Clinical and molecular predictors of response and survival following venetoclax therapy in relapsed/refractory AML

Reduced duration and dosage of venetoclax is efficient in newly diagnosed patients with acute myeloid leukemia

OBJECTIVES

The combination of Venetoclax (VEN) and Azacitidine (AZA) increases survival outcomes and yields excellent responses in patients with acute myeloid leukemia (AML). However, dose reduction (or discontinuation) is commonly encountered due to therapy-related toxicity. Thus, this study aimed to investigate the efficiency and safety of a lower dosage of venetoclax for the treatment of AML.

METHODS

This observational study analyzed the characteristics and outcomes of newly diagnosed AML patients who received 100 mg VEN combined with AZA for 14 days at our institution.

RESULTS

A total of 36 patients were enrolled, and the median age at diagnosis was 64 years. After a median follow-up of 15 (range 4-29) months, the median overall survival (OS) and progression-free survival (PFS) for the whole cohort were 17 (4-29) months and 12 (1-28) months, respectively. Meanwhile, the overall response rate (ORR) was 69.4%, and the CRc rate was 66.7% in the whole cohort. Subgroup analysis revealed that NPM1 mutations and FAB-M5 subtype were associated with higher response rates, whereas the adverse ELN risk group was predictive of an inferior response. Moreover, ASXL1, NPM1, and IDH1/2 mutations negatively impacted PFS.

DISCUSSION

Our study optimized the administration of venetoclax plus azacytidine for the treatment of AML patients. Response rates were favorable, with median survival in agreement with the findings of earlier reports, offering valuable insights for optimizing VEN-based regimens.

CONCLUSION

In summary, the VEN combination regimen is effective for the treatment of newly diagnosed AML patients in the real world despite VEN dose reductions .

Clinical efficacy and immune response of BCL-2 inhibitors combined with hypomethylating agents in the treatment of acute myeloid leukemia

OBJECTIVE

Acute myeloid leukemia (AML) is a malignant clonal proliferative disease with a high mortality rate. The combination therapy of BCL-2 inhibitor Venetoclax (VEN) and hypomethylating agents (HMAs) has significant anti-leukemia activity.

METHODS

We analyzed the efficacy, safety and immune response characteristics of AML patients who were unfit for high-dose chemotherapy and accepted the medication of VEN + HMAs.

RESULTS

After VEN + HMAs treatment, 31 newly diagnosed AML patients had the morphologic leukemia-free state rate (MLFS%) of 80.6% (25/31), complete response rate (CR%) of 54.8% (17/31), the minimal residual disease negative rate (MRD-%) of 51.6% (16/31), and the median progression-free survival (PFS) of 14 months. After treatment, the proportion of bone marrow primitive cells, the MRD level, white blood cell (WBC) count, fibrinogen (FIB) level and the proportion of B cells were significantly decreased. The red blood cell (RBC) count, hemoglobin (HGB) level, platelet count (PLT) count, activated partial thromboplastin time (APTT), the proportion of total T cells, CD8 + T cells and the IFN-γ level were significantly increased. After VEN + HMAs treatment, 12 relapsed AML patients had a MLFS% of 50% (6/12), CR% of 33.3% (4/12), MRD-% of 25% (3/12), and a median PFS of 7 months. After treatment, the proportion of bone marrow primitive cells and MRD level were slightly decreased, the proportions of CD8 + T cells and NK cells were significantly increased, the proportion of B cells and IL-10 level were significantly decreased. 12 AML patients who receive microtransplantation (MST) treatment using VEN + HMAs as a pretreatment regimen had a PFS of 20.5 months, which was much greater than VEN + HMAs group alone. Hematological recovery was better in the MST group with significantly increased RBC count, HGB level and PLT count. The most common adverse events were myelosuppression, agranulocytosis, infection and cardiovascular toxicity. No fatal adverse events were reported.

CONCLUSION

The combination of BCL-2 inhibitors and HMAs had good efficacy and safety in AML patients who were unfit for high-dose chemotherapy, which may improve the immune microenvironment and enhance anti-leukemia immune response.

Only FLT3-ITD co-mutation did not have a deleterious effect on acute myeloid leukemia patients with NPM1 mutation, but concomitant with DNMT3A co-mutation or a < 3log reduction of MRD2 predicted poor survival

Co-occurring mutations are frequently observed in acute myeloid leukemia (AML) with NPM1 mutation, and NPM1 measurable residual disease (MRD) is an effective prognostic biomarker. This retrospective study investigated the impact of gene co-mutations and NPM1 MRD on outcomes in these patients. Among 234 patients, 11.5% carried the rare type NPM1 mutation (NPM1RT). The median age was 49 years (IQR 36-58), with a median follow-up of 30.4 months (IQR 12.1-55.7). Nine genes were mutated in > 10%, with DNMT3A (53.8%) and FLT3-ITD (44.4%) being most prevalent. Univariable analysis in 137 patients showed FLT3-ITD, DNMT3A co-mutations, and MRD2 < 3 log reduction predicted poorer survival. FLT3-ITD and DNMT3A co-mutations correlated with the lowest event-free (EFS) and overall survival (OS) (3-year EFS 30.0%; 3-year OS 34.4%; both p < 0.001). FLT3-ITD alone did not worsen survival compared to patients without FLT3-ITD. Multivariable analysis identified DNMT3A co-mutation [EFS, HR = 1.9, p = 0.021; OS, HR = 2.2, p = 0.023] and MRD2 ≥ 3 log reduction (EFS, HR = 0.2; OS, HR = 0.1, both p < 0.001) as independent survival predictors. Patients with FLT3-ITD and DNMT3A co-mutations or a MRD2 < 3 log reduction were identified as high risk, but allogeneic hematopoietic stem cell transplantation (allo-HSCT) improved survival significantly compared to chemotherapy only (3-year EFS, 57.9% vs. 30.0%, p = 0.012; 3-year OS, 72.9% vs. 34.4%, p = 0.001). In AML patients with NPM1 mutation, the detrimental impact of FLT3-ITD mutation was exacerbated by DNMT3A co-mutation. Poor-risk younger patients identified by FLT3-ITD and DNMT3A co-mutations or MRD2 < 3 log reduction benefit from allo-HSCT.

Relapse and resistance in acute myeloid leukemia post venetoclax: improving second lines therapy and combinations

INTRODUCTION

The combined use of the BCL-2 inhibitor venetoclax with azacitidine now is the standard of care for patients with acute myeloid leukemia (AML) unfit for intensive chemotherapy with outcomes exceeding those achieved with hypomethylating agents alone. Venetoclax in combination with intensive chemotherapy is also increasingly used both as frontline as well as salvage therapy. However, resistance to and relapse after venetoclax-based therapies are of major concern and outcomes after treatment failure remain poor.

AREAS COVERED

A comprehensive search was performed using PubMed database (up to April 2024). Studies evaluating venetoclax-based combination treatments in AML and studies assessing markers of response and resistance to venetoclax were investigated. We summarize the status of venetoclax-based therapies in the frontline and relapsed/refractory setting with focus on the main mechanisms of resistance to BCL-2 inhibition. Further, strategies to overcome resistance including combinatorial regimens of hypomethylating agent (HMA) + venetoclax + inhibitors targeting actionable mutations like IDH1/2 or FLT3-ITD and the introduction of novel agents like menin-inhibitors are addressed.

EXPERT OPINION

Although venetoclax is reshaping the treatment of unfit and fit AML patients, prognosis of patients after HMA/VEN failure remains dismal, and strategies to abrogate primary and secondary resistance are an unmet clinical need.

Star wars against leukemia: attacking the clones

Leukemia, although most likely starts as a monoclonal genetic/epigenetic anomaly, is a polyclonal disease at manifestation. This polyclonal nature results from ongoing evolutionary changes in the genome/epigenome of leukemia cells to promote their survival and proliferation advantages. We discuss here how genetic and/or epigenetic aberrations alter intracellular microenvironment in individual leukemia clones and how extracellular microenvironment selects the best fitted clones. This dynamic polyclonal composition of leukemia makes designing an effective therapy a challenging task especially because individual leukemia clones often display substantial differences in response to treatment. Here, we discuss novel therapeutic approach employing single cell multiomics to identify and eradicate all individual clones in a patient.

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).

Clinical management of patients diagnosed with acute myeloid leukemia treated with venetoclax in combination with hypomethylating agents after achieving a response: a real-life study

Although there is an approved indication for venetoclax and hypomethylating agents (VenHMA) and its use in different AML settings will be expanded in the following years, the management of the adverse events (AEs) lacks of harmonized algorithms during treatment of these patients. We have studied the incidence of relevant AEs of 43 patients who achieved a response to VenHMA and its management. Median overall survival of our cohort was 19 months. No patients discontinued treatment due to AEs after C3D1, Regarding severe AEs, high rates of grade 4 neutropenia (97.6%) and grade 4 thrombocytopenia (65.1%) were observed. Severe infectious AEs rate was 16%. Due to severe myelotoxicity, most patients required a progressive dose reduction of both venetoclax and hypomethylating agents during follow-up, being 87.8% at C6D1. Transfusional dependence rate was 91% and G-CSF was prescribed to 86% of the patients. Finally, there was not a significant difference in hemoglobin, platelets and absolute neutrophil count after achieving complete response comparing paired samples during follow-up, although cytopenia rate was high during initial follow-up. We conclude that dose reduction of VenHMA after achieving a response in patients diagnosed with AML is required in most patients and essential to avoid prolonged cytopenia-related adverse events and a rapid and standardized method on how to perform it might decrease the AEs rate.

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.

Outcomes of adults with refractory or relapsed acute myeloid leukemia treated with azacitidine and venetoclax compared to other therapies: a multicenter retrospective study

This study reports characteristics and outcomes of adults who received Azacitidine-Venetoclax (AZA-VEN) compared to other salvage therapies (NO-AZA-VEN) as first salvage therapy for acute myeloid leukemia (AML). The clinical data of 81 patients with a diagnosis of relapsed or refractory AML were analyzed. The ORR was comparable for both groups (55% vs 57%, p = 0.852). Median OS (6.8 vs 11.2 months, p = 0.053) and median RFS (6.9 vs 11.2 months, p = 0.488) showed a trend in favor of the NO-AZA-VEN group. OS was significantly longer with NO-AZA-VEN for ELN 2022 risk category sub-group, patients under 60 years old, primary AML and for patients who underwent allo-hematopoietic stem cell transplant after salvage therapy. There was no statistical difference in complications of treatment such as febrile neutropenia, intensive care unit stay, septic shock and total parenteral nutrition. Those results do not support the preferential use of AZA-VEN over other regimens in R/R acute myeloid leukemia.

A STAT3 Degrader Demonstrates Pre-clinical Efficacy in Venetoclax resistant Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that continues to have poor prognosis despite recent therapeutic advances. Venetoclax (Ven), a BCL2-inhibitor has shown a high response rate in AML; however, relapse is invariable due to mitochondrial dysregulation that includes upregulation of the antiapoptotic protein MCL1, a central mechanism of Ven resistance (Ven-res). We have previously demonstrated that the transcription factor STAT3 is upregulated in AML hematopoietic stem and progenitor cells (HSPCs) and can be effectively targeted to induce apoptosis of these aberrant cells. We now show that overexpression of STAT3 alone is sufficient to initiate a strong AML phenotype in a transgenic murine model. Phospho-proteomic data from Ven treated AML patients show a strong correlation of high total STAT3 and phospho-STAT3 [both p-STAT3(Y705) and p-STAT3(S727)] expression with worse survival and reduced remission duration. Additionally, significant upregulation of STAT3 was observed in Ven-res cell lines, in vivo models and primary patient samples. A novel and specific degrader of STAT3 demonstrated targeted reduction of total STAT3 and resulting inhibition of its active p-STAT3(Y705) and p-STAT3(S727) forms. Treatment with the STAT3 degrader induced apoptosis in parental and Ven-res AML cell lines and decreased mitochondrial depolarisation, and thereby dependency on MCL1 in Ven-res AML cell line, as observed by BH3 profiling assay. STAT3 degrader treatment also enhanced differentiation of myeloid and erythroid colonies in Ven-res peripheral blood mononuclear cells (PBMNCs). Upregulation of p-STAT3(S727) was also associated with pronounced mitochondrial structural and functional dysfunction in Ven-res cell lines, that were restored by STAT3 degradation. Treatment with a clinical-stage STAT3 degrader, KT-333 resulted in a significant reduction in STAT3 and MCL1 protein levels within two weeks of treatment in a cell derived xenograft model of Ven-res AML. Additionally, this treatment significant improvement in the survival of a Ven-res patient-derived xenograft in-vivo study. Degradation of STAT3 resulting in downregulation of MCL1 and improvements in global mitochondrial dysfunction suggests a novel mechanism of overcoming Ven-res in AML.

Statement of Purpose

Five-year survival from AML is dismal at 30%. Our prior research demonstrated STAT3 over-expression in AML HSPC's to be associated with inferior survival. We now explore STAT3 over-expression in Ven-res AML, explain STAT3 mediated mitochondrial perturbations and describe a novel therapeutic strategy, STAT3 degradation to overcome Ven-res.

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.

Targeting Molecular Measurable Residual Disease and Low-Blast Relapse in AML With Venetoclax and Low-Dose Cytarabine: A Prospective Phase II Study (VALDAC)

PURPOSE

A prospective phase II study examined the safety and efficacy of venetoclax combined with low-dose cytarabine (LDAC) in AML at first measurable residual disease (MRD) or oligoblastic relapse.

METHODS

Patients with either MRD (≥1 log10 rise) or oligoblastic relapse (blasts 5%-15%) received venetoclax 600 mg once daily D1-28 plus LDAC once daily D1-10 in 28-day cycles. The primary objective was MRD response in the MRD relapse cohort or complete remission (CR/CRh/CRi) in the oligoblastic relapse cohort.

RESULTS

Forty-eight adults with either MRD (n = 26) or oligoblastic (n = 22) relapse were enrolled. Median age was 67 years (range, 18-80) and 94% had received previous intensive chemotherapy. Patients received a median of four cycles of therapy; 17% completed ≥12 cycles. Patients with oligoblastic relapse had more grade ≥3 anemia (32% v 4%; P = .02) and infections (36% v 8%; P = .03), whereas grade 4 neutropenia (32 v 23%) or thrombocytopenia (27 v 15%) were comparable with the MRD relapse cohort. Markers of molecular MRD relapse included mutant NPM1 (77%), CBFB::MYH11 (4%), RUNX1::RUNX1T1 (4%), or KMT2A::MLLT3 (4%). Three patients with a log10 rise in IDH1/2 (12%) were included. By cycle 2 in the MRD relapse cohort, a log10 reduction in MRD was observed in 69%; 46% achieved MRD negative remission. In the oligoblastic relapse cohort, 73% achieved CR/CRh/CRi. Overall, 21 (44%) underwent hematopoietic cell transplantation. Median overall survival (OS) was not reached in either cohort. Estimated 2-year OS rate was 67% (95% CI, 50 to 89) in the MRD and 53% (95% CI, 34 to 84) in the oligoblastic relapse cohorts.

CONCLUSION

For AML in first remission and either MRD or oligoblastic relapse, venetoclax plus LDAC is well tolerated and highly effective.

Poor prognosis of SRSF2 gene mutations in patients treated with VEN-AZA for newly diagnosed acute myeloid leukemia

Mutations in spliceosome genes (SRSF2, SF3B1, U2AF1, ZRSR2) correlate with inferior outcomes in patients treated with intensive chemotherapy for Acute Myeloid Leukemia. However, their prognostic impact in patients treated with less intensive protocols is not well known. This study aimed to evaluate the impact of Spliceosome mutations in patients treated with Venetoclax and Azacitidine for newly diagnosed AML. 117 patients treated in 3 different hospitals were included in the analysis. 34 harbored a mutation in at least one of the spliceosome genes (splice-mut cohort). K/NRAS mutations were more frequent in the splice-mut cohort (47% vs 19%, p=0.0022). Response rates did not differ between splice-mut and splice-wt cohorts. With a median follow-up of 15 months, splice mutations were associated with a lower 18-month LFS (p=0.0045). When analyzing splice mutations separately, we found SRSF2 mutations to be associated with poorer outcomes (p=0.034 and p=0.037 for OS and LFS respectively). This negative prognostic impact remained true in our multivariate analysis. We believe this finding should warrant further studies aimed at overcoming this negative impact.

Venetoclax plus cytarabine and azacitidine in relapsed/refractory AML: An open-label, single-arm, phase 2 study

BACKGROUND

The outcome of relapsed/refractory (R/R) acute myeloid leukemia (AML) remains extremely poor. Venetoclax (VEN)-based regimens have shown promise in treating R/R AML.

OBJECTIVE

This phase 2 study aimed to systematically evaluate the efficacy and safety of the VAA regimen (VEN plus Cytarabine and Azacitidine) in R/R AML patients.

METHODS

Thirty R/R AML patients were enrolled. The study adopted a stepwise ramp-up of VEN dosing, starting with 100 mg on day 1, escalating to 200 mg on day 2, and reaching 400 mg from day 3 to day 9. Cytarabine (10 mg/m2, q12h) was administered intravenously twice daily from days 1 to 10, and Azacitidine (75 mg/m2) was administered via subcutaneous injection once daily from days 1-7. The primary efficacy endpoint was the composite complete remission rate (CRc), including complete response (CR) and complete response with incomplete blood count recovery (CRi). Secondary endpoints included overall survival (OS), duration of response (DOR), and safety analysis.

RESULTS

The CRc rate was 63.3% (19/30), with CR in 36.7% of patients and CRi in 26.7%. Notably, 14 (73.7%) of 19 patients achieving CRc showed undetectable measurable residual disease by flow cytometry. With a median follow-up of 10.7 months, the median OS had not been reached, and the median DOR was 18.3 months. The most common grade 3-4 adverse events (AEs) were neutropenia (100%), anemia (96.7%), thrombocytopenia (90.0%), and leukopenia (90.0%). Infections, with pneumonia being the most prevalent (43.3%), were observed, including one fatal case of Pseudomonas aeruginosa septicemia. There were no treatment-related deaths.

CONCLUSION

The VAA regimen is an effective and safe option for patients with R/R AML, demonstrating a high CRc rate and manageable safety profile.

Recent advances in CAR-T cell therapy for acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a fatal and refractory haematologic cancer that primarily affects adults. It interferes with bone marrow cell proliferation. Patients have a 5 years survival rate of less than 30% despite the availability of several treatments, including chemotherapy, allogeneic haematopoietic stem cell transplantation (Allo-HSCT), and receptor antagonist drugs. Allo-HSCT is the mainstay of acute myeloid leukaemia treatment. Although it does work, there are severe side effects, such as graft-versus-host disease (GVHD). In recent years, chimeric antigen receptor (CAR)-T cell therapies have made significant progress in the treatment of cancer. These engineered T cells can locate and recognize tumour cells in vivo and release a large number of effectors through immune action to effectively kill tumour cells. CAR-T cells are among the most effective cancer treatments because of this property. CAR-T cells have demonstrated positive therapeutic results in the treatment of acute myeloid leukaemia, according to numerous clinical investigations. This review highlights recent progress in new targets for AML immunotherapy, and the limitations, and difficulties of CAR-T therapy for AML.

Efficacy and safety of venetoclax plus hypomethylating agents in relapsed/refractory acute myeloid leukemia: a multicenter real-life experience

Venetoclax (VEN) has been shown to play a synergistic effect in combination with hypomethylating agents (HMAs) in the frontline treatment of acute myeloid leukemia (AML). However, the potential role of this therapy in the relapsed/refractory (R/R) AML setting, still needs to be further unveiled. The aim of the current study was to retrospectively outline the safety profile, response and survival outcomes of R/R AML patients treated with VEN in association with HMAs. Clinical, biological, and molecular data were collected from 57 patients with R/R AML treated with VEN combined with azacitidine or decitabine between 2018 and 2023. The median age of patients was 63 years, 38 (66.7%) received treatment for relapsed disease while 19 (33.3%) for refractory disease, 5 (8.7%) were treated for molecular relapse. A consistent proportion of the cohort was represented by patients with unfavorable prognostic factors such as complex karyotype (36.8%), secondary AML (29.8%), previous exposure to HMAs (38.6%), and relapse after allogeneic stem cell transplant (22.8%). A total of 14 patients achieved CR (24.6%), 3 (5.3%) CRi, 3 (5.3%) MLFS, and 3 (5.3%) PR, accounting for an ORR of 40.4%. The CR/CRi rate was higher in the group treated with azacitidine than in the group treated with decitabine (37.8% vs. 15%). The median OS was 8.2 months, reaching 20.1 months among responding patients. VEN-HMAs treatment allowed to bridge to allogeneic stem cell transplantation 11 (23.9%) of eligible patients, for which a median OS of 19.8 months was shown. On multivariate analysis, ECOG performance status ≥2, complex karyotype and not proceeding to allogeneic stem cell transplantation after therapy with VEN-HMAs were the factors independently associated with shorter OS. Patients treated with the azacitidine rather than the decitabine containing regimen generally displayed a trend toward superior outcomes. The major toxicities were prolonged neutropenia and infections. In conclusion, this study showed how VEN-HMAs could represent an effective salvage therapy in patients with R/R AML, even among some of those patients harboring dismal prognostic features, with a good toxicity profile. Further prospective studies are thus warranted.

Venetoclax resistance in acute myeloid leukaemia-Clinical and biological insights

Venetoclax, an oral BCL-2 inhibitor, has been widely incorporated in the treatment of acute myeloid leukaemia. The combination of hypomethylating agents and venetoclax is the current standard of care for elderly and patient's ineligible for aggressive therapies. However, venetoclax is being increasingly used with aggressive chemotherapy regimens both in the front line and in the relapse setting. Our growing experience and intensive research demonstrate that certain genetic abnormalities are associated with venetoclax sensitivity, while others with resistance, and that resistance can emerge during treatment leading to disease relapse. In the current review, we provide a summary of the known mechanisms of venetoclax cytotoxicity, both regarding the inhibition of BCL-2-mediated apoptosis and its effect on cell metabolism. We describe how these pathways are linked to venetoclax resistance and are associated with specific mutations. Finally, we provide the rationale for novel drug combinations in current and future clinical trials.

High throughput screening aids clinical decision-making in refractory acute myeloid leukaemia

BACKGROUND

Despite advances in therapeutics for adverse-risk acute myeloid leukaemia (AML), overall survival remains poor, especially in refractory disease. Comprehensive tumour profiling and pre-clinical drug testing can identify effective personalised therapies.

CASE

We describe a case of ETV6-MECOM fusion-positive refractory AML, where molecular analysis and in vitro high throughput drug screening identified a tolerable, novel targeted therapy and provided rationale for avoiding what could have been a toxic treatment regimen. Ruxolitinib combined with hydroxyurea led to disease control and enhanced quality-of-life in a patient unsuitable for intensified chemotherapy or allogeneic stem cell transplantation.

CONCLUSION

This case report demonstrates the feasibility and role of combination pre-clinical high throughput screening to aid decision making in high-risk leukaemia. It also demonstrates the role a JAK1/2 inhibitor can have in the palliative setting in select patients with AML.

Azacitidine-venetoclax versus azacitidine salvage treatment for primary induction failure or first relapsed acute myeloid leukaemia patients

OBJECTIVES

To compare the efficacy of venetoclax-azacitidine (VEN-AZA) with AZA in the real-life for patients with first relapsed or refractory acute myeloid leukaemia (R/R AML).

METHODS

We retrospectively analysed R/R AML patients treated with VEN-AZA at the Institut Paoli Calmettes between September 2020 and February 2022. We compared them to a historical cohort of patients treated with AZA between 2010 and 2021.

RESULTS

Thirty-five patients treated with VEN-AZA were compared with 140 patients treated with AZA. There were more favourable cytogenetics (25.7% vs. 8.6%; p = 0.01) and less FLT3-ITD mutated AML (8.8% vs. 25.5%; p = .049) in the VEN-AZA group. The overall 30-day mortality rate was 7.4% and the overall 90-day mortality was 20%, with no difference between the groups. The complete remission rate was 48.6% in the VEN-AZA group versus 15% (p < .0001). The composite complete response rate was 65.7% in the VEN-AZA group versus 23.6% (p < .0001). OS was 12.8 months in the VEN-AZA group versus 7.3 months (p = 0.059). Patients with primary refractory AML, poor-risk cytogenetics, prior hematopoietic stem-cell transplantation (HSCT) and FLT3-ITD mutated AML had lower response and survival rates.

CONCLUSION

VEN-AZA was associated with a better response rate and a longer survival than AZA monotherapy in AML patients who relapsed after or were refractory to intensive chemotherapy.

Venetoclax combined chemotherapy versus chemotherapy alone for acute myeloid leukemia: a systematic review and meta-analysis

Objective

To compare the efficacy and safety of venetoclax (VEN) in combination with chemotherapy (chemo) versus chemo alone in the treatment of acute myeloid leukemia (AML).

Method

To compare the efficacy and/or safety of VEN+chemo versus chemotherapy alone for AML, PubMed, Embase, Web of Science, and the Cochrane Library were used to searching up to June 2023. Comparisons included complete remission (CR), CR with incomplete hematologic recovery (CRi), morphologic leukemia-free state (MLFS), overall response rate (ORR), and adverse events (AEs).

Result

A total of 9 articles were included, including 3124 patients. The baseline characteristics between two patient groups were similar. The combined analysis showed that compared with the group receiving chemo alone, the VEN+chemo group exhibited higher rates of CR, CRi, MLFS and ORR. Additionally, the VEN+chemo group had longer event-free survival (EFS) and overall survival (OS) durations. The incidence rates of AEs and serious AEs (SAEs) were similar between the two groups, but the early 30-day mortality rate was lower in the VEN+chemo group than in the chemo alone group.

Conclusion

The VEN+chemo therapy demonstrates significant efficacy and safety profile in AML patients. However, more prospective studies are needed in the future to provide more accurate and robust evidence for treatment selection in patients.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023439288, identifier CRD42023439288.

FLAG/FLAG-Ida Regimen in Secondary and Relapsed/Refractory Acute Myeloid Leukemia-Even in the Era of New Treatment Modalities Still a Significant Player

(1) Background: Relapsed/refractory (r/r) and secondary acute myeloid leukemia are highlighted by chemoresistance and poor outcomes. The aim of the study was to assess the efficacy and toxicity of fludarabine, cytarabine, and granulocyte-colony stimulation factor (FLAG) with or without idarubicin (-Ida) and to discuss novel therapies in this setting. (2) Methods: Clinical and cytogenetic data on 130 consecutive patients with r/r and secondary AML treated at our center were retrospectively analyzed. (3) Results: There were 48, 56, and 26 patients with relapsed, refractory, and secondary AML, respectively. The median age was 60 years. The overall response was achieved in 70% of patients. The median overall survival (OS) time for the whole group was 9.4 months. In total, 47% of patients proceeded to allogeneic hematopoietic stem cell transplantation (aHSCT) and these patients had significantly prolonged OS compared to the others (63 months vs. 4.2 months; p < 0.001). Among the variables, including age, FLT3 mutation status, European LeukemiaNet (ELN) 2022 classification risk, FLAG vs. FLAG-Ida, and aHSCT, a multivariate analysis revealed that only aHSCT significantly influenced overall survival. (4) Conclusions: FLAG(-Ida) chemotherapy remains an effective salvage chemotherapy for patients with r/r and secondary AML with a plan of proceeding to aHSCT.

Efficacy and safety of coadministration of venetoclax and anti-fungal agents under therapeutic drug monitor in unfit acute myeloid leukemia and high-risk myelodysplastic syndrome with neutropenia: a single-center retrospective study

Unfit acute myeloid leukemia and high-risk myelodysplastic syndrome patients with prolonged neutropenia demand coadministration of venetoclax and azoles. However, venetoclax dosing under drug-drug interaction with azoles remains controversial. Therapeutic drug monitoring (TDM) is expected to guide drug dosage adjustments. We retrospectively enrolled 17 patients under this coadministration and TDM. Venetoclax dosages were interfered when inappropriate drug concentrations appeared. The primary endpoints were objective response and adverse events. Venetoclax concentration outliers were more frequently evaluated before than after dose adjustment (Cmax 60.87% vs. 0.00%, p < .0001). MRD negativity rate was higher in patients staying within reference range than those having outliers (90.91% vs. 33.33%, p = .028). Objective response rate was 100%. Hematologic adverse events included neutropenia (93.3%), febrile neutropenia (53.3%), and thrombocytopenia (81.3%). Median time to neutropenia and thrombocytopenia recovery was 20 (14-32) and 16.5 (6-34) days, respectively. No invasive fungal and other life-threatening infections were observed.

Enhanced Expression of Glycolytic Enzymes and Succinate Dehydrogenase Complex Flavoprotein Subunit A by Mesothelin Promotes Glycolysis and Mitochondrial Respiration in Myeloblasts of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive malignancy characterized by rapid growth and uncontrolled proliferation of undifferentiated myeloid cells. Metabolic reprogramming is commonly observed in the bone marrow of AML patients, as leukemia cells require increased ATP supply to support disease progression. In this study, we examined the potential role of mesothelin as a metabolic modulator in myeloid cells in AML. Mesothelin is a well-known marker of solid tumors that promotes cancer cell proliferation and survival. We initially analyzed alterations in mesothelin expression in the myeloblast subpopulations, defined as SSC-Alow/CD45dim, obtained from the bone marrow of AML patients using flow cytometry. Our results showed overexpression of mesothelin in 34.8% of AML patients. Subsequently, metabolic changes in leukemia cells were evaluated by comparing the oxygen consumption rates (OCR) of bone marrow samples derived from adult AML patients. Notably, a higher OCR was observed in the mesothelin-positive compared to the mesothelin-low and non-expressing groups. Treatment with recombinant human mesothelin protein enhanced OCR and increased the mRNA expression of glycolytic enzymes and mitochondrial complex II in KG1α AML cells. Notably, siRNA targeting mesothelin in KG1α cells led to the reduction of glycolysis-related gene expression but had no effect on the mitochondrial complex gene. The collective results demonstrate that mesothelin induces metabolic changes in leukemia cells, facilitating the acquisition of a rapid supply of ATP for proliferation in AML. Therefore, the targeting of mesothelin presents a potentially promising approach to mitigating the progression of AML through the inhibition of glycolysis and mitochondrial respiration in myeloid cells.

Venetoclax-based low intensity therapy in molecular failure of NPM1-mutated AML

ABSTRACT

Molecular failure in NPM1-mutated acute myeloid leukemia (AML) inevitably progresses to frank relapse if untreated. Recently published small case series show that venetoclax combined with low-dose cytarabine or azacitidine can reduce or eliminate measurable residual disease (MRD). Here, we report on an international multicenter cohort of 79 patients treated for molecular failure with venetoclax combinations and report an overall molecular response (≥1-log reduction in MRD) in 66 patients (84%) and MRD negativity in 56 (71%). Eighteen of 79 patients (23%) required hospitalization, and no deaths were reported during treatment. Forty-one patients were bridged to allogeneic transplant with no further therapy, and 25 of 41 were MRD negative assessed by reverse transcription quantitative polymerase chain reaction before transplant. Overall survival (OS) for the whole cohort at 2 years was 67%, event-free survival (EFS) was 45%, and in responding patients, there was no difference in survival in those who received a transplant using time-dependent analysis. Presence of FLT3-ITD mutation was associated with a lower response rate (64 vs 91%; P < .01), worse OS (hazard ratio [HR], 2.50; 95% confidence interval [CI], 1.06-5.86; P = .036), and EFS (HR, 1.87; 95% CI, 1.06-3.28; P = .03). Eighteen of 35 patients who did not undergo transplant became MRD negative and stopped treatment after a median of 10 months, with 2-year molecular relapse free survival of 62% from the end of treatment. Venetoclax-based low intensive chemotherapy is a potentially effective treatment for molecular relapse in NPM1-mutated AML, either as a bridge to transplant or as definitive therapy.

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.

ATP1A1/BCL2L1 predicts the response of myelomonocytic and monocytic acute myeloid leukemia to cardiac glycosides

Myelomonocytic and monocytic acute myeloid leukemia (AML) subtypes are intrinsically resistant to venetoclax-based regimens. Identifying targetable vulnerabilities would limit resistance and relapse. We previously documented the synergism of venetoclax and cardiac glycoside (CG) combination in AML. Despite preclinical evidence, the repurposing of cardiac glycosides (CGs) in cancer therapy remained unsuccessful due to a lack of predictive biomarkers. We report that the ex vivo response of AML patient blasts and the in vitro sensitivity of established cell lines to the hemi-synthetic CG UNBS1450 correlates with the ATPase Na+/K+ transporting subunit alpha 1 (ATP1A1)/BCL2 like 1 (BCL2L1) expression ratio. Publicly available AML datasets identify myelomonocytic/monocytic differentiation as the most robust prognostic feature, along with core-binding factor subunit beta (CBFB), lysine methyltransferase 2A (KMT2A) rearrangements, and missense Fms-related receptor tyrosine kinase 3 (FLT3) mutations. Mechanistically, BCL2L1 protects from cell death commitment induced by the CG-mediated stepwise triggering of ionic perturbation, protein synthesis inhibition, and MCL1 downregulation. In vivo, CGs showed an overall tolerable profile while impacting tumor growth with an effect ranging from tumor growth inhibition to regression. These findings suggest a predictive marker for CG repurposing in specific AML subtypes.

Effectiveness of venetoclax and azacytidine against myeloid/natural killer cell precursor acute leukemia

Myeloid/natural killer (NK) cell precursor acute leukemia (MNKPL) is a rare leukemia subtype that possibly originates from precursor NK cells. The disease has a poor prognosis, and information on its treatment is lacking. We herein report the first case of a 46-year-old woman with MNKPL who was refractory to two lines of acute myeloid leukemia (AML)-type intensive chemotherapy but was successfully treated with venetoclax and azacytidine (VEN/AZA). She was diagnosed with MNKPL based on the conformations of immature lymphoblastoid morphology without myeloperoxidase reactivity that showed a CD7/CD33/CD34/CD56/HLA-DR positive phenotype and extramedullary regions. The disease was refractory to induction therapy with daunorubicin and cytarabine (DNR/Ara-C) and to reinduction therapy with mitoxantrone, etoposide, and cytarabine (MEC). After two lines of induction chemotherapy, massive pericardial and pleural effusion was found, and was suspected to be extramedullary lesions. The patient developed cardiac tamponade and required pericardiocentesis. Thus, VEN/AZA was administered as third-line therapy. After two cycles of VEN/AZA, the pericardial and pleural effusion disappeared, and complete remission was achieved. The patient received post-transplant cyclophosphamide-based haploidentical transplantation and has stayed relapse-free as of her last follow-up examination 2 years after diagnosis.

Imetelstat-mediated alterations in fatty acid metabolism to induce ferroptosis as a therapeutic strategy for acute myeloid leukemia

Telomerase enables replicative immortality in most cancers including acute myeloid leukemia (AML). Imetelstat is a first-in-class telomerase inhibitor with clinical efficacy in myelofibrosis and myelodysplastic syndromes. Here, we develop an AML patient-derived xenograft resource and perform integrated genomics, transcriptomics and lipidomics analyses combined with functional genetics to identify key mediators of imetelstat efficacy. In a randomized phase II-like preclinical trial in patient-derived xenografts, imetelstat effectively diminishes AML burden and preferentially targets subgroups containing mutant NRAS and oxidative stress-associated gene expression signatures. Unbiased, genome-wide CRISPR/Cas9 editing identifies ferroptosis regulators as key mediators of imetelstat efficacy. Imetelstat promotes the formation of polyunsaturated fatty acid-containing phospholipids, causing excessive levels of lipid peroxidation and oxidative stress. Pharmacological inhibition of ferroptosis diminishes imetelstat efficacy. We leverage these mechanistic insights to develop an optimized therapeutic strategy using oxidative stress-inducing chemotherapy to sensitize patient samples to imetelstat causing substantial disease control in AML.

Clinical and genetic characteristics predict outcomes of acute myeloid leukemia patients with FLT3 mutations receiving venetoclax-based therapy

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous disease, and its heterogeneity is associated with treatment response. Despite the demonstrated success of venetoclax (VEN)-based therapy for AML, the effect of FLT3 mutations on the efficacy of the therapy is poorly understood. We aimed to compare the efficacy of VEN-based therapy between FLT3-mutated (FLT3mut ) and FLT3 wild-type (FLT3wt ) patients and identify the predictors of efficacy in FLT3mut patients.

METHODS

A total of 266 AML patients (127 newly diagnosed [ND] and 139 refractory/relapsed [R/R]) receiving VEN-based regimens were enrolled in this study. A retrospective analysis was performed, and the treatment responses and overall survival (OS) of FLT3mut and FLT3wt patients were compared. Logistic regression and Cox proportional hazards model were applied to examine the clinical and genetic predictors of outcomes.

RESULTS

With a median of two cycles of VEN-based therapy, for the ND AML cohort, the FLT3mut group had a comparable composite complete remission (CRc) rate with the FLT3wt group (79.3% vs. 61.2%, p = 0.072). For the R/R AML cohort, the FLT3mut group exhibited a lower CRc rate than the FLT3wt group. With a median follow-up of 8.6 months (95% confidence interval [CI], 8.0-10), the median OS observed in the FLT3mut and FLT3wt groups for both cohorts were close (14.0 vs. 19.9 months, p = 0.356; 10.0 vs. 11.9 months, p = 0.680). For the ND AML cohort, in FLT3mut patients, MRD-positive and RNA-splicing mutation predicted inferior survival (hazard ratio [HR], 10.3; 95% CI: 2.0-53.8; p = 0.006; HR 11.3; 95% CI: 1.2-109.3; p = 0.036, respectively). For the R/R AML cohort, in FLT3mut patients, adverse ELN risk was associated with an inferior response (odds ratio [OR], 0.2; 95% CI: 0.1-0.8; p = 0.025), whereas NPM1 co-mutation was associated with a superior response (57.1%; OR, 6.7; 95% CI: 1.5-30.1; p = 0.014). CR/CRi predicted a better survival (HR 0.2; 95% CI: 0.1-0.8; p = 0.029), while DNMT3A mutation predicted an inferior survival (HR, 4.6; 95% CI: 1.4-14.9; p = 0.011).

CONCLUSIONS

FLT3 mutations may influence response to VEN-based therapy in R/R AML patients but not in ND AML patients. Furthermore, clinical and genetic characteristics could predict outcomes of FLT3mut patients receiving VEN-based therapy.

Venetoclax plus hypomethylating agents in DDX41-mutated acute myeloid leukaemia and myelodysplastic syndrome: Mayo Clinic series on 12 patients

Venetoclax (VEN) is an FDA-approved selective inhibitor of B-cell leukaemia/lymphoma-2 (BCL-2), used for treating elderly or unfit acute myeloid leukaemia (AML) patients unable to undergo intensive chemotherapy. Combining VEN with hypomethylating agents (HMAs) has shown impressive response rates in high-risk myelodysplastic syndromes (MDS) and relapsed/refractory AML. However, the efficacy of VEN and HMAs in treating DDX41-mutated (mDDX41) MDS/AML patients remains uncertain. Despite the favourable prognostic nature of mDDX41 MDS/AML patients, there is a lack of clinical experience regarding their response to different treatment regimens, leading to an unknown optimal therapeutic approach.

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.

Use of tamibarotene, a potent and selective RARα agonist, in combination with azacitidine in patients with relapsed and refractory AML with RARA gene overexpression

Tamibarotene-based therapy is a novel targeted approach for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML) with retinoic acid receptor alpha (RARA) gene overexpression. Approximately, 50% of higher-risk myelodysplastic syndrome (MDS) patients and approximately 30% of AML patients are positive for RARA overexpression using a blood-based biomarker test that measures RARA expression in peripheral blasts. A phase 2 study investigating the activity of tamibarotene in patients with RARA overexpression was conducted in patients with AML and MDS (NCT02807558). In 28 patients with R/R AML and RARA overexpression treated with tamibarotene in combination with azacitidine, the median overall survival was 5.9 months. In 21 response-evaluable patients, the complete remission/complete remission with incomplete hematologic recovery (CR/CRi) rate was 19%, and median time to initial CR/CRi was 1.2 months. The favorable safety profile and preliminary clinical activity support the development of combination therapies with tamibarotene in myeloid malignancies with RARA overexpression.

Venetoclax-based therapy in treatment-naïve and relapsed/refractory acute myeloid leukemia

Combining venetoclax with the hypomethylating agents azacitidine or decitabine has shown high complete response rates (60-70 %) in newly diagnosed (ND) acute myeloid leukemia (AML). However, studies addressing the efficacy of this approach in relapsed/refractory (R/R) AML remain limited. We conducted a retrospective analysis on patients treated with venetoclax-based therapy at a single institution. Objective response rates (ORR) and overall survival (OS) were assessed using logistic regression and Cox regression models, respectively. The total study population exhibited an ORR of 64 % with a complete remission at 34 %, complete remission with incomplete count recovery at 19%, and morphologic leukemia free state at 11 %. Patients with ND AML had a better ORR (71 %) compared to R/R AML (55 %), but the difference was not statistically significant. Median OS for the overall population was 14.4 months (range: 2-26 months). In the ND group, patients had a longer 6-month OS (82 % vs. 55 % in R/R AML), while both cohorts showed similar 12- and 24-month OS. Factors such as the hypomethylating agent chosen, adverse cytogenetics, TP53 mutations, prior hypomethylating agent use, and stem cell transplant status did not significantly affect ORR or OS. These findings support the effectiveness of venetoclax-based treatments in ND and R/R AML.

Venetoclax in adult acute myeloid leukemia

Venetoclax is a potent inhibitor that specifically targets B-cell lymphoma-2 (BCL-2), which has been demonstrated to be effective in preclinical studies utilizing acute myeloid leukemia (AML) cell lines and xenograft models. Significant antileukemic activity was also observed in clinical trials, both as a monotherapy and in combination with other drugs. This novel therapeutic approach has revolutionized the treatment prospects for AML patients with unfavorable prognoses and those who are unable to tolerate intensive chemotherapy. Nevertheless, further investigations are required to establish the optimal dosing, sequencing, and combinational strategies of venetoclax for AML treatments. Additionally, identifying biomarkers is crucial for predicting response and resistance to this targeted intervention. In this review, we provide an overview of venetoclax-based therapy for AML and explore potential avenues for future research.

Hypomethylating agents plus modified priming regimens compared with venetoclax-based regimens based on molecular characteristics for newly diagnosed patients with acute myeloid leukemia: a multi-center cohort study

Venetoclax (VEN)-based regimens are the standard of care for elderly or unfit patients with newly diagnosed (ND) acute myeloid leukemia (AML). Some single-arm studies have implied that hypomethylating agents (HMAs) plus priming regimens may potentially provide an alternative therapeutic approach, owing to encouraging efficacy seen. However, no comparative data exists yet regarding these two treatment approaches. In this retrospective multi-center cohort study, we enrolled 294 ND AML patients, allocating 167 to the HMA + priming group and 127 to the VEN-based group. Treatment response and overall survival (OS) were compared between groups. Molecular subgroup analyses were also conducted. With a median of two cycles for HMA + priming group, the overall response (ORR) was 65.3%, including 55.1% complete remission (CR), 9.6% CR with incomplete hematologic recovery (CRi) and 0.6% morphologic leukemia-free state (MLFS). With a median of two cycles for VEN-based group, the ORR was 70.9%, including 46.5% CR, 18.9% CRi, and 5.5% MLFS. Response differences (ORR or CR/CRi) between groups were not significant (p > 0.05). With a median follow-up of 10.1 months, median OSs were similar between groups (20.9 vs 16.3 months, p = 0.41). However, VEN regimens demonstrated superior CR/CRi for patients with mutations in FLT3, IDH1/2, and NPM1 compared to HMA + priming (80.0% vs 35.0%, p = 0.01; 90.9% vs 65.5%, p = 0.02; 90.9% and 65.5%, p = 0.02, respectively). In conclusion, HMAs plus modified priming regimens might be a potential alternative therapeutic approach for patients with ND AML, but VEN-based regimens presented predominance in specific molecular subgroups. Molecular characteristics contribute to guiding choice of treatment.

Impact of previous anthracycline therapy in patients with acute myeloid leukemia receiving venetoclax

Venetoclax (VEN) combination regimens are now recognized as effective against acute myeloid leukemia (AML). However, the prognosis of patients who do not attain a composite complete response (cCR) is extremely poor, and clinical determinants of response remain unknown. Medical records of 57 patients with AML treated with VEN combination regimens from April 2021 to March 2022 at six institutions were retrospectively analyzed. The primary endpoint was cCR, complete remission, or complete remission with incomplete hematologic recovery after one cycle of VEN combination regimen. Five patients had previously relapsed after allogeneic hematopoietic stem cell transplantation (allo-SCT). The treatment regimen was azacitidine-VEN in 48 patients (84%) and low-dose cytarabine-VEN in 9 patients (16%). Thirty patients (53%) achieved cCR after one cycle of a VEN regimen. In univariate analysis, the number of prior chemotherapy regimens, post-allo-SCT relapse, and cytogenetic risk category were associated with a decreased likelihood of achieving cCR. In multivariate analysis, second-line chemotherapy remained a significant predictor of response. Patients who received anthracycline immediately before the VEN regimen had a higher cCR rate than patients who did not receive anthracycline. In this study, prior chemotherapy/allo-SCT and cytogenetic risk were associated with VEN treatment outcomes.

Clinical Correlates of Venetoclax-Based Combination Sensitivities to Augment Acute Myeloid Leukemia Therapy

The BCL2 inhibitor venetoclax combined with the hypomethylating agent azacytidine shows significant clinical benefit in a subset of patients with acute myeloid leukemia (AML); however, resistance limits response and durability. We prospectively profiled the ex vivo activity of 25 venetoclax-inclusive combinations on primary AML patient samples to identify those with improved potency and synergy compared with venetoclax + azacytidine (Ven + azacytidine). Combination sensitivities correlated with tumor cell state to discern three patterns: primitive selectivity resembling Ven + azacytidine, monocytic selectivity, and broad efficacy independent of cell state. Incorporation of immunophenotype, mutation, and cytogenetic features further stratified combination sensitivity for distinct patient subtypes. We dissect the biology underlying the broad, cell state-independent efficacy for the combination of venetoclax plus the JAK1/2 inhibitor ruxolitinib. Together, these findings support opportunities for expanding the impact of venetoclax-based drug combinations in AML by leveraging clinical and molecular biomarkers associated with ex vivo responses.

SIGNIFICANCE

By mapping drug sensitivity data to clinical features and tumor cell state, we identify novel venetoclax combinations targeting patient subtypes who lack sensitivity to Ven + azacytidine. This provides a framework for a taxonomy of AML informed by readily available sets of clinical and genetic features obtained as part of standard care. See related commentary by Becker, p. 437 . This article is featured in Selected Articles from This Issue, p. 419.

Potent Personalized Venetoclax Partners for Acute Myeloid Leukemia Identified by Ex Vivo Drug Screening

SUMMARY

High-throughput screens (HTS) have been utilized to assess the efficacy of single drugs against patient tumor samples with the purpose of optimizing precision therapy, but testing the synergy of drug combinations can identify the ideal second drug to add. With novel sophisticated HTS, effective venetoclax combinations can be revealed that provide the cell state, phenotype, and molecular features of the susceptible and resistant cell populations. See related article by Eide, Kurtz et al., p. 452 (14) .

An oral triple pill-based cocktail effectively controls acute myeloid leukemia with high translation

Acute myeloid leukemia (AML) is a deadly hematological malignancy characterized by oncogenic translational addiction that results in over-proliferation and apoptosis evasion of leukemia cells. Various chemo- and targeted therapies aim to reverse this hallmark, but most show only modest efficacy. Here we report a single oral pill containing a low-dose triple small molecule-based cocktail, a highly active anti-cancer therapy (HAACT) with unique mechanisms that can effectively control AML. The cocktail comprises oncogenic translation inhibitor HHT, drug efflux pump P-gpi ENC and anti-apoptotic protein Bcl-2i VEN. Mechanistically, the cocktail can potently kill both leukemia stem cells (LSC) and bulk leukemic cells via co-targeting oncogenic translation, apoptosis machinery, and drug efflux pump, resulting in deep and durable remissions of AML in diverse model systems. We also identified EphB4/Bcl-xL as the cocktail response biomarkers. Collectively, our studies provide proof that a single pill containing a triple combination cocktail might be a promising avenue for AML therapy.

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.

Outpatient initiation of venetoclax in patients with acute myeloid leukemia

INTRODUCTION

Venetoclax is a treatment option in patients with acute myeloid leukemia (AML) in both the front-line and relapsed/refractory settings. Initiation of therapy has been previously restricted to the inpatient setting at some institutions due to a risk of tumor lysis syndrome (TLS) and limitations in medication access efficiency given the high cost of therapy.

METHODS

We assessed the safety of initiating venetoclax in the outpatient setting through a single-arm, retrospective study of adult AML patients between April 1, 2019 and June 30, 2020.

RESULTS

Eighty-two patients started venetoclax during this time, with 47 (57%) patients initiated in the outpatient setting. Fifty-five percent of patients received venetoclax as first-line treatment for AML (n = 45) and 45% of patients received venetoclax for relapsed/refractory AML (n = 37). Successful initiation, defined as no hospitalizations secondary to TLS within seven days of therapy initiation, occurred in 98% of patients. The rate of TLS was 2.1% (n = 1) following venetoclax initiation. TLS symptoms were managed during hospitalization, requiring only one day of missed AML therapy. Median turnaround time for medication access was three days. Hospitalizations within seven days occurred in 17% of patients (n = 8), with the majority due to febrile neutropenia.

CONCLUSIONS

The results of our study provide further evidence for the safety and feasibility of initiating venetoclax in the outpatient setting with a pharmacist-led interdisciplinary protocol.

Venetoclax-based therapy for relapsed or refractory acute myeloid leukaemia following intensive induction chemotherapy

BACKGROUND

The treatment of relapsed or refractory (R/R) acute myeloid leukaemia (AML) remains challenging and outcomes extremely poor. The introduction of venetoclax has transformed the treatment of AML and emerging data suggest that venetoclax-based therapy may enforce salvage treatment.

MATERIALS AND METHODS

In this nationwide Danish retrospective study, we analysed treatment outcomes of venetoclax-based salvage treatment for R/R AML between 2019 and 2022. Only venetoclax-naive patients who had previously received treatment with intensive chemotherapy therapy were included.

RESULTS

The cohort consisted of 43 R/R patients with a median age of 57 years. Nine (20.9%) were primary refractory and 34 (79.1%) patients had relapsed, including 21 after previous allogeneic stem cell transplantation. The overall response rate was 76.2% including 61.9% with composite complete remission (CRc: CR + CRi). Among CRc-responders with information on measurable residual disease (MRD), 8/13 (61.5%) obtained an MRD-negativity response. The overall survival was 9.3 months for all patients with an estimated 1-year overall survival of 34%. For CRc-responders the median overall survival was 13.3 months, and the median relapse-free survival was 12.8 months.

CONCLUSION

Venetoclax-based salvage treatment for R/R AML produced high response rates; however, for most patients the response was of limited duration. This study is limited by an observational design and prone to selection bias.

A phase 1b study of venetoclax and alvocidib in patients with relapsed/refractory acute myeloid leukemia

Relapsed/refractory (R/R) Acute Myeloid Leukemia (AML) is a genetically complex and heterogeneous disease with a poor prognosis and limited treatment options. Thus, there is an urgent need to develop therapeutic combinations to overcome drug resistance in AML. This open-label, multicenter, international, phase 1b study evaluated the safety, efficacy, and pharmacokinetics of venetoclax in combination with alvocidib in patients with R/R AML. Patients were treated with escalating doses of venetoclax (400, 600, and 800 mg QD, orally, days 1-28) and alvocidib (45 and 60 mg/m2 , intravenously, days 1-3) in 28-day cycles. The combination was found to be safe and tolerable, with no maximum tolerated dose reached. Drug-related Grade ≥3 adverse events were reported in 23 (65.7%) for venetoclax and 24 (68.6%) for alvocidib. No drug-related AEs were fatal. Gastrointestinal toxicities, including diarrhea, nausea, and vomiting were notable and frequent; otherwise, the toxicities reported were consistent with the safety profile of both agents. The response rate was modest (complete remission [CR] + incomplete CR [CRi], 11.4%; CR + CRi + partial response rate + morphologic leukemia-free state, 20%). There was no change in alvocidib pharmacokinetics with increasing doses of venetoclax. However, when venetoclax was administered with alvocidib, AUC24 and Cmax decreased by 18% and 19%, respectively. A recommended phase 2 dose was not established due to lack of meaningful increase in efficacy across all cohorts compared to what was previously observed with each agent alone. Future studies could consider the role of the sequence, dosing, and the use of a more selective MCL1 inhibitor for the R/R AML population.

Limited Efficacy of Venetoclax Combination Regimens in Acute Myeloid Leukemia with Extramedullary Relapse

The recently approved BCL2 inhibitor venetoclax (VEN) has achieved promising outcomes in new and relapsed/refractory (R/R) acute myeloid leukemia (AML). Although its use is not well established in R/R AML with extramedullary disease (EMD), some reports have shown promising outcomes. We retrospectively analyzed 11 patients of R/R AML with EMD (with (n = 4) or without (n = 7) concurrent marrow involvement), who were treated with VEN plus decitabine (n = 9) or low-dose cytarabine (n = 2) between May 2020 and October 2020 in Seoul St. Mary's Hospital. The median number of prior treatment lines was 3 (1-6), and most (n = 9, 81.8%) had multiple sites of EMD. Nine patients (81.8%) received concurrent therapy for extramedullary (EM) involvement sites with radiotherapy (RT) (n = 4), surgery (n = 1), and both of them (n = 4). Among 11 patients, 4 patients (36.4%) had either marrow or EM responses to VEN combination; EM response was seen in 1 patient (9.1%, partial response) who had received concurrent RT (25 Gy, 10 fx) during the 1st cycle of VEN combination, and other 3 patients showed marrow response without EM response. After median follow-up of 27.0 months, the median overall survival was estimated to be 5.4 months. To conclude, VEN combination regimens have shown only modest efficacy in EM recurrence of AML with little impact on eliciting EM response.

Single-cell multi-omics defines the cell-type-specific impact of splicing aberrations in human hematopoietic clonal outgrowths

RNA splicing factors are recurrently mutated in clonal blood disorders, but the impact of dysregulated splicing in hematopoiesis remains unclear. To overcome technical limitations, we integrated genotyping of transcriptomes (GoT) with long-read single-cell transcriptomics and proteogenomics for single-cell profiling of transcriptomes, surface proteins, somatic mutations, and RNA splicing (GoT-Splice). We applied GoT-Splice to hematopoietic progenitors from myelodysplastic syndrome (MDS) patients with mutations in the core splicing factor SF3B1. SF3B1mut cells were enriched in the megakaryocytic-erythroid lineage, with expansion of SF3B1mut erythroid progenitor cells. We uncovered distinct cryptic 3' splice site usage in different progenitor populations and stage-specific aberrant splicing during erythroid differentiation. Profiling SF3B1-mutated clonal hematopoiesis samples revealed that erythroid bias and cell-type-specific cryptic 3' splice site usage in SF3B1mut cells precede overt MDS. Collectively, GoT-Splice defines the cell-type-specific impact of somatic mutations on RNA splicing, from early clonal outgrowths to overt neoplasia, directly in human samples.

The landscape of novel strategies for acute myeloid leukemia treatment: Therapeutic trends, challenges, and future directions

Acute myeloid leukemia (AML) is a highly heterogeneous subtype of hematological malignancies with a wide spectrum of cytogenetic and molecular abnormalities, which makes it difficult to manage and cure. Along with the deeper understanding of the molecular mechanisms underlying AML pathogenesis, a large cohort of novel targeted therapeutic approaches has emerged, which considerably expands the medical options and changes the therapeutic landscape of AML. Despite that, resistant and refractory cases caused by genomic mutations or bypass signalling activation remain a great challenge. Therefore, discovery of novel treatment targets, optimization of combination strategies, and development of efficient therapeutics are urgently required. This review provides a detailed and comprehensive discussion on the advantages and limitations of targeted therapies as a single agent or in combination with others. Furthermore, the innovative therapeutic approaches including hyperthermia, monoclonal antibody-based therapy, and CAR-T cell therapy are also introduced, which may provide safe and viable options for the treatment of patients with AML.

A venetoclax and azacitidine bridge-to-transplant strategy for NPM1-mutated acute myeloid leukaemia in molecular failure

NPM1-mutated acute myeloid leukaemia (NPM1mut AML) represents a mostly favourable/intermediate risk disease that benefits from allogeneic haematopoietic stem cell transplantation (HSCT) in case of measurable residual disease (MRD) relapse or persistence after induction chemotherapy. Although the negative prognostic role of pre-HSCT MRD is established, no recommendations are available for the management of peri-transplant molecular failure (MF). Based on the efficacy data of venetoclax (VEN)-based treatment in NPM1mut AML older patients, we retrospectively analysed the off-label combination of VEN plus azacitidine (AZA) as bridge-to-transplant strategy in 11 NPM1mut MRD-positive fit AML patients. Patients were in MRD-positive complete remission (CRMRDpos ) at the time of treatment: nine in molecular relapse and two in molecular persistence. After a median number of two cycles (range 1-4) of VEN-AZA, 9/11 (81.8%) achieved CRMRD -negative (CRMRDneg ). All 11 patients proceeded to HSCT. With a median follow-up from treatment start of 26 months, and a median post-HSCT follow-up of 19 months, 10/11 patients are alive (1 died from non-relapse mortality), and 9/10 patients are in MRDneg status. This patient series highlights the efficacy and safety of VEN-AZA to prevent overt relapse, achieve deep responses and preserve patient fitness before HSCT, in patients with NPM1mut AML in MF.

Ex vivo venetoclax sensitivity testing predicts treatment response in acute myeloid leukemia

The BCL-2 inhibitor venetoclax has revolutionized the treatment of acute myeloid leukemia (AML) in patients not benefiting from intensive chemotherapy. Nevertheless, treatment failure remains a challenge, and predictive markers are needed, particularly for relapsed or refractory AML. Ex vivo drug sensitivity testing may correlate with outcomes, but its prospective predictive value remains unexplored. Here we report the results of the first stage of the prospective phase II VenEx trial evaluating the utility and predictiveness of venetoclax sensitivity testing using different cell culture conditions and cell viability assays in patients receiving venetoclax-azacitidine. Participants with de novo AML ineligible for intensive chemotherapy, relapsed or refractory AML, or secondary AML were included. The primary endpoint was the treatment response in participants showing ex vivo sensitivity and the key secondary endpoints were the correlation of sensitivity with responses and survival. Venetoclax sensitivity testing was successful in 38/39 participants. Experimental conditions significantly influenced the predictive accuracy. Blast-specific venetoclax sensitivity measured in conditioned medium most accurately correlated with treatment outcomes; 88% of sensitive participants achieved a treatment response. The median survival was significantly longer for participants who were ex vivo-sensitive to venetoclax (14.6 months for venetoclax-sensitive patients vs. 3.5 for venetoclax-insensitive patients, P<0.001). This analysis illustrates the feasibility of integrating drug-response profiling into clinical practice and demonstrates excellent predictivity. This trial is registered with ClinicalTrials.gov identifier: NCT04267081.