Low Risk AML Research Articles

Centralized MRD Assessment in Gimema AML1718 Trial, a Phase 2 Open-Label Study of Venetoclax Combined with Intensified FLAI Chemotherapy (V-FLAI) As Induction Therapy of Non Low-Risk AML

Centralized MRD Assessment in Gimema AML1718 Trial, a Phase 2 Open-Label Study of Venetoclax Combined with Intensified FLAI Chemotherapy (V-FLAI) As Induction Therapy of Non Low-Risk AML

Glutamine metabolism-related genes predict the prognostic risk of acute myeloid leukemia and stratify patients by subtype analysis

BackgroundAcute myeloid leukemia (AML) is a genetically heterogeneous disease in which glutamine (Gln) contributes to AML progression. Therefore, this study aimed to identify potential prognostic biomarkers for AML based on Gln metabolism-related genes.MethodsGln-related genes that were differentially expressed between Cancer Genome Atlas-based AML and normal samples were analyzed using the limma package. Univariate, least absolute shrinkage, selection operators, and stepwise Cox regression analyses were used to identify prognostic signatures. Risk score-based prognostic and nomogram models were constructed to predict the prognostic risk of AML. Subsequently, consistent cluster analysis was performed to stratify patients into different subtypes, and subtype-related module genes were screened using weighted gene co-expression network analysis.ResultsThrough a series of regression analyses, HGF, ANGPTL3, MB, F2, CALR, EIF4EBP1, EPHX1, and PDHA1 were identified as potential prognostic biomarkers of AML. Prognostic and nomogram models constructed based on these genes could significantly differentiate between high- and low-risk AML with high predictive accuracy. The eight-signature also stratified patients with AML into two subtypes, among which Cluster 2 was prone to a high risk of AML prognosis. These two clusters exhibited different immune profiles. Of the subtype-related module genes, the HOXA and HOXB family genes may be genetic features of AML subtypes.ConclusionEight Gln metabolism-related genes were identified as potential biomarkers of AML to predict prognostic risk. The molecular subtypes clustered by these genes enabled prognostic risk stratification.

The Addition of Venetoclax to Induction Chemotherapy in No Low-Risk AML Patients: A Propensity Score-Matched Analysis of the Gimema AML1718 and AML1310 Trials

The Addition of Venetoclax to Induction Chemotherapy in No Low-Risk AML Patients: A Propensity Score-Matched Analysis of the Gimema AML1718 and AML1310 Trials

AML-347: A Preliminary Analysis of FLAM (Italian Non-Interventional Multi-Center Study of FLT3-Mutated AML Patients): FLT3 Receptor Gene Mutational Analysis and FLT3 Inhibitor Administration in Real-Life Clinical Practice

AML-347: A Preliminary Analysis of FLAM (Italian Non-Interventional Multi-Center Study of FLT3-Mutated AML Patients): FLT3 Receptor Gene Mutational Analysis and FLT3 Inhibitor Administration in Real-Life Clinical Practice

Both the subtypes of KIT mutation and minimal residual disease are associated with prognosis in core binding factor acute myeloid leukemia: a retrospective clinical cohort study in single center.

Core binding factor acute myeloid leukemia (CBF-AML), including cases with KIT mutation, is currently defined as a low-risk AML. However, some patients have poor response to treatment, and the prognostic significance of KIT mutation is still controversial. This study aimed to explore the prognostic significance of different KIT mutation subtypes and minimal residual disease (MRD) in CBF-AML. We retrospectively evaluated continuous patients diagnosed with CBF-AML in our center between January 2014 and April 2019. Of the 215 patients, 147 (68.4%) and 68 (31.6%) patients were RUNX1-RUNX1T1- and CBFB-MYH11 positive, respectively. KIT mutations were found in 71 (33.0%) patients; of them, 38 (53.5%) had D816/D820 mutations. After excluding 10 patients who died or were lost to follow-up within a half year, 42.0% (n = 86) of the remaining 205 patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT). An MRD > 0.1% at the end of two cycles of consolidation predicted relapse (P < 0.001). Multivariate analysis showed that D816 or D820 mutations and MRD > 0.1% at the end of two cycles of consolidation were independent adverse factors affecting relapse-free survival (RFS) and overall survival (OS). Allo-HSCT could improve RFS (74.4% vs. 34.6%, P < 0.001) and OS (78.1% vs. 52.3%, P = 0.002). In conclusion, high-risk CBF-AML patients must be identified before treatment. D816/D820 mutation, MRD > 0.1% at the end of two cycles of consolidation chemotherapy predicted poor survivals, and allo-HSCT can improve the survival of properly identified patients.

A Preliminary Analysis of FLAM (Italian Non-Interventional Multi-center Study of FLT3 mutated AML patients): FLT3 Receptor Gene Mutational Analysis and FLT3 Inhibitors Administration in the Real-Life Clinical Practice

A Preliminary Analysis of FLAM (Italian Non-Interventional Multi-center Study of FLT3 mutated AML patients): FLT3 Receptor Gene Mutational Analysis and FLT3 Inhibitors Administration in the Real-Life Clinical Practice

Interferon-a-2b As a Maintenance Therapy Significantly Improves Disease-Free Survival in Patients with Low-Risk Acute Myeloid Leukemia

Background: Interferon-𝜶has a world-widely acknowledged anti-tumor activity and immunoregulatory function. Rare of the previous study reported significant efficacy of IFN-𝜶in AML (high, medium and low risk) patients. Although cytotoxic chemotherapy significantly improved the survival of low-risk AML, the reported low-risk AML 5-year OS was only 34-65%.Whether Interferon-𝜶-2b(IFN-𝜶-2b) could reduce recurrence and improve DFS in the maintenance therapy of low-risk AML subtypes has not been verified. The aim of this study was to evaluate the efficacy and safety of IFN-𝜶-2b in the maintenance of low-risk acute myeloid leukemia, in order to provide suggestions for clinical practice. Method: This study retrospectively analyzed 31 patients with low-risk AML who were treated with IFN-𝜶-2b maintenance therapy from March 2015 to March 2018 at the Peking University Institute of Hematology. The control group consisted of 1:1 matched 31 patients with low-risk AML. The pairing factors were age, gender, diagnostic time and subtype, induction and consolidation courses, and minimal residual disease (MRD) at the end of chemotherapy. Both groups of patients were AML patients who underwent 1-2 therapeutic induction chemotherapy for complete hematologic remission (CR) and completed 5-7 courses of consolidation chemotherapy. The interferon group was administered with 3 million U ofIFN-𝜶-2b three times a week; the control group was only observed and followed up after consolidation chemotherapy. We compared the treatment efficacy and prognostic improvement in low-risk AML by comparing MRD, disease-free survival (DFS), event-free survival (EFS), and overall survival (OS). Results: The median age of the 31 patients in the interferon group was 50 (21-67) years. Themolecular biological characteristicsof the interferon group were NPM1+/FLT3-ITD-8 cases; CEBPA double mutation 9 cases; CBFβ-MYH11+/C-KIT-5 cases; and ETO+/C-KIT- 9 cases. The median age of the control group was 44 (26-70) years old, and the molecular biological characteristics were paired with the interferon group. The median follow-up time of the 31 patients with low-risk AML in the interferon group and the control group was 14.5 (4-34) months and 16 (5.5-35) months, respectively. The median duration of treatment in the interferon group was 10(1-24) months. In interferongroup, patients with negative or positive MRD status were 16 and 15, respectively. Whereas, in control group, patients with negative or positive MRD status were 20 and 11, respectively. In interferon group, patients with original MRD, 10/15 (66.67%) showed MRD conversion after the median time of 5 (1-14.5) months IFN-𝜶-2b treatment, while in control group 3/11 (27.3%) of the patients showed MRD negative-positive conversion. There was a statistically significant difference in the rate of MRD conversion between the two groups (X2=3.939, P=0.047). The interferon group significantly decreased the rate of MRD compared with the control group. The conversion rate of the interferon group and the control group was (66.67%) vs (27.3%). In addition, the 2-year EFS of the interferon group was significantly higher than that of the control group (81.6±7.5) % vs (50.0±10.9) %, P=0.041(Figure 1.A). With refer to recurrence, 3 patients had hematologic recurrence in the interferon group, compared with 10 in the control group. Each group has 2 persistent MRD positive patients and MRD level increased more than 2 log-fold. 1 patient in control group had negative MRD converted to positive. The 2-year DFS of the interferon group was significantly higher than that of the control group (81.2±8.8)% vs (56.7±9.9)%, P=0.042 (Figure 1.B). There was no significant difference between the interferon group and the control group at 2 years of OS, which was (91.4±5.8)% vs (78.7±10.8)% (P=0.587) (Figure 1.C).In terms of safety, 24/31 (77.4%) had grade 1-2 fever after IFN-𝜶-2b therapy. 4/31 patients (12.9%) developed grade 3-4 hematologic toxicity, all of which were thrombocytopenia. Conclusion:IFN-𝜶-2b as maintenance therapyfor CR1 patients with low-risk AML significantly improved the rate of MRD conversion compared with patients without it. DFS and EFS were higher than those without it. Patients receiving interferon therapy have a low incidence of adverse reactions. Interferon therapy is safe and well-tolerated. Disclosures No relevant conflicts of interest to declare.

The Use of Venetoclax for Acute Myeloid Leukemia in a Real-Life Setting: A Multicenter National Experience

The Use of Venetoclax for Acute Myeloid Leukemia in a Real-Life Setting: A Multicenter National Experience

Observation on the Efficacy of Consolidation Chemotherapy Combined with Allogeneic Natural Killer Cell Infusion in the Treatment of Low and Moderate Risk AML

Objective To evaluate the efficacy of consolidation chemotherapy combined with allogeneic natural killer (NK) cell infusion in the treatment of low or intermediate-risk(LIR) AML. Methods 23 cases of LIR AML patients with hematologic complete remission (CR) were enrolled from January 2014 to June 2019 and treated with mIL-21/4-1BBL actived NK cell transfusion combined with consolidation chemotherapy after 3 consolidation courses. Control group were concurrent patients from Department of Hematology and their gender, age, diagnosis, risk stratification of prognosis, CR and the number of courses of consolidate chemotherapy before NK cell transfusion were matched with LIR AML patients. Results A total of 45 times of NK cells were injected into 23 LIR AML patients during 4 to 7 courses of chemotherapy. The median NK cell infusion quantity was 7.5 (6.6~8.64) x 109/L, and the median survival rate of NK cells was 95.4 (93.9~96.9) %. Among them, the median CD3-CD56 + cell number is 5.0(1.4 ~ 6.4) × 109/L, which accounts for 76.8(30.8 ~ 82.9) %; The number of CD3+CD56+ cells was 0.55 (0.24~1.74) x 109/L, accounting for 8.8 (4.9~20.9) %. Before NK cell infusion, the number of patients with positive MRD in the treatment group was 9/23 (39.1%), and the control group was 19/46 (41.3%) (X2=0.03, P=0.862). After NK cell infusion, There was no significant difference in MRD that went from negative to positive between the treatment group and the control group(14.3%vs 22.2%, X2=0.037, P=0.847). In the treatment group, 66.7% (6/9) of the MRD were converted from positive to negative, which was significantly higher than that in the control group10.5% (2/19) (X2=6.811, P=0.009). Morphological recurrence occurred in 1 case of MRD negative in the treatment group and 2 cases of MRD positive in the control group. By the end of the follow-up, the median follow-up was 35 (10~59) months, the number of patients with morphological recurrence in the treatment group was 30.4% (7/23), which is significantly lower than that in the control group (50.2%, 24/46)(X2=2.929, P=0.087),although there was no statistically significant difference between the two groups. There was no significant difference on MRD-negative between the treatment group and the control group(43.5% vs 43.5%, X2=1.045, P=0.307).The 3-year leukemia -free survival were better in the treatment group(65.1±11.1)% than that in the control group (50.0±7.4)%(P=0.047). The 3year overall survival in the treatment and chemotherapy groups were(78.1±10.2)%and (65.8±8.0)%(P=0.212), respectively. Conclusion The consolidation of chemotherapy combined with allogeneic NK cell infusion contributes to the further remission of patients with LMR AML and the reduction of long-term recurrence. Figure Disclosures No relevant conflicts of interest to declare.

Aza Maintenance After Consolidation Increase RFS in Mrdve+ Low Risk AML Patients

CBF-AML (translocation t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)) and NPM1 mutant AML have a favorable prognosis when treated with high dose cytarabine-based regimens. Nevertheless, a substantial proportion of these patients show disease relapses. The prevention of hematologic relapse remains the main goal in the care of patients with AML. Patients who are at an increased risk of relapse can be identified by monitoring measurable residual disease (MRD) using leukemia specific molecular markers.

Reduced Intensity Conditioned Sibling Transplantation Versus No Transplant in Intermediate or High Risk Acute Myeloid Leukemia: A Prospective Multi-Center Study in Patients 50-70 Years in First Complete Remission and with at Least One Potential Sibling Donor (ClinTrialGov 00342316)

▪Background and study design. Reduced intensity conditioning transplantation (RICT) is a commonly applied treatment option for AML patients >50 years of age. Prospective, controlled studies comparing RICT with standard chemotherapy are warranted. In this study, we aimed to prevent selection biases. Thus, patients were included prior to HLA typing of potential sibling donors, and statistical analyses were based on an intention-to-transplant, donor versus no-donor approach. Hence, the analyses also include events occurring during the donor search period and also the transplantation procedures along with post-transplant events.Patients and procedures. Between 2003 and 2016, 163 patients with AML in CR1 were included in Canada (n=69), Sweden (n=63), and Germany/Finland/Norway/New Zealand (n=31). Eighteen patients were excluded due to enrolment after the start of donor typing (n=14), lack of data (n=1), low-risk AML (n=2) or withdrawn consent (n=1). Thus, results from 145 patients with high (n=48) or intermediate (n=97) risk disease were available for analysis. Included patients were a median of 63 (50-70) years old, deemed fit for RICT and had at least one willing and healthy but not yet HLA typed sibling. The ensuing HLA typings thus yielded one RICT group including patients with ≥1 confirmed matched sibling donor (MSD), and one control group with no MSD. Date of inclusion was defined as date of HLA typing of the first potential MSD. The protocol-specified conditioning regimen for RICT was fludarabine (150-180 mg/m2) and busulfan (8 mg/kg orally or 6.4 mg/kg i.v., used in 95% of patients). Immunosuppression was ciclosporin alone (9%), with methotrexate (53%) or with MMF (35%). Peripheral blood stem cells were used in 95% of transplantations. Control patients received consolidation chemotherapy as per local routines.Statistics. Baseline factors were compared between study groups using Fisher´s exact test and rank sum tests. The primary endpoint was overall survival (OS) with secondary endpoints of relapse-free survival (RFS), relapse incidence (RI) and non-relapse mortality (NRM). Kaplan-Meier curves were used to estimate OS and RFS and cumulative incidence functions were used to estimate NRM and RI considering competing risks. The logrank test was employed for group comparisons of event rates with time censored at 5 yrs post inclusion.Results. The median follow-up time of surviving patients was 7.9 (0.24-14) yrs. Age, AML risk group and time from CR to inclusion did not differ between the study groups.Time lag from diagnosis to study inclusion was 65 (32-256) days (Controls) and 64 (29-319) days (RICT), P=0.74, Mann-Whitney test. Time from CR1 to inclusion was 22 (0-218) days (Controls) and 19 (0-131) (RICT).Excluding conditioning, patients in the RICT group received fewer chemotherapy cycles than controls. The time from start of last chemotherapy to transplant was median 63 (36-212) days. The incidence of acute (grade 2-4) and chronic extensive GvHD in transplanted patients was 25% and 39%, respectively.The non-relapse mortality at 3 years post inclusion (Table) was 12% (RICT group) and 4% (Controls). Causes of death was primarily AML, accounting for 73% and 88% of all deaths in the RICT and control groups, respectively. Twenty pts with an identified donor did not reach RICT due to relapse (n=12), co-morbidities (n=5), death (n=2), other (n=1).Total mortality at time of analysis was slightly lower in the RICT group (66% vs 75%). Overall survival (primary endpoint) at 3 years was 45% (CI 33-56) and 48% (36-60), in RICT and control groups, respectively. At 10 years after inclusion, OS in study groups were similar; RICT 27% (CI 15-41), Control 25% (CI 15-36). There were no significant differences between study groups with respect to primary or secondary endpoints (OS: P=0.27, RFS:P=0.98, RI: P=0.50, NRM: P=0.10, logrank tests. Figure).Conclusions. Applying an intention-to-treat analysis we did not demonstrate clinical benefit of sibling donor search and stem cell transplantation after a reduced intensity busulfan/fludarabine based regimen in AML patients ≥50 years in CR1. Early relapse was the main reason for preventing transplants in patients with an identified donor.Support from study groups: Canadian BMT Group, Australasian Leukaemia and Lymphoma Group, Norwegian/Swedish BMT Group, Swedish AML group [Display omitted] DisclosuresKiss:Alexion: Membership on an entity's Board of Directors or advisory committees, Research Funding; Otsuka: Membership on an entity's Board of Directors or advisory committees, Research Funding. Wallhult:Jazz Pharmaceuticals: Speakers Bureau; Amgen: Speakers Bureau; Daichii-Sankyo: Speakers Bureau. Finke:Riemser: Consultancy, Honoraria, Research Funding; Neovii: Consultancy, Honoraria, Other: travel grants, Research Funding; Novartis: Consultancy, Honoraria, Other: travel grants, Research Funding; Medac: Consultancy, Honoraria, Other: travel grants, Research Funding. Sabloff:Celgene: Membership on an entity's Board of Directors or advisory committees.

Survival and outcome data observed in 98 patients affected by acute myeloid leukemia undergoing chemotherapy consolidation courses treatment followed by autologous bone marrow transplantation (auto-BMT).

e18520Background: In a specific subset of patients, Auto-BMT may represent a good therapeutic option. It is used worldwide in consolidation of both low risk, and standard risk AML without an availa...

Comprehensive Genomic and Transcript Profiling of CBL Gene in Childhood AML: A Report from Children's Oncology Group Studies AAML03P1, AAML0531 and COG/NCI Target AML Initiative

The Casitas B-Lineage Lymphoma (CBL) gene encodes for an E3 ubiquitin ligase that targets activated receptor tyrosine kinases for degradation. Mutations of the CBL gene have been described in juvenile myelomonocytic leukemia (JMML) but less is known about mutations and variants of CBL in de novo AML. We previously reported that somatic mutations of CBL are rare in pediatric AML. In this report we present a comprehensive evaluation of genomic and transcript variants of CBL including novel deletion events as well as transcript variants which, in combination with somatic mutations, account for over 6% of pediatric AML with extreme association with inv(16) and favorable outcome.Initial assessment of CBL transcript in a cohort of 100 patients identified previously reported deletion of exon 8 (CBL ΔE8, N=2) associated with CBL splice mutations as well as a novel whole exon 8 and 9 deletion variant (CBL ΔE8+9, N=3) without identifiable underlying somatic alterations. Long distance PCR, as well as custom Nanostring CNV array evaluation revealed a genomic deletion underlying this transcript variant. Subsequent whole genome sequencing as part of COG/NCI TARGET AML initiative, identified discrete genomic deletions of 1998, 3588 and 6189 bp across exon 8 and 9, leading to the generation of this novel variant.We evaluated the functional consequence of the novel CBL ΔE8+9 deletion variant by expressing it in IL3-dependent Ba/F3 cell line. Compared to control cells, Ba/F3 cells expressing CBL ΔE8+9 demonstrated cytokine independent growth.A comprehensive profiling of CBL variants was conducted in 796 pediatric de novo AML patients by transcript profiling (transcript variants) or by exome capture sequencing (somatic mutations including point mutations and smaller indels). All patients were treated on Children's Oncology Group studies AAML03P1 (N=167) and AAML0531 (N=629) and presence of CBL variants was correlated with disease characteristics and clinical outcome. Of the 796 patient specimens tested, 50 patients (6.3%) had one of 3 distinct CBL variants; transcript variant (N=28), somatic mutation (N=14), or dual transcript variant and somatic mutation (N=8). All cases of CBL ΔE8+9 were associated with a corresponding genomic deletion. Out of 14 cases of CBL ΔE8 and 1 case of CBL ΔE9, only 4 cases (27%) had a splice site mutation identified as the underlying mechanism of splice variant.Presence of CBL variants was correlated with clinical characteristics and outcome. Those with CBL variants had a significantly higher prevalence of inv(16) compared with CBL wild type (WT) (37% vs. 13%, p<0.001). This association differed by CBL variant type; 44% transcript variants and 50% dual variants had inv(16) compared to 14% somatic mutations and 13% CBL WT (p<0.001). NPMc+ was more prevalent in those with CBL somatic mutations (29%) than transcript variant (4%), dual variant (0%) or CBL WT (8%) (p=0.035). Similarly, genetic risk groups differed between CBL variants vs. WT (Low risk 70% vs 39%, p=<0.001; Standard risk 22% vs. 46%, p=0.001; High risk 8% vs. 15%, p=0.196). Clinical characteristics including gender, age, race and ethnicity were not significantly different. FAB morphologic assessment revealed an enrichment for the M4 subtype in CBL variant vs. WT (53% vs. 23%, P<.001) which is likely accounted for by the association of inv(16) with this morphologic group.Patients with CBL variants had a 100% clinical remission rate by end of induction II compared to 89% for CBL WT patients (p=0.014). Survival from study entry was similar between CBL mutant vs. WT patients (5 year OS 72% vs. 66%, p=0.24; 5 year EFS 61% vs. 50%, p=0.11). Due to the strong association of CBL mutation with core binding factor leukemia, we assessed whether CBL variant was prognostic of outcome within this favorable risk group, but there was no significant difference in outcomes.Variants of the CBL gene in pediatric AML include genetic mutations with and without whole exon deletions. These CBL variants are highly associated with low risk AML but do not provide independent risk prognosis. The cooperating events of CBL variants in core binding factor leukemia deserve greater study. Our initial analysis of the transcript variants in a cell line model suggest that these large exon 8+9 deletions represent important oncogenic events.The authors would like to gratefully acknowledge the important contributions of the late Dr. Robert Arceci to the AML TARGET initiative. DisclosuresNo relevant conflicts of interest to declare.

Treatment of Acute Myeloid Leukemia with the NOPHO-AML 2004 Study in Chinese Children: A Single Center Study

Objectives: The objective of the present study was to investigate the therapeutic efficacy and feasibility of NOPHO-AML 2004 study in the treatment of acute myeloid leukemia (AML; excluding acute promyelocytic leukemia) in Chinese children.Methods: Thirty-one children with novo AML treated with the NOPHO-AML 2004 study were recruited from Jan. 2010 to Dec. 2013, and the clinical data were retrospectively analyzed. Among 31 AML children, their age were from 2-14 years old (median age 8 years old). There were 12,15 and 4 children classified in low risk group, intermediate risk group and high risk group by cytogenetic risk classification respectively. Eight children received concomitant hematopoietic stem cell transplantation. Kaplan Meier method with Log-Rank testing was employed for survival analysis.Results: Follow-up was for a median 24 months (range: 5–50 months). The complete remission rate was 83.8%. The predicted 3-year leukemia free survival (LFS) rate was 53.8%. The LFS rate of low, intermediate and high risk group were 55.6%, 52.5% and 50.0% respectively. There was no significance in risk groups. The LFS rate of chemotherapy and chemotherapy concomitant HSCT were 42.7% and 87.5%, P<0.05. There were 2 cases of treatment related mortality including one case of sepsis and one case of ARDS.Conclusions: NOPHO-AML 2004 study is clinically efficacious for the treatment of AML in Chinese children. HSCT treatment had better outcome than only chemotherapy in childhood with non low risk AML in CR1 phase. DisclosuresNo relevant conflicts of interest to declare.

Alternative Splicing of hTERT Exon 7 in AML: Biological Fuction and Prognostic Significance

hTERT, a telomere specific reverse transcriptase with a crucial role in telomerase activity, prevents telomeres shortening, a pro-apototic cellular event which occurs at every round of DNA replication. Its regulation is complex as alternative spliced variants which generate the full-length hTERT transcript (+α+β) and transcripts carrying α and/or β deletions (transdominant negative isoform -α+β, inactive products +α-β and -α-β) have been reported. In AML the prognostic significance of hTERT expression is still debated, even if its over-expression has been correlated with a poor clinical outcome. In contrast, up to now no study has dealt with the frequency and the prognostic significance of variant transcripts.Thus, our study was aimed at estimating hTERT isoforms distribution in a series of de novo AML patients (pts), at establishing whether their expression varied between pts with a normal and a complex chromosome pattern, at estimating their prognostic significance. The ninety-seven de novo AML pts included in the present study came to our observation in the period January 2010 and January 2013. They were thirty-eight females and fifty-nine males; their median age was 59 years (range 18-84). On conventional cytogenetic studies fifty-two, whose median age was 56 years (range 24-84), presented a normal karyotype and forty-five, whose median age was 60 years (range 33-84), presented a complex karyotype (≥3 defects); the two pts groups were comparable by age. According to WHO classification 6 (6.1%) pts were classified as M0/M1, 47 (48.4%) as M2, 38 (39.1%) as M4, 5 (5.1%) as M5 and one as M6. An internal tandem duplication (ITD) of the FLT3 gene and a NPM1 mutation were revealed in 12 and 2 chromosomally normal pts. No CK presented a FLT3 ITD. All pts received standard induction chemotherapy followed by two courses of consolidation treatment. At the time of the study 38 pts achieved a complete remission (CR) and 36 died. Median follow-up was 22.7 months (range: 13.5-60.2).hTERT isoforms expression was determined in bone marrow samples by real-time reverse transcriptase polymerase chain reaction, using SYBR Green I. hTERT transcript (+α+β) primers’ design was made using BLAST (http://www.ncbi.nlm.nih.gov/BLAST/), while for the other primers we referred to Capraro et al. 2011. Specific amplifications were confirmed by sequences analysis. In order, to estimate hTERT isoforms expression levels in normal mononuclear cells, twenty-three umbilical cord bloods (UCB) were examined (control group).When the Kruskal-Wallis rank test was applied to compare the expression of hTERT isoforms inAML pts with a normal and a complex karyotype no significant difference was observed (P=0.39, P=0.77; +α+β, -α+β respectively). Instead, independently from karyotype, in Cox univariate analysis, pts who over-expressed the trans-dominant negative isoform (-α+β) experienced a significant better response to treatment than the other pts (P=0.03, HR=2.11; 95% CI:1,13-3,93). In addition, pts who over-expressed inactive products (-α-β) (first group) presented a leukemia-free survival inferior to that of pts who presented a low expression of these products (second group) (P=0,003, HR=3,26; 95% CI:1,33-7,96). Moreover, pts who over-expressed the full-length hTERT transcript (+α+β) and the trans-dominant negative isoform (-α+β) presented only a trend towards significance. The first group of pts presented a worse overall survival (HR=1,66; 95% CI:0.94-2,91), whereas the second group a better overall survival (HR=0,58; 95% CI:0,33-1,02).We conclude that the over-expression of the hTERT trans-dominant negative isoform identifies pts with low-risk AML, whereas the over-expression of the hTERT inactive product (-α-β) identifies pts with high-risk AML. In addition, this last hTERT isoform might control the expression of its trans-dominant negative isoform. Thus, our results suggest an intriguing link between the control of hTERT isoforms expression and AML outcome. DisclosuresNo relevant conflicts of interest to declare.

BCL2L10 (Bcl-B) Is Associated with Resistance to Azacitidine (AZA) in MDS and AML, and Is a Possible Therapeutic Target in AZA Resistant Patients

AbstractAbstract 701 Background:AZA is a current reference treatment for higher-risk MDS patients, also active in AML patients unfit for intensive chemotherapy. However, no biological marker predictive of AZA resistance has been clearly established. In addition, patients not responding to AZA or relapsing after a response have very poor outcome (Prebet, JCO, 2011), and require new treatments. We have generated SKM1-R, an AZA resistant cell line (Cluzeau et al., Cell cycle 2011), that exhibits increased expression of BCL2L10, an anti-apoptotic Bcl-2 family member, as a likely cause of resistance (Yasui et al., Cancer Research 2004). We tried to correlate BCL2L10 expression with response to AZA in MDS and AML patients and analysed the effect of ABT 737 a peptidomimetic inhibitor binding the BH3 domain of the BCL-2 family of proteins (especially BCL2L10), on patient leukemic cells expressing BCL2L10. Methods:In two cohorts of 77 MDS or AML patients treated by AZA (75mg/m2/d, 7days every 4 weeks), we quantified the percentage of BCL2L10 positive bone marrow (BM) cells using flow cytometry. Cytometry assay was performed after several steps of fixation, permeabilization, primary incubation with an anti-BCL2L10 antibody (cell signalling) and secondary incubation with a donkey anti-Rabbit FITC-antibody. The first cohort included fresh BM samples from 32 higher-risk MDS (www.clinicaltrials.gov, NCT01210274) or AML patients treated with AZA. The second one is composed of 45 frozen samples from low risk MDS, higher-risk MDS or AML treated by AZA. Response and relapse after AZA initial response were assessed by IWG 2006 criteria. Cell metabolism (XTT assay) and Propidium iodide (PI) staining were performed in 10 patients treated with AZA (5 sensitive and 5 resistant) with or without ABT-737 (Abbott). Resistance to AZA was defined by primary failure or relapse after initial sensitivity to AZA Results:In the first patient cohort, the mean value for BM cells from AZA-resistant patients was significant higher than AZA-sensitive patients (85% vs 0% respectively, p<0.0001). In the second cohort, retrospective comparison of BM samples from low risk MDS patients, AZA-sensitive or AZA-resistant patients showed that the counts of BCL2L10 positive cells were also significant different (0%, 10% and 33% respectively, p<0.0001). In sub-group analysis on patients from cohort 2, we observed that quantification of BCL2L10 positive cells could predict failure to AZA at diagnosis (10% in sensitive patients vs 33% in resistant patients, p=0.023) and relapse after response to AZA (14% in AZA responding patients without relapse vs 43% in AZA responding patients who relapsed, p=0.0002). Using a cut-off of 50% BCL2L10 positive cells in patients from cohort 1, patients with > 50% of BCL2L10 positive cells had a 3 months OS at 51% compared to 95% in patients with ≤ 50% of BCL2L10 positive cells (p=0.0016).We next used high doses of ABT-737, alone or in combination with AZA. Cell metabolism (XTT assay) and Propidium iodide (PI) staining in the presence or absence of ABT 737 showed no effect in AZA-sensitive patients. By contrast, we observed a significant increase of PI positive cells and a significant decrease of cell metabolism in AZA-resistant patient samples stimulated with the combination of AZA + ABT-737 vs AZA alone. Conclusion:In this work, quantification of BCL2L10 positive cells by flow cytometry was correlated with resistance and survival with AZA treatment in MDS and AML. This possible biomarker of resistance will have to be tested prospectively. Inhibition of BCL2L10 positive cells by ABT-737 suggests that this drug, or other drugs targeting more selectively BCL2L10 could be proposed in combination with AZA in such patients. Disclosures:No relevant conflicts of interest to declare.

Association of CD33 Expression Level with Disease Risk-Group Classification and Induction Response In Pediatric AML: A Report From the Children's Oncology Group

AbstractAbstract 2732Our previous analysis of diagnostic AML bone marrow (BM) samples from a subset of patients enrolled on Children's Oncology Group (COG) AAML03P1, a pilot study in which conventional chemotherapy was used in combination with the CD33 targeted therapeutic gemtuzumab ozogamicin (GO), demonstrated that CD33 expression is highly variable in pediatric AML and that low or absent CD33 expression was not associated with inferior clinical response. Moreover, patients with the highest CD33 expression did not have superior outcomes. Low CD33 expression was associated with low risk disease [core binding factor (CBF) AML e.g. t(8;21), inv(16) or t(16;16), CEBPA mutated AML, NPM1 mutated AML] whereas the highest CD33 expression levels were seen in patients with high-risk disease [FLT3/ITD+ disease with allelic ratio >0.4, high risk cytogenetics e.g. -7, -5, -5q]. These findings refute previous adult AML data in which CD33 expression is directly correlated with response to single agent GO and suggest, within AAML03P1, that clinical response is linked to underlying disease biology. In this larger analysis, we prospectively evaluated CD33 expression levels of AML blasts isolated from 676 pediatric diagnostic BM samples (238/340 and 438/968 patients enrolled on COG AAML03P1 and COG AAML0531 respectively) to determine whether this association persists in a larger cohort. CD33 expression, as defined by mean fluorescent intensity (MFI) of the blast population, varied over 2-log fold, and a median MFI of 128 was observed (range 3–1550.07). The study population was divided into quartiles (Q) based on CD33 expression (n= 169 patients per quartile). Median MFI was 37.49 (range 3–62) for Q1, 90 (range 62.21–128) for Q2, 171 (range 128–245) for Q3 and 349 (range 245.52–1550.07) for Q4. Samples were also screened for disease-relevant molecular mutations: 89/650 (14%) were FLT3/ITD positive; 69/587 (12%) were positive for NPM1 mutations; and 35/585 (6%) positive for CEBPA mutations. FLT3/ITD prevalence significantly increased with increasing CD33 quartile (Q1 7%, Q2 10%, Q3 17%, Q4 20%; p<0.001), whereas no definitive trend in prevalence was observed for NPM1 (Q1 7%, Q2 14%, Q3 15%, Q4 12%; p=0.158) or CEBPA mutations (Q1 6%, Q2 8%, Q3 6%, Q4 4%; p=0.307). Cytogenetic data was available for 613 (91%) samples; 177 (29%) CBF AML samples were identified and their prevalence declined with increasing quartile (Q1 51%, Q2 40%, Q3 20%, Q4 6%; p<0.001). There was no apparent association between CD33 expression and high-risk cytogenetics; however, analysis was limited by the small number of patients (9/613, 1.4%) with such mutations. For risk-group classification, complete cytogenetic and molecular data were available for 535 (79%) samples: 204/535 (38%) were classified as low-risk and 64/535 (12%) were defined as high-risk. There was an inverse association between CD33 expression and prevalence of low-risk AML (Q1 59%, Q2 50%, Q3 27%, Q4 17%; p<0.001). In contrast, the prevalence of high-risk disease increased with each quartile (Q1 5%, Q2 8%, Q3 17%, Q4 18%; p<0.001). We observed a higher median CD33 MFI with high-risk disease (median MFI 195.315; range 12–720) than with low-risk (median MFI 80.5; range 5–1550.07) or intermediate-risk (i.e., neither low- nor high-risk) disease (median MFI 163.06; range 7–1351) (p<0.001). Response from end of induction I (CR) was also determined for our patient cohort. Rates of CR were similar across CD33-expression quartiles (Q1 78%, Q2 75%, Q3 75%, Q4 72%; p=0.581). Moreover, CR rates for each risk group did not vary across quartiles (low-risk: Q1 84%, Q2 85%, Q3 88%, Q4 82%; p=0.917; intermediate-risk: Q1 77%, Q2 65%, Q3 72%, Q4 71%; p=0.594; high-risk: Q1 57%, Q2 67%, Q3 60%, Q4 72%; p=0.801). This large scale analysis supports our earlier finding that CD33 expression in pediatric AML is heterogeneous and associated with conventional risk-group criteria. As outcome data matures from COG AAML0531, the phase III counterpart of AAML03P1 in which patients are randomized to GO treatment, we will determine whether the addition of GO improves survival of patients with low versus high CD33 expression and whether this finding translates into enhanced outcomes for associated disease-risk groups. Disclosures:Franklin:Amgen : Employment, Equity Ownership.