Cytarabine In Acute Myeloid Leukemia Research Articles

Phase 1b/2 Study of Escalating Doses of the NEDD8 Activating Enzyme Inhibitor Pevonedistat Administered in Combination with Standard Induction Therapy (Cytarabine and Idarubicin) in Newly Diagnosed High Risk Acute Myeloid Leukemia

Introduction: Pevonedistat is a potent and selective small-molecule inhibitor of the NEDD8-activating enzyme that has demonstrated clinical activity in acute myeloid leukemia (AML). Preclinical studies suggest that pevonedistat synergistically enhances the activity of cytarabine in AML. We investigated the safety and efficacy of pevonedistat in combination with 7+3 cytarabine and idarubicin induction chemotherapy in adults with high-risk AML. Methods: This open-label, multicenter phase 1b/2 study (NCT03330821) enrolled patients aged ≥18 years with newly diagnosed high-risk AML, defined as therapy-related AML, AML with antecedent myelodysplastic syndrome or AML with myelodysplasia-related changes, the presence of adverse genetic features per ELN 2017 guidelines, or being age ≥55. Eligible patients had an ECOG status of 0-2. Patients were administered pevonedistat on days 1, 3, and 5 of each 28-day cycle in combination with cytarabine 100 mg/m 2 on days 1-7 and idarubicin 12 mg/m 2 on days 1-3. In the phase 1b dose-escalation part of the study, a standard 3+3 design was used to evaluate 2 dose levels of pevonedistat: 15 and 20 mg/m 2. Consolidation consisted of up to 4 cycles of cytarabine (1-3 g/m 2 q12h) on days 1, 3, and 5 or transplant. For pharmacodynamic (PD) assessment, RT-PCR assays were performed on peripheral blood samples to measure expression levels of 7 NRF-2 target genes (ATF3, GCLM, GSR, NQ01, SLC7A11, SRXN1, and TXNRD1). The primary objective for the phase 1b study was to determine the RP2D of pevonedistat in combination with cytarabine and idarubicin. The primary objective for the phase 2 study was to determine the composite complete response rate (CRc; CR+CRi). Secondary objectives included relapse-free survival (RFS), overall survival (OS), and safety and tolerability. Results: A total of 28 patients were enrolled at 5 sites in the US between August 2018 and August 2021. Six patients were enrolled in the phase 1b study and 22 patients in phase 2. Baseline patient characteristics are shown in Table 1. The median age was 61 years (range 47-74). Per the 2017 ELN risk classification, 8 of 28 patients (29%) had favorable risk, 8 (29%) had intermediate risk, and 12 (43%) had adverse risk. All 28 patients were included for safety and response assessments. In phase 1b, none of the 6 patients experienced dose-limiting toxicity at 15 or 20 mg/m 2. Thus, the RP2D of pevonedistat was determined to be 20 mg/m 2. The CRc rate was 64% (95% CI 44-81) with 17 patients achieving CR and 1 patient achieving CRi. Of the 18 patients who achieved CR or CRi, 16 (89%) achieved MRD negativity by multiparameter flow cytometry, and 7 (39%) proceeded to HSCT. The CRc rates for patients in the ELN 2017 favorable, intermediate, and adverse risk groups were 100% (95% CI 63-100), 63% (95% CI 29-89), and 42% (95% CI 18-71), respectively. Eight patients were included in the interim PD analysis. Among patients who achieved CR or CRi (n=6), 4 (ATF3, GSR, SLC7A11, and SRXN1) of the 7 NRF-2 target genes measured were significantly upregulated at 5 hours post-pevonedistat induction compared to baseline. There was no significant increase in NRF-2-regulated gene transcript levels among patients with refractory disease (n=2). The median follow-up was 31.1 months (range 19.1-55.9). The median RFS was 24.4 months (95% CI 7-54.3+) and median OS was 25 months (95% CI 11.9-55.9+). The estimated 1-year and 2-year RFS were 72% (95% CI 52-93) and 55% (95% CI 23-78), respectively. The estimated 1-year and 2-year OS were 68% (95% CI 51-85) and 53% (95% CI 34-72), respectively. The most common grade ≥3 treatment-related adverse events were anemia (61%), febrile neutropenia (25%), and hypophosphatemia (18%). No treatment-related deaths were observed. Conclusion: Pevonedistat in combination with cytarabine and idarubicin was well tolerated among adults with newly diagnosed, high-risk AML and induced deep remissions with promising RFS and OS.

Venetoclax + Cladribine + Low-Dose Cytarabine in Acute Myeloid Leukemia Relapsed or Refractory to Venetoclax + Hypomethylating Agent

Background Venetoclax (Ven) in combination with hypomethylating agent (HMA) is the standard treatment for newly diagnosed elderly/unfit patients with acute myeloid leukemia (AML). Treatment options for patients with relapsed/refractory (RR) disease following Ven-HMA are limited in the absence of targetable mutations. In a recent phase 2 study, the addition of Ven to cladribine (CDA) plus low-dose cytarabine (LDAC), in newly-diagnosed elderly/unfit AML, resulted in complete remission with (CR) or without (CRi) count recovery rate of 93% ( J Clin Oncol 20;40(33)). In the current study, we share our experience with this regimen in patients relapsed or refractory to Ven-HMA, treated outside of clinical trials. Methods Under an institutional review board approved minimum risk protocol, the Mayo Clinic (MN, AZ, FL) database was searched to identify patients with AML who failed treatment with Ven-HMA and subsequently received at least one cycle of salvage therapy with Ven-CDA-LDAC: Ven 100-400 mg, dose adjusted, d1-21, CDA 5 mg/m 2 d1-5, LDAC 20 mg twice daily d1-10, outside of clinical trials. Cytogenetic and molecular studies were performed at the time of Ven-CDA-LDAC initiation in most cases, by conventional karyotype and next-generation sequencing, respectively. The 2022 European LeukemiaNet (ELN) criteria were applied to define risk and response. Survival was calculated from the time of Ven-CDA-LDAC treatment start to last follow-up or death. Results Patient characteristics A total of 39 RR AML patients (median age 65 years, 67% male, 64% de novo), with prior exposure to Ven-HMA, received Ven-CDA-LDAC (median 1 cycle; range 1-5). Study patients had received one ( n=16), two ( n=14), three ( n=5), four ( n=2), five ( n=1) or nine ( n=1) prior therapies, including Ven-HMA. Nine (23%) patients had relapsed following allogeneic hematopoietic stem cell transplant (AHSCT). ELN cytogenetic risk included intermediate (46%, n=18), and adverse (54%, n=21). Mutations involved TP53 in 9 patients (23%), K/ NRAS in 8 (21%), RUNX1 in 7 (18%), TET2 in 6 (15%), ASXL1 in 5 (13%), and STAG2 in 5 (13%). Response and toxicity Eleven (28%) patients achieved CR ( n=2; 5%) or CRi ( n=9; 23%); median time to response was 1 month and median response duration 3.4 months. In addition, 2 (5%) patients each experienced partial remission (PR) and bone marrow aplasia without fulfilling criteria for morphologic leukemia free state. Measurable residual disease (MRD) was negative by multiparametric flow cytometry in 2 of 7 (29%) informative CR/CRi cases. CR/CRi rates were higher in females (54% vs 15%; p=0.01), de novo vssecondary AML (40% vs 7%; p=0.02), and absence of adverse karyotype (50% vs 9%; p<0.01), K/NRAS (35% vs 0%, p=0.01), ASXL1 (32% vs 0%, p=0.05), or STAG2 mutations (32% vs 0%, p=0.05) (Table 1). Multivariable analysis confirmed superior response in de novo AML (p<0.01), absence of adverse karyotype, (p<0.01), and absence of K/NRAS mutations (p=0.02). CR/CRi rates were not significantly affected by relapsed vs refractory setting ( p=0.95), number of prior therapies ( p=0.51), prior AHSCT ( p=0.64), or TP53 mutations ( p=0.64) (Table 1). Treatment-emergent toxicities included infections (49%, n=19), comprising bacteremia ( n=11), pneumonia ( n=10), peri-rectal abscess ( n=6), and laboratory evidence of tumor lysis syndrome (3%, n=1). Survival At a median follow-up of 3.9 months, from initiation of Ven-CDA-LDAC, 31 deaths (79%), 6 relapses (15%), and 7 AHSCT (18%; including 5 in CR/CRi, 1 in aplasia) were documented. Median survival following Ven-CDA-LDAC was 4.6 months, and superior in the presence vs absence of CR/CRi (8.1 vs 2.9 months; p=0.01), and in patients receiving AHSCT (10.5 vs 3.4 months; p=0.02). Absence of adverse karyotype was also associated with superior survival (6 vs 3.4 months; p=0.05). Multivariable analysis confirmed the favorable survival impact of CR/CRi ( p=0.03) and AHSCT ( p=0.05); survival impact was not apparent for secondary AML ( p=0.29) or K/NRAS ( p=0.70) or TP53 ( p=0.10) mutations. Conclusions The current study suggests transplant bridging value for Ven-CDA-LDAC in AML patients relapsed or refractory to Ven-HMA, especially in the absence of adverse karyotype or K/NRAS mutation. AHSCT and achievement of CR/CRi appear to be indispensable for favorable post-Ven-CDA-LDAC survival.

Fusariosis in patients with hematological malignancies: Two case reports

Immunosuppressed patients with hematological malignancies are at risk for invasive fungal infections (IFI), including infections with Fusarium species (spp.), which are increasingly reported. Particularly at risk are patients with acute myeloid leukemia (AML) treated with high-dose cytarabine as remission-induction therapy. Whether cytarabine increases the risk of IFI in comparison to other chemotherapy remains not fully determined. Additionally, no clear correlation between the in vitro established minimal inhibitory concentrations (MICs) of antifungal agents and clinical outcome has been established for fusariosis. To increase awareness and knowledge of invasive fusariosis, we report two cases of Fusarium spp. infections in neutropenic patients following treatment with cytarabine for AML. Despite high MICs for azoles both patients were treated with an azole in combination with liposomal amphotericin B. The combination therapy was successful in one patient, however the other patient did not survive the disseminated Fusarium infection.

Chidamide Combined with Cytarabine Plays a Role in the Treatment of AML By Down-Regulating the MYC-RRP9 Pathway

Purpose: To explore the therapeutic effect and mechanism of Chidamide combined with Cytarabine in acute myeloid leukemia (AML), and to provide a new treatment strategy for AML patients. Methods: The effects of Chidamide and Cytarabine alone or in combination on the phenotype of AML cell lines were detected by MTT, flow cytometry and Western blot. Transcriptome sequencing and GSEA software were used to explore the mechanism of Chidamide combined with Cytarabine in the treatment of AML. RRP9 overexpression and knockdown AML cell lines were constructed by lentivirus to explore the effects of RRP9 on the proliferation, drug sensitivity, precursor ribosomal RNA (rRNA) process and protein production capacity of AML cell lines. Mature rRNA was detected by qPCR, nascent RNA was detected by EU kit, nucleolar area was observed by electron microscope, and nascent protein was detected by protein synthesis kit. Lentivirus and chromatin immunoprecipitation (CHIP) were used to explore the upstream regulatory genes of RRP9. The effects of Chidamide combined with Cytarabine on the survival rate and molecular level of primary AML cells were detected by CCK-8 and qPCR, respectively. An AML mouse model was constructed to explore the effects of Chidamide and Cytarabine on tumor burden and survival time in AML mice. Results: Chidamide combined with Cytarabine was more effective in killing AML cell lines than single drug, and the combination index was less than 1. The apoptosis rate (P<0.01) and the apoptotic protein level (P<0.05) induced by double drug were both higher than those induced by single drug. Chidamide combined with Cytarabine significantly down-regulated MYC pathway RRP9. In this pathway, RRP9 was selected for further research. An AML cell line overexpressing RRP9 was constructed. RRP9 overexpression promoted the proliferation of AML cell line (p<0.01) and induced the AML cell line to be resistant to the dual-drug combination (P<0.01). Construction of RRP9 knockdown AML cell line. The mature rRNA (P<0.01), nascent RNA (P<0.05), nucleolar area (P<0.0001) and nascent protein level (P<0.05) of cells in the RRP9 knockdown group were significantly lower than those in the control group. In addition, Chidamide combined with Cytarabine reduced the levels of mature rRNA (P<0.05), nascent RNA, nucleolar area (P<0.05), and nascent protein (P<0.05) in AML cell lines. The expression levels of RRP9 in MYC-overexpressing cells and knockdown cells were higher and lower than those in the control group, respectively (P<0.05). CHIP showed that the enrichment abundance of MYC at the RRP9 promoter site was significantly higher than that of IgG (P<0.05). The downregulation of MYC by dual-drug combination was stronger than that of single-drug(P<0.05). Chidamide combined with Cytarabine had stronger killing effect on AML primary cells than single drug, and the combination index was less than 1. Chidamide combined with Cytarabine down-regulated MYC (P<0.05) and RRP9 (P<0.01) mRNA levels in AML primary cells. The results of in vivo imaging of small animals showed that Chidamide alone could significantly reduce the tumor burden in mice (P<0.01), and the combination with Cytarabine further reduced the tumor burden (P<0.01). The survival time of mice in the Chidamide combined with Cytarabine treatment group was significantly longer than that in the control group (median survival time 28 days (28-31 days) vs 23 days (19-26 days)) (P<0.001), and the difference was still statistically significant compared with the single drug (P<0.05). Conclusion: Chidamide combined with cytarabine has a synergistic therapeutic effect on AML cell lines, primary cells and AML mice, which inhibits mature rRNA, total RNA and protein synthesis in AML cells caused AML cell death by synergistically down-regulating the MYC-RRP9 pathway.

Curcumin sensitizes response to cytarabine in acute myeloid leukemia by regulating intestinal microbiota

PurposeTo address whether Curcumin has synergistic effect with cytarabine (Ara-C) in treating acute myeloid leukemia (AML).MethodsA xenograft AML mouse model was established by injecting HL-60 cells into tail vein of mice to assess the function of Curcumin. Mononuclear cells (MNCs) isolated from AML mice and AML cell lines were used to examine the effect of Curcumin. Metagenomics and metabolomics were used to evaluate the alteration of intestinal microbiota and the change of metabolites in MNCs.ResultsCurcumin treatment sensitized response to Ara-C in MNCs of AML mice, but had no direct effect on AML cell lines. Metagenomics revealed an alteration of intestinal microbiota with Curcumin treatment, which contributes to sensitized response to Ara-C. Curcumin treatment led to enhanced intestinal intact to sensitize response to Ara-C in AML mice, through reducing mucus degrading bacteria. Metabolomics demonstrated that Curcumin treatment led to decreased cholesterol in MNCs of AML mice. Further study proved that Curcumin treatment resulted in inhibition of SQLE, a key enzyme of cholesterol biosynthesis, to increase sensitivity to Ara-C.ConclusionCurcumin sensitizes response to Ara-C through regulating microbiota, highlighting the importance of intestinal intact strengthening in chemoresistant therapy. Moreover, aiming at cholesterol synthesis is promising in AML treatment.

Overexpressed mitogen-and stress-activated protein kinase 1 promotes the resistance of cytarabine in acute myeloid leukemia through brahma related gene 1-mediated upregulation of heme oxygenase-1

Drug resistance remains a major challenge in the current treatment of acute myeloid leukemia (AML). Finding specific molecules responsible for mediating drug resistance in AML contributes to the effective reversal of drug resistance. Recent studies have found that mitogen- and stress-activated protein kinase 1 (MSK1) is of great significance in the occurrence and development of tumors. In the current study, MSK1 was found highly expressed in drug-resistant AML patients. Heme oxygenase-1 (HO-1) has been previously validated to be associated with drug resistance in AML. Our study revealed a positive correlation between MSK1 and HO-1 in patient samples. In vitro experiments revealed that the sensitivity of AML cell lines THP-1 and U937 to cytarabine (Ara-C) significantly decreased after overexpression of MSK1. Meanwhile, downregulation of MSK1 by siRNA transfection or treatment of pharmacological inhibitor SB-747651A in AML cell lines and primary AML cells enhanced the sensitivity to Ara-C. Flow cytometry analysis showed that downregulation of MSK1 in AML cells accelerated apoptosis and arrested cell cycle progression in G0/G1 phase. However, the increased cell sensitivity induced by MSK1 downregulation was reversed by the induction of HO-1 inducer Hemin. Through further mechanism exploration, real-time PCR, immunofluorescence and Western blot analysis demonstrated that brahma related gene 1 (BRG1) was involved in the regulatory effect of MSK1 on HO-1. High expression of MSK1 could promote the resistance of AML through BRG1-mediated upregulation of HO-1. Downregulation of MSK1 enhanced the sensitivity of AML cells to Ara-C. Our findings provide novel ideas for developing effective anti-AML targets.

Downregulation of the Tumor Suppressor SAMHD1 in Classical Hodgkin Lymphoma

Introduction: The SAM domain and HD domain 1 (SAMHD1) protein is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase, which has been initially described to restrict human immunodeficiency virus type 1 (HIV-1) in certain cell types through depletion of intracellular dNTP substrates for HIV-1 reverse transcription. Mutations of SAMHD1 gene have been linked to Aicardi-Goutières syndrome (AGS) and have been identified as putative drivers of chronic lymphocytic leukemia resulting in decreased SAMHD1 mRNA and protein levels. Therefore, a line of evidence suggests that SAMHD1 may play a role in oncogenesis as a tumour suppressor. In addition, SAMHD1 may confer resistance to nucleoside-based chemotherapies by hydrolysing their active triphosphate metabolites, and thus, it may lead to resistance to certain chemotherapeutic agents with cytarabine in acute myeloid leukemia being a recent example (Herold et al, Nat Med 2017; 23(2):256-263). The expression patterns and the potential role of SAMHD1 in the pathogenesis of classical Hodgkin lymphoma (HL) are not yet known.Methods: SAMHD1 protein levels were assessed by Western blot analysis in 20 human lymphoma and leukemia cell lines including 5 classical HL (L1236, L428, HDML2, HDMyZ, MDA-V) and 3 diffuse large B-cell lymphoma (DLBCL) (RC-K8, OCI-Ly3, U2932) cell lines. As our findings from in silico analysis revealed potential binding sites for MYC on the SAMHD1 gene promoter, HL cell lines were treated with selective MYC inhibitors to assess possible MYC-associated regulation of SAMHD1 expression. The patient cohort included 212 cases of classical HL diagnosed and treated at the University of Texas MD Anderson Cancer Center (USA), University of Athens (Greece) and University of Crete (Greece). A control group of 4 reactive lymph nodes and 76 B-cell non-Hodgkin lymphomas (58 DLBCLs) was included in the study for comparison. All tissue samples were obtained prior to therapy. SAMHD1 expression was assessed by immunohistochemistry performed on TMAs with duplicate tumor cores from each case or full tissue sections using a monoclonal antibody (Bethyl Laboratories, San Antonio, TX). An arbitrary 10% cutoff was used to define SAMHD1 positivity in the neoplastic cells. Overall survival (OS) was defined as time from diagnosis to death or last follow-up. Event-free survival (EFS) was defined as time from diagnosis to relapse, death, or last follow-up. Survival analyses were performed using the Kaplan-Meier method (log-rank test) and Cox regression models.Results: In 4 out of 5 HL cell lines, SAMHD1 protein levels were dramatically reduced as compared to all 3 DLBCL and other lymphoma and leukemia cell lines tested. Inhibition of MYC activity resulted in a substantial increase in the SAMHD1 protein level suggesting a possible MYC-associated gene regulation. Similarly, the neoplastic Hodgkin-Reed Sternberg (HRS) cells of classical HL were SAMHD1-negative in 132 of 212 (62.3%) patients. Among the SAMHD1-positive cases, the percentage of positive HRS cells ranged from 10 to 95% with a median 40%. By contrast, SAMHD1 was negative in only 15% of the control group of DLBCLs. In addition, most of the germinal center (GC) cells of the reactive lymph nodes were SAMHD1-positive with consistently higher intensity of immunostaining as compared to HRS cells of classical HL. No significant associations between SAMHD1 levels and clinicopathologic parameters were observed in the HL cohort. In a subset of 56 HL patients with long follow up period (median 195 months), FFS at 10 years was 79% vs. 71% for patients with SAMHD1-negative vs. SAMHD1-positive HL, respectively. Similarly, OS at 15 years was 71% vs. 63% for SAMHD1-negative vs. SAMHD1-positive HL, respectively. These differences did not reach statistical significance (p>0.05, log-rank) likely because of the relatively small number of patients included in this preliminary survival analysis.Conclusions: SAMHD1 is shown for the first time to be downregulated in HRS cells of classical HL further supporting its role as a tumor suppressor and its regulation may involve MYC. Preliminary survival analysis shows a statistical trend towards inferior FFS and OS for patients with SAMHD1-positive HRS cells, however, analysis of the entire cohort of HL patients is underway to draw definite conclusions. DisclosuresKhoury:Pfizer: Research Funding; Angle: Research Funding; Kiromics: Research Funding; Stemline Therapeutics: Research Funding.

Risk Score Generated from Ara-C Metabolic Pathway Predicts Leukemic Cell Intracellular Ara-CTP Levels in AML-97 Pediatric Patients

Background: Acute myeloid leukemia (AML) is the cancer of the myeloid precursor stem cells. AML was historically treated with combinations of cytarabine (ara-C) and anthracyclines. Previous studies showed that polymorphism in genes known to be involved in cytarabine pathway can affect patient's drug response and may explains part of the inter-patient variability in treatment response.Patients and methods: AML patients (n= 89) treated under St. Jude AML97 clinical trial were included in the study. Intracellular levels of ara-CTP the active metabolite of ara-C was quantitated in leukemic cells obtained 24hrs after initiation of cytarabine infusion. Morphological response to induction 1 therapy was assessed in bone marrow aspirate obtained on day 15. Genomic DNA was tested for SNPs in DCK and CMPK1 required for the drug activation, CDA, DCTD, NT5C2, NT5C3A, RRM1 and RRM2 involved in Cytarabine inactivation and the drug transporters SLC29A1, SLC28A1 and SLC28A3. Additionally, CTPS1, NME1-NME2 and NME3 that are important for the synthesis of nucleoside triphosphates other than ATP were also included. Overall 104 SNPs in genes indicated above were genotyped using Sequenom (CA, USA) based genotyping that uses MALDI-TOF-based chemistry at University of Minnesota, Biomedical Genomics Center.Results: Tweleve SNPs demonstrated a statistically significant association with ara-CTP level at day 1 post treatment (P<0.05). We found SNP rs4643786 in DCK gene significantly associated with lower ara-CTP levels and poor outcomes in white patients. CDA SNP rs12404655, was associated with high ara-CTP level at day 1 and better treatment outcomes (Fig 1B). CMPK1 SNP rs7543016, a missense cleavage site variant was associated with lower ara-CTP levels. In addition, SNP rs9916651 in NME1-NME2 was predictive of higher ara-CTP levels (Fig 1A).We observed 7 SNPs to be significantly associated with the treatment response after induction 1 this included a previously reported NT5C2 SNP rs11598702 and 4 SNPs in DCTD that were associated with poor response and occured in linkage disequilibrium with each other's (r2=1: rs3190314, rs1130902, rs7277 and rs851).Using the genotypes of SNPs associated with intracellular ara-CTP levels we created a risk score by combining the effect of SNPs reported in each patient. For this we took into consideration the direction of genotype association for each SNP. For example, if the SNP is associated with higher ara-CTP level, it takes a score ranging between 0 and +2 (0 if the patient has normal alleles, 1 if he/she is heterozygous and 2 if homozygous for the SNP). If the SNP is associated with lower ara-CTP level, it takes a score ranging between 0 and -2. Risk scores ranging between -7 and 5 were obtained after this analysis. We further compressed the risk groups into three categories (risk score ≥1, risk score 0, -1 and risk score ≤ -2 (Figure 2). Increased value of the risk score was associated with increased intracellular ara-CTP level suggesting a cumulative or synergistic effect of the reported SNPs.Conclusion: Our results suggest that SNPs in genes related to cytarabine pathway can significantly affect level of ara-CTP inside the leukemic cells. To comprehensively include the potentially significant SNPs we developed a risk score for each patient by taking into account the directional genotype for each SNP in each patient. We hope that this score although require validation in other cohorts will help in identification of patients with potentially lower levels of active form of ara-CTP in the leukemic cells. We would also like to point out that it is very challenging to perform this study as it requires obtaining bone marrow samples for determining intracellular levels of ara-CTP after day 1 of initiation of chemotherapy, which is not a standard procedure. To the best of our knowledge this is the only clinical cohort of pediatric AML patients where intracellular ara-CTP levels post ara-C treatment are available and we leveraged this to evaluate genetic variants. Our result would provide significant information in further understanding the pharmacogenomics of cytarabine in AML. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

IMGN779, a Next Generation CD33-Targeting ADC, Combines Effectively with Cytarabine in Acute Myeloid Leukemia (AML) Preclinical Models, Resulting in Increased DNA Damage Response, Cell Cycle Arrest and Apoptosis In Vitro and Prolonged Survival In Vivo

Introduction: IMGN779, a next generation CD33-targeting ADC, is comprised of a novel DNA alkylating IGN payload, an s-SPDB cleavable linker and a humanized anti-CD33 antibody. IMGN779 is currently in Phase I dose escalation in patients with relapsed/refractory AML (NCT02674763). With improved patient outcomes in mind, we set out to evaluate the mechanism, antileukemia efficacy and tolerability of the combination of IMGN779 and cytarabine using in vitro and in vivo human AML preclinical models.Methods: DNA damage, survival and apoptotic responses to IMGN779 and cytarabine were assessed using flow cytometry and immunoblotting techniques. In vitro combinations of the free IGN payload and either an MDM2 antagonist or CHK1/2 inhibitors were assessed for impact on cell viability at 72 hours across a panel of 12 AML cell lines. IMGN779 and cytarabine were evaluated in vivo for antitumor activity, using disseminated (Molm-13 and MV4-11) and subcutaneous (SC; EOL-1) AML xenograft models. All mice were monitored for body weight loss, clinical signs, and SC tumor volume (EOL-1). Assessment was terminated for weight loss >20%, clinical signs, or, in the EOL-1 model, when SC tumor volume reached approximately 1000 mm3.Results: Exposure to cytarabine in vitro led to a dose- and time-dependent increase in CD33 transcription and cell surface expression (up to 2-fold increase at 150nM at 72 hours) in multiple human AML cell lines, revealing a novel mechanism by which cytarabine may potentiate the CD33-dependent uptake of IMGN779 by AML cells. Importantly, the in vitro combination of IMGN779 and cytarabine led to dose-dependent, additive antileukemia activity (Figure A), and enhanced levels of cell cycle arrest, DNA damage response (p21, CHK2) and apoptosis (Casp3/PARP1 cleavage). Moreover, the mechanistic importance of p53 and CHK2 in IMGN779-mediated antileukemia activity was demonstrated further using the IGN free payload in in vitro combination assays with a panel of 12 human AML cell lines. The results of these experiments suggest strong synergy between IGN free payload and an MDM2 antagonist and between IGN free payload and CHK1/2 inhibitors, pointing to additional combination regimens for IMGN779.In mice, the combination of single dose (0.253 mg/kg) or repeat dosing of IMGN779 (0.0534 or 0.0107 mg/kg, weekly x3) and high-dose cytarabine (75 mg/kg, at near MTD, daily x5) was highly active in all three AML xenograft models, and was well tolerated, with no body weight loss or other toxicities noted. The IMGN779 doses in these highly active combinations were far below the MTD (48 mg/kg). In MV4-11 and Molm-13 (both FLT3-ITD) disseminated xenografts, the combination resulted in a highly active 24-26 day tumor growth delay and 42-110% Increased Life Span (ILS), compared to minimally active IMGN779 (15-33% ILS) and inactive cytarabine (0-0% ILS) single agents. In the EOL-1 (chemo-resistant) SC model, 0.253 mg/kg single dose IMGN779 plus cytarabine was also highly active, resulting in 4/6 long-term (>90 days) complete remissions (CRs), compared to 2/6 CRs for IMGN779 and no CRs for cytarabine single agents (Figure B). Tumor growth delay for the EOL-1 tumors that persisted was 17 days for the combination, compared to 8 and 0.5 days for IMGN779 and cytarabine, respectively, supporting a highly beneficial combination effect on survival.Conclusions: IMGN779 and cytarabine are a highly effective and well tolerated combination in preclinical models of AML. Mechanistically, the IMGN779 plus cytarabine combination increased DNA damage response, cell cycle arrest, and apoptosis in vitro, which lead to increased survival in vivo . Interestingly, cytarabine increased cell surface CD33 levels on AML cells, indicating a novel mechanism by which cytarabine may potentiate IMGN779 uptake and possibly efficacy. In addition to the favorable combination with cytarabine, our in vitro combination studies also reveal the potential of combining IMGN779 with DNA damage response inhibitors. These results support rapidly advancing the combination of IMGN779 and high dose cytarabine in clinical trials. [Display omitted] DisclosuresAdams:ImmunoGen: Employment. Kelly:ImmunoGen: Employment. McCarthy:ImmunoGen: Employment. Wilhelm:ImmunoGen: Employment. Watkins:ImmunoGen: Employment. Lanieri:ImmunoGen: Employment. Sloss:ImmunoGen: Employment. Romanelli:ImmunoGen: Employment.

HOXA11 plays critical roles in disease progression and response to cytarabine in AML.

Lysine methyltransferase 2A (KMT2A, also known as MLL) translocations (MLL-t) are frequently associated with mutations in RAS pathway genes in acute myeloid leukemia (AML). Previous findings with a mouse model showed that cooperation of MLL/AF10 with tyrosine-protein phosphatase non-receptor type 11 (PTPN11)G503A accelerated leukemia development, but increased cytarabine (Ara-C) sensitivity of leukemia cells. To identify the genes responsible for reduced survival and Ara-C resistance, transcriptomic profiling between six pairs of mouse MLL/AF10(OM-LZ) leukemia cells harboring activating and wild-type KRAS or PTPN11 was compared. A total of 23 differentially expressed genes (DEGs) with >1.5-fold-change between the paired cell lines were identified. The Gene Ontology (GO) terms overrepresented in these 23 DEGs included ‘immune system process’, ‘actin filament binding’, ‘cellular response to interferon-alpha’ and ‘sequence-specific DNA’. Among the four genes (Hoxa11, PR domain zinc finger protein 5, Iroquois-class homeodomain protein IRX-5 and homeobox protein PKNOX2) mapped to the GO term ‘sequence-specific DNA’, HOXA11 upregulation was associated with AML harboring MLL-t and RAS signaling mutations based on a meta-analysis using data deposited in Oncomine™ and analysis of the clinical samples in the present study. Microarray data revealed that only Hoxa11 was upregulated in those cells harboring activating PTPN11. Functional studies of Hoxa11 knockdown or overexpression in MLL/AF10(OM-LZ) cells revealed that Hoxa11 expression levels were associated with survival in vivo and Ara-C sensitivity/apoptosis in vitro. In addition, Hoxa11 regulated the expression of the apoptosis-related genes, NF-κB inhibitor α, transcription factor p65 and transformation-related protein p53. Furthermore, the results of a meta-analysis using Heuser's AML dataset supported the finding that chemotherapy responders have higher expression levels of HOXA11. These results indicated that the expression of HOXA11 increased cell apoptosis and predicted an improved response to Ara-C in AML.

Comparison of Long-Acting G-CSF (PD-Lasta) with Short-Acting G-CSF (PD-Grastim) in Neutrophil Recovery Following Consolidation Chemotherapy with High-Dose Cytarabine in Acute Myeloid Leukemia: A Randomized Clinical Trial.

Background: Acute myeloid leukemia (AML) patients are often neutropenic as a result of their disease alone or following their chemotherapy. In this randomized clinical trial the efficacy of Iranian short-acting (PD-Grastim) and long-acting G-CSF (PD-Lasta) were compared in term of time to recovery from neutropenia in de novo AML patients following the consolidation chemotherapy. Materials andMethods: Patients (n = 51) received one or two courses of Cytarabine and Daunorubicin as an induction. If complete remission was achieved, the treatment was followed by high-dose Cytarabine as consolidation chemotherapy. Twenty- four hours after the consolidation chemotherapy, patient were randomized to receive either daily short-acting G-CSF (PD-Grastim) (300 µg/kg) or single-dose long-acting G-CSF (PD-Lasta) (6 mg). Results: The median time to recovery of neutrophils was 11.00 and 13.00 days for short-acting G-CSF (PD-Grastim) (n=22) and long-acting G-CSF (PD-Lasta) (n=29) groups, respectively (U=186.5, P>0.05 two-tailed). Incidence of adverse effects was similar in both short-acting G-CSF (PD-Grastim) and long-acting G-CSF (PD-Lasta) groups. Conclusion: Overall, data show that Iranian long-acting G-CSF (PD-Lasta) was not significantly different with Iranian short-acting G-CSF (PD-Grastim).

Comparative effectiveness of glasdegib versus venetoclax combined with low-dose cytarabine in acute myeloid leukemia.

Background: Two combination therapies recently approved and recommended for use in combination with low-dose cytarabine (LDAC) in acute myeloid leukemiapatients unfit for intensive chemotherapy are glasdegib+LDACand venetoclax+LDAC. Materials & methods: An indirect treatment comparisonused median overall survival, overall survival hazard ratios, complete remission (CR), CR+CR withincomplete blood count recovery and transfusion independence to assess comparative effectiveness, and a simulated treatment comparisonaccounted for differences in patient characteristics between trials. Results: Differences in efficacy between glasdegib+LDAC and venetoclax+LDAC were suggestive and not statistically significant. Conclusion: With no significant differences in comparative effectiveness, considerations such as safety profiles, burden of administration and patient preference are likely to guide treatment decisions.

Murine double minute 2 inhibition alone or with cytarabine in acute myeloid leukemia: Results from an idasanutlin phase 1/1b study⋆

The prognosis remains poor for patients with relapsed or refractory (r/r) acute myeloid leukemia; thus, novel therapies are needed. We evaluated idasanutlin—a new, potent murine double minute 2 antagonist—alone or with cytarabine in patients with r/r acute myeloid leukemia, de novo untreated acute myeloid leukemia unsuitable for standard treatment or with adverse features, or secondary acute myeloid leukemia in a multicenter, open-label, phase 1/1b trial. Primary objectives were to determine the maximum tolerated dose (MTD) and recommended dose for expansion (RDE) and characterize the safety profile of idasanutlin monotherapy and combination therapy. Clinical activity and pharmacokinetics were secondary objectives. Two idasanutlin formulations were investigated: a microprecipitate bulk powder (MBP) and optimized spray-dried powder (SDP). Following dose escalation, patients (N = 122) received idasanutlin at the RDE in the extension cohorts. No formal MTD was identified. Idasanutlin was tolerable alone and in combination with cytarabine. The RDE was determined as 600 mg twice a day for the MBP formulation and 300 mg twice a day for the SDP formulation. Adverse events were mostly grade 1/2 (76.2 %). The most common any-grade adverse events were gastrointestinal (including diarrhea [90.2 %]). The early death rate across all patients was 14.8 %. Plasma idasanutlin exposure was dose related. In TP53 wild-type patients, composite complete remission rates were 18.9 % with monotherapy and 35.6 % with combination therapy. Based on these results, idasanutlin development continued with further investigation in the treatment of acute myeloid leukemia. ClinicalTrials.gov: NCT01773408.

DNA Methylation-Based Epigenetic Repression of SLC22A4 Promotes Resistance to Cytarabine in Acute Myeloid Leukemia.

Reduced expression of the uptake transporter, OCTN1 (SLC22A4), has been reported as a strong predictor of poor event‐free and overall survival in multiple cohorts of patients with acute myeloid leukemia (AML) receiving the cytidine nucleoside analog, cytarabine (Ara‐C). To further understand the mechanistic basis of interindividual variability in the functional expression of OCTN1 in AML, we hypothesized a mechanistic connection to DNA methylation‐based epigenetic repression of SLC22A4. We found increased basal SLC22A4 methylation was associated with decreased Ara‐C uptake in AML cell lines. Pre‐treatment with hypomethylating agents, 5‐azacytidine, or decitabine, restored SLC22A4 mRNA expression, increased cellular uptake of Ara‐C, and was associated with increased cellular sensitivity to Ara‐C compared with vehicle‐treated cells. Additionally, lower SLC22A4 methylation status was associated with distinct clinical advantages in both adult and pediatric patients with AML. These findings suggest a regulatory mechanism is involved in the interindividual variability in response to Ara‐C, and provides a basis for the integration of hypomethylating agents into Ara‐C‐based treatment regimens.

Fentanyl inhibits acute myeloid leukemia differentiated cells and committed progenitors via opioid receptor-independent suppression of Ras and STAT5 pathways.

Fentanyl is a common sedative/analgesic used for intrathecal chemotherapy injection in children with acute leukemia. Given the contradictory findings that fentanyl has both inhibitory and stimulatory activities in cancer cells, we investigated the biological effects of fentanyl alone and its combination with standard of care in acute myeloid leukemia (AML) cells at all stages of development. We showed that fentanyl at clinically relevant concentration inhibited growth and colony formation of AML differentiated cells and committed progenitors without affecting their survival. Compared to AML cells without FLT3 mutation, cells harboring FLT3-ITD mutation are likely to be more sensitive to fentanyl. However, fentanyl did not affect the most primitive AML stem cells. Fentanyl significantly augmented the efficacy of cytarabine but not midostaurin in AML differentiated cells and committed progenitors. We further demonstrated that fentanyl inhibited AML cells via suppressing Ras/Raf/MEK/ERK and STAT5 pathway, and this was not dependent on opioid receptor system. Our findings demonstrate the anti-leukemia activity of fentanyl and synergistic effects between fentanyl and cytarabine in AML, via opioid receptor-independent suppression of Ras and STAT5 pathways. Our work is the first to suggest the beneficial effects of fentanyl in children with leukemia.

The Hi's and Lo's of Cytarabine in Acute Myeloid Leukemia.

Cytarabine is the backbone of AML therapy, but the dose used during induction has remained controversial. Using an intermediate dose of cytarabine, compared with conventional dose, was shown to improve disease-free and overall survival in adult patients in China up to age 55, particularly in patients with intermediate cytogenetic risk.See related article by Wei et al., p. 3154.

Safety and Feasibility of Outpatient High Dose Cytarabine for Acute Myeloid Leukemia in the Brazilian Amazon.

Background: The attempt to manage patients with acute myeloid leukemia as outpatients has become increasingly common due to high hospitalization costs, low availability for beds and patient preference. Publications on the subject are scarce, especially in low-income regions and the safety in this population remains to be determined. The present study aims to assess the safety of consolidation with high-dose cytarabine in the outpatient setting. Materials and Methods: We retrospectively analyzed 39 patients who underwent consolidation with high-dose cytarabine, between 2009 and 2018, at Ophir Loyola Hospital, in Belém, Brazil. Patients treated after 2015 were given high-dose cytarabine as outpatients due to the decision of medical staff. Results: Twenty-seven patients received 76 cycles of cytarabine as outpatients; males were 48.14% of the total population, with a median age of approximately 45 years. The occurrence of delay between cycles was significantly lower among outpatients (48.14% vs. 83.33%, p = 0.04). There was no difference in relapse rates, transfusion requirements and non-relapse mortality between both groups. Hospitalization was required in 40.74% of patients during outpatient cycles and 18.51% of blood cultures were positive for pathogens. Non-relapse mortality was significantly higher among patients above 50 years old and treated on an outpatient basis (44.4% vs. 5.60%, p = 0.03). Conclusion: High-dose cytarabine administration on an outpatient basis appears to be safe and effective in a low-income population at the Brazilian Amazon region, but toxicity seems to be increased for patients older than 50 years.

Epigenetic priming with decitabine followed by low dose idarubicin and cytarabine in acute myeloid leukemia evolving from myelodysplastic syndromes and higher-risk myelodysplastic syndromes: a prospective multicenter single-arm trial.

Patients with acute myeloid leukemia (AML) evolving from myelodysplastic syndrome (MDS) or higher-risk MDS have limited treatment options and poor prognosis. Our previous single-center study of decitabine followed by low dose idarubicin and cytarabine (D-IA) in patients with myeloid neoplasms showed promising primary results. We therefore conducted a multicenter study of D-IA regimen in AML evolving from MDS and higher-risk MDS. Patients with AML evolving from MDS or refractory anemia with excess blasts type 2 (RAEB-2) (based on the 2008 WHO classification) were included. The D-IA regimen (decitabine, 20 mg/m2 daily, days 1 to 3; idarubicin, 6 mg/m2 daily, days 4 to 6; cytarabine 25 mg/m2 every 12 hours, days 4 to 8; granulocyte colony stimulating factor [G-CSF], 5 μg/kg, from day 4 until neutrophil count increased to 1.0 × 109 /L) was administered as induction chemotherapy. Seventy-one patients were enrolled and treated, among whom 44 (62.0%) had AML evolving from MDS and 27 (38.0%) had RAEB-2. Twenty-eight (63.6%) AML patients achieved complete remission (CR) or complete remission with incomplete blood count recovery (CRi): 14 (31.8%) patients had CR and 14 (31.8%) had CRi. Six (22.2%) MDS patients had CR and 15 (55.6%) had marrow complete remission. The median overall survival (OS) was 22.4 months for the entire group, with a median OS of 24.2 months for AML and 20.0 months for MDS subgroup. No early death occurred. In conclusion, the D-IA regimen was effective and well tolerated, representing an alternative option for patients with AML evolving from MDS or MDS subtype RAEB-2.

Increased Expression of Micro-RNA-23a Mediates Chemoresistance to Cytarabine in Acute Myeloid Leukemia.

Resistance to chemotherapy is one of the primary obstacles in acute myeloid leukemia (AML) therapy. Micro-RNA-23a (miR-23a) is frequently deregulated in AML and has been linked to chemoresistance in solid cancers. We, therefore, studied its role in chemoresistance to cytarabine (AraC), which forms the backbone of all cytostatic AML treatments. Initially, we assessed AraC sensitivity in three AML cell lines following miR-23a overexpression/knockdown using MTT-cell viability and soft-agar colony-formation assays. Overexpression of miR-23a decreased the sensitivity to AraC, whereas its knockdown had the opposite effect. Analysis of clinical data revealed that high miR-23a expression correlated with relapsed/refractory (R/R) AML disease stages, the leukemic stem cell compartment, as well as with inferior overall survival (OS) and event-free survival (EFS) in AraC-treated patients. Mechanistically, we demonstrate that miR-23a targets and downregulates topoisomerase-2-beta (TOP2B), and that TOP2B knockdown mediates AraC chemoresistance as well. Likewise, low TOP2B expression also correlated with R/R-AML disease stages and inferior EFS/OS. In conclusion, we show that increased expression of miR-23a mediates chemoresistance to AraC in AML and that it correlates with an inferior outcome in AraC-treated AML patients. We further demonstrate that miR-23a causes the downregulation of TOP2B, which is likely to mediate its effects on AraC sensitivity.

Safety and Efficacy of Venetoclax Combined with Hypomethylating Agents or Low-Dose Cytarabine for Acute Myeloid Leukemia before and after Allogeneic Hematopoietic Cell Transplantation

Introduction Venetoclax combined with hypomethylating agents (HMA) or low-dose cytarabine (LDC) has emerged as a promising therapy for acute myeloid leukemia (AML). However, there are scarce data on the use of this drug in the context of allogeneic hematopoietic cell transplantation (allo-HCT). We thus report a case series of patients using venetoclax-based therapy for AML prior to or after allo-HCT. Methods Adult patients with active AML receiving venetoclax + HMA/LDC before allo-HCT as bridge therapy or following HCT as salvage therapy were included in this report. Cases were treated at five different Brazilian centers from Jun’18 to Jul’19. Patients rescued with venetoclax-containing regimens as bridge therapy to allo-HCT were included regardless of whether they managed to undergo the procedure or not. Results We retrieved 16 patients meeting the inclusion criteria. Median age was 45 years old (range 23-83). Eight (50%) patients were male. Median follow-up time was 4 months (1.1-9.1). Ten patients had de novo AML, four secondary AML, and two therapy-related AML. Three patients were treatment-naive and thirteen had relapsed/refractory disease, including five cases of post-allo-HCT relapse. Relapsed/refractory AML patients had a median of two previous lines of treatment (1-4). Venetoclax was given with azacitidine (n=4), decitabine (n=7) or LDC (n=5). Patients received a median of two cycles of venetoclax-based therapy (1-6), and the most common toxicity was neutropenia. Fourteen evaluable patients achieved complete response (CR) or complete response with incomplete count recovery (CRi) after a median time of 38 days (23-158). Of those receiving venetoclax-based bridge therapy to allo-HCT, 9/11 patients underwent allo-HCT after achieving CR/CRi, including 7 AML patients bearing chemorefractory disease or high-risk cytogenetics. Two patients died after allo-HCT, one from AML relapse and the other from infectious complications; all the other seven patients had full engraftment and were alive with no active GVHD at last follow-up. Two did not receive the allo-HCT, one because of relapsed AML prior to transplant and the other because of death by septic shock. Five cases of post-allo-HCT AML relapse received venetoclax-based therapy. Three of them also received donor lymphocyte infusions (DLI). Four evaluable patients achieved CR/CRi. There were two deaths: one from disseminated herpes simplex virus and one from septic shock. There were two cases of grade 3-4 acute GVHD, yet both of them responded to steroids and were possibly related to concomitant DLI. Conclusion Despite the limited number of patients and short follow-up time, therapy including venetoclax seems to be safe and yield encouraging results before and after allo-HCT, even in heavily treated AML patients. These data support future clinical trials incorporating venetoclax-based therapy into the allo-HCT setting.