Poor-risk Acute Myeloid Leukemia Research Articles

Conditioning Intensity for Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia Patients with Poor-Prognosis Cytogenetics in First Complete Remission

The optimal intensity of conditioning regimen may be dependent on not only age and comorbidities but also disease characteristics and risk of relapse after allogeneic hematopoietic cell transplantation (HCT). We, therefore, analyzed the transplant outcomes of 840 adult patients with cytogenetically poor-risk acute myeloid leukemia (AML) in first complete remission (CR1) who received first allogeneic HCT with either myeloablative conditioning (MAC; n = 652) or reduced-intensity conditioning (RIC; n = 188) between 2006 and 2017.The median age at HCT was 50.5 years (range: 16 to 77 years). The multivariate analysis showed that patients receiving MAC had a significantly higher overall survival and lower leukemia-related mortality than those receiving RIC (P = .011 and P = .025, respectively). In the subgroup analysis, these results applied to patients aged 16 to 59 years, with HCT-comorbidity index scores ≥3, and with cytogenetic remission. Among MAC regimens, there was a trend for worse survival and nonrelapse mortality with the busulfan/fludarabine-based regimen compared with the total body irradiation (TBI) ≥8 Gy-based regimen (P = .082 and P = .062, respectively), whereas the busulfan/cyclophosphamide-based regimen and the fludarabine/melphalan-based regimen had similar outcomes with the TBI-based regimen. These data suggest that MAC is preferable to RIC for patients with cytogenetically poor-risk AML undergoing allogeneic HCT in CR1.

Role of alternative donor allogeneic hematopoietic stem cell transplantation in patients with intermediate- or poor-risk acute myeloid leukemia in first complete remission.

Allogeneic hematopoietic stem cell transplantation (HCT) offers the most effective prevention of relapse and has significant overall survival (OS) benefits for patients with acute myeloid leukemia (AML) in first complete remission (CR1). We conducted a retrospective analysis of a cohort of patients with intermediate- or poor-risk AML. The purpose of the present study was to investigate the role of alternative donors for AML in CR1. We analyzed 1561 patients who underwent HCT from an HLA-matched related donor (MRD), HLA 8/8-matched unrelated donor (MUD), or umbilical cord blood (UCB). The results of a multivariate analysis showed that HCT from UCB (HR = 1.28, 95% CI: 1.07-1.52), age ≥50 years (HR = 1.36, 95% CI: 1.14-1.62), male (HR = 1.42, 95% CI: 1.21-1.66), PS > 1 (HR = 1.68, 95% CI: 1.17-2.42), and poor-risk cytogenetics (HR = 1.53, 95% CI: 1.29-1.81) had an inferior prognostic impact on OS. We conclude that an MUD is the best alternative to an HLA identical MRD for patients with AML in CR1. UCB is an alternative option if neither MRD nor MUD are available, or when patients need to receive urgent HCT for poor-risk AML in CR1.

Busulfan/Melphalan/Fludarabine (Bu/Mel/Flu) Conditioning Versus Total Body Irradiation/Thiotepa/Cyclophosphamide (HFTBI/Thio/Cy) Based Conditioning in Patients with Acute Myeloid Leukemia (AML) or Myelodysplastic Syndrome (MDS) Undergoing CD34-Selected T-Cell Depleted Allogeneic Stem Cell Transplantation (alloSCT)

Introduction In patients with poor risk AML or MDS in first complete remission (CR1), alloSCT can be potentially curative. Comparison of the non-hematologic toxicities between total body irradiation (TBI)-based conditioning versus chemotherapy alone prior to CD34-selected alloSCT requires further validation. Objective The primary objective of this analysis is to review the incidence of grade 3 or 4 non-hematologic toxicities at day 100 and 365. Methods Patients with AML or MDS in CR1 who underwent their first CD34-selected alloSCT were identified from our institutional database. Transplant outcomes and toxicity rates were assessed using cox proportional hazards regression. Toxicities were graded according to the NCI Common Technology Criteria for Adverse Effects v4.03. Baseline characteristics were assessed using the Wilcoxon rank-sum test, Fisher's exact test, and the chi-squared test. The cumulative incidence method was used to control for competing risks. Results 221 patients underwent CD34-selected alloSCT from Jan 2010-Dec 2016. 48 (22%) received HFTBI/Thio/Cy and 173 (78%) Bu/Mel/Flu. A statistically significant difference was noted in age, disease state, and Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) score as summarized in Table 1. The cumulative incidence of non-hematologic toxicities most frequently reported at 12mo were infections (87.8%, 95% CI: 82.6-91.5), oral/GI (72.4%, 95% CI: 66-77.8) and metabolic (69.2%, 95% CI: 62.7-74.9). Incidence of gr 3/4 cardiovascular (43.4% vs. 18.8%, P = 0.002) at 12mo were significantly higher in the Bu/Mel/Flu arm. Incidence of gr 3/4 oral/GI toxicities (93.8% vs. 66.5%, P Conclusion Amongst adults with AML or MDS undergoing CD34-selected alloSCT, chemotherapy-based and TBI-based conditioning regimens appear to be associated with similar toxicity profiles. Most differences observed in the incidence of toxicities between the 2 groups can be attributed to the known side effects of the individual conditioning agents, however, we cannot determine impact of age on the toxicities due to the significant difference in age distribution between the 2 groups.

Clinical Outcomes and Persistence of Somatic Mutations in Acute Myeloid Leukemia Patients after Transplantation

Introduction Allogeneic hematopoietic stem cells transplant (HSCT) is a curative treatment for acute myeloid leukemia (AML). The persistence of disease-associated somatic mutations following HSCT for myelodysplastic syndrome has been shown to be associated with a high risk of disease progression. While a recent study in AML found that the presence of somatic mutations at day 21 post-HSCT is associated with higher risk of relapse, there is paucity of data at a later time point. We hypothesized that persistence of mutations at day 100 resulted in increased relapse rates and inferior outcomes than in patients who had cleared their mutations. Methods All adult patients with AML, diagnosed in 2016-2017, who underwent allogeneic HSCT, were included in the study. Somatic mutations in diagnostic and post-transplantation bone marrow specimens were detected by a 97-gene next generation sequencing (NGS) assay. Baseline characteristics including age, sex, risk stratification, type of transplant, conditioning regimen and presence of acute and chronic graft-versus-host disease (GHVD) were collected. We evaluated somatic mutations in bone marrow samples obtained 100 days after transplantation (T+100). Results We identified 32 patients, four had no detectable mutations in the diagnostic bone marrow NGS and were excluded from the analysis. Most patients were >60 years with male-predominance (68%). Fourteen (50%) patients fell into the poor-risk AML category. Twenty eight (87.5%) patients had at least one mutation in the diagnostic bone marrow; the mean number of mutations at diagnosis was 3 (1-11). FLT3, NPM1, RUNX1, TET2, RAS and ASXL-1 were the most common mutations. Eighteen patients (64%) underwent matched unrelated HSCT and 15 (54%) had reduced-intensity conditioning (RIC) chemotherapy. Twenty three (82%) out of 28 patients had no detectable mutations in the day 100 bone marrow. All five patients with persistent mutations at T+ 100 had evidence of disease relapse. The T+100 bone marrow demonstrated evidence of relapse in two patients while the other three relapsed after a median of 6.53 months from transplant. This compared to a relapse rate of 17% in patients with no detectable mutations at T+100 (p=0.001, Fisher-Exact test). Median progression-free survival (PFS) was longer in patients who had no mutations at day 100 compared to those with persistent mutations (15.03 months vs. 5.50 months). Conclusions Our data show, that the persistence of somatic mutations at T+100 after allogeneic HCT can predict relapse. While the number of patients in this study is limited, the signal observed is significant and expansion of this analysis to a larger study is warranted, as identification of this high-risk population for relapse potentially allows for the initiation of early post-transplantation intervention strategies.

Treatment Patterns and Outcomes of Unselected Elderly Acute Myeloid Leukemia (AML) Patients Referred to a Combined Acute Leukemia and Hematopoietic Stem Cell Transplant (HSCT) Program

The median age of acute myeloid leukemia (AML) diagnosis is 69 years with 60% of newly diagnosed patients > 60 years. Due to a perceived intolerance to therapy, many elderly AML patients do not receive therapy. Of those that do, few are eligible for curative intent therapy with hematopoietic stem cell transplantation (HSCT) due to perceived lack of fitness, excessive comorbidity or absence of a donor. To better understand the outcomes of elderly AML patients, we evaluated a cohort of 323 consecutive elderly AML patients (≥60 years) referred to the Leukemia Program at Northside Hospital from January 2009 to December 2017 for evaluation and management. Our treatment algorithm is to offer intensive chemotherapy (IC) to all potentially eligible patients and HSCT to all transplant-eligible non-favorable risk patients that achieve complete remission, with or without complete platelet recovery (CR1(p)). Median patient age was 70 years (range 60-88). AML occurred de novo in 218 (67%), therapy-related in 33 (10%) and secondary in 72 (22%) patients. NCCN risk category was favorable (fav) in 48 (15%), intermediate (int) in 112 (35%) and poor in 161 (50%). Leukemia induction therapy, either IC (n=204) or hypomethylating agents (HMA, n=58), was given to all but 61 (19%) patients (IC - 78%, HMA - 22%). Of patients receiving IC, the major regimens were FLAG+/-Ida (n=117), 7+3 (n=58) and CPX-351 (n=18). Of the IC/HMA-treated patients (n=262), 130 (50%) achieved CR1(p) with the first induction, while 158 (60%) ultimately achieved CR1(p). In patients with fav, int and poor risk AML, CR1(p) was achieved in 73%, 52% and 41% respectively. HSCT was performed on 63 patients (59 - int/poor risk, 4- fav risk): autologous [5], matched sibling donor [21], matched unrelated donor [24], haploidentical donor [13]. Of the non-fav risk AML CR1(p) patients, where the treatment goal is HSCT if feasible, 57 (46%) of 124 received HSCT. After a median f/u of 34 months, 2-year overall survival (OS) for the whole cohort was 31%; corresponding rates for fav, int and poor risk AML was 58%, 35% and 20% respectively. Survival was similar in patients aged 60-66 and 67-72 years (2-yr OS 35% and 38%), but superior to those in the 73-88 yr tertile (2-yr OS 19%, p<0.001). The 2-yr OS was similar for IC- or HMA-treated patients (40% and 33% respectively) vs. 0% for patients not receiving induction therapy. For patients achieving CR1(p), 2-yr OS was 50% vs. 16% for those never reaching CR1(p). Of the patients receiving HSCT, 2-yr OS was 64%. In the subset of non-fav risk AML CR1(p) patients, OS was improved with HSCT (p<0.001, 2-yr OS 66% vs. 27%). In multivariate analysis, we analyzed factors associated with mortality including age, gender, race, year of diagnosis, WBC, de novo vs. secondary, NCCN risk category, and induction chemo type (receipt of HSCT was not analyzed given inherent bias in such as analysis). Factors associated with superior OS included WBC <2.5 at diagnosis (2.5-25.7, HR 1.92, p<0.001; ≥25.8, HR 1.93, p<0.001), NCNN fav risk (int, HR 2.02, p=0.002; poor, HR 2.71, p<0.001) and receipt of either IC or HMA induction (no induction vs. IC, HR 7.65, p<0.001; HMA vs. IC, HR 1.20, p=0.315). With the caveat that any such analysis is subject to referral bias, these results suggest that survival may be improved in elderly AML patients through a coordinated approach of remission induction therapy followed by HSCT when feasible. [Display omitted] DisclosuresSolh:Celgene: Speakers Bureau; Amgen: Speakers Bureau; ADC Therapeutics: Research Funding.

Allogeneic Hematopoietic Stem Cell Transplantation in Older Patients with Acute Myeloid Leukemia: Analysis of the Francophone Society for Stem Cell Transplantation and Cell Therapy

Background: Nowadays acute myeloid leukemia (AML) patients above the age of 60 years are often candidates for Allogeneic Hematopoietic Stem Cell Transplantation (HSCT). However, little is known about the outcomes of HSCT in this particular population, due to the low number of HSCT with robust follow-up, the heterogeneity between centers, as well as reports usually mixing AML and other diseases such as myelodysplastic syndrome. We used the database of the Francophone society for stem cell transplantation and cellular therapy to address this question in a large cohort of patients in a recent time period.Patients and methods: 1167 consecutive patients aged ≥60 years with AML in complete remission (CR), transplanted between January 1st 2006 and January 1st 2016, reported to ProMISe (Project Manager Internet Server), an internet-based system shared by 36 Francophone transplantation centers, were reviewed. Classical post-HSCT endpoints were studied such as engraftment, acute and chronic graft-versus-host disease (GvHD), non-relapse mortality (NRM), relapse rate, leukemia free survival (LFS) as well as overall survival (OS). Cytogenetic risk was assessed according to the European Leukemia Network 2017 for patients in first complete remission. Data were analyzed using proportional hazards models and proportional sub-distribution hazards models in presence of competing risks.Results: Patients' Characteristics are detailed in Table 1. The median age at HSCT was 62.9 years (Interquartile range -IQR 61.9-66.1). Patients aged ≥60 years but less of 65 represented 63.8% of the population with 68.2% of patients transplanted in the recent period (2011-2016). Most patient had de novo AML (91.6%), in first CR (76.9%) with intermediate risk (83.8%) according to ELN-2017 classification. A matched unrelated donor (MUD) was used in 45 % of transplants and the majority of patients received peripheral blood stem cells (83.7%). Half of the patients received fludarabine and 2 days busulfan as conditioning regimen. The majority of patients (70.9%) received anti-thymocyte globuline (ATG). Engraftment occurred in 1089 patients (93.3%; 95%CI, 91.9-94.8). Day 100 cumulative incidence of grade II-IV acute GVHD was 24.6% (15.7% grade II; 5.8% grade III; 3% grade IV). At last follow up, 378 patients had developed chronic GVHD (severe in 37.2% of them; 95%CI, 34.0-40.3). With a median follow-up of 3.5 years (95%CI, 3.1-3.7 years), overall survival (OS) and LFS probabilities at 3 years were 50.7% (95%CI, 47.7-54.0) and 44.8% (95%CI, 41.8-48.1), respectively. In multivariable analysis, the only factor associated with worse OS was the use of a mismatched unrelated donor compare to MUD [Hazard Ratio (HR): 1.35 (95% CI, 1.01 to 1.80), p=0.04]. At 3 years, relapse incidence was 34.4% (95% CI, 31.5-37.4). The use of a sibling donor compared to MUD [Sub-distribution Hazard Ratio (SHR): : 1.49 (95% CI, 1.19 to 1.87), p<0.001], poor risk AML in CR1 according to ELN classification [SHR: 1.49 (95% CI, 1.10 to 2.02), p=0.01], as well as the use of ATG in the conditioning regimen [SHR: 1.57 (95% CI, 1.21 to 2.05), p<0.001] were associated with a higher risk of relapse. During the study, 534 patients died (main causes of death was relapse, 53%); leading to a CI of NRM of 20.7% at 3 years (95%CI, 18.2-23.2). A karnofsky score above 90% [SHR: 0.74 (95% CI, 0.56 to 0.98), p=0.04] and the use of a sibling donor compare to MUD [SHR : 0.43(95% CI, 0.30 to 0.63), p<0.001] were associated with reduced NRM.Conclusion: With more than 3 years follow-up, which is long enough for our results to be considered to be robust, the use of a mismatched unrelated donor was the only factor associated with worse overall survival in this population of AML patients aged of 60 years or more. Relapse appeared as the first cause of death, independently related to AML ELN poor risk classification, but also to the use of a sibling donor and of ATG in the conditioning regimen. This study highlights the major role of alloreactivity in this particular population, where modulation of T-cell alloreactivity as well as donor choice should be urgently addressed in well-designed prospective trials. [Display omitted] DisclosuresPeffault De Latour:Amgen Inc.: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Pfizer Inc.: Consultancy, Honoraria, Research Funding; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding. Chalandon:Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel costs.

Transplant Rates and Outcomes of Young Acute Myeloid Leukemia (AML) Patients with Intermediate and Poor Risk Disease Referred to a Coordinated Acute Leukemia and Hematopoietic Stem Cell Transplant (HSCT) Program

▪Patients with intermediate and poor risk AML have unsatisfactory outcomes with conventional chemotherapy-based treatment. Allogeneic HSCT offers the best chance of long-term survival for patients who achieve complete remission (CR) and are eligible for such a procedure. There are several potential barriers to receiving an allogeneic HSCT, including but not limited to: achieving CR, timely referral to a transplant center, identifying a donor, and performing the HSCT prior to relapse or significant complications arising from induction and consolidation therapy. To better understand the outcomes of young, newly diagnosed non-favorable risk AML patients, we evaluated 271 consecutive adult patients (age ≤65 years) referred to our center between January of 2009 and July of 2017 for management. Patients were treated in an integrated acute leukemia and transplant management unit and it is our policy to offer intensive chemotherapy to all potentially eligible patients and HSCT to all transplant-eligible, non-favorable risk AML patients that achieve CR, with or without complete blood count recovery. Patient characteristics were as follows: Median age 55 (19, 65) years, male sex 50%, NCCN risk (intermediate 51%, poor 49%), FLT 3 ITD positive 15% and normal cytogenetics in 39%. Remission induction chemotherapy was given to 262patients with FLAG+/-IDA being the most commonly used regimen in 161 patients (61%) followed by 3+7 in 63 (24%)patients. Following induction, 211 (81%) achieved a CR1 after one (n=178), two (n=26) or three (n=7) courses of induction with a median follow up for survivors of 44.5 months. For patients with intermediate and poor risk NCCN categories, CR was achieved in 86% and 73% respectively. HSCT was performed on 146 (69%) patients (NCCN intermediate risk n=83, poor risk n=63): Myeloablative conditioning n=103 (71%), autologous (n=10), matched related donor (n=45), matched unrelated donor (n=51) and haploidentical mismatched related donor (n=40). Of the 65 patients in CR1 who did not receive HSCT, the reasons for not receiving HSCT were as follows: relapse prior to transplant (n=23), lack of psychosocial support (n=14), persistent active infection or organ dysfunction (n=16) at time of transplant evaluation, patient declined transplant (n=7) and poor performance status post induction (n=5). The 3 year estimates for OS and DFS were 50% and 44% respectively. Patients who received HSCT had a better 3 year OS and DFS of 59% and 52% compared to 27% and 27% for patients not receiving HSCT (p<0.001). In multivariate analysis, we analyzed factors associated with OS and DFS among patients in CR1 after induction. The variables considered were age at CR1 (≤49, 50-64, ≥65), gender, race (white, black), NCCN risk, induction regimen, cytogenetics at diagnosis (normal, abnormal), FISH at diagnosis (normal, abnormal), FLT3 ITD status, number of cycles to CR1 (1, ≥2), transplantation and year of CR1 (2008-2011, 2012-2014, 2015-2017). ). Transplantation was modelled as a time-dependent covariate where hazard of mortality for transplantation was only evaluated after transplantation was conducted. A forward stepwise algorithm was implemented and variables were selected if p values were less than 0.05. Factors associated with superior overall survival were age at CR1 (≤49 vs ≥60; HR 0.38, p<0.001), NCCN risk (intermediate vs poor HR 0.51, P<0.001), number of cycles to reach CR1 (1 vs ≥2, HR 0.58, p0.025) and receiving HSCT (Yes vs No, HR 0.71, p0.049). Factors associated with improved DFS were age at CR1 (≤49 vs ≥60 years, HR 0.45, p<0.001), NCCN risk (intermediate vs poor, HR0.53, p0.008) and receiving HSCT (yes vs no, HR 0.57, p0.006). This analysis shows that a timely coordinated approach of remission induction followed by HSCT in the majority of patients with non-favorable risk AML can lead to superior outcomes with more than half of the patients achieving long term survival. DisclosuresSolh:Amgen: Speakers Bureau; Celgene: Speakers Bureau; ADC Therapeutics: Research Funding.

Adipogeneis in the Bone Marrow Microenvironment Confers a Proliferative Advantage in Residual Leukaemic Cell Populations in Acute Myeloid Leukaemia after Allogeneic Stem Cell Transplantation

Up to 40% of poor risk Acute Myeloid Leukaemia (AML) patients receiving an allogeneic bone marrow transplant (BMT) from a donor will suffer disease recurrence/relapse within a year, significantly shortening their overall survival. Drug development to date has focused on clearing the bulk of leukaemic cells and how to target residual ‘Leukaemic stem cells,‘ which may give rise to relapse, however little work has been undertaken to discover the mechanisms by which the bone marrow niche may be unable to support normal haematopoietic stem cell growth and this may have a significant impact on the re-emergence of the patient's leukaemia. With the rise in the use of reduced intensity conditioning (RIC) regimes prior to transplant, the role of the patient microenvironment into which donor HSCs are engrafted warrants closer investigation.Stromal layers (AML-MSC) were derived from a cohort of 45 serial diagnostic, early (1-3 month), mid (6-9 month) and late (12 month+) post-transplant AML patients. Uniformity of stromal immunophenotyping markers (CD29, CD73, CD90, CD105, CD166, CD44, CD146) was present from passage 2 with concomitant loss of CD45 and other myeloid lineage markers (CD14, CD13, CD33, CD34). Diagnostic AML-MSCs showed a significant increase in stromal multipotency (CFU-F colony assays and CD146 expression, p<0.001) compared to both NBM and post-transplant MSCs. In comparison, early post-transplant colony formation was significantly reduced compared to other timepoints.AML-MSC supportive capacity for matched allogeneic donor (normal HSC) or autologous (malignant) blast populations was investigated using 14 day co-culture assays. Flow cytometric analysis of suspension and adherent co-culture fractions revealed AML blast cell numbers were consistently higher than comparative donor cell cultures at all post-transplant stages (p<0.001), suggesting patient AML-MSCs retain a preference for supporting their own blasts throughout different treatment stages. This observation was also confirmed in long-term LTC-IC assays in the stroma-adherent cobblestone fraction. Throughout serial samples, supportive capacity increased in later transplant AML-MSCs samples, confirming previous multipotency observations that stromal fitness to support stem cell growth may be compromised early post-transplant.Cytokine induced differentiation of AML-MSCs to osteoblast and adipocyte lineages resulted in a significant enhancement of adhesion and supportive capacity in the adipocyte lineage for AML blasts at all timepoints (p<0.002), which was absent in donor cell cultures. Osteoblast cultures gave results similar to that of the undifferentiated stromal layers for both AML and donor blast support. Parallel experiments using donor NBM-MSC layers revealed reduced support for AML blasts compared to that of matched AML-MSC stroma, however the same predisposition for adipogenic support of AML blasts was also observed.Luminex secretome profiling of serial AML-MSC supernatants using a panel of 105 pro-survival, inflammatory, migratory and immunomodulation cytokines revealed significant alterations in a number of targets associated with the diagnostic and post-transplant setting. Of the 80/105 targets detectable (>100pg/ml), high expression levels were seen in adhesion and ECM remodelling targets highlighting the ability of stromal secretory molecules to modify the surrounding environment. Hierarchical clustering analysis revealed post-transplant AML profiles correlated more closely with that of NBM-MSC at later time points, however significant increases in inflammatory/metabolic stress signalling molecules including IGFBP-3, Protein S, DKK1, VEGF, MMP1,MMP3, TPO (p,0.001), which have all been implicated HSC quiescence were associated with diagnostic and early post-transplant secretory profiles.In conclusion we identified several changes in the molecular and functional behaviour of the patient bone marrow microenvironment that may promote pro-leukaemic cell survival in post-transplant AML. Alterations in stromal fitness, adipogenic preference and metabolic stress signalling may contribute to a failing ability to support normal donor blood cells. Further exploration of therapies that target these alterations and prime the niche in favour of donor cells may provide a critical window for early clinical intervention and improved patient outcome. DisclosuresOttmann:Novartis: Consultancy; Celgene: Consultancy, Research Funding; Pfizer: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Fusion Pharma: Consultancy, Research Funding; Incyte: Consultancy, Research Funding.

Outcomes of Patients with Newly-Diagnosed Acute Myeloid Leukemia and Hyperleukocytosis Who Did Not Undergo Intensive Chemotherapy: Results from a Large International Database

Outcomes of Patients with Newly-Diagnosed Acute Myeloid Leukemia and Hyperleukocytosis Who Did Not Undergo Intensive Chemotherapy: Results from a Large International Database

Response to Venetoclax and Hypomethylating Agents Among Prognostic Risk Groups and Genetic Subtypes of Acute Myeloid Leukemia

▪The combination of venetoclax and hypomethylating agents (HMA) has demonstrated potent activity in acute myeloid leukemia (AML), both in newly diagnosed patients (pts) and those with relapsed/refractory (r/r) disease. We analyzed the association between response to therapy and leukemic somatic mutations, cytogenetics, and other pertinent patient- and leukemia-related features in a large series of newly diagnosed and r/r AML in adults treated with venetoclax in combination with HMA at City of Hope between October 2016 and May 2018.We identified 107 evaluable adults with AML treated with the combination of venetoclax and HMA. Sixty-one (57%) pts had r/r AML at the time of initiating treatment (median prior lines of therapy: 2; range: 1-10), while 46 (43%) were treated in the frontline setting. The median age of pts was 68 years (range: 19-86). AML was de novo in 57 (53%), therapy-related in 23 (21%) and secondary in 27 (25%) pts. Thirty-six (34%) pts had prior exposure to HMA, and 21 (20%) pts had relapsed following prior allogeneic hematopoietic cell transplantation (HCT). The majority of treated pts had unfavorable (52%) or intermediate-risk (39%) AML based on combined cytogenetics and molecular profiles. The most common detected somatic mutations (majority by next generation sequencing) were FLT3 (17%), followed by DNMT3A (15%), RAS and TET2 (each 14%), RUNX1 (13%), TP53 (12%), and IDH1/2 (11%). Most pts received decitabine in combination with venetoclax (N=97, 91%); only 10 (9%) pts received 5-azacitidine together with venetoclax.Complete remission (CR)/CR with incomplete hematologic recovery (CRi) was achieved in 57 (53%) pts after a median of 2 (range 1-4) cycles. For 36 pts who achieved CR/CRi and had available minimal residual disease (MRD) assessment by multicolor flow cytometry (MFC), 23 (64%) became MRD-. CR/CRi was higher in pts carrying favorable- or intermediate-risk AML compared to poor-risk AML (100% vs. 60% vs. 45%, P=0.029). CR/CRi was 48% in those with complex cytogenetics (N = 31), 45% in monosomal karyotype (N = 22), 36% in KMT2A gene rearrangement (N = 11), 74% in normal karyotype (N = 19), and 25% in inversion 3 (N =4). The CR/CRi rate was not significantly different between newly diagnosed or r/r AML (61% vs. 48%, P = 0.17), nor was there a difference associated with AML type (de novo vs. therapy-related vs. secondary, P= 0.26), patient age (> or ≤ 65 years) at time of therapy (P = 0.13), prior allogeneic HCT (P = 0.29), prior administration of HMA (P = 0.37) and the type or schedule (5- or 10-day decitabine) of HMA (P = 0.52). In multivariate analysis, only favorable- or intermediate-risk cytogenetics was associated with better CR/CRi (P = 0.036). CR/CRi was also comparable regardless of the presence or absence of various analyzed somatic AML mutations. However, in recursive partitioning analysis of detectable somatic mutations and response to therapy, the combined lack of RAS, TP53 and RUNX1 mutations was linked to an improved rate of CR/CRi. When AML cases were stratified into functional gene alteration subgroups (according to the TCGA data set), there was no significant difference in CR/CRi according to the presence or absence of certain functional genes/fusions.Median overall survival (OS) for all pts was 12.5 months and was 14.6 months for pts who achieved CR/CRi, in contrast to 4.6 months for non-responders (P <0.001). Only AML subtype (de novo vs. therapy-related vs. secondary) (P <0.001) and AML genetic risk (favorable/intermediate vs. high) (P = 0.042) independently impacted OS in multivariate analysis. None of the AML individual somatic mutations influenced OS for this cohort, however, in recursive partitioning analysis of detectable mutations, the presence of any of SRSF2, IDH1/2 or RUNX1 were associated with improved OS. Furthermore, the presence of myeloid transcription factor (P = 0.033) and spliceosome complex mutations (P = 0.004) predicted superior OS, whereas the presence of a chromatin modifying mutation predicted inferior OS (P = 0.004). Thirteen (23%) responders subsequently underwent allogeneic HCT.We report remarkable activity with venetoclax and HMA across various high-risk genetics and clinical features in AML patients. Prospective studies are warranted to compare this combination directly with chemotherapy in all AML subsets. This is particularly true for high risk AML where response to conventional chemotherapy is poor. [Display omitted] DisclosuresAli:Incyte Corporation: Membership on an entity's Board of Directors or advisory committees. Salhotra:Kadmon Corporation, LLC: Consultancy. Khaled:Alexion: Consultancy, Speakers Bureau; Juno: Other: Travel Funding; Daiichi: Consultancy. Stein:Celgene: Speakers Bureau; Amgen Inc.: Speakers Bureau. Forman:Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding.

Outcomes of fludarabine, high dose cytarabine and granulocyte-colony stimulating factor (FLAG) as re-induction for residual acute myeloid leukemia on day 14 bone marrow

BackgroundPatients with acute myeloid leukemia (AML) treated with intensive chemotherapy may require re-induction based on the evaluation of day 14 bone marrow biopsy. Methods: A retrospective chart review was performed to evaluate adult patients with AML who received re-induction with fludarabine, high dose cytarabine and granulocyte colony stimulating factor (FLAG) regimen for residual disease (≥ 5% blasts by morphology) on day 14 bone marrow examination between September 2012 and July 2017 at our institution. ResultsWe identified 27 patients who received FLAG therapy for treatment of residual disease on day 14 marrow examination following initial induction. The median age at diagnosis was 61 years and the majority of patients had poor risk AML. The overall response rate was 78% and 15 patients proceeded to allogeneic hematopoietic stem cell transplantation. ConclusionThe regimen was well tolerated and is a viable re-induction option for patients with residual disease on a day 14 bone marrow.

Mutational Landscape of Intermediate-Risk and Poor-Risk Acute Myeloid Leukemia (AML) Adult Patients by Next-Generation Sequencing (NGS): One Academic Center’s Experience

Mutational Landscape of Intermediate-Risk and Poor-Risk Acute Myeloid Leukemia (AML) Adult Patients by Next-Generation Sequencing (NGS): One Academic Center’s Experience

Abstract 4821: A targeted differentiation therapy for the treatment of acute myeloid leukemia

Abstract Objectives: Acute myeloid leukemia (AML) is a heterogeneous disease with diverse genetic abnormalities present in all ages, but mainly prevalent in an elderly population with an average age of above 60 years. The treatment of elderly AML remains a formidable challenge as the long-term outcomes of elderly AML patients have not improved in the last three decades, with ≤5% overall survival recorded at 5 years, calling for novel treatment options. Epigenetic therapy has a significant impact on the management of hematologic malignancies. Recent findings show that using very low dosages of decitabine depletes DNA methyl transferase 1 (DNMT1) without cytotoxicity. Decitabine-mediated epigenetic therapy does not induce FLT3 (fms-like tyrosine kinase 3) ligand, which hinders the effectiveness of FLT3 inhibitors. The inhibition of FLT3 and DNMT1 is associated with terminal myeloid differentiation of AML cells. Therefore, combining the inhibitors of FLT3 and DNMT1 may be an effective therapeutic approach for the treatment of poor-risk AML. Ponatinib is a third-generation receptor tyrosine kinase inhibitor. Various in vitro and in vivo preclinical studies demonstrated antileukemic activities of ponatinib against AML cells bearing FLT3-ITD mutations. Methods: Apoptosis and CD11b were measured by flow cytometry. FLT3 signaling and DNMT1 levels were analyzed by immunoblotting. Results: FLT3-ITD expressing AML cell lines MV4-11, MOLM-13, and MOLM-14 were used in the study. Co-treatment with decitabine (10-100 nM) and ponatinib (2 nM) in AML cells induced apoptosis in association with PARP cleavage. Increased levels of pro-apoptotic protein BAD and decreased levels of anti-apoptotic protein MCL1 were observed in these treated cells. The combination of decitabine and ponatinib also showed similar effects in primary AML cells expressing FLT3-ITD. The Western blot analysis demonstrated that treatment of decitabine decreased levels of DNMT1 and ponatinib inhibited FLT3 signaling and activation of downstream effectors STAT5, AKT, and ERK1/2 with induction of PU.1 a key regulator of myeloid differentiation. Co-treatment with ponatinib and decitabine using low concentrations in MV4-11 and MOLM14 cells induced myeloid differentiation. The percentage of differentiated cells was measured by increased surface expression of CD11b analyzed by flow cytometry and granulocytic/monocytic morphology examined by Wright-Giemsa staining. Conclusions: Mechanistically, the hypomethylating agent initiates the differentiation process and FLT3 inhibition augments differentiation leading to apoptosis of AML cells. Altogether, these preclinical findings of downregulation of DNMT1 and induction of PU.1 are a novel differentiation approach to induce apoptosis in AML cells and warrant future therapeutic potential for the treatment of AML patients expressing FLT3 mutations. Citation Format: Sudhakiranmayi Kuravi, Myles Taylor, Tara L. Lin, Jensen Roy, Joseph McGuirk, Ramesh Balusu. A targeted differentiation therapy for the treatment of acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4821.

A randomized, open-label, phase II study of azacitidine (AZA) in combination with durvalumab in patients (pts) with previously untreated higher-risk myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) ineligible for hematopoietic stem cell transplantation (HSCT).

TPS7074 Background: Hypomethylating agents (HMAs) induce hematologic response in ~ 50% of higher-risk MDS pts; however, there are few treatment options for nonresponding pts at increased risk of AML progression and death. While older AML pts ineligible for HSCT have similar overall survival (OS) with AZA and chemotherapy (13.3 vs 12.2 months) (Döhner et al. Haematologica 2015;100:P566), there is an opportunity to further improve responses and OS in these pts. Blockade of the programmed cell death-1 (PD-1)/PD-ligand 1 (PD-L1) pathway with immune checkpoint inhibitors is an emerging paradigm in anticancer therapy. PD-L1 is expressed on cells from AML and MDS pts; expression is upregulated on myeloblasts following HMA therapy (Yang et al. Leukemia 2014;28:1280) and during MDS transformation to AML (Ogata et al. Leuk Res 2012;36:1229). Durvalumab (MEDI-4736), a human anti-PD-L1 monoclonal antibody, is well tolerated and induces durable responses in pts with solid tumors (Lutzky et al. JCO 2014;32:3001). This randomized, open-label, phase 2 study evaluates efficacy and safety of subcutaneous (SC) AZA ± durvalumab in pts with higher-risk MDS and older pts with AML. Methods: Eligible MDS pts ( &lt; 20% blasts) aged ≥ 18 years, with IPSS intermediate- or high-risk MDS, and AML pts (≥ 20% blasts) aged ≥ 65 years, are randomized 1:1 to receive either AZA 75 mg/m2 SC for 7/28 days or AZA 75 mg/m2 SC for 7/28 days plus durvalumab 1500 mg IV on day 1 of 28-day cycles. Pts are stratified by cytogenetic risk: intermediate- vs poor-risk AML, and intermediate- vs poor-/very-poor-risk MDS. Primary endpoint is overall response rate per IWG 2006 criteria in MDS pts, and proportion of pts achieving complete response (CR) or CR with incomplete blood count recovery (CRi) per modified IWG 2003 criteria in AML pts. Other endpoints include safety, time to response, overall survival and PD-1/PD-L1 activity. Pts will be followed every 3 months until discontinuation. Target enrollment is 182 pts: 72 MDS pts and 110 AML pts. Enrollment began in June 2016 (ClinicalTrials.gov NCT02775903).

Alternative donors for allogeneic hematopoietic stem cell transplantation in poor-risk AML in CR1

AbstractAllogeneic hematopoietic stem cell transplantation (alloHSCT) remains the treatment of choice to consolidate remission in patients with poor-risk acute myeloid leukemia (AML). With increasing alternative donors available, the preferred donor or stem cell source is debated. We set out to study outcome in recipients of alloHSCT with poor-risk AML in first complete remission (CR1) by donor type. A total of 6545 adult patients with poor-risk AML in CR1 receiving an alloHSCT using matched related donor (MRD, n = 3511) or alternative donors, including 10/10 (n = 1959) or 9/10 matched unrelated donors (MUDs, n = 549), umbilical cord blood (UCB) grafts (n = 333), or haplo-identical (haplo) donors (n = 193) were compared. Overall survival (OS) at 2 years following MRD alloHSCT was an estimated 59 ± 1%, which did not differ from 10/10 MUD (57 ± 1%) and haplo alloHSCT (57 ± 4%). OS, however, was significantly lower for 9/10 MUD alloHSCT (49 ± 2%) and UCB grafts (44 ± 3%), respectively (P < .001). Nonrelapse mortality (NRM) depended on donor type and was estimated at 26 ± 3% and 29 ± 3% after haplo alloHSCT and UCB grafts at 2 years vs 15 ± 1% following MRD alloHSCT. Multivariable analysis confirmed the impact of donor type with OS following MRD, 10/10 MUD, and haplo alloHSCT not being statistically significantly different. NRM was significantly higher for alternative donors as compared with MRD alloHSCT. Collectively, these results suggest that alloHSCT with MRDs and 10/10 MUDs may still be preferred in patients with poor-risk AML in CR1. If an MRD or 10/10 MUD is not available, then the repertoire of alternative donors includes 9/10 MUD, UCB grafts, and haplo-identical donors. The latter type of donor is increasingly applied and now approximates results with matched donors.

Early Post-Transplant Epigenetic Therapy By Panobinostat and Decitabine Followed By Donor Lymphocyte Infusion (DLI): Interim Results of the HOVON-116 Phase I/II Feasibility Study in Poor-Risk AML Recipients of Allogeneic Stem Cell Transplantation (alloHSCT)

▪While recent studies showed that the allogeneic graft versus leukemia (GVL) effect is operational in poor-risk acute myeloid leukemia (AML), the relapse rate remains high. In order to exploit GVL more effectively, we explored the early initiation of epigenetic therapy after alloHSCT, interspersed with successive, low dosage DLI in patients (pts) with AML, characterized as poor- or very poor-risk, according to the latest (2015) HOVON-SAKK AML risk classification. This study started as a phase I study in very poor-risk AML pts exploring the feasibility of combination epigenetic therapy at dose levels 1, 2, and 3, consisting of either panobinostat (PNB) alone (20 mg at days 1, 4, 8, 11 of a 4 wk-cycle) or PNB combined with decitabine (DCB, 10 or 20 mg/m2 at days 1-3 of every 4 wk-cycle). DLI consisted of 106 CD3 T-cells/kg at day 90 and 3 x 106 at day 180 in case of a matched sibling (sib) donor and 30% of that dose in case of a matched unrelated donor (MUD). Reduced intensity conditioning was applied by a combination of cyclophosphamide, fludarabine, and reduced-dose total body irradiation (TBI). Graft versus host disease (GVHD) prophylaxis consisted of post-transplant (PT) cyclophosphamide and short course cyclosporine. Phase II is focusing on actual delivery of transplantation, epigenetic therapy, and subsequent DLI in newly diagnosed AML pts upon confirmation of poor-risk or very poor-risk status, at which time point pts are registered for the study. Secondary endpoints include toxicities, GVHD, non-relapse mortality (NRM), relapse, overall survival (OS), and relapse free survival (RFS) as from transplantation. Pts lacking a sib or MUD proceeded off-protocol to alloHSCT with an alternative donor.Currently (July 2016), 94 pts are registered early after diagnosis during induction chemotherapy and so far 59 of them have actually proceeded to alloHSCT by either a MUD or sib donor. Interim results refer to 54 pts actually transplanted, and with sufficient follow-up (median: 9 months, range: 2-25 after transplantation). Pts received their transplant at a median number of 109 days (range: 69-200) after diagnosis. After 2 cycles of induction therapy, 35 pts were in hematological CR, 16 in CR without complete blood recovery, and 3 in PR. Median percentage of blasts prior to alloHSCT was 2 (range: 0-10). Median age was 54 years (18-70), 48 pts were classified as very poor-risk, 6 pts as poor-risk AML. Donors included 23 sib and 31 MUD. OS at 12 months from transplantation is 81% (±7). 10 pts died, including 5 due to NRM and 5 due to relapse. RFS at 12 months is 66% (±9). A historical HOVON control group of very poor-risk AML CR1 recipients of alloHSCT showed OS of 52% ±6 at 12 months and RFS of 43% ±5.Forty-one out of 54 pts received PT epigenetic therapy, including 13 PNB alone, 13 PNB/DCB (20 mg/m2), and 15 PNB/DCB. Pts started at a median time point of 33 days (range: 27-54) after transplantation. Combining PNB with DCB at a dose of 20 mg/m2 proved not feasible due to cytopenia, causing extension of successive cycles of PNB/DCB, which was considered a dose limiting toxicity (DLT). CTC grade 3 and 4 side-effects after the first cycle of PNB/DCB included gastrointestinal nausea in 2 pts (grade 3), neutropenia in 3 pts and general fatigue in 1 pt. After the second cycle PNB/DCB, 1 pt experienced nausea (grade 3), and 1 pt fatigue (grade 3). No opportunistic CTC grade 3 and 4 infections were observed after the first 2 cycles of PNB/DCB. DLI could so far be administered in 34 pts, including 19 receiving 2 DLI's, and 9 pts a third DLI. None of the pts developed grade 3 or 4 acute GVHD before DLI. Out of 34 recipients of DLI, severe chronic GVHD occurred in 5 (15%) pts.Collectively, these results suggest that: 1. alloHSCT with GVHD-prophylaxis by cyclophosphamide PT allows for early initiation of epigenetic therapy and DLI, and 2. as compared to historical HOVON-data in very poor-risk AML pts receiving alloHSCT, encouraging results with respect to relapse, DFS, and OS are observed in patients actually receiving PNB alone or PNB combined with DCB, followed by DLI. 3. Limited side effects were observed in recipients of PNB alone or the combination of PNB and DCB at a dose of 10 mg/m2; the incidence GVHD also appeared limited. Altogether these results might suggest enhanced GVL and, therefore, have set the stage for an international prospective randomized study in (very) poor-risk AML patients. DisclosuresMaertens:Gilead: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding, Speakers Bureau; Astellas: Consultancy, Speakers Bureau; Amgen: Consultancy.

A Phase 1 Clinical Trial of Selinexor in Combination with Decitabine in Patients with Newly Diagnosed and Relapsed or Refractory Acute Myeloid Leukemia

Introduction: Exportin-1 (XPO1), a nuclear transport protein critical for the export of tumor suppressor proteins (TSPs) and select mRNAs to the cytoplasm, is highly expressed in acute myeloid leukemia (AML) and correlates with poor survival. Selinexor, an oral, first-in-class, selective inhibitor of nuclear export, blocks XPO1 function. We previously reported that sequential treatment of AML blasts using the hypomethylating agent decitabine followed by selinexor exhibited strong anti-leukemic effects in vivo by inducing the expression of silenced TSPs that are kept in the nucleus by XPO1 inhibition (Ranganathan, Blood 2015).Methods: Based on these findings, a phase I dose-escalation study was initiated to evaluate the safety, feasibility, maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), and preliminary clinical activity of selinexor in combination with decitabine in poor-risk AML pts (NCT02093403). Adults with relapsed or refractory (R/R) AML and older (age ≥60) unfit pts with untreated AML were eligible. Pts received 10-day decitabine induction(s) at 20mg/m2 on days 1-10 for up to four 28-day cycles in combination with selinexor once daily, twice weekly beginning on day 11. Pts with <5% marrow blasts after any cycle received 5-day decitabine maintenance with selinexor as described.Results: Twenty-four pts were enrolled (see Table 1 for baseline pt characteristics). Nineteen pts had R/R AML (median of 3 prior chemotherapy regimens, range 1-4); five pts had previously untreated AML. Seventeen pts were treated on the dose escalation phase receiving selinexor doses ranging from 23mg/m2 to 55mg/m2. After two patients in DL 1 declined continuation of study therapy beyond cycle 1 due to grade <3 GI toxicities (nausea, anorexia), dosing of selinexor was limited to days 11, 13, 18, and 20 of each cycle (twice weekly for only 2 weeks instead of 3 weeks). At the maximum administered dose of 55mg/m2, three pts were treated with no grade ≥3 drug-related toxicities, but two pts declined continuation of study therapy after cycle 1, due to chronic low-level GI toxicities. Based on this and also emerging experience from a separate trial with single-agent selinexor, dosing of selinexor was changed to a flat dose of 60mg (~35 mg/m2) given twice weekly. Six additional pts were enrolled at 60mg of selinexor with improved tolerability; this is the RP2D. Overall, the most common grade ≥3 non-hematologic toxicities regardless of attribution were asymptomatic hyponatremia (n=17, 71%), febrile neutropenia (n=11, 46%), sepsis (n=10, 42%), hypertension (n=9, 38%), hyperglycemia (n=8, 33%), hypophosphatemia (n=7, 29%) and lung infections (n=7, 29%). Notably, the median number of treatment cycles given was only one (range 1-5). Ten pts discontinued study participation due to intolerable regimen related toxicities (nausea, fatigue, anorexia, and weight loss), five of these after cycle 1. Other reasons for treatment discontinuation included refractory AML (n=6), induction death during cycle 1 (n=3), death in remission (unknown cause, n=1), allogeneic transplantation (n=3), and uncontrolled infection (n=1). Of the five previously untreated pts, two achieved complete response (CR), and 2 had CR with incomplete count recovery (CRi). Of these responders, pts presented with normal karyotype (n=2), monosomy 7 (n=1), and del(7q), +13 (n=1). The latter two pts achieved cytogenetic remission. Of the 19 R/R pts, three had induction death not felt to be drug related. Of the 16 other pts in the R/R group, one patient achieved CR, two had CRi, one had marrow CR (mCR). The CR/CRi/mCR rate for the entire cohort was 33%. For untreated pts, the CR/CRi/mCR rate was 80% and, for R/R pts the CR/CRi/mCR rate was 21%. Six of the R/R pts subsequently underwent allogeneic stem cell transplant (four with no evidence of AML at the time of transplant).Conclusions: The combination of selinexor plus decitabine is an active regimen in poor-risk AML pts, with CR/CRi/mCR rate of 80% in older untreated and 21% in R/R AML pts. Modification of selinexor exposure (flat dose of 60mg given twice weekly for 2 weeks after decitabine) improved tolerability of the regimen. Correlative studies, including targeted mutation analysis to assess whether specific mutations are associated with response, are ongoing and will be presented. [Display omitted] [Display omitted] DisclosuresBhatnagar:Karyopharm: Research Funding.

TCA Cycle Inhibition By Cpi-613 Increases Sensitivity to Chemotherapy in Older and Poor Risk Acute Myeloid Leukemia (AML)

Background: CPI-613 is a first in class agent that inhibits pyruvate dehydrogenase (PDH) and a-ketogluterate dehydrogenase. We have previously shown CPI-613 inhibits mitochondrial respiration, causes phosphorylation of PDH, activation of adenosine monophosphate activated kinase (AMPK) in AML cells and was well tolerated by patients with myeloid malignancies.Methods: We completed a phase I trial of CPI-613 in combination with high dose cytarabine (HiDAC) and mitoxantrone for relapsed or refractory AML patients. RNA sequencing analysis was conducted on a subset of patient samples to explore gene expression profiles associated with response. To explore genetic determinants of response, Cas-9 expressing AML cells were used to knock out p53 and AMPK.Results: In the phase I trial 67 patients were enrolled and 62 were evaluable. One patient died before completion of therapy, three died prior to the day 14 nadir marrow and one patient with accelerated phase CML was enrolled in error. The median age was 60 years (range 21-79). In patients with relapsed disease the median duration of CR1 was 11.2 months. Cytogenetics were poor risk in 27 patients, intermediate in 33, and good in 6. In the 62 evaluable patients the results were as follows. The overall response rate was 50% (26CR+5CRi) with a median survival of 6.7 months. Response was significantly associated with survival with a median survival of 13.2 months in responders compared to 3 months for all others. In patients ≥60 years old the CR/CRi rate was 47% (15/32) with a median survival of 6.9 months. This was not significantly different from patients younger than 60 years old. Surprisingly, the response rate for patients with poor risk cytogenetics was 46% (9CR+2CRi/24) with a median survival of 5.5 months. In a historical cohort, only 19% (3/16) of patients with poor risk cytogenetics responded with a median survival of 2.8 months (Figure 1). The most common toxicities of CPI-613 were diarrhea and nausea. Thirteen patients (21%) went on to allogeneic stem cell transplantation. Several patients had blood samples taken before and after CPI-613 infusion. Three of these patients had increased phosphorylation of PDH consistent with its inhibition. Additionally, two patients demonstrated a robust phosphorylation of AMPK consistent with preclinical studies. The role of AMPK in response was assessed by competition assays using Cas-9 expressing AML cells that have deleted AMPK. Normal cells out-competed AMPK deleted cells when treated with CPI-613 but not when treated with cytarabine, suggesting AMPK is a specific resistance factor against TCA cycle inhibition. To explore if loss of p53 function (common in poor risk cytogenetics) affected response we tested CPI-613 alone or with an anthracycline against an AML cell line with and without p53 knockdown. Suppression of p53 function resulted in significant resistance to anthracyclines but no change in response to CPI-613; the combination enhanced cell kill over either agent alone. To gain insight into the transcriptional programs that distinguish responders from non-responders prior to treatment, we sequenced the transcriptomes of mononuclear cells from 25 baseline patient samples: 19 from bone marrow and 9 from peripheral blood. These samples corresponded to 14 responders and 11 non-responders. Analysis for enrichment of gene ontologies revealed several significant biological categories for the genes overexpressed in responders, while none were identified for the non-responders. The responders showed significant enrichment for gene categories related to immune involvement, particularly genes associated with B lymphocytes.Conclusions: TCA cycle inhibition with CPI-613 is a promising novel approach in the treatment of AML patients, especially in the elderly and those with poor risk cytogenetics. Low levels of AMPK may identify patients with an increased likelihood of response. Finally, the presence of gene expression profiles consistent with immune cells raises the possibility that in addition to direct effects on leukemia cells, TCA cycle inhibition may alter microenvironment immune responses. [Display omitted] DisclosuresPardee:Cornerstone Pharmaceutical: Consultancy; Celgene: Speakers Bureau; Novartis: Speakers Bureau; Merck: Consultancy. Manuel:Novartis: Speakers Bureau.

The Cell of Origin in NPM1 Positive Acute Myeloid Leukemia (AML) Is Prognostic

Abstract Mutations in the nucleophosmingene (NPM1) are common in patients with cytogenetically-normal acute myeloid leukemia (AML) and have been associated with positive outcomes. Although most leukemic stem cells (LSCs) arise from CD34+ primitive progenitors, our recent data suggest that a fraction arise from less primitive CD34- progenitors and seem to have a better prognosis (Gerber et al. Haematologica 2016). Conversely, poor-risk AMLs such as those harboring internal tandem duplications of the FMS-like tyrosine kinase 3 (FLT3-ITD) or with poor-risk cytogenetics appear to arise from LSCs with a primitive hematopoietic stem cell (HSC) phenotype. NPM1-mutated AMLs can be either CD34- or CD34+, and have been associated with variable prognoses. We hypothesize that the cell of origin, CD34- or CD34+, of NPM1-mutated AML has prognostic implications. A retrospective cohort analysis was conducted using electronic medical record data from patients aged 18 or older with newly-diagnosed NPM1-mutated AML treated with intensive induction chemotherapy at Johns Hopkins Hospital from 2008-2015. NPM1 and FLT3-ITD mutations were determined from PCR assays on diagnostic samples. We (Gerber et al. Haematologica2016) and others have shown that CD34+ cells represent normal, non-leukemia progenitors when they comprise &lt;1% of mononuclear cells (MNCs); thus, &gt;/= 1% MNCs was the cut-off used to distinguish CD34+ from CD34- AMLs. Clinical outcomes including complete remission (CR) rate were compared using Chi-squared tests and event-free survival (EFS) and overall survival (OS) were estimated per the Kaplan-Meier method, using Wilcoxon tests to determine the impact of CD34 status. Of 46 consecutive, newly diagnosed NPM1-positive patients treated between 2008-15, 36 (78%) had normal cytogenetics and 37 (80%) had de novo AML. 26/46 (57%) had CD34+ disease; of these, 18/26 (69%) had FLT3-ITD mutations, compared to 9/20 (45%) with CD34- AML (p=0.10). In the CD34- patients with FLT3-ITD, the mean allelic ratio (mutant to wild type allele) ±SEM was 0.26±.08 compared to 2.3±1.0 in the CD34+ patients (p=0.07). Comparing CD34+ and CD34- patients, there were no significant differences in mean age at diagnosis (52 vs 59), sex, initial hemoglobin, platelet count, or lactate dehydrogenase, but CD34+ patients had significantly higher baseline white blood cell count (mean 78 vs 38 x 103 cells/mm3; p=0.04). There was a trend toward lower CR rates following induction for CD34+ patients (69 vs 89%; p=0.11), and similar proportions of patients underwent bone marrow transplantation (BMT) (50% vs 37%, p=0.38). However, CD34+ patients had significantly shorter EFS (figure 1; median 8.0 vs 34.3 months; p=0.04), and a trend toward inferior OS (15.4 vs 35.4 months; p=0.36). The lack of statistical significance in OS may reflect effective salvage by allogeneic transplantation. In conclusion, in this small retrospective cohort analysis of NPM1-mutated AML patients, CD34 expression was associated with significantly reduced EFS and, among FLT3-ITD mutated patients, a trend toward higher allelic ratios. Hence, CD34 positivity may be an early indicator of poor prognosis in NPM1+ AML and requires further characterization to determine its full prognostic and predictive value in guiding AML therapy. These data support evidence that the biology of AML is not only a function of genetic mutations, but also in part a functionof the stage of hematopoietic differentiation at which the leukemogenic mutations develop. Figure 1 EFS of NPM1-mutated AML patients by CD34 expression. Median follow-up of 23 months. EFS was significantly shorter for CD34+ patients (median 8.0 vs 34.3 months; p=0.01). Figure 1. EFS of NPM1-mutated AML patients by CD34 expression. Median follow-up of 23 months. EFS was significantly shorter for CD34+ patients (median 8.0 vs 34.3 months; p=0.01). Disclosures No relevant conflicts of interest to declare.

The Clinical Characteristics, Genetic Alterations and Prognostic Significance of De Novo Acute Myeloid Leukemia (AML) with Hyperleukocytosis (HL)

IntroductionAcute myeloid leukemia (AML) with hyperleukocytosis (HL), commonly defined as white blood cell (WBC) counts >100,000/uL, are intuitively thought as a unique group with dismal prognosis. However, comprehensive studies regarding the clinical characteristics, genetic alterations in this group of patients are limited, and the role of hematopoietic stem cell transplantation (HSCT) is controversial.MethodA cohort of 755 de novo AML patients diagnosed from 1994 to 2011 who had cryopreserved cells for analysis were enrolled. The mutation status of 18 genes was determined by Sanger sequencing and/or next generation sequencing (NGS). We compared cytogenetics and relevant mutations in these genes between AML patients with and without HL, and exposed their prognostic implications.ResultsThe median age was 54 (range 15-94). 101 (13.4%) patients had HL. HL was associated with younger age (median age 47 vs. 54, P=0.022), higher peripheral blast percentage (77.6% vs. 39%, P<0.0001), and higher lactate dehydrogenase levels (1921.5 U/L vs. 778 U/L, P<0.0001). HL was correlated with French-American-British (FAB) M1, M4 or M5 subtypes, but inversely with M2 or M3 subtypes. The HL patients had more frequently AML with intermediate-risk cytogenetics (85.4 vs. 63.6%, P< 0.0001), but less commonly good-risk (9.3 vs. 21.7%, P=0.004) or poor-risk cytogenetic AML (5.2 vs. 14.6%, P=0.01). Specifically, HL occurred less frequently in core-binding factor AML, or complex karyotype. The most common molecular event in the patients with HL was FLT3/ITD (38.9%), followed by NPM1 (28.7%), CEBPA (26%), NRAS (20.9%), and TET2 (19.4%) mutations. The HL patients had significantly higher incidences of NPM1 (28.7% vs. 18.2%, P=0.013), FLT3/ITD(38.9% vs. 19.1%, P<0.0001), CEBPA (26% vs. 11.1%, P<0.0001), and TET2 (19.4% vs. 9.9%, P=0.006) mutations. In contrast, HL was mutually exclusive with KRAS mutations.Survival analysis was performed on the 525 patients who received standard intensive chemotherapy; among whom 69 patients had HL. The HL patients had lower complete remission (CR) rates compared to those without (63.8% vs. 78.2%, P=0.009). Further, the HL patients had significantly poorer overall survival (OS) and disease-free survival (DFS) than those without (median 24 months vs. not reached (NR), P=0.042; 6.5 vs. 11.8 months, P=0.005, respectively, Figure 1). Older age, poor-risk cytogenetics, RUNX1, TP53 and WT1 mutations were other poor prognostic factors for OS (median, 18.1 months vs. NR, P<0.0001; 8.5 months vs. NR, P<0.0001; 18 months vs. NR, P=0.001; 5.9 months vs. NR, P<0.0001; 14.0 months vs. NR, P=0.006, respectively) and DFS (median, 7.7 vs. 15.2 months, P=0.005; 0 vs. 12,2 months, P<0.0001; 5.2 vs. 12 months, P=0.001; 0 vs. 11.8 months, P<0.0001; 6.5 vs. 12 months, P=0.001, respectively). NPM1+/FLT3-ITD-, and biallelic CEBPA mutations were favourable prognostic factors for both OS and DFS. In the multivariate Cox proportional hazards regression analysis, HL was still an independent poor prognosis factor for OS and DFS (RR, 1.67; 95% CI, 1.15-2.43, P=0.007 and RR, 1.58; 95% CI, 1.12-2.25, P=0.010, respectively). Intriguingly, among the HL patients, those with HSCT had longer OS than those without (58.2 vs 10.7 months, P=0.004, Figure 2). Among the 172 patients receiving allogeneic HSCT, the poor prognostic impact of HL on OS and DFS was lost (P=0.832 and P=0.678, respectively). HSCT could ameliorate the poor survival impact of HL.ConclusionThe HL patients represented 13.4% of our AML cohort and showed distinct clinic features and genetic alterations compared to those without HL. HL was an independent poor prognosis factor irrespective of cytogenetics change or mutation status, and the HL patients may potentially benefit from HSCT. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.