Venetoclax and hypomethylating agents in TP53-mutated acute myeloid leukaemia

TP53 mutations in myeloid neoplasms: implications for accurate laboratory detection, diagnosis, and treatment

Genetic alterations that affect the function of p53 tumor suppressor have been extensively investigated in myeloid neoplasms, revealing their significant impact on disease progression, treatment response, and patient outcomes. The identification and characterization of TP53 mutations play pivotal roles in subclassifying myeloid neoplasms and guiding treatment decisions. Starting with the presentation of a typical case, this review highlights the complicated nature of genetic alterations involving TP53 and provides a comprehensive analysis of TP53 mutations and other alterations in myeloid neoplasms. Currently available methods used in clinical laboratories to identify TP53 mutations are discussed, focusing on the importance of establishing a robust testing protocol within clinical laboratories to ensure the delivery of accurate and reliable results. The treatment implications of TP53 mutations in myeloid neoplasms and clinical trial options are reviewed. Ultimately, we hope that this review provides valuable insights into the patterns of TP53 alterations in myeloid neoplasms and offers guidance to establish practical laboratory testing protocols to support the best practices of precision oncology.

Novel insights and therapeutic approaches in secondary AML

Secondary acute myeloid leukemia (sAML) presents as a complex and multifaceted ensemble of disorders, positioning itself as both a challenge and an intriguing frontier within hematologic oncology. Its origins are diverse, stemming from antecedent hematologic conditions, germline predisposing mutations, or the sequelae of cytotoxic therapies, and its development is driven by intricate genetic and epigenetic modifications. This complexity necessitates a diverse array of therapeutic strategies, each meticulously tailored to address the distinctive challenges sAML introduces. Such strategies require a personalized approach, considering the variegated clinical backgrounds of patients and the inherent intricacies of the disease. Allogeneic stem cell transplantation stands as a cornerstone, offering the potential for curative outcomes. This is complemented by the emergence of innovative treatments such as CPX-351, venetoclax, and glasdegib, which have demonstrated promising results in enhancing prognosis. The evolving landscape of sAML treatment underscores the importance of continued research and innovation in the field, aiming not only to improve patient outcomes but also to deepen our understanding of the disease's biological underpinnings, thereby illuminating pathways toward more effective and individualized therapies.

Therapy-Related Myeloid Neoplasm: Biology and Mechanistic Aspects of Malignant Progression

Therapy-related myeloid neoplasms (t-MN) arise after a documented history of chemo/radiotherapy as treatment for an unrelated condition and account for 10-20% of myelodysplastic syndromes and acute myeloid leukemia. T-MN are characterized by a specific genetic signature, aggressive features and dismal prognosis. The nomenclature and the subsets of these conditions have changed frequently over time, and despite the fact that, in the last classification, they lost their autonomous entity status and became disease qualifiers, the recognition of this feature remains of major importance. Furthermore, in recent years, extensive studies focusing on clonal hematopoiesis and germline variants shed light on the mechanisms of positive pressure underpinning the rise of driver gene mutations in t-MN. In this manuscript, we aim to review the evolution of defining criteria and characteristics of t-MN from a clinical and biological perspective, the advances in mechanistic aspects of malignant progression and the challenges in prevention and management.

TP53 in MDS and AML: Biological and clinical advances

Recently, the WHO-5 and the ICC 2022 criteria have emphasized poor prognosis in AML/MDS patients with multi-hit TP53 mutations, whereas mutated TP53 plays a critical role in tumorigenesis, drawing substantial interest in exploring its biological behaviors. Diverse characteristics of TP53 mutations, including types, VAF, CNVs, allelic status, karyotypes, and concurrent mutations have been extensively studied. Novel potential targets and comprehensive treatment strategies nowadays are under swift development, owing to great advances in technology. However, accurately predicting prognosis of patients with TP53-mutated myeloid neoplasms remains challenging. And there is still a lack of effective treatment for those patients.

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

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

Real-world results of venetoclax combined with hypomethylating agents in young adults with relapsed/refractory acute myeloid leukemia

OBJECTIVES

Young adults with acute myeloid leukemia (AML) often fail to achieve permanent complete remission (CR) and frequently relapse, indicating an urgent need to explore effective salvage therapies. Recent advances in AML treatment have been attributed to the combination of the B-cell lymphoma 2 (Bcl-2) inhibitor venetoclax (VEN) with hypomethylating agents (HMAs); however, the use of this combination in young adults with relapsed or refractory (R/R) AML has not been reported.

METHODS

We retrospectively examined 31 young patients with R/R AML treated with VEN plus an HMA. We evaluated the demographic data, cytogenetic characteristics, AML types, response rates, and transplantation-related data for the patients in our cohort.

RESULTS

The combination of VEN + HMA yielded a CR rate of 48.4%. The most prominent hematologic adverse event was neutropenia, which occurred in all patients, with 90.3% of cases being grade ≥3. Non-hematologic toxicities were relatively mild and infrequent, with an incidence of 45.2%. More than half of the patients with sustained CR had received an allogeneic hematopoietic stem cell transplantation (allo-HSCT), of whom two died of transplant-related complications.

CONCLUSION

Our results showed that the combination of VEN + HMA appeared to be a highly effective and well-tolerated salvage therapy option for young patients with R/R AML, enabling more young patients to proceed to potentially curative allo-HSCT. However, additional, well-designed studies with larger numbers of patients are required to confirm the advantages of VEN + HMA in this population.

Targeting apoptosis dysregulation in myeloid malignancies - The promise of a therapeutic revolution

In recent years, the therapeutic landscape of myeloid malignancies has been completely revolutionized by the introduction of several new drugs, targeting molecular alterations or pathways crucial for leukemia cells survival. Particularly, many agents targeting apoptosis have been investigated in both pre-clinical and clinical studies. For instance, venetoclax, a pro-apoptotic agent active on BCL-2 signaling, has been successfully used in the treatment of acute myeloid leukemia (AML). The impressive results achieved in this context have made the apoptotic pathway an attractive target also in other myeloid neoplasms, translating the experience of AML. Therefore, several drugs are now under investigation either as single or in combination strategies, due to their synergistic efficacy and capacity to overcome resistance. In this paper, we will review the mechanisms of apoptosis and the specific drugs currently used and under investigation for the treatment of myeloid neoplasia, identifying critical research necessities for the upcoming years.

Current Advances and Future Strategies for BCL-2 Inhibitors: Potent Weapons against Cancers

Targeting the intrinsic apoptotic pathway regulated by B-cell lymphoma-2 (BCL-2) antiapoptotic proteins can overcome the evasion of apoptosis in cancer cells. BCL-2 inhibitors have evolved into an important means of treating cancers by inducing tumor cell apoptosis. As the most extensively investigated BCL-2 inhibitor, venetoclax is highly selective for BCL-2 and can effectively inhibit tumor survival. Its emergence and development have significantly influenced the therapeutic landscape of hematological malignancies, especially in chronic lymphocytic leukemia and acute myeloid leukemia, in which it has been clearly incorporated into the recommended treatment regimens. In addition, the considerable efficacy of venetoclax in combination with other agents has been demonstrated in relapsed and refractory multiple myeloma and certain lymphomas. Although venetoclax plays a prominent antitumor role in preclinical experiments and clinical trials, large individual differences in treatment outcomes have been characterized in real-world patient populations, and reduced drug sensitivity will lead to disease recurrence or progression. The therapeutic efficacy may vary widely in patients with different molecular characteristics, and key genetic mutations potentially result in differential sensitivities to venetoclax. The identification and validation of more novel biomarkers are required to accurately predict the effectiveness of BCL-2 inhibition therapy. Furthermore, we summarize the recent research progress relating to the use of BCL-2 inhibitors in solid tumor treatment and demonstrate that a wealth of preclinical models have shown promising results through combination therapies. The applications of venetoclax in solid tumors warrant further clinical investigation to define its prospects.

In Vitro Insights Into the Influence of Marrow Mesodermal/Mesenchymal Progenitor Cells on Acute Myelogenous Leukemia and Myelodysplastic Syndromes

The study of marrow-resident mesodermal progenitors can provide important insight into their role in influencing normal and aberrant hematopoiesis as occurs in acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS). In addition, the chemokine competency of these cells provides links to the inflammatory milieu of the marrow microenvironment with additional implications for normal and malignant hematopoiesis. While in vivo studies have elucidated the structure and function of the marrow niche in murine genetic models, corollary human studies have not been feasible, and thus the use of culture-adapted mesodermal cells has provided insights into the role these rare endogenous niche cells play in physiologic, malignant, and inflammatory states. This review focuses on culture-adapted human mesenchymal stem/stromal cells (MSCs) as they have been utilized in understanding their influence in AML and MDS as well as on their chemokine-mediated responses to myeloid malignancies, injury, and inflammation. Such studies have intrinsic limitations but have provided mechanistic insights and clues regarding novel druggable targets.

15-days duration of venetoclax combined with azacitidine in the treatment of relapsed/refractory high-risk myelodysplastic syndromes: A retrospective single-center study

The treatment of patients with refractory and/or relapsed (R/R) high-risk myelodysplastic syndrome (HR-MDS) remains a daunting clinical challenge. Venetoclax is a selective BCL-2 inhibitor, which combined with hypomethylating agents (HMAs), increased responses and prolonged survival in unfit and previously untreated acute myeloid leukemia. We performed a retrospective study of patients with R/R HR-MDS receiving combination azacytidine (AZA) plus 15-days duration of venetoclax (VEN-15d) in order to determine their efficacy and toxicity in this context. We showed that the overall response rate was 57.2% (20/35) and the median over survival was 14 months in R/R MDS. The most common treatment-emergent adverse events were peripheral blood cytopenias and infectious complications. Our retrospective study showed that the real-world experience of treating R/R MDS with AZA plus VEN-15d highlights an encouraging response rate with myelosuppression being the major toxicity. Of note, VEN-15d with AZA may salvage patients failing to respond optimally to HMAs and reduce the disease-burden for subsequent allogeneic stem cell transplantation in our analysis. These data of combination AZA plus VEN-15d in R/R MDS warrant further prospective evaluation in clinical trials.

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.

TP53 in AML and MDS: The new (old) kid on the block

MDS and AML are clonal hematopoietic stem cell disorders of increasing incidence, having a variable prognosis based, among others, on co-occurring molecular abnormalities. TP53 mutations are frequently detected in these myeloid neoplasms and portend a poor prognosis with known therapeutic resistance. This article provides a timely review of the complexity of TP53 alterations, providing updates in diagnosis and prognosis based on new 2022 International Consensus Classification (ICC) and World Health Organization (WHO) guidelines. The article addresses optimal testing strategies and reviews current and arising therapeutic approaches. While the treatment landscape for this molecular subgroup is under active development, further exploration is needed to optimize the care of this group of patients with unmet needs.

The Role of Venetoclax in Relapsed/Refractory Acute Myeloid Leukemia: Past, Present, and Future Directions

Relapsed and/or refractory (R/R) acute myeloid leukemia (AML) is hallmarked by dramatic prognosis. Treatment remains challenging, with allogeneic hematopoietic stem cell transplantation (HSCT) as the only curative option. The BCL-2 inhibitor venetoclax (VEN) has proven to be a promising therapy for AML and is currently the standard of care in combination with hypomethylating agents (HMAs) for newly diagnosed AML patients ineligible for induction chemotherapy. Given its satisfactory safety profile, VEN-based combinations are increasingly being investigated as a part of the therapeutic strategy for R/R AML. The current paper aims to provide a comprehensive review of the main evidence regarding VEN in the setting of R/R AML, with a specific focus on combinational strategies, including HMAs and cytotoxic chemotherapy, as well as different clinical settings, especially in view of the crucial role of HSCT. A discussion of what is known about drug resistance mechanisms and future combinational strategies is also provided. Overall, VEN-based regimes (mainly VEN + HMA) have provided unprecedented salvage treatment opportunities in patients with R/R AML, with low extra-hematological toxicity. On the other hand, the issue of overcoming resistance is one of the most important fields to be addressed in upcoming clinical research.

Eprenetapopt combined with venetoclax and azacitidine in TP53-mutated acute myeloid leukaemia: a phase 1, dose-finding and expansion study

BACKGROUND

TP53-mutated acute myeloid leukaemia is associated with poor outcomes. Eprenetapopt (APR-246) is a first-in-class, small-molecule p53 reactivator. We aimed to evaluate the combination of eprenetapopt and venetoclax with or without azacitidine in patients with TP53-mutated acute myeloid leukaemia.

METHODS

This phase 1, multicentre, open-label, dose-finding and cohort expansion study was done at eight academic research hospitals in the USA. Inclusion criteria were age of at least 18 years; at least one pathogenic TP53 mutation; treatment-naive acute myeloid leukaemia according to the 2016 WHO classification; an ECOG performance status of 0-2; and a life expectancy of at least 12 weeks. In dose-finding cohort 1 patients received previous therapy with hypomethylating agents for myelodysplastic syndromes. In dose-finding cohort 2, previous use of hypomethylating agents was not permitted. Treatment cycles were 28 days. Patients in cohort 1 received intravenous eprenetapopt 4·5 g/day on days 1-4 and oral venetoclax 400 mg/day on days 1-28; those in cohort 2 also received subcutaneous or intravenous azacitidine 75 mg/m² on days 1-7. The expansion part of the study proceeded with patients enrolled as in cohort 2. Primary endpoints were safety in all cohorts (assessed in patients receiving at least one dose of assigned treatment) and complete response in the expansion cohort (assessed in patients who completed at least one treatment cycle and had at least one post-treatment clinical response assessment). The trial is registered with ClinicalTrials.gov, NCT04214860, and is complete.

FINDINGS

Between Jan 3, 2020, and July 22, 2021, 49 patients were enrolled across all cohorts. Six patients were initially enrolled into each of dose-finding cohorts 1 and 2; after no dose-limiting toxicities were observed, cohort 2 was expanded to enrol an additional 37 patients. The median age was 67 years (IQR 59-73). 24 (49%) of 49 patients were female and 25 (51%) male, and 40 (82%) were White. At data cutoff (Oct 1, 2021), the median length of follow-up was 9·5 months (IQR 6·1-11·5). No dose-limiting toxicities were recorded and the recommended phase 2 dose for eprenetapopt combinations was 4·5 g/day on days 1-4. Across all patients, adverse events of grade 3 or worse occurring in at least 20% of patients were febrile neutropenia (23 [47%] of 49 patients), thrombocytopenia (18 [37%] patients), leukopenia (12 [25%] patients), and anaemia (11 [22%] patients). Treatment-related serious adverse events occurred in 13 (27%) of 49 patients and there was one (2%) treatment-related death (sepsis). 25 (64%, 95% CI 47-79) of 39 patients had an overall response with eprenetapopt and venetoclax with azacytidine; 15 (38%, 23-55) had a complete response.

INTERPRETATION

Eprenetapopt and venetoclax with azacitidine had an acceptable safety profile and encouraging activity, supporting further frontline evaluation of this combination in the treatment of TP53-mutated acute myeloid leukaemia.

FUNDING

Aprea Therapeutics.

Novel high-risk acute myeloid leukemia subgroup with ERG amplification and Biallelic loss of TP53

ETS-related gene (ERG) amplification, observed in 4-6% of acute myeloid leukemia (AML), is associated with unfavorable prognosis. To determine coincident effects of additional genomic abnormalities in AML with ERG amplification (ERGamp), we examined 11 ERGamp cases of 205 newly diagnosed AML using chromosomal microarray analysis and next generation sequencing. ERGamp cases demonstrated a distinct pattern of high genetic complexity: loss of 5q, chromothripsis and TP53 loss of function variants. Remarkably, allelic TP53 loss or loss of heterozygosity (LOH) co-occurring with TP53 inactivating mutation dramatically effected ERGamp tumor patient outcome. In the presence of homozygous TP53 loss of function, ERGamp patients demonstrated no response to induction chemotherapy with median overall survival (OS) of 3.8 months (N = 9). Two patients with heterozygous loss of TP53 function underwent alloSCT without evidence of relapse at one year. Similarly, a validation TCGA cohort, 6 of the 8 ERGamp cases with TP53 loss of function demonstrated median OS of 2.5 months. This suggests that with TP53 mutant ERGamp AML, successive loss of the second TP53 allele, typically by 17p deletion or LOH identifies a specific high-risk subtype of AML patients who are resistant to standard induction chemotherapy and need novel approaches to avert the very poor prognosis.

AVALON: The Italian cohort study on real-life efficacy of hypomethylating agents plus venetoclax in newly diagnosed or relapsed/refractory patients with acute myeloid leukemia

BACKGROUND

Venetoclax in combination with hypomethylating agents (HMA) is revolutionizing the therapy of acute myeloid leukemia (AML). However, evidence on large sets of patients is lacking, especially in relapsed or refractory leukemia.

METHODS

AVALON is a multicentric cohort study that was conducted in Italy on patients with AML who received venetoclax-based therapies from 2015 to 2020. The study was approved by the ethics committee of the participating institution and was conducted in accordance with the Declaration of Helsinki. The effectiveness and toxicity of venetoclax + HMA in 190 (43 newly diagnosed, 68 refractory, and 79 relapsed) patients with AML are reported here.

RESULTS

In the newly diagnosed AML, the overall response rate and survival confirmed the brilliant results demonstrated in VIALE-A. In the relapsed or refractory AML, the combination demonstrated a surprisingly complete remission rate (44.1% in refractory and 39.7% in relapsed evaluable patients) and conferred to treated patients a good expectation of survival. Toxicities were overall manageable, and most incidents occurred in the first 60 days of therapy. Infections were confirmed as the most common nonhematologic adverse event.

CONCLUSIONS

Real-life data show that the combination of venetoclax and HMA offers an expectation of remission and long-term survival to elderly, newly diagnosed patients, and to relapsed or chemoresistant AML, increasing the chance of cure through a different mechanism of action. The venetoclax + HMA combination is expected to constitute the base for triplet combinations and integration of target therapies. Our data contribute to ameliorate the understanding of venetoclax + HMA effectiveness and toxicities in real life.

Therapeutic approaches for the management of higher risk myelodysplastic syndromes

The heterogeneous nature of myelodysplastic syndromes (MDS) demands a risk-adapted therapeutic approach, and higher risk MDS, characterized by an increased risk of transformation into acute myeloid leukemia and inferior survival, is typically defined based on an integrated assessment of cytopenias, bone marrow blast percentage, and cytogenetic findings using the revised International Prognostic Scoring System. Incorporating mutational data could further refine the risk assessment and identify those with higher-than-expected disease risk. The principal therapeutic goal in this disease subset is to modify the natural history and prolong survival. Allogeneic stem cell transplant, the only potentially curative treatment, should be offered to eligible patients. Hypomethylating agents are the only approved treatment with unsatisfactory response rates and duration, and patients who failed prior hypomethylating agents unfortunately have dismal outcomes with urgent need of novel therapeutic agents. In this review, we provide the therapeutic landscape in higher risk MDS based on the current evidence and discuss the investigational treatment options under development.

DRP1 Inhibition Enhances Venetoclax-Induced Mitochondrial Apoptosis in TP53-Mutated Acute Myeloid Leukemia Cells through BAX/BAK Activation

Although TP53 mutations in acute myeloid leukemia (AML) are associated with poor response to venetoclax, the underlying resistance mechanism remains unclear. Herein, we investigated the functional role of dynamin-related protein 1 (DRP1) in venetoclax sensitivity in AML cells with respect to TP53 mutation status. Effects of DRP1 inhibition on venetoclax-induced cell death were compared in TP53-mutated (THP-1 and Kasumi-1) and TP53 wild-type leukemia cell lines (MOLM-13 and MV4-11), as well as in primary AML cells obtained from patients. Venetoclax induced apoptosis in TP53 wild-type AML cells but had limited effects in TP53-mutated AML cells. DRP1 expression was downregulated in MOLM-13 cells after venetoclax treatment but was unaffected in THP-1 cells. Cotreatment of THP-1 cells with venetoclax and a TP53 activator NSC59984 downregulated DRP1 expression and increased apoptosis. Combination treatment with the DRP1 inhibitor Mdivi-1 and venetoclax significantly increased mitochondria-mediated apoptosis in TP53-mutated AML cells. The combination of Mdivi-1 and venetoclax resulted in noticeable downregulation of MCL-1 and BCL-xL, accompanied by the upregulation of NOXA, PUMA, BAK, and BAX. These findings suggest that DRP1 is functionally associated with venetoclax sensitivity in TP53-mutated AML cells. Targeting DRP1 may represent an effective therapeutic strategy for overcoming venetoclax resistance in TP53-mutated AML.

Multilineage Lymphoblastic Lymphoma as an Initial Presentation of Mixed Phenotype Acute Leukemia

Mixed phenotype acute leukemia (MPAL) is characterized by leukemic blasts that express markers of multiple lineages. Compared with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), MPAL is considered to have a poor treatment outcome. We report a case of MPAL T/myeloid not otherwise specified that was initially presented as multilineage lymphoblastic lymphoma and subsequently developed into leukemic MPAL. An acute lymphoblastic leukemia-based treatment regimen was ineffective, but azacitidine and venetoclax therapy resulted in hematological complete remission. Our case suggests that multilineage lymphoblastic lymphoma should be considered to be the same disease as MPAL, albeit with different clinical presentations. Optimal treatment for MPAL has not been established yet, but azacitidine and venetoclax therapy may be a potential approach.

The Growing Role of the BH3 Mimetic Drug Venetoclax in the Therapy of Acute Myeloid Leukemia

Despite recent progress, acute myeloid leukemia (AML) remains a disease associated with poor prognosis, particularly in older AML patients unfit to tolerate intensive chemotherapy treatment. The development and introduction in the therapy of Venetoclax (VEN), a potent BH3 mimetic targeting the antiapoptotic protein BCL-2, inducing apoptosis of leukemic cells, has shown to be a promising treatment for newly diagnosed, relapsed, and refractory AML patients ineligible for induction chemotherapy. Combination treatments using Ventoclax and a hypomethylating agent (azacitidine or decitabine) or low-intensity chemotherapy have shown in newly diagnosed patients variable response rates, with highly responsive patients with NPM1, IDH1-IDH2, TET2, and RUNX1 mutations and with scarcely responsive patients with FLT3, TP53 and ASXL1 mutations, complex karyotypes, and secondary AMLs. Patients with refractory/relapsing disease are less responsive to Venetoclax-based regimens. However, in the majority of patients, the responses have only a limited duration, and the development of resistance is frequently observed. Therefore, understanding the resistance mechanisms is crucial for developing new strategies and identifying rational drug combination regimens. In this context, two strategies seem to be promising: (i) triplet therapies based on the combined administration of Venetoclax, a hypomethylating agent (or low-dose chemotherapy), and an agent targeting a specific genetic alteration of leukemic cells (i.e., FLT3 inhibitors in FLT3-mutated AMLs) or an altered signaling pathway; (ii) combination therapies based on the administration of two BH3 mimetics (i.e., BCL-2 +MCL-1 mimetics) and a hypomethylating agent.

How I Treat TP53-Mutated Acute Myeloid Leukemia and Myelodysplastic Syndromes

TP53-mutated acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are among the myeloid malignancies with the poorest prognosis. In this review, we analyze the prognosis of these two diseases, focussing particularly on the extent of the mono or biallelic mutation status of TP53 mutation, which is largely correlated with cytogenetic complexity. We discuss the possible/potential improvement in outcome based on recent results obtained with new drugs (especially eprenetapopt and magrolimab). We also focus on the impact of allogeneic hematopoietic stem cell transplantation (aHSCT) including post aHSCT treatment.

Targeting Acute Myeloid Leukemia with Venetoclax; Biomarkers for Sensitivity and Rationale for Venetoclax-Based Combination Therapies

Simple Summary

Venetoclax has proven to be a promising therapy for newly diagnosed, relapsed and refractory AML patients ineligible for induction chemotherapy. Current ongoing clinical trials are evaluating its effectivity as frontline therapy for all acute myeloid leukemia (AML) patients. However, response rates vary wildly, depending on patient characteristics and mutational profiles. This review elaborates on the efficacy and safety of venetoclax compared to conventional chemotherapy for treatment of AML patients, comparing the response rates, overall survival and adverse events. Moreover, it gives an overview of genetic and epigenetic AML cell characteristics that give enhanced or decreased response to venetoclax and offers insights into the pathogenesis of venetoclax sensitivity and resistance. Additionally, it suggests possible treatment combinations predicted to be successful based on identified mechanisms influencing venetoclax sensitivity of AML cells.

Abstract

Venetoclax is a BCL-2 inhibitor that effectively improves clinical outcomes in newly diagnosed, relapsed and refractory acute myeloid leukemia (AML) patients, with complete response rates (with and without complete blood count recovery) ranging between 34–90% and 21–33%, respectively. Here, we aim to give an overview of the efficacy of venetoclax-based therapy for AML patients, as compared to standard chemotherapy, and on factors and mechanisms involved in venetoclax sensitivity and resistance in AML (stem) cells, with the aim to obtain a perspective of response biomarkers and combination therapies that could enhance the sensitivity of AML cells to venetoclax. The presence of molecular aberrancies can predict responses to venetoclax, with a higher response in NPM1-, IDH1/2-, TET2- and relapsed or refractory RUNX1-mutated AML. Decreased sensitivity to venetoclax was observed in patients harboring FLT3-ITD, TP53, K/NRAS or PTPN11 mutations. Moreover, resistance to venetoclax was observed in AML with a monocytic phenotype and patients pre-treated with hypomethylating agents. Resistance to venetoclax can arise due to mutations in BCL-2 or pro-apoptotic proteins, an increased dependency on MCL-1, and usage of additional/alternative sources for energy metabolism, such as glycolysis and fatty acid metabolism. Clinical studies are testing combination therapies that may circumvent resistance, including venetoclax combined with FLT3- and MCL-1 inhibitors, to enhance venetoclax-induced cell death. Other treatments that can potentially synergize with venetoclax, including MEK1/2 and mitochondrial complex inhibitors, need to be evaluated in a clinical setting.

Real-life experience of venetoclax and hypomethylating agents in acute myeloid leukemia patients not candidates for intensive chemotherapy or who are refractory/relapsed: A single-centre experience

We report our experience with venetoclax/hypomethylating agents (Ven/HMA) in 8 AML patients not candidates for intensive CT or refractory/relapsed with limited treatment options. The response rate was 50%. Venetoclax was well-tolerated in 62.5% of the patients. Ven/HMA provides a benefit particularly when used in patients without prior HMA exposure.

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.

Venetoclax resistance: mechanistic insights and future strategies

Acute myeloid leukemia (AML) is historically associated with poor prognosis, especially in older AML patients unfit for intensive chemotherapy. The development of Venetoclax, a potent oral BH3 (BCL-2 homology domain 3) mimetic, has transformed the AML treatment. However, the short duration of response and development of resistance remain major concerns. Understanding mechanisms of resistance is pivotal to devising new strategies and designing rational drug combination regimens. In this review, we will provide a comprehensive summary of the known mechanisms of resistance to Venetoclax and discuss Venetoclax-based combination therapies. Key contributing factors to Venetoclax resistance include dependencies on alternative anti-apoptotic BCL-2 family proteins and selection of the activating kinase mutations. Mutational landscape governing response to Venetoclax and strategic approaches developed considering current knowledge of mechanisms of resistance will be addressed.

Targeting TP53-Mutated Acute Myeloid Leukemia: Research and Clinical Developments

TP53 is a key tumor suppressor gene that plays an important role in regulating apoptosis, senescence, and DNA damage repair in response to cellular stress. Although somewhat rare, TP53-mutated AML has been identified as an important molecular subgroup with a prognosis that is arguably the worst of any. Survival beyond one year is rare after induction chemotherapy with or without consolidative allogeneic stem cell transplant. Although response rates have been improved with hypomethylating agents, outcomes remain particularly poor due to short response duration. Improvements in our understanding of AML genetics and biology have led to a surge in novel treatment options, though the clinical applicability of these agents in TP53-mutated disease remains largely unknown. This review will focus on the epidemiology, molecular characteristics, and clinical significance of TP53 mutations in AML as well as emerging treatment options that are currently being studied.

Venetoclax cooperates with ionizing radiation to attenuate Diffuse Midline Glioma tumor growth

PURPOSE

Tumor relapse after radiation therapy (RT) is a major hurdle in treating pediatric H3K27M-mutant diffuse midline gliomas (DMGs). RT-induced stress increases association of BCL2 family of proteins with BH3 pro-apoptotic activators preventing apoptosis. We hypothesized that inhibition of RT-induced BCL2 with a clinically relevant inhibitor, venetoclax, will block BCL2 activity leading to increased apoptosis. BCL2 has never been implicated in DMG as a RT-induced resistant mechanism.

EXPERIMENTAL DESIGN

We performed an integrated genomic analysis to determine genes responsible for radioresistance and a targeted drug screen to identify drugs that synergize with radiation in DMG. Effect of venetoclax on radiation-na�ve and 6Gy radiation on cells was evaluated by studying cell death, changes in BCL2 phosphorylation, reactive oxygen species (ROS), and apoptosis, as well as BCL2 association with BH3 apoptosis initiators. The efficacy of combining venetoclax with radiation was evaluated in vivo using orthotopic xenograft models.

RESULTS

BCL2 was identified as a key regulator of tumor growth after radiation in DMGs. Radiation sensitizes DMGs to venetoclax treatment independent of p53 status. Venetoclax as a monotherapy was not cytotoxic to DMG cells. Post-radiation venetoclax treatment significantly increased cell death, reduced BCL2-BIM association and augmented mitochondrial ROS leading to increased apoptosis. Combining venetoclax with RT significantly enhanced the survival of mice with DMG tumors.

CONCLUSIONS

This study shows that venetoclax impedes the anti-apoptotic function of radiation-induced BCL2 in DMG leading to increased apoptosis. Results from these pre-clinical studies demonstrate the potential use of the BCL2 inhibitor, venetoclax, combined with RT for pediatric DMG.

Translatome changes in acute myeloid leukemia cells post-exposure to pegcrisantaspase and venetoclax

The clinical outcomes of patients with AML treated with available therapy remains unsatisfactory. We recently reported that the BCL-2 inhibitor, venetoclax, synergized with pegcrisantaspase (PegC) and demonstrated remarkable in vivo efficacy in a preclinical model of AML with complex karyotype. Ven-PegC combination blocks synthesis of proteins in AML cells by inhibiting cap-dependent translation of mRNA. To further explore the impact of Ven-PegC on protein translation, we used polysome profiling and high-throughput RNA-seq to characterize Ven-PegC dependent changes to the translatome. Here we report that the translation of five mRNAs, including two microRNAs, one rRNA, and two mitochondrial genes was altered after exposure to all three treatments (Ven, PegC and Ven-PegC). We focused our translatome validation studies on six additional genes related to translational efficiency that were modified by Ven-PegC. Notably, Ven-PegC treatment increased the RNA translation and protein level of Tribbles homolog 3 (TRIB3), eukaryotic translation initiation factor 3 subunit C (eIF3C), doublesex and mab-3 related transcription factor 1 (DMRT1), salt inducible kinase 1 (SIK1). We validated the observed changes in gene/protein expression in vitro and confirmed our cell line-based studies in the bone marrow of an AML PDX model after Ven-PegC treatment. These results support examining alterations in the translatome post-chemotherapy to offer insight into drug mechanism of action and to inform future therapeutic decisions.

Venetoclax in Relapsed/Refractory Acute Myeloid Leukemia: Are Supporting Evidences Enough?

Simple Summary

Venetoclax (VEN) is a potent oral inhibitor of the anti-apoptotic molecule BCL2, approved for adults with chronic lymphocytic leukemia (CLL), and recently for naïve acute myeloid leukemia (AML) unfit for intensive chemotherapy. Therefore, VEN is not approved for relapsed/refractory (R/R) AML patients; consequently, this use falls within the so-called off-label use. This review provides evidence of the role of VEN-based therapy in R/R AML patients, including data from clinical trials and from retrospective studies.

Abstract

Despite the progress in the development of new therapeutic strategies, relapsed/refractory (R/R) acute myeloid leukemia (AML) still represents a high unmet medical need. Treatment options in this setting include enrollment into clinical trials, allogeneic stem cell transplantation and/or targeted therapy. Nevertheless, it is associated with poor outcomes. Thus, the development of new treatments, which could ameliorate the prognosis of these patients with a good safety profile are highly demanded. Recently, venetoclax (VEN) has been approved for naïve AML patients unfit for intensive chemotherapy. In this regard, regimens including VEN could represent a valuable treatment option even in those with R/R disease and several studies have been conducted to demonstrate its role in this clinical setting. This review aims to summarize the current evidence on the use of VEN regimens in the treatment of R/R AML.

Use of Azacitidine or Decitabine for the Up-Front Setting in Acute Myeloid Leukaemia: A Systematic Review and Meta-Analysis

Simple Summary

Azacitidine and decitabine have been increasingly used for the treatment of acute myeloid leukaemia in older patients. The choice between azacitidine and decitabine depends mostly on the experience and preference of the attending physician, since they have not been compared directly in a randomised clinical trial. In this study, we identified the best treatment regimen for each drug and compare the efficacy of decitabine and azacitidine monotherapy in newly diagnosed acute myeloid leukaemia. We found no significant differences regarding 1-year mortality and overall survival for azacitidine and decitabine (roughly 9 months). Moreover, there were no significant differences in the efficacy of 5-day versus 10-day schedules of decitabine. However, patients treated with the shortened 5-day azacitidine scheme showed worsened outcomes compared to the standard 7-day regimen. Hopefully, our results might be helpful for the design of azacitidine/decitabine-based combination schedules to be tested in future trials.

Abstract

Irruption of decitabine and azacitidine has led to profound changes in the upfront management of older acute myeloid leukaemia (AML). However, they have not been directly compared in a randomised clinical trial. In addition, there are no studies comparing the optimal treatment schedule of each drug in AML. A systematic review and meta-analysis on the efficacy of decitabine and azacitidine monotherapy in newly diagnosed AML was conducted. Randomised controlled trials and retrospective studies were included. A total of 2743 patients from 23 cohorts were analysed (10 cohorts of azacitidine and 13 of decitabine). Similar response rates were observed for azacitidine (38%, 95% CI: 30–47%) compared to decitabine (40%, 95% CI: 32–48%) (p = 0.825). Overall survival (OS) between azacitidine (10.04 months, 95% CI: 8.36–11.72) and decitabine (8.79 months, 95% CI: 7.62–9.96) was also similar (p = 0.386). Patients treated with azacitidine showed a lower median OS when azacitidine was administered for 5 days (6.28 months, 95% CI: 4.23–8.32) compared to the standard 7-day schedule (10.83 months, 95% CI: 9.07–12.59, p = 0.002). Among patients treated with decitabine, response rates and OS were not significantly different between 5-day and 10-day decitabine regimens. Despite heterogeneity between studies, we found no differences in response rates and OS in AML patients treated with azacitidine or decitabine.

Outcomes of TP53-mutant acute myeloid leukemia with decitabine and venetoclax

BACKGROUND

TP53 mutation (TP53mut ) confers an adverse prognosis in acute myeloid leukemia (AML). Venetoclax with hypomethylating agents is a current standard for older patients; however, recent reports suggest that TP53mut confers resistance to venetoclax. The authors investigated the outcomes of patients with TP53mut AML who were treated with a 10-day decitabine and venetoclax (DEC10-VEN) (ClinicalTrials.gov identifier NCT03404193).

METHODS

Patients with newly diagnosed AML received decitabine 20 mg/m2 for 10 days every 4 to 6 weeks for induction, followed by decitabine for 5 days after response. The venetoclax dose was 400 mg daily. TP53mut was identified in bone marrow samples using next-generation sequencing, with sensitivity of 5%. Outcomes were analyzed according to European LeukemiaNet 2017 guidelines.

RESULTS

Among 118 patients (median age, 72 years; age range, 49-89 years), 63 (53%) had secondary AML, 39 (33%) had AML with complex karyotype, and 35 (30%) had TP53mut AML. The median TP53 variant allele frequency was 32% (interquartile range, 16%-65%), 8 patients (23%) had only a single TP53 mutation, 15 (43%) had multiple mutations, and 12 (34%) had mutation and deletion. Outcomes were significantly worse in patients who had TP53mut AML compared with those who had wild-type TP53 AML, with an overall response rate of 66% vs 89% (P = .002), a complete response/complete response with incomplete hematologic recovery rate of 57% vs 77% (P = .029), and a 60-day mortality of 26% vs 4% (P < .001), respectively. Patients with TP53mut versus wild-type TP53 had shorter overall survival at 5.2 versus 19.4 months, respectively (hazard ratio, 4.67; 95% CI, 2.44-8.93; P < .0001), and shorter relapse-free survival at 3.4 versus 18.9 months (hazard ratio, 4.80; 95% CI, 1.97-11.69; P < .0001), respectively. Outcomes with DEC10-VEN in patients with TP53mut AML were comparable to historical results with 10-day decitabine alone.

CONCLUSIONS

Patients with TP53mut AML have lower response rates and shorter survival with DEC10-VEN.

Venetoclax combination therapy with hypomethylating agents in young adults with relapsed/refractory acute myeloid leukaemia

In recent years, one of the most successful advances in treating acute myeloid leukaemia (AML) has been the combination of the B-cell lymphoma 2 (BCL-2) inhibitor venetoclax with hypomethylating agents (decitabine or azacytidine). This combination treatment has an accelerated approval by the Food and Drug Administration for newly diagnosed AML adults who are 75 years of age or older or who have comorbidities and are not eligible to receive intensive induction chemotherapy. AML is the most common form of acute leukaemia in adults, with a median age at diagnosis of 68 years. Consequently, most of the patients included in the studies are elderly. Traditionally, young patients achieve higher remission rates compared with the elderly AML population. Although venetoclax combination therapy could become a treatment option for treating young patients with relapsed/refractory AML, this regimen has not been systematically tested in this setting. In this study, we summarize the currently available evidence on the treatment of venetoclax in combination with hypomethylating agents for the treatment of young relapsed/refractory AML patients, in addition to our experience in clinical practice with two case reports. Venetoclax, combined with hypomethylating agents, seems to be an effective option for young relapsed/refractory AML patients. However, due to the poor quality of the evidence, additional well-designed studies with greater numbers of patients are needed to confirm the effectiveness and safety of venetoclax combination regimens for this population.

Outcomes in patients with newly diagnosed TP53-mutated acute myeloid leukemia with or without venetoclax-based therapy

BACKGROUND

Venetoclax (VEN) in combination with a hypomethylating agent (HMA) has become the standard of care for patients aged >75 years and for those not eligible for intensive chemotherapy who have newly diagnosed acute myeloid leukemia (AML). The benefit of VEN-based therapy in patients who have newly diagnosed AML with mutations in the TP53 gene (TP53^mut ) over standard therapy is undefined.

METHODS

In this single-institutional, retrospective analysis, the authors assessed the clinical outcomes of 238 patients with newly diagnosed TP53^mut AML and compared the clinical characteristics, response to different therapies, and outcomes of those who received VEN-based (n = 58) and non-VEN-based (n = 180) regimens.

RESULTS

Patients who received VEN-based regimens were older (aged >65 years: 81% vs 65%; P = .02) and had higher response rates (complete remission, 43% vs 32%; P = .06) than those who received non-VEN-based regimens. Compared with patients who received non-VEN-based regimens, no difference in overall survival (median, 6.6 vs 5.7 months; P = .4) or relapse-free survival (median, 4.7 vs 3.5 months; P = .43) was observed in those who received VEN-based regimens, regardless of age or intensity of treatment.

CONCLUSIONS

The addition of VEN to standard treatment regimens did not improve outcomes in younger or older patients who had TP53^mut AML. These data highlight the need for novel therapies beyond VEN to improve the outcome of patients with TP53^mut AML.

Small molecules in targeted cancer therapy: advances, challenges, and future perspectives

Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

Targeting Bcl-2 for cancer therapy

Apoptosis deficiency is one of the most important features observed in neoplastic diseases. The Bcl-2 family is composed of a subset of proteins that act as decisive apoptosis regulators. Research and clinical studies have both demonstrated that the hyperactivation of Bcl-2-related anti-apoptotic effects correlates with cancer occurrence, progression and prognosis, also having a role in facilitating the radio- and chemoresistance of various malignancies. Therefore, targeting Bcl-2 inactivation has provided some compelling therapeutic advantages by enhancing apoptotic sensitivity or reversing drug resistance. Therefore, this pharmacological route turned into one of the most promising routes for cancer treatment. This review discusses some of the well-defined and emerging roles of Bcl-2 as well as its potential clinical value in cancer therapeutics.

Venetoclax-containing regimens in acute myeloid leukemia

Venetoclax in combination with hypomethylating agents (HMAs) or low-dose cytarabine (LDAC) has demonstrated exceptional activity in elderly and unfit patients with newly diagnosed acute myeloid leukemia (AML). Notably, the safety profile of venetoclax-based induction regimens was favorable, with a low rate of early treatment-related mortality, even in frail study participants. Thus, the introduction of venetoclax has transformed the landscape of AML therapy in elderly patients. Given these promising results, venetoclax in combination with other agents is now being studied as a frontline therapy in younger patients with AML, as well as in relapsed/refractory AML patients. Here, we review clinical data for venetoclax-based therapy in AML, both from prospective as well as retrospective studies, and highlight ongoing novel studies of venetoclax-containing regimens and discuss future research directions.

TP53 Mutations in Acute Myeloid Leukemia: Still a Daunting Challenge?

TP53 is a key tumor suppressor gene with protean functions associated with preservation of genomic balance, including regulation of cellular senescence, apoptotic pathways, metabolism functions, and DNA repair. The vast majority of de novo acute myeloid leukemia (AML) present unaltered TP53 alleles. However, TP53 mutations are frequently detected in AML related to an increased genomic instability, such as therapy‐related (t-AML) or AML with myelodysplasia-related changes. Of note, TP53 mutations are associated with complex cytogenetic abnormalities, advanced age, chemoresistance, and poor outcomes. Recent breakthroughs in AML research and the development of targeted drugs directed at specific mutations have led to an explosion of novel treatments with different mechanisms. However, optimal treatment strategy for patients harboring TP53 mutations remains a critical area of unmet need. In this review, we focus on the incidence and clinical significance of TP53 mutations in de novo and t-AML. The influence of these alterations on response and clinical outcomes as well as the current and future therapeutic perspectives for this hardly treatable setting are discussed.

Decitabine treatment in 311 patients with acute myeloid leukemia: outcome and impact of TP53 mutations - a registry based analysis

We performed a registry-based analysis of 311 AML patients treated with decitabine in a standard of care setting to assess response and survival data with a distinct focus on the impact of the TP53 mutation status. Median age was 73 years. 172 patients received decitabine first-line and 139 in r/r disease. The ORR (whole cohort) was 30% with a median overall survival of 4.7 months. First-line patients achieved better responses than r/r-patients (ORR: 38% vs. 21%) resulting in a median OS of 5.8 months vs. 3.9 months. NGS based mutation analysis was performed in 180 patients. 20 patients (11%) harbored a TP53 mutation. Response rates and survival did not differ significantly between TP53 mutated patients and wild-type patients. This analysis of a large cohort of AML patients provides response rates and OS data after decitabine treatment. Interestingly, outcome was not negatively influenced by a TP53 mutation.

Venetoclax and hypomethylating agents in acute myeloid leukemia: Mayo Clinic series on 86 patients

Venetoclax and hypomethylating agent (HMA) combination therapy is FDA-approved for elderly or unfit acute myeloid leukemia (AML) patients unable to withstand intensive chemotherapy. The primary objective of the current study was to impart our institutional experience with the above regimen, outlining response, survival outcomes, and its determinants amongst 86 treatment- naïve and relapsed/refractory AML patients. A total of 44 treatment-naïve AML patients, median age 73.5 years, enriched with secondary, therapy related and ELN adverse risk disease (n = 27) were studied. The CR/CRi rates of 50% (22 of 44 patients) were superior to 23% in a matched AML cohort treated with HMA alone (P = .005). Response rates were similar with TP53, FLT3, NPM1 and IDH mutations (P = .31). Moreover, CEPBA mutations (P = .03) and neutropenia (P = .05) emerged as predictors of complete response. Survivalwas prolonged in patients achieving CR/CRi (17 vs 3 months without CR/CRi, P < .001; conversely adverse ELN risk portended inferior survival. Amongst 42 relapsed/refractory AML patients, half received ≥2 prior therapies excluding transplant, and 15 (35.7%) had received HMA. A group of 14 patients (33.3%) attained CR/CRi; age > 65 years, AML with myelodysplasia, JAK2, DNMT3A, and BCOR mutations predicted complete response. Survival distinctions were based on CR/CRi (median survival 15 vs 3 months with/without CR/CRi; P < .001), and TP53 mutation status (P = .04). In summary, we corroborate existing reports demonstrating superior response and prolonged survival with venetoclax and HMA in treatment -naïve and relapsed/refractory AML patients regardless of genotype. Additionally, we identify unique predictors of response to therapy which require validation.

Venetoclax-based chemotherapy in acute and chronic myeloid neoplasms: literature survey and practice points

Venetoclax (VEN), a small-molecule inhibitor of B cell leukemia/lymphoma-2, is now FDA approved (November 2018) for use in acute myeloid leukemia (AML), specific to newly diagnosed elderly or unfit patients, in combination with a hypomethylating agent (HMA; including azacitidine or decitabine) or low-dose cytarabine. A recent phase-3 study compared VEN combined with either azacitidine or placebo, in the aforementioned study population; the complete remission (CR) and CR with incomplete count recovery (CRi) rates were 28.3% and 66.4%, respectively, and an improvement in overall survival was also demonstrated. VEN-based chemotherapy has also shown activity in relapsed/refractory AML (CR/CRi rates of 33-46%), high-risk myelodysplastic syndromes (CR 39% in treatment naïve, 5-14% in HMA failure), and blast-phase myeloproliferative neoplasm (CR 25%); in all instances, an additional fraction of patients met less stringent criteria for overall response. Regardless, venetoclax-induced remissions were often short-lived (less than a year) but long enough to allow some patients transition to allogeneic stem cell transplant. Herein, we review the current literature on the use of VEN-based combination therapy in both acute and chronic myeloid malignancies and also provide an outline of procedures we follow at our institution for drug administration, monitoring of adverse events and dose adjustments.

Venetoclax and hypomethylating agents in FLT3-mutated acute myeloid leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are prevalent in acute myeloid leukemia (AML), and their presence confers adverse risk. FLT3-mutated (FLT3m) AML is a challenging leukemia to manage, particularly in older and unfit patients as well as patients with relapsed/refractory (r/r) disease. We retrospectively analyzed the outcomes of 50 FLT3m AML patients (17 treatment-naïve, 33 r/r) treated with venetoclax (VEN) and hypomethylating agents (HMA). The overall CR/CRi rate with VEN-HMA was 60% (94% in treatment-naïve AML and 42% in r/r AML). Early (60-days) treatment related mortality was 2%. The r/r AML setting was an independent predictor of lower complete response (OR: 0.08; 95%CI: 0.00-0.60, P = .03). Cytogenetics-molecular risk, concurrent mutations, the type of FLT3 mutation (ITD vs TKD), the ITD allelic ratio, the type of HMA, age, prior exposure to HMA and receipt of prior allogeneic transplant did not independently impact response or leukemia-free survival (LFS). Concurrent IDH mutations were associated with lower CR/CRi (P = .01), while ASXL1 or TET2 mutations showed a non-significant association toward higher CR/CRi (P = .07, for both). However, none of the concurrent mutations were an independent predictor for response when adjusted to AML setting. In conclusion, VEN-HMA is associated with encouraging efficacy in FLT3m AML among both newly diagnosed unfit and r/r patients.

Outcome of Allogeneic Hematopoietic Cell Transplantation after Venetoclax and Hypomethylating Agent Therapy for Acute Myelogenous Leukemia

The combination of hypomethylating agents with the selective Bcl-2 inhibitor venetoclax (HMA-VEN) has emerged as a highly active regimen in patients with acute myelogenous leukemia (AML) in both the upfront and relapsed/refractory (r/r) settings. We report our early experience with a cohort of patients who were able to proceed to allogeneic hematopoietic cell transplantation (alloHCT) after HMA-VEN therapy. Thirty-two patients with AML (19 r/r and 13 de novo) with a median age of 62 years underwent alloHCT after HMA-VEN therapy. Twenty-two (68.8%) were in complete remission (CR)/CR with incomplete count recovery at time of HCT. With a median follow up of 14.4 months, the 1-year overall survival (OS) was 62.5%, and disease-free survival was 43.8%. The 1-year nonrelapse mortality rate was 18.8%, and the cumulative incidence of relapse was 37.5%. Among patients who underwent alloHCT in CR, the 1-year OS was 77.3%, and the cumulative incidence of nonrelapse mortality was 9.1%. The cumulative incidence of grade II-IV acute graft-versus-host disease was 43.8%. We conclude that alloHCT after HMA-VEN is therapy associated with favorable allogeneic HCT outcomes in newly diagnosed older patients with AML, as well as those with r/r AML.

Venetoclax and hypomethylating agents (HMAs) induce high response rates in MDS, including patients after HMA therapy failure

Treatment-naive and relapsed/refractory MDS patients receiving venetoclax and HMAs have an ORR of 59% with 63% of responders proceeding to transplant. Allogeneic stem cell transplantation after treatment with venetoclax in combination with HMA is associated with prolonged survival.

Tumor protein 53 mutations in acute myeloid leukemia: conventional induction chemotherapy or novel therapeutics

PURPOSE OF REVIEW

Tumor protein 53 (TP53) protein is involved in fundamental processes of cancer, aging, and DNA repair. Thus, TP53 dysfunction is implicated in malignant processes and remains the most commonly mutated gene in cancer but represents a relatively small proportion in acute myeloid leukemia (AML). Patients with TP53-mutated AML attain inferior responses to therapy resulting in poor overall outcomes.

RECENT FINDINGS

Traditional treatment approaches with conventional chemotherapy yields suboptimal responses for patients with TP53 mutant AML compared with wildtype TP53. In recent years, there is increasing interest in understanding the role and underlying biology of TP53 mutations in AML with efforts to harness the physiological tumor suppressive function of TP53 protein. Novel combination and targeted therapies may contribute to improved outcomes; however, responses to therapy may be short-lived and ongoing research is indicated to evaluate relapse-risk reduction strategies. These patients may benefit from consideration of enrollment in clinical trials or lower intensity therapy approaches in lieu of intensive chemotherapy.

SUMMARY

Pharmacological treatments targeting the TP53 pathway in addition to novel emerging therapeutics and immunotherapy-based approaches hold promise for treatment of TP53 mutant AML.