunotherapy in AML.

Histamine H2 Receptor in Blood Cells: A Suitable Target for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) consists in a cancer of early hematopoietic cells arising in the bone marrow, most often of those cells that would turn into white blood cells (except lymphocytes). Chemotherapy is the treatment of choice for AML but one of the major complications is that current drugs are highly toxic and poorly tolerated. In general, treatment for AML consists of induction chemotherapy and post-remission therapy. If no further post-remission is given, almost all patients will eventually relapse. Histamine, acting at histamine type-2 (H₂) receptors on phagocytes and AML blast cells, helps prevent the production and release of oxygen-free radicals, thereby protecting NK and cytotoxic T cells. This protection allows immune-stimulating agents, such as interleukin-2 (IL-2), to activate cytotoxic cells more effectively, enhancing the killing of tumor cells. Based on this mechanism, post-remission therapy with histamine and IL-2 was found to significantly prevent relapse of AML. Alternatively, another potentially less toxic approach to treat AML employs drugs to induce differentiation of malignant cells. It is based on the assumption that many neoplastic cell types exhibit reversible defects in differentiation, which upon appropriate treatment results in tumor reprogramming and the induction of terminal differentiation. There are promissory results showing that an elevated and sustained signaling through H₂ receptors is able to differentiate leukemia-derived cell lines, opening the door for the use of H₂ agonists for specific differentiation therapies. In both situations, histamine acting through H₂ receptors constitutes an eligible treatment to induce leukemic cell differentiation, improving combined therapies.

Maintenance therapy with decitabine in younger adults with acute myeloid leukemia in first remission: a phase 2 Cancer and Leukemia Group B Study (CALGB 10503)

In this prospective phase 2 clinical trial conducted by Cancer and Leukemia Group B (CALGB, now the Alliance), we studied decitabine as maintenance therapy for younger adults with acute myeloid leukemia (AML) who remained in first complete remission (CR1) following intensive induction and consolidation. Given that decitabine is clinically active in AML and with hypomethylating activity distinct from cytotoxic chemotherapy, we hypothesized that one year of maintenance therapy would improve disease-free survival (DFS) for AML patients <60 years who did not receive allogeneic stem cell transplantation (alloHCT) in CR1. After blood count recovery from final consolidation, patients received decitabine at 20mg/m² IV daily for 4–5 days, every 6 weeks for 8 cycles. One-hundred-thirty-four patients received decitabine, 85 (63%) had favorable risk AML. The median number of cycles received was 7 (range, 1–8), and the primary reason for discontinuation was relapse. DFS at 1-year and 3-years was 79% and 54%, respectively. These results are similar to the outcomes in the historical control comprised of similar patients treated on recent CALGB trials. Thus, maintenance with decitabine provided no benefit overall. Standard use of decitabine maintenance in younger AML patients in CR1 is not warranted. This trial was registered at www.clinicaltrials.gov as NCT00416598.

Exploitation of natural killer cells for the treatment of acute leukemia

Natural killer (NK) cells play an important role in surveillance and elimination of malignant cells. Their spontaneous cytotoxicity was first demonstrated in vitro against leukemia cell lines, and NK cells might play a crucial role in the therapy of leukemia. NK cell activity is controlled by an array of germ line-encoded activating and inhibitory receptors, as well as modulating coreceptors. This biologic feature can be exploited in allogeneic cell therapy, and the recognition of "missing-self" on target cells is crucial for promoting NK cell-mediated graft-versus-leukemia effects. In this regard, NK cells that express an inhibitory killer immunoglobulin-like receptor (iKIR) for which the respective major histocompatibility complex class I ligand is absent on leukemic target cells can exert alloreactivity in vitro and in vivo. Several models regarding potential donor-patient constellations have been described that have demonstrated the clinical benefit of such alloreactivity of the donor-derived NK cell system in patients with adult acute myeloid leukemia and pediatric B-cell precursor acute lymphoblastic leukemia after allogeneic stem cell transplantation. Moreover, adoptive transfer of mature allogeneic NK cells in the nontransplant or transplant setting has been shown to be safe and feasible, whereas its effectivity needs further evaluation. NK cell therapy can be further improved by optimal donor selection based on phenotypic and genotypic properties, by adoptive transfer of NK cells with ex vivo or in vivo cytokine stimulation, by the use of antibodies to induce antibody-dependent cellular cytotoxicity or to block iKIRs, or by transduction of chimeric antigen receptors.

Design of the randomized, Phase III, QUAZAR AML Maintenance trial of CC-486 (oral azacitidine) maintenance therapy in acute myeloid leukemia

Older patients with acute myeloid leukemia (AML) have worse rates of complete remission and shorter overall survival than younger patients. The epigenetic modifier CC-486 is an oral formulation of azacitidine with promising clinical activity in patients with AML in Phase I studies. The Phase III, randomized, double-blind, placebo-controlled QUAZAR AML Maintenance trial (CC-486-AML-001) examines CC-486 maintenance therapy (300 mg/day for 14 days of 28-day treatment cycles) for patients aged ≥55 years with AML in first complete remission. The primary end point is overall survival. Secondary end points include relapse-free survival, safety, health-related quality of life and healthcare resource utilization. This trial will investigate whether CC-486 maintenance can prolong remission and improve survival for older patients with AML.

Novel therapies in AML: reason for hope or just hype?

We have entered the genomic sequencing era in the treatment of acute myeloid leukemia (AML); our patients increasingly and justifiably demand personalized treatment based on aberrations of their own leukemia. Except in rare cases we are not yet able to provide truly personalized therapy, so the question of "hope or hype?" posed by the American Society for Clinical Oncology (ASCO) for this educational topic is quite timely. The answer based solely on advances in genomic sequencing is "both". There is an element of expectation among the public that we are "almost there" in solving the genetic cancer puzzle, an expectation indeed based on hype. However, there is no question that ultimate success lies in understanding the genetic underpinnings of disease. When decades of research in molecular biology and immunology are combined with transformative advances in cancer genetics, the answer is undeniably that our patients finally have reason for hope. Here, we review selected novel therapies for AML in areas such as immunotherapeutics, epigenetics, kinase inhibition/pathway inhibition, and the marrow microenvironment.

Interleukin-2 as maintenance therapy for children and adults with acute myeloid leukaemia in first complete remission

BACKGROUND

Acute myeloid leukaemia (AML) is a malignant cancer of hematopoietic stem cells. The treatment of AML consists of two treatment phases: the remission induction phase to achieve a rapid, complete remission (CR) and the consolidation phase to achieve a durable molecular remission. People in CR are at risk of AML relapse, and people with relapsed AML have poor survival prospects. Thus, there is a continuous need for treatments to further improve prognosis. Interleukin-2 (IL-2), an immune-stimulatory cytokine, is an alternative to standard treatment for people with AML to maintain the efficacy after consolidation therapy. Maintenance therapy is not an integral part of the standard treatment for AML. Studies have been conducted to evaluate the efficacy of IL-2 as maintenance therapy for people with AML in first CR, but the effect of IL-2 is not yet fully established.

OBJECTIVES

To evaluate the efficacy and safety of IL-2 as maintenance therapy for children and adults with AML who have achieved first CR and have not relapsed.

SEARCH METHODS

We systematically searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library 2015, Issue 8), MEDLINE (1950 to August 2015), EMBASE (1950 to August 2015), LILACS (1982 to August 2015), CBM (1978 to August 2015), relevant conference proceedings (2000 to 2015), and metaRegister of Controlled Trials (since inception to August 2015) of ongoing and unpublished trials. In addition, we screened the reference lists of relevant trials and reviews.

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs) comparing IL-2 with no treatment in people with AML who had achieved first CR and had not relapsed. We did not identify studies comparing IL-2 versus best supportive care or maintenance chemotherapy or studies comparing IL-2 plus maintenance chemotherapy versus maintenance chemotherapy alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies, extracted data with a predefined extraction form, and assessed risk of bias of included studies. We extracted data on the following outcomes: disease-free survival, overall survival, event-free survival, treatment-related mortality, adverse events, and quality of life. We measured the treatment effect on time-to-event outcomes and dichotomous outcomes with hazard ratio (HR) and risk ratio, respectively. We used inverse-variance method to combine HRs with fixed-effect model unless there was significant between-study heterogeneity.

MAIN RESULTS

We included nine RCTs with a total of 1665 participants, comparing IL-2 with no treatment. Six studies included adult participants, and three studies included both adults and children. However, the latter three studies did not report data for children, thus we were unable to conduct subgroup analysis of children. One Chinese study did not report any outcomes of interest for this review. We included six trials involving 1426 participants in the meta-analysis on disease-free survival, and included five trials involving 1355 participants in the meta-analysis on overall survival. There is no evidence for difference between IL-2 group and no-treatment group regarding disease-free survival (HR 0.95; 95% CI 0.86 to 1.06, P = 0.37; quality of evidence: low) or overall survival (HR 1.05; 95% CI 0.95 to 1.16, P = 0.35; quality of evidence: moderate). Based on one trial of 161 participants, IL-2 exerted no effect on event-free survival (HR 1.02; 95% CI 0.79 to 1.32, P = 0.88; quality of evidence: low). Adverse events (including thrombocytopenia, neutropenia, malaise/fatigue, and infection/fever) were more frequent in participants receiving IL-2, according to one trial of 308 participants. No mortality due to adverse events was reported. None of the included studies reported treatment-related mortality or quality of life.

AUTHORS' CONCLUSIONS

There is no evidence for a difference between IL-2 maintenance therapy and no treatment with respect to disease-free survival or overall survival of people with AML in first CR; however, the quality of the evidence is moderate or low, and further research is likely or very likely to have an important impact on the estimate or our confidence in the estimate. Adverse events seem to be more frequent in participants treated with IL-2, but the quality of the evidence is very low and our confidence in the estimates is very uncertain. Thus, further prospective randomised trials are needed before definitive conclusions can be drawn on these issues.

Advances in the treatment of elderly and frail patients with acute myeloid leukemia

PURPOSE OF REVIEW

Significant advances have been made in the treatment of younger patients with acute myeloid leukemia over the past 3 decades, but prognosis in the elderly has remained dismal, with median survival times of only a few months. Although a small percentage of older patients may be cured by standard chemotherapy, it is clear that several aspects of frontline management require improvement and novel approaches are urgently needed. This review focuses on treatment options currently available to older patients with acute myeloid leukemia, with an emphasis on new therapeutics.

RECENT FINDINGS

Developing risk-assessment tools is critical to identify older patients who are most likely to benefit from intensive chemotherapy, but optimal induction and postremission therapies have yet to be determined in this population. New strategies and treatments are emerging and under current assessment. In particular, investigations of monoclonal antibodies, hypomethylating agents, signal transduction inhibitors, and novel cytotoxics hold promise for improving outcomes in older patients with acute myeloid leukemia, including those for whom traditional chemotherapy is not considered appropriate.

SUMMARY

Acute myeloid leukemia remains a therapeutic challenge in elderly patients, but, following a period of paucity in discoveries, several new treatments are finally emerging that may offer future improvement for these patients.

Role of natural killer cell subsets and natural cytotoxicity receptors for the outcome of immunotherapy in acute myeloid leukemia

In a phase IV trial, 84 patients (age 18–79) with acute myeloid leukemia (AML) in first complete remission (CR) received cycles of immunotherapy with histamine dihydrochloride (HDC) and low-dose human recombinant interleukin 2 (IL-2) for 18 months to prevent leukemic relapse. During cycles, the treatment resulted in expansion of CD56^bright (CD3⁻/16⁻/56^bright) and CD16⁺ (CD3⁻/16⁺/56⁺) natural killer (NK) cells in the blood along with increased NK cell expression of the natural cytotoxicity receptors (NCRs) NKp30 and NKp46. Multivariate analyses correcting for age and risk group demonstrated that high CD56^bright NK cell counts and high expression of NKp30 or NKp46 on CD16⁺ NK cells independently predicted leukemia-free survival (LFS) and overall survival (OS). Our results suggest that the dynamics of NK cell subsets and their NCR expression may determine the efficiency of relapse-preventive immunotherapy in AML.