Search

ETNK1 mutation has been suggested as a useful tool to support the diagnosis of atypical chronic myeloid leukemia. ETNK1 mutations, however, occur in other myeloid neoplasms.The authors assessed the clinicopathologic and molecular genetic features of 80 ETNK1-mutated myeloid neoplasms.Thirty-seven neoplasms (46%) were classified as myelodysplastic syndrome, 17 (21%) were classified as myelodysplastic/myeloproliferative neoplasm, 14 (18%) were classified as acute myeloid leukemia, and 12 (15%) were classified as myeloproliferative neoplasm. ETNK1 mutations were detected at the first test in 96% of patients, suggesting that ETNK1 mutation is an early event in pathogenesis. ETNK1 mutations represented the dominant clone in 63% of patients and was persistently dominant in 93%. The variant allele frequencies were usually higher in acute myeloid leukemia and increased upon leukemic transformation. ETNK1 mutation was accompanied by coexisting mutations in all patients, with ASXL1 (50%), TET2 (25%), EZH2 (24%), RUNX1 (24%), and SRSF2 (24%) mutations being the most common. Neoplasms with ETNK1 mutations were associated with morphologic dysplasia, increased blasts, myelofibrosis, and noncomplex karyotypes. With a median follow-up of 16.5 months, 30 patients died, 44 had persistent disease, and four achieved complete remission after stem cell transplantation.ETNK1 mutation is present in various myeloid neoplasms, often as an early event and a dominant clone and always with concurrent mutations. It may play an important role in the pathogenesis and progression of myeloid neoplasms by causing DNA damage and inducing other mutations and genomic instability, and it may serve as a potential therapeutic target. ETNK1 mutation is not disease-specific and should be interpreted with caution to classify myeloid neoplasms.

Nelarabine is a purine nucleoside analogue prodrug approved for the treatment of relapsed and refractory T-cell acute lymphoblastic leukemia (R/R T-ALL) and lymphoblastic lymphoma (T-LBL). Although effective in R/R T-ALL, significant neurotoxicity is dose-limiting and such neurotoxicity associated with nucleoside analogues can be related to dosing schedule.The authors conducted a phase 1 study to evaluate the pharmacokinetics and toxicity of nelarabine administered as a continuous infusion (CI) for 5 days (120 hours), rather than the standard, short-infusion approach.Twenty-nine patients with R/R T-ALL/LBL or T-cell prolymphocytic leukemia (T-PLL) were treated, with escalating doses of nelarabine from 100 to 800 mg/mPreliminary evaluation of continuous infusion schedule of nelarabine suggests that the safety profile is acceptable for this patient population, with clinical activity observed even at low doses and could broaden the use of nelarabine both as single agent and in combinations by potentially mitigating the risk of central nervous system toxicities.

Mutant TP53 is an adverse risk factor in acute myeloid leukemia (AML), but large-scale integrated genomic-proteomic analyses of TP53 alterations in patients with AML remain limited. We analyzed TP53 mutational status, copy number (CN), and protein expression data in AML (N = 528) and provide a compilation of mutation sites and types across disease subgroups among treated and untreated patients. Our analysis shows differential hotspots in subsets of AML and uncovers novel pathogenic variants involving TP53 splice sites. In addition, we identified TP53 CN loss in 70.2% of TP53-mutated AML cases, which have more deleterious TP53 mutations, as well as copy neutral loss of heterozygosity in 5/32 (15.6%) AML patients who had intact TP53 CN. Importantly, we demonstrate that mutant p53 protein expression patterns by immunohistochemistry evaluated using digital image-assisted analysis provide a robust readout that integrates TP53 mutation and allelic states in patients with AML. Expression of p53 by immunohistochemistry informed mutation status irrespective of TP53 CN status. Genomic analysis of comutations in TP53-mutant AML shows a muted landscape encompassing primarily mutations in genes involved in epigenetic regulation (DNMT3A and TET2), RAS/MAPK signaling (NF1, KRAS/NRAS, PTPN11), and RNA splicing (SRSF2). In summary, our data provide a rationale to refine risk stratification of patients with AML on the basis of integrated molecular and protein-level TP53 analyses.

Although venetoclax-based lower-intensity regimens have greatly improved outcomes for older adults with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy, the optimal induction for older patients with newly diagnosed AML who are suitable candidates for hematopoietic stem cell transplant (HSCT) is controversial. We retrospectively analyzed post-HSCT outcomes of 127 patients ≥60 years of age who received induction therapy at our institution with intensive chemotherapy (IC, n=44), lower-intensity therapy (LIT) without venetoclax (n=29) or LIT with venetoclax (n=54) and who underwent allogeneic HSCT in first remission. The 2-year relapse-free survival with LIT with venetoclax was 60%, versus 54% with IC and 41% with LIT without venetoclax, and 2-year overall survival for LIT with venetoclax was 72%, versus 58% with IC and 41% with LIT without venetoclax. The benefit to LIT with venetoclax induction was greatest in patients with adverse-risk AML (2-year OS 74%, 46%, and 29%, respectively). Induction with LIT, with or without venetoclax, was associated with the lowest rate of non-relapse mortality (NRM) (2-year NRM 17% versus 27% with IC; P=0.04). By multivariate analysis, type of induction therapy did not significantly impact any of the post-HSCT outcomes evaluated; hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was the only factor that independently predicted for RFS and OS. LIT plus venetoclax followed by HSCT is feasible treatment strategy in older, fit, and HSCT-eligible patients with newly diagnosed AML and may be particularly beneficial in those with adverse-risk disease.

The safety and efficacy of combining the IDH1 inhibitor ivosidenib (IVO) with the BCL2 inhibitor venetoclax (VEN; IVO+VEN) +/- azacitidine (AZA; IVO+VEN+AZA) was 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 vs. IVO+VEN was 90% vs. 83%. Among 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 EFS and OS were 36 (95% CI: 23-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 co-occurring mutations, anti-apoptotic 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.

MCL-1 is known to play a major role in resistance to BCL-2 inhibition, but the contribution of other BCL-2 family proteins has not been fully explored. We, here, demonstrate the ineffectiveness of MCL-1 inhibitor AMG176 in venetoclax-resistant, and conversely, of venetoclax in AMG176-resistant acute myelogenous leukemia (AML). Like cells with acquired resistance to venetoclax, cells with acquired resistance to AMG176 express increased MCL-1. Both cells with acquired resistance to venetoclax and to AMG176 express increased levels of BCL-2 and BCL-2A1, decreased BAX, and/or altered levels of other BCL-2 proteins. Cotargeting BCL-2 and MCL-1 was highly synergistic in AML cell lines with intrinsic or acquired resistance to BH3 mimetics or engineered to genetically overexpress BCL-2 or BCL-2A1 or downregulate BAX. The combination effectively eliminated primary AML blasts and stem/progenitor cells resistant to or relapsed after venetoclax-based therapy irrespective of mutations and cytogenetic abnormalities. Venetoclax and AMG176 combination markedly suppressed antiapoptotic BCL-2 proteins and AML stem/progenitor cells and dramatically extended mouse survival (median 336 vs. control 126 days; P < 0.0001) in a patient-derived xenograft (PDX) model developed from a venetoclax/hypomethylating agent therapy-resistant patient with AML. However, decreased BAX levels in the bone marrow residual leukemia cells after 4-week combination treatment may represent a resistance mechanism that contributed to their survival. Enhanced antileukemia activity was also observed in a PDX model of monocytic AML, known to be resistant to venetoclax therapy. Our results support codependence on multiple antiapoptotic BCL-2 proteins and suppression of BAX as mechanisms of AML resistance to individual BH3 mimetics. Cotargeting of MCL-1 and BCL-2 eliminates otherwise apoptosis-resistant cells.

Supplementary Figure from Maximal Activation of Apoptosis Signaling by Cotargeting Antiapoptotic Proteins in BH3 Mimetic–Resistant AML and AML Stem Cells

Supplementary Data from Maximal Activation of Apoptosis Signaling by Cotargeting Antiapoptotic Proteins in BH3 Mimetic–Resistant AML and AML Stem Cells

We aimed to study the risks of graft-versus-host disease (GVHD), non-relapse mortality (NRM) and survival outcomes of allogeneic stem cell transplantation (alloSCT) in patients with chronic lymphocytic leukemia (n=17), Richter’s syndrome (n=14), or lymphoma (n=18) after small molecule inhibitors (SMIs). Patients had a median of 4 prior therapies, including ibrutinib (n=46; 94%), venetoclax (n=19; 39%), and idelalisib (n=6; 12%). Twenty-one (43%) had >1 SMI. P53 mutation was detected in 58% of patients. The 3-year overall and progression-free survival rates were 68% and 59%, respectively. The rates of grade II-IV and III-IV acute GVHD were 33% and 7%. The 1-year rates of chronic GVHD, NRM and relapse were 19%, 10% and 21%, respectively. Results were comparable to a historical control of patients who received alloSCT without a prior exposure to SMI. We conclude that a prior use of SMI does not impair the outcomes after alloSCT.

PDF file - 50KB, Correlation between RPPA and immunoblotting in samples from the patients treated on MK-2206 trial.

PDF file - 62KB

PDF file - 131KB, Effects of MK-2206 on AKT signaling in FLT3-mutant AML cells.

Progression-free survival curves for groups A, B, C, and D.

PDF file - 145KB, The subtraction heat maps of selected markers in paired PB samples.

PDF file - 60KB, MK-2206 promotes accumulation of OCI-AML3 cells in the G1 phase of the cell cycle.

Purpose: We evaluated the effect on long-term survival of adding rituximab (R) to BEAM (carmustine, etoposide, cytarabine, and melphalan) conditioning with or without yttrium-90 ibritumomab tiuxetan (90YIT) in patients with relapsed diffuse large B-cell lymphoma (DLBCL) undergoing autologous stem cell transplant (ASCT).Experimental design: Patients were enrolled on three consecutive phase II clinical trials. Patients received two doses of rituximab (375 and 1,000 mg/m2) during mobilization of stem cells, followed by 1,000 mg/m2 on days +1 and +8 after ASCT with R-BEAM or 90YIT-R-BEAM (90YIT dose of 0.4 mCi/kg) conditioning.Results: One hundred thirteen patients were enrolled, with 73 receiving R-BEAM and 40 receiving 90YIT-R-BEAM. All patients had a prior exposure to rituximab. The median follow-up intervals for survivors were 11.8, 8.1, and 4.2 years in the three trials, respectively. The 5-year disease-free survival (DFS) rates were 62% for R-BEAM and 65% for 90YIT-R-BEAM (P = 0.82). The 5-year overall survival rates were 73% and 77%, respectively (P = 0.65). In patients with de novo DLBCL, survival outcomes of the germinal center/activated b-cell histologic subtypes were similar with 5-year OS rates (P = 0.52) and DFS rates (P = 0.64), irrespective of their time of relapse (1 year) after initial induction chemotherapy (P = 0.97).Conclusions: Administering ASCT with rituximab during stem cell collection and immediately after transplantation induces long-term disease remission and abolishes the negative prognostic impact of cell-of-origin in patients with relapsed DLBCL. The addition of 90YIT does not confer a further survival benefit. Clin Cancer Res; 24(10); 2304–11. ©2018 AACR.

Purpose: Recent studies suggested that AKT activation might confer poor prognosis in acute myelogenous leukemia (AML), providing the rationale for therapeutic targeting of this signaling pathway. We, therefore, explored the preclinical and clinical anti-AML activity of an oral AKT inhibitor, MK-2206.Experimental Methods: We first studied the effects of MK-2206 in human AML cell lines and primary AML specimens in vitro. Subsequently, we conducted a phase II trial of MK-2206 (200 mg weekly) in adults requiring second salvage therapy for relapsed/refractory AML, and assessed target inhibition via reverse phase protein array (RPPA).Results: In preclinical studies, MK-2206 dose-dependently inhibited growth and induced apoptosis in AML cell lines and primary AML blasts. We then treated 19 patients with MK-2206 but, among 18 evaluable participants, observed only 1 (95% confidence interval, 0%–17%) response (complete remission with incomplete platelet count recovery), leading to early study termination. The most common grade 3/4 drug-related toxicity was a pruritic rash in 6 of 18 patients. Nevertheless, despite the use of MK-2206 at maximum tolerated doses, RPPA analyses indicated only modest decreases in Ser473 AKT (median 28%; range, 12%–45%) and limited inhibition of downstream targets.Conclusions: Although preclinical activity of MK-2206 can be demonstrated, this inhibitor has insufficient clinical antileukemia activity when given alone at tolerated doses, and alternative approaches to block AKT signaling should be explored. Clin Cancer Res; 20(8); 2226–35. ©2014 AACR.

Patient demographic characteristics and baseline disease characteristics for groups A, B, C, and D

Autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy has recently been added to the armamentarium in the battle against B-ALL. In the current review, we discuss the trials that led to FDA approval of CAR T therapies in patients with B-ALL. We evaluate the evolving role of allogeneic hematopoietic stem cell transplantation in the CAR T era, and discuss lessons learned from the first steps with CAR T in ALL. Upcoming innovations in CAR technology are presented, including combined and alternative targets and off-the-shelf allogeneic CAR T cell strategies. Finally, we envision the role that CAR T could take in the management of adult patients with B-ALL in the near future.

Acute myeloid leukemia (AML) can be treated with either high or low-intensity regimens. Highly sensitive assays for measurable residual disease (MRD) now allow for a more precise assessment of response quality. We hypothesized that treatment intensity may not be a key predictor of outcomes assuming an optimal response to therapy is achieved. We performed a single-center retrospective study including 635 patients with newly diagnosed AML responding to either intensive cytarabine/anthracycline-based chemotherapy (IA, n=385) or low-intensity venetoclax-based regimens (LOW + VEN, n=250) and who had adequate flow cytometry-based MRD testing performed at the time of best response. The median overall survival (OS) was 50.2, 18.2, 13.6, and 8.1 months for the IA MRD(-), LOW + VEN MRD(-), IA MRD(+), and LOW + VEN MRD(+) cohorts, respectively. The 2-year cumulative incidence of relapse (CIR) was 41.1%, 33.5%, 64.2%, and 59.9% for the IA MRD(-), LOW + VEN MRD(-), IA MRD(+), and LOW + VEN MRD(+) cohorts, respectively. The CIR was similar between patients within MRD categories irrespective of the treatment regimen received. The IA cohort was enriched for younger patients and more favorable AML cytogenetic/molecular categories. By multivariate analysis (MVA), age, best response (CR/CRi/MLFS), MRD status, and ELN 2017 risk remained significantly associated with OS, whereas best response, MRD status, and ELN 2017 risk were significantly associated with CIR. Treatment intensity was not significantly associated with either OS or CIR. Achievement of MRD-negative complete remission should be the key objective of AML therapy in both high- and low-intensity treatment regimens.

Acute lymphoblastic leukemia, commonly known to affect the younger population, is a disease that is affecting the elderly in an increasing amount as the human life span continues to lengthen. Traditional cytotoxic agents are intolerable to elderly individuals owing to comorbidities, weakened immune systems, and organ dysfunction. Alternative agents and regimens are needed to allow for elderly patient to tolerate full cycles of therapy while providing complete and durable remissions. With the advent of targeted agents, such as monoclonal antibodies and bispecific T-cell engagers, a number of options have proven themselves to be effective in the elderly and optimal for tolerability. Here, we review and discuss the literature addressing regimens that use new agents, such as blinatumomab, inotuzumab ozogamicin, and venetoclax, and those that use modified dosing strategies of traditional chemotherapy.

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).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.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.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 T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinct subtype of T-ALL with a unique immunophenotype and high treatment failure rate. The molecular genetic abnormalities and their prognostic impact in ETP-ALL patients are poorly understood.The authors performed systematic analyses of the clinicopathologic features with an emphasis on molecular genetic aspects of 32 patients with ETP-ALL.The median age was 43 years (range, 16-71). The blasts were positive for cytoplasmic CD3 and CD7 and negative for CD1a and CD8. Other markers expressed included CD34 (88%), CD33 (72%), CD117 (68%), CD13 (58%), CD5 (partial, 56%), CD2 (38%), CD10 (25%), CD56 (partial, 19%), and CD4 (6%). Cytogenetic analyses revealed a diploid karyotype in 10 patients, simple (1-2) abnormalities in 10 patients, and complex karyotype in 10 patients. Next-generation sequencing for 21 patients demonstrated that all had gene mutations (median, four mutations per patient). The most frequently mutated genes were WT1 (38%), NOTCH1 (29%), NRAS (29%), PHF6 (25%), TP53 (24%), ASXL1 (19%), FLT3 (19%), and IKZF1 (19%). All patients except one received multi-agent chemotherapy, and 22 patients underwent allogeneic stem cell transplantation. Thrombocytopenia, an abnormal karyotype, and TP53 mutation were associated with markedly shortened overall survival. Stem cell transplantation significantly improved overall survival.Patients with ETP-ALL often have high mutation burden with increased genomic instability. TP53 mutation was the only molecular prognostic marker and was associated with complex karyotype and greater than or equal to five mutations. These patients may benefit from stem cell transplantation, and recurrent gene mutations may be novel therapeutic markers.

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

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.

Fludarabine, cytarabine, GCSF (FLAG)-based induction/consolidation results in high remission rates in core binding factor (CBF) acute myelogenous leukemia. We treated 174 consecutive patients with newly diagnosed CBF-AML in a prospective clinical trial of FLAG-based induction/consolidation in combination with gemtuzumab ozogamicin (FLAG-GO; N = 65) or in combination with idarubicin (FLAG-IDA; N = 109). The 5 year RFS in the FLAG-GO cohort was significantly better than the FLAG-IDA cohort, 78% versus 59%, respectively (p-value = .02). In multivariate analysis for RFS, age (p = .0001), FLAG-GO regimen (p = .04), 4 log reduction in CBF-related fusion transcript by quantitative polymerase chain reaction (qPCR) in bone marrow samples at end of consolidation therapy (p = .03), and additional cytogenetic abnormalities (p = .03) were significant variables. Lower age (p = .0001) and 3 log or more transcript reduction at end of induction (p = .04) were significant variables predicting for better overall survival (OS), while there was strong trend for better OS with FLAG-GO (p = .06) regimen. FLAG-GO regimen was superior in optimal disease specific fusion transcript reduction at end of induction (p = .002), mid-consolidation (p .01), and end of consolidation (p .001) therapy. Induction/consolidation with FLAG-GO regimen results in better clinical outcomes in newly diagnosed patients with CBF-AML compared to FLAG-IDA and achieves deeper molecular clearance by qPCR assessment of the fusion transcripts.

MCL-1 is known to play a major role in resistance to BCL-2 inhibition, but the contribution of other BCL-2 family proteins has not been fully explored. We, here, demonstrate the ineffectiveness of MCL-1 inhibitor AMG176 in venetoclax-resistant, and conversely, of venetoclax in AMG176-resistant acute myelogenous leukemia (AML). Like cells with acquired resistance to venetoclax, cells with acquired resistance to AMG176 express increased MCL-1. Both cells with acquired resistance to venetoclax and to AMG176 express increased levels of BCL-2 and BCL-2A1, decreased BAX, and/or altered levels of other BCL-2 proteins. Cotargeting BCL-2 and MCL-1 was highly synergistic in AML cell lines with intrinsic or acquired resistance to BH3 mimetics or engineered to genetically overexpress BCL-2 or BCL-2A1 or downregulate BAX. The combination effectively eliminated primary AML blasts and stem/progenitor cells resistant to or relapsed after venetoclax-based therapy irrespective of mutations and cytogenetic abnormalities. Venetoclax and AMG176 combination markedly suppressed antiapoptotic BCL-2 proteins and AML stem/progenitor cells and dramatically extended mouse survival (median 336 vs. control 126 days; P < 0.0001) in a patient-derived xenograft (PDX) model developed from a venetoclax/hypomethylating agent therapy-resistant patient with AML. However, decreased BAX levels in the bone marrow residual leukemia cells after 4-week combination treatment may represent a resistance mechanism that contributed to their survival. Enhanced antileukemia activity was also observed in a PDX model of monocytic AML, known to be resistant to venetoclax therapy. Our results support codependence on multiple antiapoptotic BCL-2 proteins and suppression of BAX as mechanisms of AML resistance to individual BH3 mimetics. Cotargeting of MCL-1 and BCL-2 eliminates otherwise apoptosis-resistant cells.

Allosteric inhibitors of mutant IDH1 or IDH2 induce terminal differentiation of the mutant leukemic blasts and provide durable clinical responses in approximately 40% of acute myeloid leukemia (AML) patients with the mutations. However, primary resistance and acquired resistance to the drugs are major clinical issues. To understand the molecular underpinnings of clinical resistance to IDH inhibitors (IDHi), we perform multipronged genomic analyses (DNA sequencing, RNA sequencing and cytosine methylation profiling) in longitudinally collected specimens from 60 IDH1- or IDH2-mutant AML patients treated with the inhibitors. The analysis reveals that leukemia stemness is a major driver of primary resistance to IDHi, whereas selection of mutations in RUNX1/CEBPA or RAS-RTK pathway genes is the main driver of acquired resistance to IDHi, along with BCOR, homologous IDH gene, and TET2. These data suggest that targeting stemness and certain high-risk co-occurring mutations may overcome resistance to IDHi in AML. The regulation of resistance to IDH inhibitors in acute myeloid leukaemia is not completely understood. Here the authors reveal with integrative multi-omics analyses that stemness features are major drivers of primary resistance, while high-risk mutations drive acquired resistance.

Background There are limited data on the clonal mechanisms underlying leukemogenesis, prognostic factors, and optimal therapy for atypical chronic myeloid leukemia (aCML). Methods The authors evaluated the clinicopathologic features, outcomes, and responses to therapy of 65 patients with aCML. The median age was 67 years (range, 46-89 years). Results The most frequently mutated genes included ASXL1 (83%), SRSF2 (68%), and SETBP1 (58%). Mutations in SETBP1, SRSF2, TET2, and GATA2 appeared at variant allele frequencies (VAFs) greater than 40%, whereas other RAS pathway mutations were more likely to appear at low VAFs. The acquisition of new, previously undetectable mutations at transformation was observed in 63% of the evaluable patients, with the most common involving signaling pathway mutations. Hypomethylating agents (HMAs) were associated with the highest response rates but with a short duration of response (median, 2.7 months). Therapy with ruxolitinib was not associated with clinically significant responses as a single agent or in combination with an HMA. Allogeneic stem cell transplantation was the only therapy associated with improved outcomes (hazard ratio, 0.144; 95% CI, 0.035-0.593; P = .007). Age, platelet counts, bone marrow blast percentages, and serum lactate dehydrogenase (LDH) levels were independent predictors of survival and were integrated in a multivariable model that allowed the prediction of 1- and 3-year survival. Conclusions aCML is characterized by high frequencies of ASXL1, SRSF2, and SETBP1 mutations and is associated with a high risk of acute myeloid leukemia transformation. Response and survival outcomes with current therapies remain poor. The incorporation of age, platelet counts, bone marrow blast percentages, and LDH levels can allow survival prediction, and allogeneic stem cell transplantation should be considered for all eligible patients.