Practical considerations in clinical application of WHO 5th and ICC classification schemes for acute myeloid leukemia.

The updated WHO 5th edition and ICC 2022 classification systems for AML aim to refine our diagnostic criteria and definitions of AML with deeper incorporation of cytogenetic and molecular aberrations. The two classification systems diverge, however, in numerous AML defining criteria and subclassifications, including the incorporation of blast enumeration and the integration of specific genomic mutations. These differences often create challenges for clinicians in not only establishing a diagnosis of AML, but also in determining the best treatment plan for patients. In this review, we highlight the literature surrounding the contrasting areas between the WHO and ICC guidelines and offer guidance in the clinical application of these guidelines in the management of patients with AML.

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.

A Phase Ib/II Study of Ivosidenib with Venetoclax ± Azacitidine in IDH1-Mutated Myeloid Malignancies.

The safety and efficacy of combining the isocitrate dehydrogenase-1 (IDH1) inhibitor ivosidenib (IVO) with the BCL2 inhibitor venetoclax (VEN; IVO + VEN) ± azacitidine (AZA; IVO + VEN + AZA) were evaluated in four cohorts of patients with IDH1-mutated myeloid malignancies (n = 31). Most (91%) adverse events were grade 1 or 2. The maximal tolerated dose was not reached. Composite complete remission with IVO + VEN + AZA versus IVO + VEN was 90% versus 83%. Among measurable residual disease (MRD)-evaluable patients (N = 16), 63% attained MRD--negative remissions; IDH1 mutation clearance occurred in 64% of patients receiving ≥5 treatment cycles (N = 14). Median event-free survival and overall survival were 36 [94% CI, 23-not reached (NR)] and 42 (95% CI, 42-NR) months. Patients with signaling gene mutations appeared to particularly benefit from the triplet regimen. Longitudinal single-cell proteogenomic analyses linked cooccurring mutations, antiapoptotic protein expression, and cell maturation to therapeutic sensitivity of IDH1-mutated clones. No IDH isoform switching or second-site IDH1 mutations were observed, indicating combination therapy may overcome established resistance pathways to single-agent IVO. SIGNIFICANCE: IVO + VEN + AZA is safe and active in patients with IDH1-mutated myeloid malignancies. Combination therapy appears to overcome resistance mechanisms observed with single-agent IDH-inhibitor use, with high MRD-negative remission rates. Single-cell DNA ± protein and time-of-flight mass-cytometry analysis revealed complex resistance mechanisms at relapse, highlighting key pathways for future therapeutic intervention. This article is highlighted in the In This Issue feature, p. 247.

Molecularly Targeted Therapy in Acute Myeloid Leukemia: Current Treatment Landscape and Mechanisms of Response and Resistance.

Treatment for acute myeloid leukemia (AML) has evolved rapidly over the last decade as improved understanding of cytogenetic and molecular drivers of leukemogenesis refined survival prognostication and enabled development of targeted therapeutics. Molecularly targeted therapies are now approved for the treatment of FLT3 and IDH1/2-mutated AML and additional molecularly and cellularly targeted therapeutics are in development for defined patient subgroups. Alongside these welcome therapeutic advancements, increased understanding of leukemic biology and treatment resistance has resulted in clinical trials investigating combinations of cytotoxic, cellular, and molecularly targeted therapeutics resulting in improved response and survival outcomes in patients with AML. Herein, we comprehensively review the current landscape of IDH and FLT3 inhibitors in clinical practice for the treatment of AML, highlight known resistance mechanisms, and discuss new cellular or molecularly targeted therapies currently under investigation in ongoing early phase clinical trials.

Comparison and validation of the 2022 European LeukemiaNet guidelines in acute myeloid leukemia.

Risk stratification in acute myeloid leukemia (AML) remains principle in survival prognostication and treatment selection. The 2022 European LeukemiaNet (ELN) recommendations were recently published, with notable updates to risk group assignment. The complexity of risk stratification and comparative outcomes between the 2022 and 2017 ELN guidelines remains unknown. This comparative analysis evaluated outcomes between the 2017 and 2022 ELN criteria in patients enrolled within the multicenter Beat AML cohort. Five hundred thirteen patients were included. Most patients had 1 or 2 ELN risk-defining abnormalities. In patients with ≥2 ELN risk-defining mutations, 44% (n = 132) had mutations spanning multiple ELN risk categories. Compared with ELN 2017 criteria, the updated ELN 2022 guidelines changed the assigned risk group in 15% of patients, including 10%, 26%, and 6% of patients categorized as being at ELN 2017 favorable-, intermediate-, and adverse-risk, respectively. The median overall survival across ELN 2022 favorable-, intermediate-, and adverse-risk groups was not reached, 16.8, and 9.7 months, respectively. The ELN 2022 guidelines more accurately stratified survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy compared with ELN 2017 guidelines. The updated ELN 2022 guidelines better stratify survival between patients with intermediate- or adverse-risk AML treated with induction chemotherapy. The increased complexity of risk stratification with inclusion of additional cytogenetic and molecular aberrations necessitates clinical workflows simplifying risk stratification.

Contemporary outcomes in IDH-mutated acute myeloid leukemia: The impact of co-occurring NPM1 mutations and venetoclax-based treatment.

Isocitrate dehydrogenase 1 or 2 (IDH1 or IDH2) mutations occur frequently in newly diagnosed (ND) acute myeloid leukemia (AML) often with co-occurring NPM1 mutations, which may influence treatment outcomes. Detailed analysis of IDH-mutated AML treated with venetoclax and influence of co-occurring NPM1 mutations remains unclear. This retrospective single-center cohort study evaluated clinical and molecular demographics,response and survival, and impact of co-occurring NPM1 mutations in patients with IDH1 or IDH2-mutated AML. 556 patients with IDH1, IDH2, and/or NPM1 mutated AML were included. Patients with IDH1mut AML (N = 119) were more likely to have older age, sAML, ELN-adverse risk disease, and adverse-risk cytogenetics compared to those with IDH2mut (N = 229) or IDHwt /NPM1mut AML (N = 208). In multivariate analysis, patients with IDH2mut (HR 0.61 [95%CI: 0.43-0.88], p value: .007) or IDHwt /NPM1mut (HR 0.65 [95% CI: 0.45-0.94], p value: .024) AML had a decreased risk of death versus IDH1mut AML. Venetoclax-based lower-intensity regimens partially abrogated the detrimental effect of IDH1mut with similar OS observed between IDH1mut /NPM1wt , IDH2mut /NPM1wt , and IDHwt /NPM1mut AML. With regards to the influence of IDHmut /NPM1mut cases, IC improved survival in IDH2mut /NPM1mut versus IDH2mut /NPM1wt AML (HR: 0.54 [95% CI: 0.2644-1.082], p value: .077), while venetoclax-based therapy improved survival in IDH1mut /NPM1mut versus IDH1mut /NPM1wt AML (HR: 0.094 [95% CI: 0.01-0.74], p value: .0056). Differing outcomes were observed in IDH1mut versus IDH2mut or NPM1mut AML which were influenced by co-occurring NPM1 mutations and partially abrogated with venetoclax-based therapy. Given the differing biology and survival in IDH1mut AML, investigations incorporating molecularly targeted therapies such as IDH inhibitors remain warranted in this subgroup.

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.

Advancing the standard: venetoclax combined with intensive induction and consolidation therapy for acute myeloid leukemia.

The B-cell lymphoma 2 (BCL-2) inhibitor venetoclax (VEN) in combination with lower-intensity therapy is an efficacious treatment for acute myeloid leukemia (AML). VEN in combination with the hypomethylating agent azacitidine improved rates of response and measurable residual disease (MRD)-negative remissions in addition to overall survival in the pivotal phase 3 VIALE-A trial compared with azacitidine monotherapy and has since emerged as the current standard of care in older or unfit patients with AML. In younger, fit patients with AML, intensive induction and consolidation chemotherapy (IC) is commonly employed as frontline therapy; however, relapse remains the principal cause of treatment failure in approximately 30-40% of patients. Improved IC regimens that increase MRD-negative response rates, result in durable remissions, and enable transition to curative allogeneic hematopoietic stem cell transplantation in appropriate patients remain an area of active inquiry. Preliminary results from trials investigating the combination of VEN with IC have reported promising findings to date, with composite complete remission and MRD-negative remission rates of approximately 89-94% and 82-93%, respectively, correlating with improved 12-month event-free and overall survival compared to historical outcomes with IC. Herein, we discuss ongoing trials investigating VEN in combination with IC in addition to outcomes within specific molecularly defined subgroups; review the molecular mechanisms of sensitivity and resistance to VEN, and highlight future combinations of VEN with novel targeted therapies for the treatment of AML.

Venetoclax combined with induction chemotherapy in patients with newly diagnosed acute myeloid leukaemia: a post-hoc, propensity score-matched, cohort study.

BACKGROUND: Venetoclax combined with intensive chemotherapy has been shown to be safe with promising activity in fit patients with newly diagnosed acute myeloid leukaemia. The aim of this study was to compare the activity of venetoclax plus intensive chemotherapy with intensive chemotherapy alone. METHODS: This was a post-hoc propensity score matched analysis of prospective clinical trials (NCT03214562, NCT02115295, and NCT01289457) in patients at The University of Texas MD Anderson Cancer Center, Texas, USA between March 29, 2010, and June 15, 2021. Eligible patients were aged 18 years and older, and had newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome, and were treated within trials incorporating purine analogues with an anthracycline and cytarabine either with venetoclax plus intensive chemotherapy or with intensive chemotherapy alone. Patients in the venetoclax plus intensive chemotherapy cohort were matched with patients in the intensive chemotherapy cohort. Morphological response and measurable residual disease (MRD) was assessed using bone marrow aspiration and biopsy and eight-colour multiparameter flow cytometry. The primary objectives were rate of MRD negative composite complete response and cumulative incidence of transition to allogeneic haematopoietic stem-cell transplantation (HSCT). All patients who had response within two treatment cycles (induction and re-induction) were included in the analyses. Secondary objectives included assessment of event-free and overall survival. FINDINGS: The propensity matched cohort included 279 patients (median age 49 years [IQR 39-57]; 131 [47%] were men and 148 [53%] were women); 85 in the venetoclax plus intensive chemotherapy cohort and 194 in the intensive chemotherapy cohort. After a median follow up of 30 months (95% CI 26-36), 64 (86%) of 74 patients in the venetoclax plus intensive chemotherapy cohort had an MRD-negative composite complete response rate compared with 86 [61%] of 140 patients in the intensive chemotherapy cohort (odd ratio 3·2 [95% CI 1·5-6·7]; p=0·0028). The overall cumulative incidence of allogeneic HSCT in responding patients was higher with venetoclax plus intensive chemotherapy than intensive chemotherapy (79% [95% CI 67-88] vs 57% [49-65]; hazard ratio [HR] 1·52 [95% CI 1·11-2·08]; p=0·012). Venetoclax plus intensive chemotherapy improved event-free survival (median not reached [NR; 95% CI NR-NR] vs 14·3 months [10·7-33·5]; HR 0·57 [95% CI 0·34-0·95]; p=0·030), but overall survival did not significantly differ between the two cohorts (median NR [95% CI 24-NR] vs 32 months [19-NR]; HR 0·63 [95% CI 0·35-1·1], p=0·13). INTERPRETATIONS: Venetoclax combined with intensive induction chemotherapy induced deep MRD-negative remissions, allowing transition to allogeneic HSCT in first remission, and improvement in event-free survival. These results highlight the incremental benefit of venetoclax added to intensive induction chemotherapy across European LeukemiaNet risk groups, and serve as a benchmark to inform enrolment on future confirmatory prospective clinical trials. FUNDING: None.

Venetoclax Combined With FLAG-IDA Induction and Consolidation in Newly Diagnosed and Relapsed or Refractory Acute Myeloid Leukemia.

PURPOSE: Sixty percent of newly diagnosed patients with acute myeloid leukemia (ND-AML) receiving frontline therapy attain a complete response (CR), yet 30%-40% of patients relapse. Relapsed or refractory AML (R/R-AML) remains a particularly adverse population necessitating improved therapeutic options. This phase Ib/II study evaluated the safety and efficacy of fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin combined with the B-cell lymphoma-2 inhibitor venetoclax in ND-AML and R/R-AML. MATERIALS AND METHODS: The phase IB portion (PIB) enrolled patients with R/R-AML using a 3 + 3 dose escalation and de-escalation algorithm for identification of maximum tolerated dose and dose-limiting toxicities. The phase II portion enrolled patients into two arms to evaluate response and time-to-event end points: phase IIA (PIIA): ND-AML and phase IIB (PIIB): R/R-AML. RESULTS: Sixty-eight patients have enrolled to date (PIB, 16; PIIA, 29; PIIB, 23). Median age was 46 years (range, 20-73). Grade 3 and 4 adverse events occurring in ≥ 10% of patients included febrile neutropenia (50%), bacteremia (35%), pneumonia (28%), and sepsis (12%). The overall response rate for PIB, PIIA, and PIIB was 75%, 97%, and 70% with 75%, 90%, and 61%, respectively, achieving a composite CR. Measurable residual disease-negative composite CR was attained in 96% of ND-AML and 69% of R/R-AML patients. After a median follow-up of 12 months, median overall survival (OS) for both PII cohorts was not reached. Fifty-six percent of patients proceeded to allogeneic hematopoietic stem-cell transplantation (ND-AML, 69%; R/R-AML, 46%). In R/R-AML, allogeneic hematopoietic stem-cell transplantation resulted in a significant improvement in OS (median OS, NR; 1-year OS, 87%). One-year survival post-HSCT was 94% in ND-AML and 78% in R/R-AML. CONCLUSION: Fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin + venetoclax represents an effective intensive treatment regimen in ND-AML and R/R-AML patients, associated with deep remissions and a high rate of transition to successful transplantation.

Impact of splicing mutations in acute myeloid leukemia treated with hypomethylating agents combined with venetoclax.

Spliceosome mutations (SRSF2, SF3B1, U2AF1, ZRSR2), are encountered in ∼50% of secondary acute myeloid leukemia cases (sAML) and define a molecular subgroup with outcomes similar to sAML in de novo AML patients treated with intensive chemotherapy. Outcomes in patients with spliceosome mutations treated with hypomethylating agents in combination with venetoclax (HMA+VEN) remains unknown. The primary objective was to compare outcomes in patients with spliceosome mutations vs wild-type patients treated with HMA+VEN. Secondary objectives included analysis of the mutational landscape of the spliceosome cohort and assessing the impact of co-occurring mutations. We performed a retrospective cohort analysis of patients treated with HMA+VEN-based regimens at The University of Texas MD Anderson Cancer Center. A total of 119 patients (spliceosome mutated n = 39 [SRSF2, n = 24; SF3B1, n = 8; U2AF1, n = 7]; wild-type, n = 80) were included. Similar responses were observed between spliceosome and wild-type cohorts for composite complete response (CRc; 79% vs 75%, P = .65), and measurable residual disease-negative CRc (48% vs 60%, P = .34). Median overall survival for spliceosome vs wild-type patients was 35 vs 14 months (P = .58), and was not reached; 35 months and 8 months for patients with SRSF2, SF3B1, and U2AF1 mutations, respectively. IDH2 mutations were enriched in patients with SRSF2 mutations and associated with favorable outcomes (1- and 2-year overall survival [OS] of 100% and 88%). RAS mutations were enriched in patients with U2AF1 mutations and associated with inferior outcomes (median OS, 8 months). Comparable outcomes were observed between patients with vs without spliceosome mutations treated with HMA+VEN regimens, with specific co-mutation pairs demonstrating favorable outcomes.

Outcomes of older patients with NPM1-mutated AML: current treatments and the promise of venetoclax-based regimens.

Nucleophosmin-1 mutations (NPM1+) occur in ∼30% of acute myeloid leukemia (AML) patients. Although typically associated with favorable prognosis, the beneficial impact of NPM1+ decreases with increasing age in patients treated with standard intensive chemotherapy (IC) or hypomethylating agents (HMAs). This retrospective analysis compared outcomes of NPM1+ AML patients treated with 1 of 3 induction approaches: HMA plus BCL-2 inhibitor venetoclax (VEN), HMA, or IC therapy. Composite complete response (CRc: CR + CR with incomplete count recovery) was seen in 96% (27/28), 36% (17/47), and 89% (204/228) of HMA + VEN, HMA, and IC patients, respectively (HMA + VEN vs HMA, P < .001; HMA + VEN vs IC, P = .10). Older patients (age >65 years) treated with HMA + VEN, HMA, or IC had CR rates of 88%, 28%, and 56%, respectively (HMA + VEN vs HMA, P < .001; HMA + VEN vs IC, P = .01). Significant improvement in overall survival (OS) was seen in patients age >65 years treated with HMA + VEN vs HMA (not reached [NR] vs 0.4 years; P < .001) or IC (NR vs 0.93 years; P = .001). Older patients treated with HMA + VEN had OS of 80% after median 1-year follow-up, with estimated 2-year OS of 70%. In the multivariable Cox model analysis, HMA + VEN was associated with a 69% lower risk of death compared with IC (hazard ratio, 0.31; 95% confidence interval, 0.12-0.83; type I error-adjusted P = .038). HMA + VEN combinations demonstrated impressive results compared with traditional standard-of-care regimens in older patients with NPM1+ AML.