BRD4 degraders may effectively counteract therapeutic resistance of leukemic stem cells in AML and ALL.

Acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) are life-threatening hematopoietic malignancies characterized by clonal expansion of leukemic blasts in the bone marrow and peripheral blood. The epigenetic reader BRD4 and its downstream effector MYC have recently been identified as potential drug targets in human AML and ALL. We compared anti-leukemic efficacies of the small-molecule BET inhibitor JQ1 and the recently developed BRD4 degraders dBET1 and dBET6 in AML and ALL cells. JQ1, dBET1, and dBET6 were found to suppress growth and viability in all AML and ALL cell lines examined as well as in primary patient-derived AML and ALL cells, including CD34+/CD38- and CD34+/CD38+ leukemic stem and progenitor cells, independent of the type (variant) of leukemia or molecular driver expressed in leukemic cells. Moreover, we found that dBET6 overcomes osteoblast-induced drug resistance in AML and ALL cells, regardless of the type of leukemia or the drug applied. Most promising cooperative or even synergistic drug combination effects were seen with dBET6 and the FLT3 ITD blocker gilteritinib in FLT3 ITD-mutated AML cells, and with dBET6 and the multi-kinase blocker ponatinib in BCR::ABL1+ ALL cells. Finally, all BRD4-targeting drugs suppressed interferon-gamma- and tumor necrosis factor-alpha-induced expression of the resistance-related checkpoint antigen PD-L1 in AML and ALL cells, including LSC. In all assays examined, the BRD4 degrader dBET6 was a superior anti-leukemic drug compared with dBET1 and JQ1. Together, BRD4 degraders may provide enhanced inhibition of multiple mechanisms of therapy resistance in AML and ALL.

Phenotypic characterization of disease-initiating stem cells in JAK2- or CALR-mutated myeloproliferative neoplasms.

Myeloproliferative neoplasms (MPN) are characterized by uncontrolled expansion of myeloid cells, disease-related mutations in certain driver-genes including JAK2, CALR, and MPL, and a substantial risk to progress to secondary acute myeloid leukemia (sAML). Although behaving as stem cell neoplasms, little is known about disease-initiating stem cells in MPN. We established the phenotype of putative CD34+ /CD38- stem cells and CD34+ /CD38+ progenitor cells in MPN. A total of 111 patients with MPN suffering from polycythemia vera, essential thrombocythemia, or primary myelofibrosis (PMF) were examined. In almost all patients tested, CD34+ /CD38- stem cells expressed CD33, CD44, CD47, CD52, CD97, CD99, CD105, CD117, CD123, CD133, CD184, CD243, and CD274 (PD-L1). In patients with PMF, MPN stem cells often expressed CD25 and sometimes also CD26 in an aberrant manner. MPN stem cells did not exhibit substantial amounts of CD90, CD273 (PD-L2), CD279 (PD-1), CD366 (TIM-3), CD371 (CLL-1), or IL-1RAP. The phenotype of CD34+ /CD38- stem cells did not change profoundly during progression to sAML. The disease-initiating capacity of putative MPN stem cells was confirmed in NSGS mice. Whereas CD34+ /CD38- MPN cells engrafted in NSGS mice, no substantial engraftment was produced by CD34+ /CD38+ or CD34- cells. The JAK2-targeting drug fedratinib and the BRD4 degrader dBET6 induced apoptosis and suppressed proliferation in MPN stem cells. Together, MPN stem cells display a unique phenotype, including cytokine receptors, immune checkpoint molecules, and other clinically relevant target antigens. Phenotypic characterization of neoplastic stem cells in MPN and sAML should facilitate their enrichment and the development of stem cell-eradicating (curative) therapies.

Impact of gemtuzumab ozogamicin on MRD and relapse risk in patients with NPM1-mutated AML: results from the AMLSG 09-09 trial.

Monitoring of measurable residual disease (MRD) provides prognostic information in patients with Nucleophosmin1-mutated (NPM1mut) acute myeloid leukemia (AML) and represents a powerful tool to evaluate treatment effects within clinical trials. We determined NPM1mut transcript levels (TLs) by quantitative reverse-transcription polymerase chain reaction and evaluated the prognostic impact of NPM1mut MRD and the effect of gemtuzumab ozogamicin (GO) on NPM1mut TLs and the cumulative incidence of relapse (CIR) in patients with NPM1mut AML enrolled in the randomized phase 3 AMLSG 09-09 trial. A total of 3733 bone marrow (BM) samples and 3793 peripheral blood (PB) samples from 469 patients were analyzed. NPM1mut TL log10 reduction ≥ 3 and achievement of MRD negativity in BM and PB were significantly associated with a lower CIR rate, after 2 treatment cycles and at end of treatment (EOT). In multivariate analyses, MRD positivity was consistently revealed to be a poor prognostic factor in BM and PB. With regard to treatment effect, the median NPM1mut TLs were significantly lower in the GO-Arm across all treatment cycles, resulting in a significantly greater proportion of patients achieving MRD negativity at EOT (56% vs 41%; P = .01). The better reduction in NPM1mut TLs after 2 treatment cycles in MRD positive patients by the addition of GO led to a significantly lower CIR rate (4-year CIR, 29.3% vs 45.7%, P = .009). In conclusion, the addition of GO to intensive chemotherapy in NPM1mut AML resulted in a significantly better reduction in NPM1mut TLs across all treatment cycles, leading to a significantly lower relapse rate.

Measurable residual disease monitoring in acute myeloid leukemia with t(8;21)(q22;q22.1): results from the AML Study Group.

We performed serial measurable residual disease (MRD) monitoring in bone marrow (BM) and peripheral blood (PB) samples of 155 intensively treated patients with RUNX1-RUNX1T1+ AML, using a qRT-PC-based assay with a sensitivity of up to 10-6. We assessed both reduction of RUNX1-RUNX1T1 transcript levels (TLs) and achievement of MRD negativity (MRD-) for impact on prognosis. Achievement of MR2.5 (>2.5 log reduction) after treatment cycle 1 and achievement of MR3.0 after treatment cycle 2 were significantly associated with a reduced risk of relapse (P = .034 and P = .028, respectively). After completion of therapy, achievement of MRD- in both BM and PB was an independent, favorable prognostic factor in cumulative incidence of relapse (4-year cumulative incidence relapse: BM, 17% vs 36%, P = .021; PB, 23% vs 55%, P = .001) and overall survival (4-year overall survival rate BM, 93% vs 70%, P = .007; PB, 87% vs 47%, P < .0001). Finally, during follow-up, serial qRT-PCR analyses allowed prediction of relapse in 77% of patients exceeding a cutoff value of 150 RUNX1-RUNX1T1 TLs in BM, and in 84% of patients exceeding a value of 50 RUNX1-RUNX1T1 TLs in PB. The KIT mutation was a significant factor predicting a lower CR rate and inferior outcome, but its prognostic impact was outweighed by RUNX1-RUNX1T1 TLs during treatment. Virtually all relapses occurred within 1 year after the end of treatment, with a very short latency from molecular to morphologic relapse, necessitating MRD assessment at short intervals during this time period. Based on our data, we propose a refined practical guideline for MRD assessment in RUNX1-RUNX1T1+ AML.

Presence of viremia during febrile neutropenic episodes in patients undergoing chemotherapy for malignant neoplasms.

The importance of viral infections as a leading cause of morbidity and mortality is well documented in severely immunosuppressed patients undergoing allogeneic stem cell transplantation. By contrast, viral infections generally receive less attention in patients with malignant disorders undergoing chemotherapy, where the onset of neutropenic fever is mostly associated with bacterial or fungal infections, and screening for viral infections is not routinely performed. To address the occurrence of invasive viral infections in a clinical setting commonly associated with less pronounced immunosuppression, we have prospectively screened 237 febrile neutropenic episodes in pediatric (n = 77) and adult (n = 69) patients undergoing intensive chemotherapy, primarily for treatment of acute leukemia. Serial peripheral blood specimens were tested by RQ-PCR assays for the presence and quantity of the clinically relevant viruses CMV, EBV, HHV6 and HAdV, commonly reactivated in highly immunocompromised patients. Viremia was documented in 36 (15%) episodes investigated, including the detection of HHV6 (n = 14), EBV (n = 15), CMV (n = 6), or HAdV (n = 1). While low or intermediate levels of viremia (<104 virus copies/mL) were commonly associated with bacterial or fungal co-infection, viremia at higher levels (>104 copies/mL) was documented in patients without evidence for other infections, raising the possibility that at least in some instances the onset of fever may have been attributable to the virus detected. The observations suggest that viral infections, potentially resulting from reactivation, might also play a clinically relevant role in patients receiving chemotherapy for treatment of malignant neoplasms, and routine screening for viremia in this clinical setting might be warranted.

CGRP Signaling via CALCRL Increases Chemotherapy Resistance and Stem Cell Properties in Acute Myeloid Leukemia.

The neuropeptide CGRP, acting through the G-protein coupled receptor CALCRL and its coreceptor RAMP1, plays a key role in migraines, which has led to the clinical development of several inhibitory compounds. Recently, high CALCRL expression has been shown to be associated with a poor prognosis in acute myeloid leukemia (AML). We investigate, therefore, the functional role of the CGRP-CALCRL axis in AML. To this end, in silico analyses, human AML cell lines, primary patient samples, and a C57BL/6-based mouse model of AML are used. We find that CALCRL is up-regulated at relapse of AML, in leukemic stem cells (LSCs) versus bulk leukemic cells, and in LSCs versus normal hematopoietic stem cells. CGRP protects receptor-positive AML cell lines and primary AML samples from apoptosis induced by cytostatic drugs used in AML therapy, and this effect is inhibited by specific antagonists. Furthermore, the CGRP antagonist olcegepant increases differentiation and reduces the leukemic burden as well as key stem cell properties in a mouse model of AML. These data provide a basis for further investigations into a possible role of CGRP-CALCRL inhibition in the therapy of AML.

High-dose Bendamustine-EAM followed by autologous stem cell rescue results in long-term remission rates in lymphoma patients, without renal toxicity.

BACKGROUND: Autologous stem cell transplantation (ASCT) following BEAM (BCNU, etoposide, cytarabine, melphalan) conditioning is standard of care in relapsed low- and high-grade B-cell lymphoma (DLBCL) and other lymphoproliferative disorders, but BCNU is associated with interstitial pneumonia and an increased mortality. A less toxic regimen might improve the outcome of patients with lymphoma after transplantation. OBJECTIVES: We investigated the role of bendamustine replacing BCNU in the BEAM regimen in patients with lymphoma undergoing ASCT. PATIENTS/METHODS: The conditioning regimen BendaEAM consisted of bendamustine, cytarabine, etoposide, and melphalan and was used in patients with Hodgkin's disease (HD) and Non-Hodgkin lymphoma (NHL). RESULTS: Forty-one patients with HD (n = 9) or NHL (n = 32) were consecutively treated with Benda-BEAM replacing BCNU. No pulmonary or renal toxicities occurred, and no patient died related to transplant. After a median follow-up of 55 months, CR rate was 56%, 18 patients (44%) showed progression after a median time of 7 months after transplantation (range: 2-29 months), and 11 patients (24%) have died, all due to lymphoma progression. The 1-, 2-, and 4-year PFS are 73.2%, 58.6%, and 55.6% and the 1-, 2-, and 4-year OS 85.4%, 78.0%, and 72.6%, respectively. CONCLUSION: BendaEAM seems to be feasible with a promising response rate and acceptable toxicity.

Valproic acid in combination with all-trans retinoic acid and intensive therapy for acute myeloid leukemia in older patients.

The outcome of patients with acute myeloid leukemia who are older than 60 years has remained poor because of unfavorable disease characteristics and patient-related factors. The randomized German-Austrian AML Study Group 06-04 protocol was designed on the basis of in vitro synergistic effects of valproic acid (VPA) and all-trans retinoic acid with chemotherapy. Between 2004 and 2006, 186 patients were randomly assigned to receive 2 induction cycles with idarubicin, cytarabine, and all-trans retinoic acid either with VPA or without (STANDARD). In all patients, consolidation therapy was intended. Complete remission rates after induction tended to be lower in VPA compared with STANDARD (40% vs 52%; P = .14) as a result of a higher early death rate (26% vs 14%; P = .06). The main toxicities attributed to VPA were delayed hematologic recovery and grade 3/4 infections, observed predominantly during the second induction cycle. After restricting VPA to the first induction cycle and reducing the dose of idarubicin, these toxicities dropped to rates observed in STANDARD. After a median follow-up time of 84 months, event-free and overall survival were not different between the 2 groups (P = .95 and P = .57, respectively). However, relapse-free-survival was significantly superior in VPA compared with STANDARD (24.4% vs 6.4% at 5 years; P = .02). Explorative subset analyses revealed that AML with mutated Nucleophosmin 1 (NPM1) may particularly benefit from VPA. This trial was registered at www.clinicaltrials.gov as #NCT00151255.

Salvage therapy with high-dose cytarabine and mitoxantrone in combination with all-trans retinoic acid and gemtuzumab ozogamicin in acute myeloid leukemia refractory to first induction therapy.

Outcome of patients with primary refractory acute myeloid leukemia remains unsatisfactory. We conducted a prospective phase II clinical trial with gemtuzumab ozogamicin (3 mg/m(2) intravenously on day 1), all-trans retinoic acid (45 mg/m(2) orally on days 4-6 and 15 mg/m(2) orally on days 7-28), high-dose cytarabine (3 g/m(2)/12 h intravenously on days 1-3) and mitoxantrone (12 mg/m(2) intravenously on days 2-3) in 93 patients aged 18-60 years refractory to one cycle of induction therapy. Primary end point of the study was response to therapy; secondary end points included evaluation of toxicities, in particular, rate of sinusoidal obstruction syndrome after allogeneic hematopoietic cell transplantation. Complete remission or complete remission with incomplete blood count recovery was achieved in 47 (51%) and partial remission in 10 (11%) patients resulting in an overall response rate of 61.5%; 33 (35.5%) patients had refractory disease and 3 patients (3%) died. Allogeneic hematopoietic cell transplantation was performed in 71 (76%) patients; 6 of the 71 (8.5%) patients developed moderate or severe sinusoidal obstruction syndrome after transplantation. Four-year overall survival rate was 32% (95% confidence interval 24%-43%). Patients responding to salvage therapy and undergoing allogeneic hematopoietic cell transplantation (n=51) had a 4-year survival rate of 49% (95% confidence intervaI 37%-64%). Patients with fms-like tyrosine kinase internal tandem duplication positive acute myeloid leukemia had a poor outcome despite transplantation. In conclusion, the described regimen is an effective and tolerable salvage therapy for patients who are primary refractory to one cycle of conventional intensive induction therapy. (clinicaltrials.gov identifier: 00143975).

Intensive chemotherapy with or without gemtuzumab ozogamicin in patients with NPM1-mutated acute myeloid leukaemia (AMLSG 09-09): a randomised, open-label, multicentre, phase 3 trial.

BACKGROUND: Acute myeloid leukaemia with mutated NPM1 is associated with high CD33 expression and intermediate-risk cytogenetics. The aim of this study was to evaluate intensive chemotherapy with or without the anti-CD33 antibody-drug conjugate gemtuzumab ozogamicin in participants with newly diagnosed, NPM1-mutated acute myeloid leukaemia. METHODS: This open-label, phase 3 trial was conducted at 56 hospitals in Germany and Austria. Eligible participants were 18 years or older and had newly diagnosed NPM1-mutated acute myeloid leukaemia and an Eastern Cooperative Oncology Group performance status of 0-2. Participants were randomly assigned, using age as a stratification factor (18-60 years vs >60 years), 1:1 to the two treatment groups using allocation concealment; there was no masking of participants and investigators to treatment groups. Participants received two cycles of induction therapy (idarubicin, cytarabine, and etoposide) plus all-trans retinoic acid (ATRA) followed by three consolidation cycles of high-dose cytarabine (or an intermediate dose for those older than 60 years) and ATRA, without or with gemtuzumab ozogamicin (3 mg/m2 administered intravenously on day 1 of induction cycles 1 and 2, and consolidation cycle 1). The primary endpoints were short-term event-free survival and overall survival in the intention-to-treat population (overall survival was added as a co-primary endpoint after amendment four of the protocol on Oct 13, 2013). The secondary endpoints were event-free survival with long-term follow-up, rates of complete remission, complete remission with partial haematological recovery (CRh), and complete remission with incomplete haematological recovery (CRi), cumulative incidences of relapse and death, and number of days in hospital. This trial is registered with ClinicalTrials.gov (NCT00893399) and has been completed. FINDINGS: Between May 12, 2010, and Sept 1, 2017, 600 participants were enrolled, of which 588 (315 women and 273 men) were randomly assigned (296 to the standard group and 292 to the gemtuzumab ozogamicin group). No difference was found in short-term event-free survival (short-term event-free survival at 6-month follow-up, 53% [95% CI 47-59] in the standard group and 58% [53-64] in the gemtuzumab ozogamicin group; hazard ratio [HR] 0·83; 95% CI 0·65-1·04; p=0·10) and overall survival between treatment groups (2-year overall survival, 69% [63-74] in the standard group and 73% [68-78] in the gemtuzumab ozogamicin group; 0·90; 0·70-1·16; p=0·43). There was no difference in complete remission or CRi rates (n=267 [90%] in the standard group vs n=251 [86%] in the gemtuzumab ozogamicin group; odds ratio [OR] 0·67; 95% CI 0·40-1·11; p=0·15) and complete remission or CRh rates (n=214 [72%] vs n=195 [67%]; OR 0·77; 0·54-1·10; p=0·18), whereas the complete remission rate was lower with gemtuzumab ozogamicin (n=172 [58%] vs n=136 [47%]; OR 0·63; 0·45-0·80; p=0·0068). Cumulative incidence of relapse was significantly reduced by gemtuzumab ozogamicin (2-year cumulative incidence of relapse, 37% [95% CI 31-43] in the standard group and 25% [20-30] in the gemtuzumab ozogamicin group; cause-specific HR 0·65; 0·49-0·86; p=0·0028), and there was no difference in the cumulative incidence of death (2-year cumulative incidence of death 6% [4-10] in the standard group and 7% [5-11] in the gemtuzumab ozogamicin group; HR 1·03; 0·59-1·81; p=0·91). There were no differences in the number of days in hospital across all cycles between treatment groups. The most common treatment-related grade 3-4 adverse events were febrile neutropenia (n=135 [47%] in the gemtuzumab ozogamicin group vs n=122 [41%] in the standard group), thrombocytopenia (n=261 [90%] vs n=265 [90%]), pneumonia (n=71 [25%] vs n=64 [22%]), sepsis (n=85 [29%] vs n=73 [25%]). Treatment-related deaths were documented in 25 participants (4%; n=8 [3%] in the standard group and n=17 [6%] in the gemtuzumab ozogamicin group), mostly due to sepsis and infections. INTERPRETATION: The primary endpoints of the trial of event-free survival and overall survival were not met. However, an anti-leukaemic efficacy of gemtuzumab ozogamicin in participants with NPM1-mutated acute myeloid leukaemia is shown by a significantly lower cumulative incidence of relapse rate, suggesting that the addition of gemtuzumab ozogamicin might reduce the need for salvage therapy in these participants. The results from this study provide further evidence that gemtuzumab ozogamicin should be added in the standard of care treatment in adults with NPM1-mutated acute myeloid leukaemia. FUNDING: Pfizer and Amgen.

Clinical significance of genetic aberrations in secondary acute myeloid leukemia.

The study aimed to identify genetic lesions associated with secondary acute myeloid leukemia (sAML) in comparison with AML arising de novo (dnAML) and assess their impact on patients' overall survival (OS). High-resolution genotyping and loss of heterozygosity mapping was performed on DNA samples from 86 sAML and 117 dnAML patients, using Affymetrix Genome-Wide Human SNP 6.0 arrays. Genes TP53, RUNX1, CBL, IDH1/2, NRAS, NPM1, and FLT3 were analyzed for mutations in all patients. We identified 36 recurrent cytogenetic aberrations (more than five events). Mutations in TP53, 9pUPD, and del7q (targeting CUX1 locus) were significantly associated with sAML, while NPM1 and FLT3 mutations associated with dnAML. Patients with sAML carrying TP53 mutations demonstrated lower 1-year OS rate than those with wild-type TP53 (14.3% ± 9.4% vs. 35.4% ± 7.2%; P = 0.002), while complex karyotype, del7q (CUX1) and del7p (IKZF1) showed no significant effect on OS. Multivariate analysis confirmed that mutant TP53 was the only independent adverse prognostic factor for OS in sAML (hazard ratio 2.67; 95% CI: 1.33-5.37; P = 0.006). Patients with dnAML and complex karyotype carried sAML-associated defects (TP53 defects in 54.5%, deletions targeting FOXP1 and ETV6 loci in 45.4% of the cases). We identified several co-occurring lesions associated with either sAML or dnAML diagnosis. Our data suggest that distinct genetic lesions drive leukemogenesis in sAML. High karyotype complexity of sAML patients does not influence OS. Somatic mutations in TP53 are the only independent adverse prognostic factor in sAML. Patients with dnAML and complex karyotype show genetic features associated with sAML and myeloproliferative neoplasms.

CPX-351 (Vyxeos®) can cause severe rash in acute myeloid leukemia-A case report.

CPX-351, a promising new agent for patients with treatment-related and secondary acute myeloid leukemia can lead to a severe whole-body rash. Although severe side effects are rare, treatment should be carefully monitored at specialized centers.

IL2RA Promotes Aggressiveness and Stem Cell-Related Properties of Acute Myeloid Leukemia.

Overexpression of IL2RA, which encodes the alpha chain of the IL2 receptor, is associated with chemotherapy resistance and poor outcome in acute myeloid leukemia (AML). The clinical potential of anti-IL2RA therapy is, therefore, being explored in early-stage clinical trials. Notwithstanding, only very limited information regarding the biological function of IL2RA in AML is available. Using genetic manipulation of IL2RA expression as well as antibody-mediated inhibition of IL2RA in human cell lines, mouse models, and primary patient samples, we investigated the effects of IL2RA on AML cell proliferation and apoptosis, and on pertinent signaling pathways. The impact of IL2RA on the properties of leukemic stem cells (LSC) and on leukemogenesis were queried. IL2RA promoted proliferation and cell-cycle activity and inhibited apoptosis in human AML cell lines and primary cells. These phenotypes were accompanied by corresponding alterations in cell-cycle machinery and in pathways associated with cell survival and apoptosis. The biological roles of IL2RA were confirmed in two genetically distinct AML mouse models, revealing that IL2RA inhibits differentiation, promotes stem cell-related properties, and is required for leukemogenesis. IL2RA antibodies inhibited leukemic, but not normal, hematopoietic cells and synergized with other antileukemic agents in this regard. Collectively, these data show for the first time that IL2RA plays key biological roles in AML and underscore its value as a potential therapeutic target in this disease. SIGNIFICANCE: This study identifies IL2RA as a potential therapeutic target in AML, where it is shown to regulate proliferation, differentiation, apoptosis, stem cell-related properties, and leukemogenesis.

Genomic heterogeneity in core-binding factor acute myeloid leukemia and its clinical implication.

Core-binding factor (CBF) acute myeloid leukemia (AML) encompasses AML with inv(16)(p13.1q22) and AML with t(8;21)(q22;q22.1). Despite sharing a common pathogenic mechanism involving rearrangements of the CBF transcriptional complex, there is growing evidence for considerable genotypic heterogeneity. We comprehensively characterized the mutational landscape of 350 adult CBF-AML [inv(16): n = 160, t(8;21): n = 190] performing targeted sequencing of 230 myeloid cancer-associated genes. Apart from common mutations in signaling genes, mainly NRAS, KIT, and FLT3, both CBF-AML entities demonstrated a remarkably diverse pattern with respect to the underlying cooperating molecular events, in particular in genes encoding for epigenetic modifiers and the cohesin complex. In addition, recurrent mutations in novel collaborating candidate genes such as SRCAP (5% overall) and DNM2 (6% of t(8;21) AML) were identified. Moreover, aberrations altering transcription and differentiation occurred at earlier leukemic stages and preceded mutations impairing proliferation. Lasso-penalized models revealed an inferior prognosis for t(8;21) AML, trisomy 8, as well as FLT3 and KIT exon 17 mutations, whereas NRAS and WT1 mutations conferred superior prognosis. Interestingly, clonal heterogeneity was associated with a favorable prognosis. When entering mutations by functional groups in the model, mutations in genes of the methylation group (ie, DNMT3A, TET2) had a strong negative prognostic impact.

Gemtuzumab Ozogamicin in NPM1-Mutated Acute Myeloid Leukemia: Early Results From the Prospective Randomized AMLSG 09-09 Phase III Study.

PURPOSE: High CD33 expression in acute myeloid leukemia (AML) with mutated NPM1 provides a rationale for the evaluation of gemtuzumab ozogamicin (GO) in this AML entity. We conducted a randomized trial to evaluate GO in combination with intensive induction and consolidation therapy in NPM1-mutated AML. PATIENTS AND METHODS: Between May 2010 and September 2017, patients ≥ 18 years old and considered eligible for intensive therapy were randomly assigned up front for induction therapy with idarubicin, cytarabine, etoposide, and all-trans-retinoic acid with or without GO. The early (P = .02) primary end point of event-free survival (EFS) was evaluated 6 months after completion of patient recruitment. RESULTS: Five hundred eighty-eight patients were randomly assigned (standard arm, n = 296; GO arm, n = 292). EFS in the GO arm was not significantly different compared with that in the standard arm (hazard ratio, 0.83; 95% CI, 0.65 to 1.04; P = .10). The early death rate during induction therapy was 10.3% in the GO arm and 5.7% in the standard arm (P = .05). Causes of death in both arms were mainly infections. The cumulative incidence of relapse (CIR) in patients achieving a complete remission (CR) or CR with incomplete hematologic recovery (CRi) was significantly reduced in the GO arm compared with the standard arm (P = .005), with no difference in the cumulative incidence of death (P = .80). Subgroup analysis revealed a significant beneficial effect of GO in female, younger (≤ 70 years), and FLT3 internal tandem duplication-negative patients with respect to EFS and CIR. CONCLUSION: The trial did not meet its early primary end point of EFS, mainly as a result of a higher early death rate in the GO arm. However, in patients achieving CR/CRi after induction therapy, significantly fewer relapses occurred in the GO compared with the standard arm.

Gene mutations and response to treatment with all-trans retinoic acid in elderly patients with acute myeloid leukemia. Results from the AMLSG Trial AML HD98B.

BACKGROUND: In a previous randomized trial, AML HD98B, we showed that administration of all-trans retinoic acid in addition to intensive chemotherapy improved the outcome of older patients with acute myeloid leukemia. The objectives of this study were to evaluate the prognostic impact of gene mutations and to identify predictive genetic factors for the all-trans retinoic acid treatment effect. DESIGN AND METHODS: Data from mutation analyses of the NPM1, CEBPA, FLT3, and MLL genes were correlated with outcome in patients 61 years and older treated within the AML HD98B trial. RESULTS: The frequencies of mutations were: NPM1, 23%; CEBPA, 8.5% (analysis restricted to patients with a normal karyotype); FLT3 internal tandem duplications (ITD), 17%; FLT3 tyrosine kinase domain mutations, 5%; and MLL partial tandem duplications, 4.5%. The genotype mutant NPM1 was positively and adverse cytogenetics as well as higher white blood cell count negatively correlated with achievement of complete remission. In Cox regression analysis, a significant interaction between the genotype mutant NPM1 without FLT3-ITD and treatment with all-trans retinoic acid was identified, in that the beneficial effect of all-trans retinoic acid on relapse-free and overall survival was restricted to this subgroup of patients. Other significant factors for survival were age, adverse cytogenetics, and logarithm of white cell count. CONCLUSIONS: In elderly patients with acute myeloid leukemia, NPM1 mutations are associated with achievement of complete remission, and the genotype 'mutant NPM1 without FLT3-ITD' appears to be a predictive marker for response to all-trans retinoic acid given as an adjunct to intensive chemotherapy (ClinicalTrials.gov Identifier: NCT00151242).

Expression and prognostic significance of different mRNA 5'-end variants of the oncogene EVI1 in 266 patients with de novo AML: EVI1 and MDS1/EVI1 overexpression both predict short remission duration.

Rearrangements of chromosome band 3q26.2 lead to overexpression of the EVI1 gene and are associated with a poor prognosis in myeloid malignancies. EVI1 is also overexpressed in some cases without 3q26 rearrangements. To uncover its prognostic significance in this patient group, however, it may be necessary to distinguish among several known 5'-end variants of its mRNA. According to a recent report, overexpression of the transcript variant EVI1_1d was associated with shortened survival in acute myeloid leukemia (AML), but overexpression of MDS1/EVI1, whose protein product differs structurally and functionally from that of all other known EVI1 5'-end variants, was not. The aim of the present study was to determine, for the first time, the expression and prognostic significance of all known EVI1 5'-end variants in AML. Quantitative RT-PCR was used to measure the expression of EVI1_1a, EVI1_1b, EVI1_1d, EVI1_3L, and MDS1/EVI1 in 266 samples from patients with de novo AML. To correlate expression of the EVI1 5'-end variants with survival parameters, regression analyses were performed. 41/266 patients (15.4%) overexpressed at least one, but more often several or all, EVI1 transcript type(s). High expression of each of the EVI1 mRNA variants, including MDS1/EVI1, was significantly associated with shortened continuous complete remission in the total patient population as well as in the subgroups of patients with intermediate risk or normal cytogenetics. The present study therefore shows that high levels of each of the known EVI1 mRNA 5'-end variants represents an adverse prognostic factor in de novo AML without 3q26 rearrangements. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

All-trans retinoic acid enhances, and a pan-RAR antagonist counteracts, the stem cell promoting activity of EVI1 in acute myeloid leukemia.

Ecotropic virus integration site 1 (EVI1), whose overexpression characterizes a particularly aggressive subtype of acute myeloid leukemia (AML), enhanced anti-leukemic activities of all-trans retinoic acid (atRA) in cell lines and patient samples. However, the drivers of leukemia formation, therapy resistance, and relapse are leukemic stem cells (LSCs), whose properties were hardly reflected in these experimental setups. The present study was designed to address the effects of, and interactions between, EVI1 and retinoids in AML LSCs. We report that Evi1 reduced the maturation of leukemic cells and promoted the abundance, quiescence, and activity of LSCs in an MLL-AF9-driven mouse model of AML. atRA further augmented these effects in an Evi1 dependent manner. EVI1 also strongly enhanced atRA regulated gene transcription in LSC enriched cells. One of their jointly regulated targets, Notch4, was an important mediator of their effects on leukemic stemness. In vitro exposure of leukemic cells to a pan-RAR antagonist caused effects opposite to those of atRA. In vivo antagonist treatment delayed leukemogenesis and reduced LSC abundance, quiescence, and activity in Evi1high AML. Key results were confirmed in human myeloid cell lines retaining some stem cell characteristics as well as in primary human AML samples. In summary, our study is the first to report the importance of EVI1 for key properties of AML LSCs. Furthermore, it shows that atRA enhances, and a pan-RAR antagonist counteracts, the effects of EVI1 on AML stemness, thus raising the possibility of using RAR antagonists in the therapy of EVI1high AML.

Oxidation by hypochlorite converts protective HDL into a potent platelet agonist.

High density lipoproteins (HDL) represent a protective factor of central importance that counteracts the development of cardiovascular disease, in part by normalizing platelet (hyper)reactivity. As HDL represent an efficient scavenger of the naturally occurring oxidant hypochlorite, this work was intended to investigate the influence of hypochlorite-oxidized HDL on platelet function. Addition of hypochlorite-oxidized HDL to human platelets results in an immediate and transient raise in intracellular calcium, surface expression of P-selectin and platelet aggregation. The observed effects are dose dependent and can be blocked by an antibody directed against the lipoprotein-binding domain of platelet thrombospondin- and scavenger receptor CD36.

Platelet-stimulating effects of oxidized LDL are not attributable to toxic properties of the lipoproteins.

One prominent feature of oxidized LDL (OxLDL) is their ability to activate human platelets and effects of OxLDL on platelet function have been shown to depend on the chemical mechanisms that form the basis for the oxidation process. In this regard, the possibility that the observed platelet-stimulating properties of OxLDL might be a direct consequence of cytotoxic effects mediated by these lipoproteins merits further investigation, as experimental strategies to overcome the toxic effects of OxLDL towards a variety of different cell types did not yield conclusive results. In the present work, we show that copper-oxidized LDL mediate severe toxic effects towards a macrophage cell line (decrease in both the number of adherent cells and the amount of incorporated tritiated thymidine, induction of apoptosis and subsequent loss of membrane integrity)--effects that are presumably attributable to products emerging from lipid peroxidation. When added to resting human platelets, copper oxidized LDL stimulate platelets but are not able to trigger an aggregation response on their own. In contrast, hypochlorite-oxidized LDL are able to trigger platelet aggregation, but do not mediate toxic effects towards nucleated cells. Even in the absence of exogenous antioxidants, these lipoproteins mediate cytostatic effects but do not negatively affect cell viability. As a conclusion, platelet-activating effects of oxidatively modified LDL are not attributable to toxic properties of the lipoproteins and this finding might expand possibilities for therapeutical intervention.