Interrogating bromodomain inhibitor resistance in KMT2A-rearranged leukemia through combinatorial CRISPR screens.

Bromo- and extra-terminal domain inhibitors (BETi) have exhibited therapeutic activities in many cancers. However, the mechanisms controlling BETi response and resistance are not well understood. We conducted genome-wide loss-of-function CRISPR screens using BETi-treated KMT2A-rearranged (KMT2A-r) cell lines. We revealed that Speckle-type POZ protein (SPOP) gene (Speckle Type BTB/POZ Protein) deficiency caused significant BETi resistance, which was further validated in cell lines and xenograft models. Proteomics analysis and a kinase-vulnerability CRISPR screen indicated that cells treated with BETi are sensitive to GSK3 perturbation. Pharmaceutical inhibition of GSK3 reversed the BETi-resistance phenotype. Based on this observation, a combination therapy regimen inhibiting both BET and GSK3 was developed to impede KMT2A-r leukemia progression in patient-derived xenografts in vivo. Our results revealed molecular mechanisms underlying BETi resistance and a promising combination treatment regimen of ABBV-744 and CHIR-98014 by utilizing unique ex vivo and in vivo KMT2A-r PDX models.

Venetoclax and idasanutlin in relapsed/refractory AML: a nonrandomized, open-label phase 1b trial.

This phase 1b trial (NCT02670044) evaluated venetoclax-idasanutlin in patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) ineligible for cytotoxic chemotherapy. Two-dimensional dose escalation (DE, n = 50) was performed for venetoclax daily with idasanutlin on days 1 to 5 in 28-day cycles, followed by dosing schedule optimization (n = 6) to evaluate reduced venetoclax schedules (21-/14-day dosing). Common adverse events (occurring in ≥40% of patients) included diarrhea (87.3% of patients), nausea (74.5%), vomiting (52.7%), hypokalemia (50.9%), and febrile neutropenia (45.5%). During DE, across all doses, composite complete remission (CRc; CR + CR with incomplete blood count recovery + CR with incomplete platelet count recovery) rate was 26.0% and morphologic leukemia-free state (MLFS) rate was 12%. For anticipated recommended phase 2 doses (venetoclax 600 mg + idasanutlin 150 mg; venetoclax 600 mg + idasanutlin 200 mg), the combined CRc rate was 34.3% and the MLFS rate was 14.3%. Pretreatment IDH1/2 and RUNX1 mutations were associated with higher CRc rates (50.0% and 45.0%, respectively). CRc rate in patients with TP53 mutations was 20.0%, with responses noted among those with co-occurring IDH and RUNX1 mutations. In 12 out of 36 evaluable patients, 25 emergent TP53 mutations were observed; 22 were present at baseline with low TP53 variant allele frequency (median 0.0095% [range, 0.0006-0.4]). Venetoclax-idasanutlin showed manageable safety and encouraging efficacy in unfit patients with R/R AML. IDH1/2 and RUNX1 mutations were associated with venetoclax-idasanutlin sensitivity, even in some patients with co-occurring TP53 mutations; most emergent TP53 clones were preexisting. Our findings will aid ongoing/future trials of BCL-2/MDM2 inhibitor combinations. This trial was registered at www.clinicaltrials.gov as #NCT02670044.

Pivekimab sunirine (IMGN632), a novel CD123-targeting antibody-drug conjugate, in relapsed or refractory acute myeloid leukaemia: a phase 1/2 study.

BACKGROUND: Pivekimab sunirine (IMGN632) is a first-in-class antibody-drug conjugate comprising a high-affinity CD123 antibody, cleavable linker, and novel indolinobenzodiazepine pseudodimer payload. CD123 is overexpressed in several haematological malignancies, including acute myeloid leukaemia. We present clinical data on pivekimab sunirine in relapsed or refractory acute myeloid leukaemia. METHODS: This first-in-human, phase 1/2 dose-escalation and dose-expansion study enrolled participants aged 18 years or older at nine hospitals in France, Italy, Spain, and the USA with CD123+ haematological malignancies (Eastern Cooperative Oncology Group performance status of 0-1); participants reported here were in a cohort of participants with acute myeloid leukaemia who were refractory to or had relapsed on one or more previous treatments for acute myeloid leukaemia. The 3 + 3 dose-escalation phase evaluated two dosing schedules: schedule A (once every 3 weeks, on day 1 of a 3-week cycle) and fractionated schedule B (days 1, 4, and 8 of a 3-week cycle). The dose-expansion phase evaluated two cohorts: one cohort given 0·045 mg/kg of bodyweight (schedule A) and one cohort given 0·090 mg/kg of bodyweight (schedule A). The primary endpoints were the maximum tolerated dose and the recommended phase 2 dose. Antileukaemia activity (overall response and a composite complete remission assessment) was a secondary endpoint. The study is ongoing and registered with ClinicalTrials.gov, NCT03386513. FINDINGS: Between Dec 29, 2017, and May 27, 2020, 91 participants were enrolled (schedule A, n=68; schedule B, n=23). 30 (44%) of schedule A participants were female and 38 (56%) were male; 60 (88%) were White, six (9%) were Black or African American, and two (3%) were other races. Pivekimab sunirine at doses of 0·015 mg/kg to 0·450 mg/kg in schedule A was administered in six escalating doses with no maximum tolerated dose defined; three dose-limiting toxicities were observed (reversible veno-occlusive disease; 0·180 mg/kg, n=1 and 0·450 mg/kg, n=1; and neutropenia; 0·300 mg/kg, n=1). Schedule B was not pursued further on the basis of comparative safety and antileukaemia findings with schedule A. The recommended phase 2 dose was selected as 0·045 mg/kg once every 3 weeks. At the recommended phase 2 dose (n=29), the most common grade 3 or worse treatment-related adverse events were febrile neutropenia (three [10%]), infusion-related reactions (two [7%]), and anaemia (two [7%]). Treatment-related serious adverse events occurring in 5% or more of participants treated at the recommended phase 2 dose were febrile neutropenia (two [7%]) and infusion-related reactions (two [7%]). Among 68 participants who received schedule A, one death (1%) was considered to be treatment-related (cause unknown; 0·300 mg/kg cohort). At the recommended phase 2 dose, the overall response rate was 21% (95% CI 8-40; six of 29) and the composite complete remission rate was 17% (95% CI 6-36; five of 29). INTERPRETATION: Pivekimab sunirine showed single-agent activity across multiple doses, with a recommended phase 2 dose of 0·045 mg/kg once every 3 weeks. These findings led to a phase 1b/2 study of pivekimab sunirine plus azacitidine and venetoclax in patients with CD123-positive acute myeloid leukaemia. FUNDING: ImmunoGen.

Molecular responses in decitabine- and decitabine/venetoclax-treated patients with acute myeloid leukemia and myelodysplastic syndromes.

Not available.

Triple combination targeting methyltransferase, BCL-2, and PD-1 facilitates antileukemia responses in acute myeloid leukemia.

BACKGROUND: A recent breakthrough therapy combining the BCL-2 inhibitor venetoclax with hypomethylating agents (HMAs) targeting DNA methyltransferase has improved outcomes for patients with acute myeloid leukemia (AML), but the responses and long-term survival in older/unfit patients and in patients with relapsed/refractory AML remain suboptimal. Recent studies showed that inhibition of BCL-2 or DNA methyltransferase modulates AML T-cell immunity. METHODS: By using flow cytometry and time-of-flight mass cytometry, the authors examined the effects of the HMA decitabine combined with the BCL-2 inhibitor venetoclax (DAC/VEN therapy) on leukemia cells and T cells in patients with AML who received DAC/VEN therapy in a clinical trial. The authors investigated the response of programmed cell death protein 1 (PD-1) inhibition in the DAC/VEN-treated samples in vitro and investigated the triple combination of PD-1 inhibition with HMA/venetoclax in the trial patients who had AML. RESULTS: DAC/VEN therapy effectively targeted leukemia cells and upregulated the expression of the immune checkpoint-inhibitory receptor PD-1 in T cells while preserving CD4-positive and CD8-positive memory T cells in a subset of patients with AML who were tested. In vitro PD-1 inhibition potentiated the antileukemia response in DAC/VEN-treated AML samples. The combined use of azacitidine, venetoclax, and nivolumab eliminated circulating blasts and leukemia stem cells/progenitor cells and expanded the percentage of CD8-positive memory T cells in an illustrative patient with relapsed AML who responded to the regimen in an ongoing clinical trial. CONCLUSIONS: Immunomodulation by targeting PD-1 enhances the therapeutic effect of combining an HMA and venetoclax in patients with AML.

A retrospective study of cladribine and low-dose cytarabine-based regimens for the treatment of chronic myelomonocytic leukemia and secondary acute myeloid leukemia.

BACKGROUND: Patients with higher risk chronic myelomonocytic leukemia (CMML) have limited therapeutic options beyond hydroxyurea and hypomethylating agents (HMAs). Regimens based on a backbone of cladribine (CLAD), low-dose cytarabine (LDAC), and an HMA are effective low-intensity therapies for acute myeloid leukemia (AML). METHODS: The authors conducted a retrospective chart review to evaluate the efficacy of CLAD/LDAC/HMA in CMML and secondary acute myeloid leukemia (sAML) arising from CMML. Responses were evaluated according to the 2006 International Working Group criteria for CMML and the 2017 European LeukemiaNet criteria for AML. The overall survival (OS), leukemia-free survival (LFS), and duration of response were evaluated with the Kaplan-Meier method. Patients were stratified on the basis of prior HMA exposure. RESULTS: The authors identified 21 patients with CMML (eight with HMA-naive CMML and 13 with HMA-failure CMML) and 33 patients with sAML (11 with HMA-naive sAML and 22 with HMA-failure sAML) treated with CLAD/LDAC/HMA-based regimens. The CMML cohort was enriched for high-risk features (proliferative type, elevated blasts, and RAS/MAPK mutations). The overall response rate was 33% in CMML (50% in HMA-naive CMML and 23% in HMA-failure CMML) and 48% in sAML (82% in HMA-naive sAML and 32% in HMA-failure sAML). The median OS was 14.4, 8.8, 42.9, and 2.9 months for HMA-naive CMML, HMA-failure CMML, HMA-naive sAML, and HMA-failure sAML, respectively. The median LFS was 14.4 and 3.9 months for HMA-naive CMML and HMA-failure CMML, respectively. CONCLUSIONS: CLAD/LDAC/HMA-based regimens are effective in a subset of patients with higher risk CMML and sAML arising from CMML who have not previously experienced HMA failure. These findings must be confirmed in prospective studies.

Early mortality in acute myeloid leukemia with KMT2A rearrangement is associated with high risk of bleeding and disseminated intravascular coagulation.

BACKGROUND: Acute myeloid leukemia (AML) with rearrangement of lysine methyltransferase 2a gene (KMT2Ar) is characterized by chemotherapy resistance and high rates of relapse. However, additional causes of treatment failure or early mortality have not been well-defined in this entity. METHODS: In a retrospective analysis, causes and rates of early mortality following induction treatment were compared between a cohort of adults with KMT2Ar AML (N = 172) and an age-matched cohort of patients with normal karyotype AML (N = 522). RESULTS: The 60-day mortality in patients with KMT2Ar AML was 15% compared with 7% with normal karyotype (p = .04). We found a significantly higher occurrence of major bleeding events (p = .005) and total bleeding events (p = .001) in KMT2Ar AML compared with diploid AML. Among evaluable patients with KMT2Ar AML, 93% exhibited overt disseminated intravascular coagulopathy compared with 54% of patients with a normal karyotype before death (p = .03). In a multivariate analysis, KMT2Ar and a monocytic phenotypic were the only independent predictors of any bleeding event in patients who died within 60 days (odds ratio, 3.5; 95% CI, 1.4-10.4; p = .03; odds ratio, 3.2; 95% CI, 1-1-9.4; p = .04, respectively). CONCLUSION: In conclusion, early recognition and aggressive management of disseminated intravascular coagulopathy and coagulopathy are important considerations that could mitigate the risk of death during induction treatment in KMT2Ar AML. PLAIN LANGUAGE SUMMARY: Acute myeloid leukemia (AML) with rearrangement of KMT2A is characterized by chemotherapy resistance and high rates of relapse. However, additional causes of treatment failure or early mortality have not been well-defined in this entity. In this article, that KMT2A-rearranged AML is demonstrably associated with higher early mortality and an increased risk of bleeding and coagulopathy, specifically, disseminated intravascular coagulation, compared with normal karyotype AML. These findings emphasize the importance of monitoring and mitigating coagulopathy in KMT2A-rearranged leukemia similar to what is done in acute promyelocytic leukemia.

DYRK1a mediates BAFF-induced noncanonical NF-κB activation to promote autoimmunity and B-cell leukemogenesis.

B-cell-activating factor (BAFF) mediates B-cell survival and, when deregulated, contributes to autoimmune diseases and B-cell malignancies. The mechanism connecting BAFF receptor (BAFFR) signal to downstream pathways and pathophysiological functions is not well understood. Here we identified DYRK1a as a kinase that responds to BAFF stimulation and mediates BAFF-induced B-cell survival. B-cell-specific DYRK1a deficiency causes peripheral B-cell reduction and ameliorates autoimmunity in a mouse model of lupus. An unbiased screen identified DYRK1a as a protein that interacts with TRAF3, a ubiquitin ligase component mediating degradation of the noncanonical nuclear factor (NF)-κB-inducing kinase (NIK). DYRK1a phosphorylates TRAF3 at serine-29 to interfere with its function in mediating NIK degradation, thereby facilitating BAFF-induced NIK accumulation and noncanonical NF-κB activation. Interestingly, B-cell acute lymphoblastic leukemia (B-ALL) cells express high levels of BAFFR and respond to BAFF for noncanonical NF-κB activation and survival in a DYRK1a-dependent manner. Furthermore, DYRK1a promotes a mouse model of B-ALL through activation of the noncanonical NF-κB pathway. These results establish DYRK1a as a critical BAFFR signaling mediator and provide novel insight into B-ALL pathogenesis.

Venetoclax enhances T cell-mediated antileukemic activity by increasing ROS production.

Venetoclax, a Bcl-2 inhibitor, in combination with the hypomethylating agent azacytidine, achieves complete remission with or without count recovery in ∼70% of treatment-naive elderly patients unfit for conventional intensive chemotherapy. However, the mechanism of action of this drug combination is not fully understood. We discovered that venetoclax directly activated T cells to increase their cytotoxicity against acute myeloid leukemia (AML) in vitro and in vivo. Venetoclax enhanced T-cell effector function by increasing reactive oxygen species generation through inhibition of respiratory chain supercomplexes formation. In addition, azacytidine induced a viral mimicry response in AML cells by activating the STING/cGAS pathway, thereby rendering the AML cells more susceptible to T cell-mediated cytotoxicity. Similar findings were seen in patients treated with venetoclax, as this treatment increased reactive oxygen species generation and activated T cells. Collectively, this study presents a new immune-mediated mechanism of action for venetoclax and azacytidine in the treatment of AML and highlights a potential combination of venetoclax and adoptive cell therapy for patients with AML.

Clonal dynamics and clinical implications of postremission clonal hematopoiesis in acute myeloid leukemia.

Although clonal hematopoiesis (CH) can precede the development of acute myeloid leukemia (AML), it can also persist after achieving remission. Long-term clonal dynamics and clinical implications of persistent CH are not well understood. Here, we studied the prevalence, dynamics, and clinical implications of postremission CH in 164 AML patients who attained complete remission after induction chemotherapies. Postremission CH was identified in 79 (48%) patients. Postremission CH persisted long term in 91% of the trackable patients despite treatment with various types of consolidation and maintenance therapies. Postremission CH was eradicated in 20 out of 21 (95%) patients who underwent allogeneic stem cell transplant. Although patients with postremission CH as a group had comparable hematopoiesis with those without it, patients with persistent TET2 mutations showed significant neutropenia long term. Postremission CH had little impact on relapse risk, nonrelapse mortality, and incidence of atherosclerotic cardiovascular disease, although the clinical impact of post-CR CH was heterogeneous among different mutations. These data suggest that although residual clonal hematopoietic stem cells are generally resistant to consolidation and maintenance therapies, they retain the ability to maintain normal hematopoiesis and have little impact on clinical outcomes. Larger study is needed to dissect the gene-specific heterogeneity.

2021 Update on MRD in acute myeloid leukemia: a consensus document from the European LeukemiaNet MRD Working Party.

Measurable residual disease (MRD) is an important biomarker in acute myeloid leukemia (AML) that is used for prognostic, predictive, monitoring, and efficacy-response assessments. The European LeukemiaNet (ELN) MRD Working Party evaluated standardization and harmonization of MRD in an ongoing manner and has updated the 2018 ELN MRD recommendations based on significant developments in the field. New and revised recommendations were established during in-person and online meetings, and a 2-stage Delphi poll was conducted to optimize consensus. All recommendations are graded by levels of evidence and agreement. Major changes include technical specifications for next-generation sequencing-based MRD testing and integrative assessments of MRD irrespective of technology. Other topics include use of MRD as a prognostic and surrogate end point for drug testing; selection of the technique, material, and appropriate time points for MRD assessment; and clinical implications of MRD assessment. In addition to technical recommendations for flow- and molecular-MRD analysis, we provide MRD thresholds and define MRD response, and detail how MRD results should be reported and combined if several techniques are used. MRD assessment in AML is complex and clinically relevant, and standardized approaches to application, interpretation, technical conduct, and reporting are of critical importance.

Characteristics and clinical outcomes of patients with acute myeloid leukemia with inv(3)(q21q26.2) or t(3;3)(q21;q26.2).

Acute myeloid leukemia (AML) with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) has a very poor prognosis. Determinants of clinical outcomes and optimal treatment remain uncertain. We retrospectively reviewed 108 cases of AML with inv(3)/t(3;3) and evaluated clinicopathological characteristics and clinical outcomes: 53 newly diagnosed (ND) AML and 55 relapsed/refractory (R/R) AML. Median age was 55 years. White blood cell (WBC) count ≥20x109/L and platelet count ≥140x109/L was observed in 25% and 32% of ND patients, respectively. Anomalies involving chromosome 7 were identified in 56% of patients. The most frequently mutated genes were SF3B1, PTPN11, NRAS, KRAS and ASXL1. In ND patients, the composite complete remission (CRc) rate was 46% overall; 46% with high-intensity treatments and 47% with lowintensity treatments. The 30-day mortality was 14% and 0%, with high- and low-intensity treatment, respectively. In R/R patients, the CRc rate was 14%. Venetoclax based-regimens were associated with a CRc rate of 33%. The 3-year overall survival (OS) was 8.8% and 7.1% in ND and R/R patients, respectively. The 3-year cumulative incidence of relapse was 81.7% overall. Older age, high WBC, high peripheral blast count, secondary AML and KRAS, ASXL1, DNMT3A mutations were associated with worse OS in univariable analyses. The 5-year OS rates were 44% and 6% with or without hematopoietic stem cell transplantation in CR1, respectively. AML with inv(3)/t(3;3) is associated with low CR rates, very high risk of relapse and dismal long-term survival. Intensive chemotherapy and hy pomethylating agents provide similar rates of remission and patients achieving CR benefit from hematopoietic stem cell transplantation in first CR.

Pneumonitis after immune checkpoint inhibitor therapies in patients with acute myeloid leukemia: A retrospective cohort study.

BACKGROUND: Immune checkpoint inhibitors (ICI), combined with hypomethylating agents, can be used to treat acute myeloid leukemia (AML), but this strategy results in a high rate of pneumonitis. The authors sought to determine risk factors for pneumonitis development and whether pneumonitis increased mortality. METHODS: The authors conducted a retrospective review of 258 AML patients who received ICI-containing regimens from 2016 to 2018. A multidisciplinary adjudication committee diagnosed pneumonia and pneumonitis by reviewing symptoms, imaging, microbiology, and response to therapies. To measure risk factors for pneumonitis and mortality, multivariate Cox proportional hazards models were constructed. Pneumonia, pneumonitis, and disease progression were modeled as a time-dependent variable and incorporated a standard risk set modifying variables into the models. RESULTS: Thirty patients developed pneumonitis (12%). Of these, 17 had partial or complete resolution, whereas 13 patients died from pneumonitis. Increasing age (hazard ratio [HR], 1.04 per year; 95% confidence interval [CI], 1.00-1.08), and baseline shortness of breath increased pneumonitis risk (HR, 2.51; 95% CI, 1.13-5.55). Female sex (HR, 0.33; 95% CI, 0.15-0.70) and increasing platelet count (HR, 0.52 per log-unit increase; 95% CI, 0.30-0.92) decreased pneumonitis risk. In adjusted models, ICI-related pneumonitis significantly increased mortality (HR, 2.84; 95% CI, 1.84-4.37). CONCLUSIONS: ICI-related pneumonitis occurs at a high rate in AML patients and increases mortality. LAY SUMMARY: Immune checkpoint inhibitors (ICIs) remove inhibitory signals that reduce T-cell function and allow T-cells to better attack cancer cells. In acute myeloid leukemia (AML), the effectiveness of ICIs is limited in part by inflammation of the lung, called pneumonitis. This study reviewed 258 patients with AML who received ICIs and identified 30 patients who developed pneumonitis, nearly half of whom died. Older age and baseline shortness of breath increased pneumonitis risk, whereas female sex and higher baseline platelet counts decreased pneumonitis risk. Pneumonitis increased mortality by nearly 3-fold. This work highlights the significant harm imposed by pneumonitis after ICI therapies.

Improved outcomes among newly diagnosed patients with FMS-like tyrosine kinase 3 internal tandem duplication mutated acute myeloid leukemia treated with contemporary therapy: Revisiting the European LeukemiaNet adverse risk classification.

Mutations in fms-like tyrosine kinase 3 (FLT3) gene are common genomic alterations in acute myeloid leukemia (AML). FLT3 internal tandem duplication mutations (FLT3-ITD) have consistently been shown to be adversely prognostic, particularly those with high allelic ratio (AR). Current AML treatment strategies, including high dose cytarabine, purine analogs, FLT3 inhibitors (FLT3i), and with or without allogeneic stem cell transplant (SCT) have been shown to improve the outcomes in patients with FLT3 mutations. We analyzed a consecutive cohort of newly diagnosed patients with AML treated at a large academic medical center from January 2012 to January 2020. A total of 1576 patients with a new diagnosis of AML were reviewed. Among these, 1438 (91%) had molecular testing for FLT3 mutations and 21% (304/1438) had an FLT3 mutation, including 17% with an FLT3-ITD mutation. We show that FLT3-ITD high AR with NPM1 wild-type have significantly improved survival compared with other European LeukemiaNet (ELN) adverse risk disease. In multivariable cox proportional hazards model of patients receiving intensive or low-intensity induction regimens, FLT3 mutations did not have prognostic significance. The use of allogeneic SCT in CR1 for patients with FLT3 mutations appears to improve survival, particularly in those with ELN adverse risk disease. Overall, this data highlights the changing prognostic impact of FLT3 mutations in a contemporary era with appropriate use of induction therapy combined with targeted agents and allogenic SCT.

Venetoclax combined with FLAG-IDA induction and consolidation in newly diagnosed acute myeloid leukemia.

Multi-agent induction chemotherapy (IC) improves response rates in younger patients with acute myeloid leukemia (AML); however, relapse remains the principal cause of treatment failure. Improved induction regimens are needed. A prospective single-center phase Ib/II study evaluating fludarabine, cytarabine, G-CSF, and idarubicin combined with venetoclax (FLAG-IDA + VEN) in patients with newly diagnosed (ND) or relapsed/refractory AML. The primary efficacy endpoint was assessment of overall activity (overall response rate [ORR]: complete remission [CR] + CR with partial hematologic recovery [CRh] + CR with incomplete hematologic recovery [CRi] + morphologic leukemia free state + partial response). Secondary objectives included additional assessments of efficacy, overall survival (OS), and event-free survival (EFS). Results of the expanded ND cohort with additional follow-up are reported. Forty-five patients (median age: 44 years [range 20-65]) enrolled. ORR was 98% (N = 44/45; 95% credible interval 89.9%-99.7%). Eighty-nine percent (N = 40/45) of patients attained a composite CR (CRc + CRh + CRi) including 93% (N = 37/40) who were measurable residual disease (MRD) negative. Twenty-seven (60%) patients transitioned to allogeneic stem cell transplant (alloHSCT). Common non-hematologic adverse events included febrile neutropenia (44%; N = 20), pneumonia (22%, N = 10), bacteremia (18%, N = 8), and skin/soft tissue infections (44%, N = 20). After a median follow-up of 20 months, median EFS and OS were not reached. Estimated 24-month EFS and OS were 64% and 76%, respectively. FLAG-IDA + VEN is an active regimen in ND-AML capable of producing high MRD-negative remission rates and enabling transition to alloHSCT when appropriate in most patients. Toxicities were as expected with IC and were manageable. Estimated 24-month survival appears favorable compared to historical IC benchmarks.

A phase 1b/2 study of azacitidine with PD-L1 antibody avelumab in relapsed/refractory acute myeloid leukemia.

BACKGROUND: Patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) have limited treatment options. In preclinical models of AML, inhibition of the PD-1/PD-L1 axis demonstrated antileukemic activity. Avelumab is an anti-PD-L1 immune checkpoint inhibitor (ICI) approved in multiple solid tumors. The authors conducted a phase 1b/2 clinical trial to assess the safety and efficacy of azacitidine with avelumab in patients with R/R AML. METHODS: Patients aged ≥18 years who had R/R AML received azacitidine 75 mg/m2 on days 1 through 7 and avelumab on days 1 and 14 of 28-day cycles. RESULTS: Nineteen patients were treated. The median age was 66 years (range, 22-83 years), 100% had European LeukemiaNet 2017 adverse-risk disease, and 63% had prior exposure to a hypomethylating agent. Avelumab was dosed at 3 mg/kg for the first 7 patients and at 10 mg/kg for the subsequent 12 patients. The most common grade ≥3 treatment-related adverse events were neutropenia and anemia in 2 patients each. Two patients experienced immune-related adverse events of grade 2 and grade 3 pneumonitis, respectively. The overall complete remission rate was 10.5%, and both were complete remission with residual thrombocytopenia. The median overall survival was 4.8 months. Bone marrow blasts were analyzed for immune-related markers by mass cytometry and demonstrated significantly higher expression of PD-L2 compared with PD-L1 both pretherapy and at all time points during therapy, with increasing PD-L2 expression on therapy. CONCLUSIONS: Although the combination of azacitidine and avelumab was well tolerated, clinical activity was limited. High expression of PD-L2 on bone marrow blasts may be an important mechanism of resistance to anti-PD-L1 therapy in AML. LAY SUMMARY: This report describes the results of a phase 1b/2 study of azacitidine with the anti-PD-L1 immune checkpoint inhibitor avelumab for patients with relapsed/refractory acute myeloid leukemia (AML). The clinical activity of the combination therapy was modest, with an overall response rate of 10.5%. However, mass cytometry analysis revealed significantly higher expression of PD-L2 compared with PD-L1 on AML blasts from all patients who were analyzed at all time points. These data suggest a novel potential role for PD-L2 as a means of AML immune escape.

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.

Ten-day decitabine with venetoclax versus intensive chemotherapy in relapsed or refractory acute myeloid leukemia: A propensity score-matched analysis.

BACKGROUND: Relapsed/refractory (R/R) acute myeloid leukemia (AML) has poor outcomes. Although lower-intensity venetoclax-containing regimens are standard for older/unfit patients with newly diagnosed AML, it is unknown how such regimens compare with intensive chemotherapy (IC) for R/R AML. METHODS: Outcomes of R/R AML treated with 10-day decitabine and venetoclax (DEC10-VEN) were compared with IC-based regimens including idarubicin with cytarabine, with or without cladribine, clofarabine, or fludarabine, with or without additional agents. Propensity scores derived from patient baseline characteristics were used to match DEC10-VEN and IC patients to minimize bias. RESULTS: Sixty-five patients in the DEC10-VEN cohort were matched to 130 IC recipients. The median ages for the DEC10-VEN and IC groups were 64 and 58 years, respectively, and baseline characteristics were balanced between the 2 cohorts. DEC10-VEN conferred significantly higher responses compared with IC including higher overall response rate (60% vs 36%; odds ratio [OR], 3.28; P < .001), complete remission with incomplete hematologic recovery (CRi, 19% vs 6%; OR, 3.56; P = .012), minimal residual disease negativity by flow cytometry (28% vs 13%; OR, 2.48; P = .017), and lower rates of refractory disease. DEC10-VEN led to significantly longer median event-free survival compared with IC (5.7 vs 1.5 months; hazard ratio [HR], 0.46; 95% CI, 0.30-0.70; P < .001), as well as median overall survival (OS; 6.8 vs 4.7 months; HR, 0.56; 95% CI, 0.37-0.86; P = .008). DEC10-VEN was independently associated with improved OS compared with IC in multivariate analysis. Exploratory analysis for OS in 27 subgroups showed that DEC10-VEN was comparable with IC as salvage therapy for R/R AML. CONCLUSION: DEC10-VEN represents an appropriate salvage therapy and may offer better responses and survival compared with IC in adults with R/R AML.

Duration of cytopenias with concomitant venetoclax and azole antifungals in acute myeloid leukemia.

BACKGROUND: Venetoclax (VEN) combined with the hypomethylating agent (HMA) azacitidine improves survival in patients aged ≥75 years with newly diagnosed acute myeloid leukemia (AML). VEN and HMA treatment can result in prolonged and often profound neutropenia, and this warrants antifungal prophylaxis. Azole antifungals inhibit cytochrome P450 3A4, the primary enzyme responsible for VEN metabolism; this results in VEN dose reductions for each concomitant antifungal. Limited clinical data exist on outcomes for patients treated with VEN, an HMA, and various azoles. METHODS: The time to neutrophil recovery (absolute neutrophil count [ANC] > 1000 cells/mm3 ) and platelet (PLT) recovery (PLT count > 100,000 cells/mm3 ) in 64 patients with newly diagnosed AML who achieved a response after course 1 of VEN plus an HMA were evaluated. HMA therapy included azacitidine (75 mg/m2 intravenously/subcutaneously for 7 days) or decitabine (20 mg/m2 intravenously for 5 or 10 days). RESULTS: Forty-seven patients (73%) received an azole: posaconazole (n = 17; 27%), voriconazole (n = 9; 14%), isavuconazole (n = 20; 31%), or fluconazole (n = 1; 2%). The median time to ANC recovery were similar for patients who did receive an azole (37 days; 95% confidence interval [CI], 34-38 days) and patients who did not receive an azole (39 days; 95% CI, 30 days to not estimable; P = .8). The median time to PLT recovery was significantly longer for patients receiving azoles (28 vs 22 days; P = .01). The median times to ANC recovery (35 vs 38 days) and PLT recovery (26 vs 32 days) were similar with posaconazole and voriconazole. CONCLUSIONS: VEN plus an HMA resulted in neutropenia and thrombocytopenia, with the latter prolonged in patients receiving concomitant azoles. Concomitant posaconazole or voriconazole and VEN (100 mg) resulted in similar ANC and PLT recovery times, suggesting the safety of these dosage combinations during course 1.

AMP-activated protein kinase links acetyl-CoA homeostasis to BRD4 recruitment in acute myeloid leukemia.

Altered metabolism fuels 2 hallmark properties of cancer cells: unlimited proliferation and differentiation blockade. Adenosine monophosphate-activated protein kinase (AMPK) is a master regulator of bioenergetics crucial for glucose metabolism in acute myeloid leukemia (AML), and its inhibition delays leukemogenesis, but whether the metabolic function of AMPK alters the AML epigenome remains unknown. Here, we demonstrate that AMPK maintains the epigenome of MLL-rearranged AML by linking acetyl-coenzyme A (CoA) homeostasis to Bromodomain and Extra-Terminal domain (BET) protein recruitment to chromatin. AMPK deletion reduced acetyl-CoA and histone acetylation, displacing BET proteins from chromatin in leukemia-initiating cells. In both mouse and patient-derived xenograft AML models, treating with AMPK and BET inhibitors synergistically suppressed AML. Our results provide a therapeutic rationale to target AMPK and BET for AML therapy.