Pevonedistat and azacitidine upregulate NOXA (PMAIP1) to increase sensitivity to venetoclax in preclinical models of acute myeloid leukemia

The BCL2 family: from apoptosis mechanisms to new advances in targeted therapy

The B cell lymphoma 2 (BCL2) protein family critically controls apoptosis by regulating the release of cytochrome c from mitochondria. In this cutting-edge review, we summarize the basic biology regulating the BCL2 family including canonical and non-canonical functions, and highlight milestones from basic research to clinical applications in cancer and other pathophysiological conditions. We review laboratory and clinical development of BH3-mimetics as well as more recent approaches including proteolysis targeting chimeras (PROTACs), antibody-drug conjugates (ADCs) and tools targeting the BH4 domain of BCL2. The first BCL2-selective BH3-mimetic, venetoclax, showed remarkable efficacy with manageable toxicities and has transformed the treatment of several hematologic malignancies. Following its success, several chemically similar BCL2 inhibitors such as sonrotoclax and lisaftoclax are currently under clinical evaluation, alone and in combination. Genetic analysis highlights the importance of BCL-XL and MCL1 across different cancer types and the possible utility of BH3-mimetics targeting these proteins. However, the development of BH3-mimetics targeting BCL-XL or MCL1 has been more challenging, with on-target toxicities including thrombocytopenia for BCL-XL and cardiac toxicities for MCL1 inhibitors precluding clinical development. Tumor-specific BCL-XL or MCL1 inhibition may be achieved by novel targeting approaches using PROTACs or selective drug delivery strategies and would be transformational in many subtypes of malignancy. Taken together, we envision that the targeting of BCL2 proteins, while already a success story of translational research, may in the foreseeable future have broader clinical applicability and improve the treatment of multiple diseases.

A phase I study of pevonedistat, azacitidine, and venetoclax in patients with relapsed/refractory acute myeloid leukemia

Azacitidine/venetoclax is an active regimen in patients with newly diagnosed acute myeloid leukemia (AML). However, primary or secondary resistance to azacitidine/venetoclax is an area of unmet need and overexpression of MCL1 is suggested to be a potential resistance mechanism. Pevonedistat inhibits MCL1 through activation of NOXA, and pevonedistat/azacitidine has previously shown activity in AML. To assess the tolerability and efficacy of adding pevonedistat to azacitidine/ venetoclax in relapsed/refractory AML, we conducted a phase I, multicenter, open-label study in 16 adults with relapsed/ refractory AML. Patients were treated with azacitidine, venetoclax along with pevonedistat intravenously on days 1, 3 and 5 of each 28-day cycle at doses of 10, 15 or 20 mg/m2 in successive cohorts in the dose escalation phase. The impact of treatment on protein neddylation as well as expression of pro-apoptotic BCL2 family members was assessed. The recommended phase II dose of pevonedistat was 20 mg/m2. Grade 3 or higher adverse events included neutropenia (31%), thrombocytopenia (13%), febrile neutropenia (19%), anemia (19%), hypertension (19%) and sepsis (19%). The overall response rate was 46.7% for the whole cohort including complete remission in five of seven (71.4%) patients who had not previously been treated with the hypomethylating agent/venetoclax. No measurable residual disease was detected in 80.0% of the patients who achieved complete remission. The median time to best response was 50 (range, 23-77) days. Four patients were bridged to allogeneic stem cell transplantation. The combination of azacitidine, venetoclax and pevonedistat is safe and shows encouraging preliminary activity in patients with relapsed/refractory AML. (NCT04172844).

CRISPR screen of venetoclax response-associated genes identifies transcription factor ZNF740 as a key functional regulator

BCL-2 inhibitors such as venetoclax offer therapeutic promise in acute myeloid leukemia (AML) and other cancers, but drug resistance poses a significant challenge. It is crucial to understand the mechanisms that regulate venetoclax response. While correlative studies have identified numerous genes linked to venetoclax sensitivity, their direct impact on the drug response remains unclear. In this study, we targeted around 1400 genes upregulated in venetoclax-sensitive primary AML samples and carried out a CRISPR knockout screen to evaluate their direct effects on venetoclax response. Our screen identified the transcription factor ZNF740 as a critical regulator, with its expression consistently predicting venetoclax sensitivity across subtypes of the FAB classification. ZNF740 depletion leads to increased resistance to ventoclax, while its overexpression enhances sensitivity to the drug. Mechanistically, our integrative transcriptomic and genomic analysis identifies NOXA as a direct target of ZNF740, which negatively regulates MCL-1 protein stability. Loss of ZNF740 downregulates NOXA and increases the steady state protein levels of MCL-1 in AML cells. Restoring NOXA expression in ZNF740-depleted cells re-sensitizes AML cells to venetoclax treatment. Furthermore, we demonstrated that dual targeting of MCL-1 and BCL-2 effectively treats ZNF740-deficient AML in vivo. Together, our work systematically elucidates the causal relationship between venetoclax response signature genes and establishes ZNF740 as a novel transcription factor regulating venetoclax sensitivity.

Decreased apoptotic priming and loss of BCL-2 dependence are functional hallmarks of Richter's syndrome

Richter's syndrome (RS) is the transformation of chronic lymphocytic leukemia (CLL) into a high-grade B-cell malignancy. Molecular and functional studies have pointed out that CLL cells are close to the apoptotic threshold and dependent on BCL-2 for survival. However, it remains undefined how evasion from apoptosis evolves during disease transformation. Here, we employed functional and static approaches to compare the regulation of mitochondrial apoptosis in CLL and RS. BH3 profiling of 17 CLL and 9 RS samples demonstrated that RS cells had reduced apoptotic priming and lower BCL-2 dependence than CLL cells. While a subset of RS was dependent on alternative anti-apoptotic proteins and was sensitive to specific BH3 mimetics, other RS cases harbored no specific anti-apoptotic addiction. Transcriptomics of paired CLL/RS samples revealed downregulation of pro-apoptotic sensitizers during disease transformation. Albeit expressed, effector and activator members were less likely to colocalize with mitochondria in RS compared to CLL. Electron microscopy highlighted reduced cristae width in RS mitochondria, a condition further promoting apoptosis resistance. Collectively, our data suggest that RS cells evolve multiple mechanisms that lower the apoptotic priming and shift the anti-apoptotic dependencies away from BCL-2, making direct targeting of mitochondrial apoptosis more challenging after disease transformation.

ASXL1 mutations are associated with a response to alvocidib and 5-azacytidine combination in myelodysplastic neoplasms

Inhibitors of anti-apoptotic BCL-2 family proteins in combination with chemotherapy and hypomethylating agents (HMA) are promising therapeutic approaches in acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS). Alvocidib, a cyclin-dependent kinase 9 (CDK9) inhibitor and indirect transcriptional repressor of the anti-apoptotic factor MCL-1, has previously shown clinical activity in AML. Availability of biomarkers for response to the alvocidib + 5-azacytidine (5-AZA) could also extend the rationale of this treatment concept to high-risk MDS. In this study, we performed a comprehensive in vitro assessment of alvocidib and 5-AZA effects in N=45 high-risk MDS patients. Our data revealed additive cytotoxic effects of the combination treatment. Mutational profiling of MDS samples identified ASXL1 mutations as predictors of response. Further, increased response rates were associated with higher gene expression of the pro-apoptotic factor NOXA in ASXL1-mutated samples. The higher sensitivity of ASXL1 mutant cells to the combination treatment was confirmed in vivo in ASXL1Y588X transgenic mice. Overall, our study demonstrated augmented activity for the alvocidib + 5-AZA combination in higher-risk MDS and identified ASXL1 mutations as a biomarker of response for potential stratification studies.

Meta‑analysis of the efficacy of venetoclax and azacitidine combination therapy and azacitidine monotherapy for treating acute myeloid leukemia

The present study aimed to compare the efficacy of combination therapy with venetoclax and azacitidine with that of azacytidine monotherapy in the treatment of acute myeloid leukemia (AML). The Web of Science, PubMed, Embase, The Cochrane Library, Weipu Database, Wanfang Digital Periodicals, Sinomed, China National Knowledge Infrastructure, ProQuest Dissertations and Theses and Cumulative Index to Nursing and Allied Health Literature were searched for publications on the treatment of AML with venetoclax combined with azacitidine or with azacitidine monotherapy. A total of 5,271 relevant studies were retrieved, of which 10 were included. Literature quality was evaluated according to the Cochrane systematic review methodology, and data were extracted for meta-analysis using Review Manager 5.4. The combination of venetoclax and azacitidine demonstrated greater overall efficacy than azacitidine monotherapy for AML treatment. Notably, combination therapy resulted in a higher frequency of complete remission. By contrast, combined treatment and monotherapy showed no significant differences in partial remission, whereas there was a statistically significant decrease in the frequency of no remission in the combination therapy group compared with in the monotherapy group. The results also revealed a significantly higher incidence of adverse reactions when venetoclax and azacitidine were combined in the treatment of AML compared with the observed rates in response to azacitidine monotherapy. Moreover, subgroup analyses showed that no statistically significant differences were observed between the two groups regarding adverse events, including hypokalemia and liver insufficiency. In conclusion, the combination of venetoclax and azacitidine was more effective than azacitidine alone, and had a good clinical application value in the treatment of AML. Although some adverse reactions occurred in response to the combination therapy, they did not significantly affect the prognosis of AML. To better evaluate the efficacy and safety of this treatment regimen, multicenter clinical studies with larger sample sizes are required.

Synergistic cytotoxicity of decitabine and YM155 in leukemia cells through upregulation of SLC35F2 and suppression of MCL1 and survivin expression

The hypomethylation agent decitabine (DAC), in combination with other apoptosis inducers, is considered a potential modality for cancer treatment. We investigated the mechanism underlying the combined cytotoxicity of DAC and YM155 in acute myeloid leukemia (AML) cells because of increasing evidence that YM155 induces apoptosis in cancer cells. Co-administration of DAC and YM155 resulted in synergistic cytotoxicity in AML U937 cells, which was characterized by the induction of apoptosis, NOXA-dependent degradation of MCL1 and survivin, and depolarization of mitochondria. Restoration of MCL1 or survivin expression attenuated DAC/YM155-induced U937 cell death. DAC initiated AKT and p38 MAPK phosphorylation in a Ca2+/ROS-dependent manner, thereby promoting autophagy-mediated degradation of β-TrCP mRNA, leading to increased Sp1 expression. DAC-induced Sp1 expression associated with Ten-eleven-translocation (TET) dioxygenases and p300 was used to upregulate the expression of SLC35F2. Simultaneously, the activation of p38 MAPK induced by DAC, promoted CREB-mediated NOXA expression, resulting in survivin and MCL1 degradation. The synergistic cytotoxicity of DAC and YM155 in U937 cells was dependent on elevated SLC35F2 expression. Additionally, YM155 facilitated DAC-induced degradation of MCL1 and survivin. A similar mechanism explained DAC/YM155-mediated cytotoxicity in AML HL-60 cells. Our data demonstrated that the synergistic cytotoxicity of DAC and YM155 in AML cell lines U937 and HL-60 is dependent on AKT- and p38 MAPK-mediated upregulation of SLC35F2 and p38 MAPK-mediated degradation of survivin and MCL1. This indicates that a treatment regimen that amalgamates YM155 and DAC may be beneficial for AML.

How I treat refractory and relapsed acute myeloid leukemia

ABSTRACT

Most patients with acute myeloid leukemia (AML) develop refractory/relapsed (R/R) disease even in the presence of novel and targeted therapies. Given the biological complexity of the disease and differences in frontline treatments, there are therapies approved for only subgroups of R/R AML, and enrollment in clinical trials should be first priority. Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative strategy for most patients. Therapeutic approaches, including allogeneic HCT, triggered by the presence of measurable residual disease (MRD), have recently evolved to prevent overt hematologic relapse. Salvage therapy with chemotherapy or targeted therapy is frequently administered before HCT to reduce the leukemic burden. Gilteritinib is approved by the Food and Drug Administration and European Medicines Agency for patients with relapsed FLT3 mutated AML, whereas targeted therapy for relapsed IDH1/2 mutated AML has only FDA approval. Patients who are R/R after azacitidine and venetoclax (AZA/VEN) have a dismal outcome. In this setting, even available targeted therapies show unsatisfactory results. Examples of ongoing developments include menin inhibitors, a targeted therapy for patients with mutated NPM1 or KMT2A rearrangements, antibodies targeting the macrophage immune checkpoint CD47, and triple combinations involving AZA/VEN. The latter cause significant myelosuppressive effects, which make it challenging to find the right schedule and dose.

Venetoclax and Hypomethylating Agent Combination in Myeloid Malignancies: Mechanisms of Synergy and Challenges of Resistance

There has been a widespread adoption of hypomethylating agents (HMA: 5-Azacytidine (5-Aza)/decitabine) and venetoclax (Ven) for the treatment of acute myeloid leukemia (AML); however, the mechanisms behind the combination's synergy are poorly understood. Monotherapy often encounters resistance, leading to suboptimal outcomes; however, the combination of HMA and Ven has demonstrated substantial improvements in treatment responses. This study elucidates multiple synergistic pathways contributing to this enhanced therapeutic effect. Key mechanisms include HMA-mediated downregulation of anti-apoptotic proteins, notably MCL-1, and the priming of cells for Ven through the induction of genes encoding pro-apoptotic proteins such as Noxa. Moreover, Ven induces sensitization to HMA, induces overcoming resistance by inhibiting the DHODH enzyme, and disrupts antioxidant pathways (Nrf2) induced by HMA. The combination further disrupts oxidative phosphorylation in leukemia stem cells, amplifying the therapeutic impact. Remarkably, clinical studies have revealed a favorable response, particularly in patients harboring specific mutations, such as IDH1/2, NPM1, CEBPA, or ASXL1. This prompts future studies to explore the nuanced underpinnings of these synergistic mechanisms in AML patients with these molecular signatures.

PLK1 as a cooperating partner for BCL2-mediated antiapoptotic program in leukemia

The deregulation of BCL2 family proteins plays a crucial role in leukemia development. Therefore, pharmacological inhibition of this family of proteins is becoming a prevalent treatment method. However, due to the emergence of primary and acquired resistance, efficacy is compromised in clinical or preclinical settings. We developed a drug sensitivity prediction model utilizing a deep tabular learning algorithm for the assessment of venetoclax sensitivity in T-cell acute lymphoblastic leukemia (T-ALL) patient samples. Through analysis of predicted venetoclax-sensitive and resistant samples, PLK1 was identified as a cooperating partner for the BCL2-mediated antiapoptotic program. This finding was substantiated by additional data obtained through phosphoproteomics and high-throughput kinase screening. Concurrent treatment using venetoclax with PLK1-specific inhibitors and PLK1 knockdown demonstrated a greater therapeutic effect on T-ALL cell lines, patient-derived xenografts, and engrafted mice compared with using each treatment separately. Mechanistically, the attenuation of PLK1 enhanced BCL2 inhibitor sensitivity through upregulation of BCL2L13 and PMAIP1 expression. Collectively, these findings underscore the dependency of T-ALL on PLK1 and postulate a plausible regulatory mechanism.

Targeting NEDD8-activating enzyme for cancer therapy: developments, clinical trials, challenges and future research directions

NEDDylation, a post-translational modification through three-step enzymatic cascades, plays crucial roles in the regulation of diverse biological processes. NEDD8-activating enzyme (NAE) as the only activation enzyme in the NEDDylation modification has become an attractive target to develop anticancer drugs. To date, numerous inhibitors or agonists targeting NAE have been developed. Among them, covalent NAE inhibitors such as MLN4924 and TAS4464 currently entered into clinical trials for cancer therapy, particularly for hematological tumors. This review explains the relationships between NEDDylation and cancers, structural characteristics of NAE and multistep mechanisms of NEDD8 activation by NAE. In addition, the potential approaches to discover NAE inhibitors and detailed pharmacological mechanisms of NAE inhibitors in the clinical stage are explored in depth. Importantly, we reasonably investigate the challenges of NAE inhibitors for cancer therapy and possible development directions of NAE-targeting drugs in the future.

A phase 1/2 study of azacitidine, venetoclax and pevonedistat in newly diagnosed secondary AML and in MDS or CMML after failure of hypomethylating agents

BACKGROUND

Pevonedistat is a first-in-class, small molecular inhibitor of NEDD8-activating enzyme that has clinical activity in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Preclinical data suggest synergy of pevonedistat with azacitidine and venetoclax.

METHODS

This single-center, phase 1/2 study evaluated the combination of azacitidine, venetoclax and pevonedistat in older adults with newly diagnosed secondary AML or with MDS or chronic myelomonocytic leukemia (CMML) after failure of hypomethylating agents. Patients received azacitidine 75 mg/m2 IV on days 1-7, venetoclax at maximum dose of 200-400 mg orally on days 1-21 (AML cohort) or days 1-14 (MDS/CMML cohort) and pevonedistat 20 mg/m2 IV on days 1, 3 and 5 for up to 24 cycles. The primary endpoints for the phase 2 portion of the study were the CR/CRi rate in the AML cohort and the overall response rate (CR + mCR + PR + HI) in the MDS/CMML cohort.

FINDINGS

Forty patients were enrolled (32 with AML and 8 with MDS/CMML). In the AML cohort, the median age was 74 years (range 61-86 years), and 27 patients (84%) had at least one adverse risk cyto-molecular feature, including 15 (47%) with a TP53 mutation or MECOM rearrangement; seventeen patients (53%) had received prior therapy for a preceding myeloid disorder. The CR/CRi rate was 66% (CR 50%; CRi 16%), and the median overall survival (OS) was 8.1 months. In the MDS/CMML cohort, 7 patients (87%) were high or very high risk by the IPSS-R. The overall response rate was 75% (CR 13%; mCR with or without HI 50%; HI 13%). The most common grade 3-4 adverse events were infection in 16 patients (35%), febrile neutropenia in 10 patients (25%) and hypophosphatemia in 9 patients (23%). In an exploratory analysis, early upregulation of NOXA expression was observed, with subsequent decrease in MCL-1 and FLIP, findings consistent with preclinical mechanistic studies of pevonedistat. Upregulation of CD36 was observed, which may have contributed to therapeutic resistance.

CONCLUSIONS

The triplet combination of azacitidine, venetoclax and pevonedistat shows encouraging activity in this very poor-risk population of patients with AML, MDS or CMML. Trial registration ClinicalTrials.gov (NCT03862157).

TP53-Mutated Myelodysplasia and Acute Myeloid Leukemia

TP53-mutated myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) form a distinct and heterogeneous group of myeloid malignancies associated with poor outcomes. Studies carried out in the last years have in part elucidated the complex role played by TP53 mutations in the pathogenesis of these myeloid disorders and in the mechanisms of drug resistance. A consistent number of studies has shown that some molecular parameters, such as the presence of a single or multiple TP53 mutations, the presence of concomitant TP53 deletions, the association with co-occurring mutations, the clonal size of TP53 mutations, the involvement of a single (monoallelic) or of both TP53 alleles (biallelic) and the cytogenetic architecture of concomitant chromosome abnormalities are major determinants of outcomes of patients. The limited response of these patients to standard treatments, including induction chemotherapy, hypomethylating agents and venetoclax-based therapies and the discovery of an immune dysregulation have induced a shift to new emerging therapies, some of which being associated with promising efficacy. The main aim of these novel immune and nonimmune strategies consists in improving survival and in increasing the number of TP53-mutated MDS/AML patients in remission amenable to allogeneic stem cell transplantation.

Novel Investigational Agents and Pathways That May Influence the Future Management of Acute Myeloid Leukemia

Acute Myeloid leukemia (AML) is a clinically heterogeneous disease with a 5-year overall survival of 32% between 2012 to 2018. The above number severely dwindles with age and adverse risk of disease, presenting opportunities for new drug development and is an area of dire unmet need. Basic science and clinical investigators across the world have been working on many new and old molecule formulations and combination strategies to improve outcomes in this disease. In this review, we discuss select promising novel agents in various stages of clinical development for patients with AML.

Targeting a mitochondrial E3 ubiquitin ligase complex to overcome AML cell-intrinsic Venetoclax resistance

To identify molecules/pathways governing Venetoclax (VEN) sensitivity, we performed genome-wide CRISPR/Cas9 screens using a mouse AML line insensitive to VEN-induced mitochondrial apoptosis. Levels of sgRNAs targeting March5, Ube2j2 or Ube2k significantly decreased upon VEN treatment, suggesting synthetic lethal interaction. Depletion of either Ube2j2 or Ube2k sensitized AML cells to VEN only in the presence of March5, suggesting coordinate function of the E2s Ube2j2 and Ube2k with the E3 ligase March5. We next performed CRISPR screens using March5 knockout cells and identified Noxa as a key March5 substrate. Mechanistically, Bax released from Bcl2 upon VEN treatment was entrapped by Mcl1 and Bcl-XL and failed to induce apoptosis in March5 intact AML cells. By contrast, in March5 knockout cells, liberated Bax did not bind to Mcl1, as Noxa likely occupied Mcl1 BH3-binding grooves and efficiently induced mitochondrial apoptosis. We reveal molecular mechanisms underlying AML cell-intrinsic VEN resistance and suggest a novel means to sensitize AML cells to VEN.

Targeting Apoptosis in AML: Where Do We Stand?

Simple Summary

In patients with acute myeloid leukemia (AML), genetic mutations can cause cells to evade regulated cell death (RCD), resulting in excessive cell proliferation. The best-known form of RCD is apoptosis, which prevents the emergence of cancer cells; disturbances in this process are an important factor in the development and progression of AML. Clearly, it is essential to understand the mechanisms of apoptosis to establish a personalized, patient-specific approach in AML therapy. Therefore, this paper comprehensively reviews the current range of AML treatment approaches related to apoptosis and highlights other promising concepts such as neddylation.

Abstract

More than 97% of patients with acute myeloid leukemia (AML) demonstrate genetic mutations leading to excessive proliferation combined with the evasion of regulated cell death (RCD). The most prominent and well-defined form of RCD is apoptosis, which serves as a defense mechanism against the emergence of cancer cells. Apoptosis is regulated in part by the BCL-2 family of pro- and anti-apoptotic proteins, whose balance can significantly determine cell survival. Apoptosis evasion plays a key role in tumorigenesis and drug resistance, and thus in the development and progression of AML. Research on the structural and biochemical aspects of apoptosis proteins and their regulators offers promise for new classes of targeted therapies and strategies for therapeutic intervention. This review provides a comprehensive overview of current AML treatment options related to the mechanism of apoptosis, particularly its mitochondrial pathway, and other promising concepts such as neddylation. It pays particular attention to clinically-relevant aspects of current and future AML treatment approaches, highlighting the molecular basis of individual therapies.

Inhibition of NEDD8 NEDDylation induced apoptosis in acute myeloid leukemia cells via p53 signaling pathway

MLN4924 is a potent and selective small-molecule inhibitor of NEDD8-activating enzyme, which showed antitumor effect in several types of malignant tumor types. However, the mechanism of action of MLN4924 in acute myeloid leukemia (AML) requires further investigation. Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) was conducted to detect the mRNA levels of genes. Gene expression was knocked down by short hairpin RNA (shRNA). Moreover, the protein expression was detected by Western blotting (WB) assay. The proliferation and apoptosis of AML cells were measured by Cell Counting Kit-8 (CCK8) assay and flow cytometry (FCM). In the present study, we observed that the mRNA expression levels of NEDD8, UBA3, UBE2M and RBX1 in AML patients were up-regulated compared with healthy controls, which were correlated with worse overall survival (OS) of patients. Besides, knockdown of UBA3, UBE2M and RBX1 inhibited the NEDDylation of CULs and increased the protein expression of p53 and p21 in MOLM-13 cell line. In AML cells, MLN4924 inhibited cell proliferation, promoted cell apoptosis, and induced cell cycle arrest at the G₂/M phase. As revealed by experiments in vivo and in vitro, the NEDDylation of CULs was significantly inhibited and the p53 signaling pathway was activated after MLN4924 treatment. So, we concluded that NEDD8, UBA3, UBE2M and RBX1 may serve as the prognostic biomarkers and novel therapeutic targets for AML. Inhibition of the NEDDylation pathway resulted in an anti-leukemia effect by activating the p53 signaling pathway.

The development of pevonedistat in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML): hope or hype?

Myelodysplastic syndrome (MDS) is a clonal hematopoietic stem cell disorder clinically defined by cytopenias, bone marrow failure, and an increased risk of progressing to acute myeloid leukemia (AML). Traditionally, first-line treatment for patients with higher-risk MDS has been hypomethylating agents (HMAs). However, these agents have modest clinical activity as single agents. A one-size-fits-all treatment paradigm is insufficient for such a heterogeneous disease in the modern era of precision medicine. Several new agents have been developed for MDS with the hopes of improving clinical outcomes and survival. Pevonedistat is a first-in-class, novel inhibitor of neuronal precursor cell-expressed developmentally down-regulated protein-8 (NEDD8) activating enzyme (NAE) blocking the neddylation pathway leading to downstream effects on the ubiquitin-proteosome pathway. Pevonedistat ultimately leads to apoptosis and inhibition of the cell cycle in cancer cells. Studies have demonstrated the safety profile of pevonedistat, leading to the development of multiple trials investigating combination strategies with pevonedistat in MDS and AML. In this review, we summarize the preclinical and clinical rationale for pevonedistat in MDS and AML, review the clinical data of this agent alone and in combination with HMAs to date, and highlight potential future directions for this agent in myeloid malignancies.

Are We Moving the Needle for Patients with TP53-Mutated Acute Myeloid Leukemia?

The currently available therapeutic options for patients with TP53-mutated acute myeloid leukemia (AML) are insufficient, as they translate to a median overall of only 6-9 months, and less than 10% of patients undergoing the most aggressive treatments, such as intensive induction therapy and allogeneic hematopoietic stem cell transplantation, will be cured. The lack of clear differences in outcomes with different treatments precludes the designation of a standard of care. Recently, there has been growing attention on this critical area of need by way of better understanding the biology of TP53 alterations and the disparities in outcomes among patients in this molecular subgroup, reflected in the development and testing of agents with novel mechanisms of action. Promising preclinical and efficacy data exist for therapies that are directed at the p53 protein rendered dysfunctional via mutation or that inhibit the CD47/SIRPα axis or other immune checkpoints such as TIM-3. In this review, we discuss recently attractive and emerging therapeutic agents, their preclinical rationale and the available clinical data as a monotherapy or in combination with the currently accepted backbones in frontline and relapsed/refractory settings for patients with TP53-mutated AML.

Cost-effectiveness analysis of azacitidine maintenance therapy in patients with acute myeloid leukemia

BACKGROUND

The QUAZAR AML-001 trial (NCT01757535) showed survival benefits with the maintenance treatment of oral azacitidine(CC-486) for acute myeloid leukemia(AML) in first complete remission. We conducted a cost-effectiveness analysis to explore the costs and benefits of oral azacitidine in AML from the perspective of payers in the United States.

METHODS

We constructed a Markov model to evaluate the economic value of oral azacitidine. The model was conducted with a 10-year time horizon. The health utility scores and until prices of medical costs were acquired from previous studies and GoodRX. The transition probabilities were derived from the survival curves of the QUAZAR AML-001 study. Outcomes were measured in quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER).

RESULTS

Compared with placebo, oral azacitidine improved 0.39 QALY, with an increasing cost of $458928.66. The ICER of oral azacitidine is $1176740.15, higher than the willingness to pay (P < 0.05). Deterministic sensitivity analysis showed that the price of oral azacitidine has a significant impact on ICERs (P < 0.05). Probability sensitivity analysis showed that the probability of cost-effectiveness for oral azacitidine is 0.

CONCLUSION

In the United States, oral azacitidine is unlikely to be cost-effective for AML patients at current prices.

CLINICAL TRIAL REGISTRATION

The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT01757535).

The manipulation of apoptosis for cancer therapy using BH3-mimetic drugs

Apoptosis is a form of programmed cell death that is regulated by the balance between prosurvival and proapoptotic BCL-2 protein family members. Evasion of apoptosis is a hallmark of cancer that arises when this balance is tipped in favour of survival. One form of anticancer therapeutic, termed 'BH3-mimetic drugs', has been developed to directly activate the apoptosis machinery in malignant cells. These drugs bind to and inhibit specific prosurvival BCL-2 family proteins, thereby mimicking their interaction with the BH3 domains of proapoptotic BCL-2 family proteins. The BCL-2-specific inhibitor venetoclax is approved by the US Food and Drug Administration and many regulatory authorities worldwide for the treatment of chronic lymphocytic leukaemia and acute myeloid leukaemia. BH3-mimetic drugs targeting other BCL-2 prosurvival proteins have been tested in preclinical models of cancer, and drugs targeting MCL-1 or BCL-X_L have advanced into phase I clinical trials for certain cancers. As with all therapeutics, efficacy and tolerability need to be carefully balanced to achieve a therapeutic window whereby there is significant anticancer activity with an acceptable safety profile. In this Review, we outline the current state of BH3-mimetic drugs targeting various prosurvival BCL-2 family proteins and discuss emerging data regarding primary and acquired resistance to these agents and approaches that may overcome this. We highlight issues that need to be addressed to further advance the clinical application of BH3-mimetic drugs, both alone and in combination with additional anticancer agents (for example, standard chemotherapeutic drugs or inhibitors of oncogenic kinases), for improved responses in patients with cancer.

What to use to treat AML: the role of emerging therapies

The development and approval of novel substances have resulted in substantial improvements in the treatment of acute myeloid leukemia (AML). In the current era of novel treatment options, genetic and molecular testing at the time of diagnosis and relapse becomes increasingly relevant. Midostaurin in combination with intensive chemotherapy is the standard of care as upfront therapy in younger AML patients with mutated fms-related tyrosine kinase 3 (FLT3). Gilteritinib, a second- generation FLT3 inhibitor, represents a key drug for relapsed/refractory (R/R) FLT3-mutated AML patients. Targeted therapy has also been developed for patients with mutated isocitrate dehydrogenase 1 (IDH1) and IDH2. The US Food and Drug Administration (FDA) approved ivosidenib as a monotherapy for newly diagnosed older adult IDH1-mutated patients and enasidenib for R/R IDH2-mutated AML patients. CPX-351, a liposomal formulation of daunorubicin and cytarabine, has become an important upfront treatment strategy for fit patients with therapy-related AML or AML with myelodysplasia-related changes that are generally challenging to treat. The antibody drug conjugate gemtuzumab ozogamicin was approved in combination with intensive therapy for patients with newly diagnosed (FDA/European Medicines Agency [EMA]) as well as R/R CD33+ AML. The combination of venetoclax, an oral selective B-cell leukemia/lymphoma-2 inhibitor, with hypomethylating agents or low-dose AraC (LDAC) has changed the treatment landscape and prognosis for older adult patients very favorably. The addition of glasdegib, a small-molecule hedgehog inhibitor, to LDAC is another example of novel options in older patients. Further substances have shown promising results in early clinical trials.

Venetoclax in Acute Myeloid Leukemia: Molecular Basis, Evidences for Preclinical and Clinical Efficacy and Strategies to Target Resistance

Venetoclax is a BH3-mimetics agent specifically interacting with the antiapoptotic protein BCL-2, facilitating cytochrome c release from mitochondria, subsequent caspases activation, and cell death. Utilization of venetoclax has profoundly changed the landscape of treatment for the poor-prognosis category of AML patients unfit for intensive chemotherapy. In the phase III VIALE-A study, Venetoclax, in combination with the hypomethylating agent azacitidine, showed a 65% overall response rate and 14.7-month overall survival, in comparison with 22% and 8 months in the control arm. These results led to the widespread use of venetoclax in this indication. Other combination regimens, consisting of low-intensity, intensive, or targeted therapies are currently under evaluation. Despite promising results, preventing relapses or resistance to venetoclax is still an unmet clinical need. Numerous studies have been conducted to identify and overcome venetoclax resistance in preclinical models or in clinical trials, including the inhibition of other antiapoptotic proteins, the induction of proapoptotic BH3-only proteins, and/or the targeting of the mitochondrial metabolism and machinery.