Abstract: Inosine 5'- monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme that catalyzes de novo synthesis of the guanine nucleotide and is overexpressed in both hematologic and solid tumors. FF-10501-01 is a potent new competitive IMPDH inhibitor. We investigated the anti-leukemia effect of FF-10501-01 in a Phase 1 clinical study in advanced AML and MDS, including HMA failures. Previous preclinical studies demonstrated potent anti-proliferative and apoptotic effects of FF-10501-01 on AML cell lines, including HMA-resistant derivatives, through inhibition of de novo guanine nucleotide synthesis. Therefore, we performed a standard 3+3 dose-escalation Phase 1 trial to access the safety and clinical activity of FF-10501-01 in patients with advanced AML, MDS and chronic myelomonocytic leukemia (CMML). Eligibility criteria: age ≥ 18 years, high risk MDS/CMML, AML with documented PD following previous therapy, AML ≥ 60 years of age and not a candidate for other therapy, adequate renal and hepatic function, and no known history of significant cardiac disease. A total of 29 patients, 15M and 14F (23 AML, 6 MDS) have been treated in 7 dose cohorts (50 - 500 mg/m2 PO BID) for 14 days on and 14 days off, and 400 mg/m2 for 21 days on and 7 days off, each 28-day cycle. Median (range) values: age 75 yrs (59 - 88); baseline bone marrow blast counts for AML 34% (12 - 82), for MDS 10% (5 - 16), and overall 30% (5 - 82); and prior treatment regimens 2 (1 - 7). All patients relapsed from, or progressed on, prior HMAs. At baseline, mutations in FLT3, NPM1, GATA2, TET2, ASXL1, DNMT3A, NOTCH1, JAK2, IDH2, PTPN11, KRA, TP53, RUNX1, EZH2 and/or MDM2 were present in 13 of 29 (45%) of patients. Atrial fibrillation (Gr 2) was reported in 2 subjects at a dose of 500 mg/m2 BID. This met the definition of dose-limiting toxicity (DLT) and no further enrollment was made at this dose level. The maximally tolerated dose (MTD) was declared at 1 dose level lower, 400 mg/m2 BID, and this cohort was expanded to 6 subjects. No DLTs have been observed in N=7 total subjects treated at 400 mg/m2 BID x 14 days. FF-10501-01 has been very well tolerated through 24 cycles. The most frequent drug-related AEs have been Gr 1-2 nausea, diarrhea and fatigue. Drug-related thrombocytopenia, neutropenia and bone marrow aplasia (all Gr 4) were reported in 1 patient at 200 mg/m2 BID. The median number of FF-10501-01 cycles received to date is 2 (range 1 - 24). Partial remissions have occurred in 2 AML patients (50 and 100 mg/m2 BID) after 3 cycles, lasting for 5 and 24 cycles, respectively, with the higher dose patient still on study after 24 cycles. A total of 8/23 (34.8%) AML patients, including the 2 PRs, have attained stable disease (SD) control with no disease progression over 3 - 24 cycles. Three AML patients remain on study through 3, 23 and 24 cycles, respectively. A bone marrow complete response was achieved in 1 MDS patient treated at 400 mg/m2 BID after 1 cycle. Although the bone marrow blast counts have increased since, this patient remains stable and is still on therapy through 14 cycles. Three of 6 MDS patients (50%), including the marrow CR, attained SD control with no disease progression over 3, 14 and 14 cycles, and 2 remain on study through 3 and 14 cycles, respectively. FF-10501-01 was rapidly absorbed with mean Tmax of 2.74 hours and mean t1/2 of 4.05 hours. Drug exposure (AUC0-24 and AUCcourse) increased with dose in a near linear manner. Potent suppression of circulating xanthine monophosphate (XMP), a marker of IMPDH activity, has been observed following FF-10501-01 administration on Day 1 of Cycles 1 and 2 at dose levels of 50 mg/m2 BID and above. FF-10501-01 is a promising new agent for the treatment of advanced AML and MDS in patients who have failed or progressed on HMAs and with one or more baseline mutations in pathways known to be affected in AML and MDS. Preclinical activity was seen in multiple leukemia cell lines, including HMA-resistant derivatives. In a Phase 1 trial, clinical activity with a marrow CR, PRs, long-term disease stabilization (≥ 5 cycles) and a highly tolerable safety profile were observed. The Phase 2a expansion phase of the study is soon to begin. Disclosures DiNardo: Agios: Research Funding; Daiichi Sankyo: Research Funding; Celgene: Research Funding; Novartis: Research Funding; Abbvie: Research Funding. Jabbour:ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Daver:BMS: Research Funding; Kiromic: Research Funding; Pfizer: Consultancy, Research Funding; Otsuka: Consultancy, Honoraria; Ariad: Research Funding; Karyopharm: Honoraria, Research Funding; Sunesis: Consultancy, Research Funding. Denton:Westat Corporation: Employment. Smith:Westat Corporation: Employment. Tiefenwerth:Westat Corporation: Employment. Iwamura:FUJIFILM Corporation: Employment. Gipson:Strategia Therapeutics, Inc.: Employment. Rosner:Strategia Therapeutics, Inc.: Employment. Myers:Strategia Therapeutics, Inc.: Employment. Paradiso:Strategia Therapeutics, Inc.: Employment.

Abstract: Background: Treatment with HMAs such as azacitidine and decitabine has changed the overall outcome of patients with MDS. Failure to respond to or relapse from HMA treatment is associated with poor prognosis without further approved therapy. Clofarabine is a second-generation nucleoside analog with single-agent activity in MDS. Aim: This is a phase II trial to evaluate the safety and activity of the combination of clofarabine and low-dose cytarabine in the treatment of patients with high-risk MDS who failed prior HMA therapy. Materials and Methods: Eligible patients were adults older than 18 years with MDS who had no response, progressed, or relapsed following at least 4 cycles of therapy with either azacitidine and/or decitabine and an ECOG performance status of ≤ 2 at the time of study entry. Responses were defined according to IWG 2006 criteria. Induction therapy consisted of clofarabine 15 mg/m2 IV daily for 5 days (days 1-5) and cytarabine 20 mg SC twice daily for 7 days (days 1-7). Responding patients proceeded with consolidation therapy with clofarabine 15 mg/m2 IV daily for 3 days (days 1-3) and cytarabine 20 mg SC twice daily for 5 days (days 1-5) every 4 weeks for a maximum of 12 cycles. Overall survival (OS) was defined as the time between the date of the first dose of clofarabine and the date of death from any cause. Univariate (UVA) and multivariate analysis (MVA) related to response and survival were performed with Cox regression analysis. Results: Between January 2012 and December 2013, 56 patients were enrolled. Fifty-two patients were evaluable for response (4 patients had not been on-study long enough to evaluate). The median follow-up is 15.3 months (range, 1.2-27.7+), and the median age at enrollment was 71 years (31-83). Ten patients (19%) had prior chemotherapy and 12 (23%) had prior radiation therapy. Median bone marrow blast percentage was 15% (6-30%). Three patients (6%) had CMML-1, 4 (8%) had CMML-2, 7 (14%) had RAEB-1, 19 (37%) had RAEB-2, and 19 (37%) had RAEB-T. Eight (15%) patients had intermediate-1 risk, 23 (44%) had intermediate-2 risk, and 21 (40%) had poor risk by IPSS. By IPSS cytogenetic risk, 25 patients (48%) had low-risk cytogenetics, 15 (29%) had intermediate-risk, and 12 (23%) had high-risk. Mutational analysis detected 2 (4%) FLT3-ITD, 0 FLT3-D835, 7 (13%) RAS, 2 (4%) NPM1, and 2 (4%) JAK2 mutations. Thirty-nine patients (75%) received prior azacitidine therapy and 15 (29%) received prior decitabine therapy. The overall response rate (ORR) was 48% (9 [17%] achieved complete remission [CR] , 3 [6%] complete remission with incomplete platelet recovery [CRp] , 7 [13%] marrow CR, and 6 [12%] had stable disease with hematological improvement), and median duration of response was 12.0 months (range, 2.0-26.7+). Five patients (10%) went on to receive allogeneic stem cell transplantation. Of the 25 patients with low-risk cytogenetics, 16 (64%) achieved OIR, 5 (20%) CR, 3 (12%) CRp, 6 (24%) mCR, and 2 (8%) HI. Of the 15 patients with intermediate-risk cytogenetics, 5 (33%) had OIR, 4 (27%) CR, and 1 (4%) mCR. Of 12 patients with high-risk cytogenetics, 2 (17%) had OIR, 1 (8%), CR, and 1 (8%) HI. Median OS was 6.8 months (range, 0.4-27.7+). The median OS in patients with response and those without response was 〉 12.4 months (range, 3.5-27.7+) and 3.4 months (range, 0.4-16.1), respectively. Most toxicities were of grade ≤ 2 and included elevated liver enzymes in 41% of patients, elevated bilirubin in 38%, rash in 28%, nausea in 31%, headache in 24%, and febrile neutropenia in 28%. Grade ≥ 3 toxicities included elevated liver enzymes (3%) and elevated bilirubin (3%). 21 (40%) patients had clofarabine dose reduction after a median of 2 courses (range, 1-8). UVA and MVA for survival identified performance status ≥2 (p=0.002; HR, 4.860; 95%CI, 1.784-13.244), stable disease or progressive disease after clofarabine (p 〈 0.001; HR, 8.372; 95%CI, 3.233-21.677), thrombocytopenia 〈 30 (/109L) (p=0.001; HR, 3.659; 95%CI 1.682-7.958), and complex cytogenetics (UVA, p 〈 0.001; MVA, p= 0.110, HR, 2.329; 95%CI 0.826-6.564) as prognostic factors for poorer OS. Conclusion: The combination of clofarabine and low-dose cytarabine has an ORR of 48% in patients with MDS who failed prior therapy with HMA. The study continues to accrue, and updated results with longer follow up will be presented at the meeting. Disclosures Daver: Novartis: Research Funding. Kadia:GSK: Research Funding; ARIAD: Honoraria. Borthakur:Tetralogic Pharmaceuticals: Research Funding. O'Brien:Amgen, Celgene, GSK: Consultancy; CLL Global Research Foundation: Membership on an entity's Board of Directors or advisory committees; Emergent, Genentech, Gilead, Infinity, Pharmacyclics, Spectrum: Consultancy, Research Funding; MorphoSys, Acerta, TG Therapeutics: Research Funding. Kantarjian:ARIAD: Research Funding; Pfizer: Research Funding; Amgen: Research Funding. Garcia-Manero:Epizyme, Inc: Research Funding.

Abstract: INTRODUCTION: Frequency of NPM1 mutations in patients with myelodysplastic syndromes (MDS) is 〈 1%. Patients with acute myeloid leukemia and NPM1 mutations have favorable outcomes and high complete response (CR) rate with chemotherapy. In this study we analyzed the characteristics and clinical outcomes of patients with MDS and NPM1 mutations. METHODS: We analyzed the clinical characteristics of all patients with MDS and NPM1mut treated at MD Anderson Cancer Center from 2009 until 2016. Detection of exon 12 NPM1 mutations (W288fs*12) was performed by Sanger sequencing from 2009 until 2012 and by a 28 or 53 gene panel PCR-based next generation sequencing platform from 2012 to 2016. All clinical and demographic characteristics were obtained from clinical records. Response was defined following 2006 IWG criteria. The Kaplan-Meir product limit method was used to estimate the median overall survival (OS) and leukemia-free survival (LFS). Univariate Cox proportional hazards were used to identify association between variables and outcomes. RESULTS: A total of 22 patients with MDS had detectable W288fs*12 NPM1 mutations. Patient characteristics are detailed in Table 1. Median age was 58 years (range 19-86). Thirteen (59%) patients were classified as Int-1 and 9 (41%) as Int-2 by IPSS. Two (9%) patients had CMML and the remaining had MDS. Nineteen (82%) patients had normal karyotype. All patients had available FLT3, NRAS and KIT mutational evaluation with an additional 2 (9%) patients having sequencing data on 28 genes and 11 (50%) on 53 genes. A total of 2 (9%) patients had co-occurring FLT3-ITD mutations and 1 (4.5%) had a co-occurring FLT3 D835 mutation. Other detectable mutations included NRAS in 6/22 (27%) patients, DNMT3A and WT1 in 4/13 (31%), PTPN11, TET2 and IDH2 in 2/13 (15%) and RUNX1 and IDH1 in 1/13 (8%). A total of 15 (68%) patients were treated with azacitidine or decitabine based therapy, 6 (27%) with intensive chemotherapy and 1 (4.5%) with lenalidomide. Patients treated with chemotherapy tended to be younger (44 vs 62 years, p=0.023) and have higher bone marrow blasts (14% vs 8%, p=0.018). Seven (33%) patients underwent allogeneic stem-cell transplantation: 4 of the treated with chemotherapy and 3 of the patients treated with hypomethylating agents (p=0.12). Patients treated with chemotherapy had higher overall response rates (100% vs 38%, p=0.015) and complete response rates (84% vs 13%, OR 32.5, 95% CI 2.38-443.14, p=0.006) than patients treated with hypomethylating agents. A total of 6 patients had transformation to AML. Median follow up was 10 months (range 1-115). Median OS of all the population was not reached at current follow up. Median leukemia-free survival (LFS) was not reached at current follow up. Chemotherapy was associated with a trend to improved OS compared with hypomethylating agents (NR vs 58 months, p=0.086) as shown in Figure 1A. Allogeneic stem-cell transplant was associated with improved OS irrespective of treatment (NR vs 58 months, p=0.034) as shown in Figure 1B. By univariate analysis, presence of either FLT3-ITD or D835 mutation was associated with shorter median OS (6.9 vs 115.9 months, HR = 7.42, 95% CI: 1.03-53.45, p=0.047). No other mutations were found to significantly impact outcome. CONCLUSIONS: NPM1 mutations are extremely rare in the context of MDS and tend to appear in younger patients with excess blasts and normal karyotype. Our results suggest treatment of this subset of patients with AML-type chemotherapy followed by stem-cell transplantation could be associated with improved outcomes. Confirmation in larger studies is required. Table 1 Table 1. Figure 1 Figure 1. Disclosures Jabbour: ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. DiNardo:Novartis: Research Funding; Celgene: Research Funding; Abbvie: Research Funding; Agios: Research Funding; Daiichi Sankyo: Research Funding. Konopleva:Calithera: Research Funding; Cellectis: Research Funding.

Abstract: Background Treatment with hypomethylating agents (HMA) such as azacitidine and decitabine has changed the overall outcome of patients with MDS. Failure to responed to or relapse from treatment with HMA carries a poor outcome and no approved therapy for these patients exists. Clofarabine is a second generation nucleoside analog with single agent activity in MDS. Aim This is a phase II trial to evaluate the safety and activity of the combination of clofarabine and low dose cytarabine in the treatment of patients with high risk MDS who failed prior HMA therapy. Material and Method Eligible were adults older than 18 years with MDS who have had no response, progressed, or relapsed following at least 4 cycles of therapy with either azacitidine and/or decitabine. Patients were required to have an ECOG performance status of 〈 /=2 at the time of study entry. Responses were defined according to IWG 2006 criteria. Induction therapy consisted of clofarabine 15 mg/m2 IV daily X 5 days (days 1-5) and cytarabine 20 mg SC twice daily X 7 days (days 1-7). Patients could receive up to 3 induction cycles as long as they tolerated the therapy and had stable disease. Responding patients proceeded with consolidation therapy with clofarabine 15 mg/m2IV daily X 3 days (days 1-3) and cytarabine 20 mg SC twice daily X 5 days (days 1-5) for a maximum of 12 cycles. Cycles were repeated every 4 to 8 weeks depending on hematopoietic recovery and resolution of toxicities. Results Between January 2012 and March 2013, 29 patients were enrolled. The clinical characteristics are summarized in Table 1. Twenty four patients were evaluable for response (5 patients were too early for response). The overall response rate (ORR) was 50% (8 [33%] achieved complete remission (CR)/ complete remission with incomplete platelets recovery (CRp)/marrow CR, and 4 [17%] had stable disease with hematological improvement). With a median follow up of 4.9 months (range, 1.9-16.7), the median overall survival (OS) was 4.8 months (range, 0.5-13.5). Most toxicities were grade 〈 /= 2 and included: elevated liver enzymes in 41% of the patients, elevated bilirubin (38%), rash (28%), nausea (31%), headache (24%), and febrile neutropenia (28%). Grade 〉 /= 3 toxicities included: elevated liver enzymes (3%) and elevated bilirubin (3%). Four-week mortality was 12%. Conclusion The combination of clofarabine and low-dose cytarabine has an ORR of 50% in patients with MDS who failed prior therapy with HMA. The study continues to accrue and updated results with longer follow up will be presented at the meeting. Disclosures: Off Label Use: Clofarabine use in MDS. Faderl:Sanofi-Aventis: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Research Funding.

Abstract: Background: Nilotinib is a BCR-ABL tyrosine kinase inhibitor with approximately 50-fold higher inhibitory activity than imatinib in preclinical studies. Aim: We initiated a phase II study (in 2005) to evaluate the efficacy of frontline nilotinib in pts with newly diagnosed CML-CP. The primary objective of this report was to estimate major molecular response (MMR) and complete molecular response (CMR: minimum 100,000 ABL copies) rates with prolonged follow-up, and the impact of MMR and CMR on long-term outcome. Methods: Pts with Ph-positive or BCR-positive CML in early CML-CP [i.e., time from diagnosis 12 months] with 〈 1 month of prior interferon-alpha and/or imatinib were eligible. Nilotinib was initiated at a dose of 400 mg twice daily. Results for CCyR and MMR are reported as intent-to-treat unless specifically annotated as response among evaluable pts (eval). Results: 140 pts have been treated as of August 1, 2014. Herein we focus on the initial 109 pts who have a minimum follow-up of 12 months. The median (med) follow-up for these 109 pts is 52.2 months (range, 0.9 to 108.0+). The med age was 50 years (range, 17 to 86). 73% of pts had Sokal low risk. 17 (16%) had received imatinib for 〈 1 months (med 18 days; range, 5 to 29 days). Overall, 92% (100/109) pts achieved a complete cytogenetic response [CCyR] with a med time to CCyR of 2.9 months (range, 2.1 to 8.1+). The rates of CCyR at 3, 6, 12 and 18 months were 80% (eval:83%), 86% (eval:95%), 83% (eval:99%), and 77% (eval:100%), respectively. Overall, MMR and CMR were achieved in 90% (98/109) and 45% (49/109) of the pts. Med time to MMR and CMR was 3.3 months (range, 2.4 to 48.0+) and 23.1 months (range, 3.2 to 86.0+), respectively. BCR-ABL/ABL at 3 months was 〈 10% in 94% (eval:100%) and 〈 1% in 89% (eval: 94%). BCR-ABL/ABL at 6 months was 〈 1% in 81% (eval:89%) and 〈 0.1% in 65% (eval:72%) in pts evaluated at these time points. MMR was observed in 65% (eval:72%) at 6 months, 71% (eval:87%) at 12 months, and 70% (eval:90%) at 18 months. CMR was observed in 9% (eval:11%) at 6 months, 14% (eval:17%) at 12 months, and 15% (eval:19%) at 18 months. We further analyzed the association between CCyR and molecular response (Table 1). For example, among the 84 pts who were in CCyR at 18 months: MMR was achieved in 90% of these pts including MR3 in 31%, MR4 in 13%, MR4.5 in 27%, and CMR in 19%. Estimated 3-year and 5-year overall survival (OS) is 98% and 91%, respectively. Estimated 3-year and 5-year failure-free survival (FFS) is 82% and 73%, respectively. On an intent-to-treat analysis the FFS among pts who achieved CMR was superior to those who did not achieve CMR (P 〈 0.001, respectively). On a landmark analysis, which included only those pts who received nilotinib for a minimum of 24 months (med time to CMR among pts who achieved CMR=23.1 months) the FFS among pts who achieved CMR was superior to those who did not achieve CMR (P=0.008) (Figure 1). Dose-reductions were performed in 41 (38%) pts: 30 pts required 1 dose-reduction and 11 pts required 2 or more dose-reductions. The most frequent reasons for dose-reductions included increased liver enzymes (n=8), rash (n=5), pain/arthralgia (n=4), cardiac and QTc (n=4), fatigue (n=5), and neutropenia (n=2). The actual med dose remains 800 mg daily. 29 (27%) pts are off study due to toxicity in 8 (cardiac=3, liver enzymes=4, fatigue=1), inadequate response in 5 (3 never achieved adequate and 2 lost adequate response), progression to blast-phase in 3, death in 5 (all 5 non-CML related causes), 8 due to pt choice (financial=1, non-compliance=3, pt choice=1) Conclusion: Nilotinib 400 mg twice daily is very effective. The cumulative rates of CCyR, MMR and CMR were 92%, 90%, and 45%, respectively. CMR rates continue to improve with long-term follow-up. Attainment of CMR is associated with improved long-term outcome. Table 1: Molecular response rates among pts who achieve CCyR CCyR MR3 but not MR4 MR4 but not MR4.5 MR4.5 but not CMR CMR No MMR 3 months 87/105 (83%) 39/87 (45%) 5/87 (6%) 8/87 (9%) 2/87 (2%) 33/87 (38%) 6 months 94/99 (88%) 35/94 (38%) 6/94 (6%) 20/94 (21%) 10/94 (11%) 23/94 (24%) 12 months 90/91 (99%) 38/90 (42%) 3/90 (3%) 23/90 (26%) 15/90 (17%) 11/90 (12%) 18 months 84/84 (100%) 26/84 (31%) 11/84 (13%) 23/84 (27%) 16/84 (19%) 8/84 (10%) PCyr, partial cytogenetic response; Min, mimimal; Inev, inevaluable; IM, insufficient metaphase Figure 1: FFS CMR versus no CMR by landmark analysis for pts who received at least 24.0 months of nilotinib Figure 1:. FFS CMR versus no CMR by landmark analysis for pts who received at least 24.0 months of nilotinib Disclosures Daver: Novartis: Research Funding. Jabbour:Novartis: Advisory board membership Other, Research Funding. Cortes:Novartis: Advisory Board membership Other, Research Funding.

Abstract: Background: Acute myeloid leukemia (AML) remains a therapeutic challenge in elderly or unfit patients (pts) and high-risk subgroups. DEC10-VEN has shown high efficacy in these pts. However, outcomes in specific mutational subgroups are unknown. Here we present the results in mutational subgroups and resistance patterns in pts treated with DEC10-VEN (NCT03404193). Methods: This single-institution phase II study enrolled pts with newly diagnosed (ND) AML ( & gt;60 years) ineligible for intensive chemotherapy, relapsed or refractory (R/R) AML, and secondary AML (sAML) with or without prior therapy. DEC was given 20 mg/m2 IV daily on day 1-10 until CR/CRi, followed by 5-day cycles. VEN was given for 21-28 days in cycle 1 and day 1-21 or shorter duration thereafter. BCR-ABL1 and FLT3 inhibitors (FLT3i) were allowed as appropriate. Amplicon-based next-generation sequencing targeting the entire coding regions of 81 myeloid genes was performed on screening bone marrow aspirate with a MiSeq platform. The analytical sensitivity was established at 5% mutant reads in a background of wild type reads. Previously described somatic mutations registered in COSMIC were considered as potential driver mutations. Results: High response rates were noted across mutational subgroups of both previously untreated and previously treated AML (Table 1 and 2). The median follow-up for the entire cohort was 8.1 months (mo). In previously untreated AML (ND AML and untreated sAML, n=49), the CR/CRi rate in NPM1mut pts was 100% (n=13), in RUNX1mut pts was 100% (n=8), in IDH1/2mut pts was 92% (n=12), in TP53mut pts was 85% (n=13), and in N/KRASmut pts was 77% (n=13, Table 1). The median overall survival (OS) among previously untreated NPM1mut pts was not reached (NR), for RUNX1mut pts was NR, for IDH1/2mut pts was 12.4 mo, for TP53mut pts was 5.8 mo, and for N/KRASmut was 12.4 mo. The median DOR for NPM1mut pts was 8.5 mo, for RUNX1mut pts was NR, for IDH1/2mut pts was NR, for TP53mut pts was 5.7 mo, and for N/KRASmut pts was 6.7 mo (Table 1). The one pt with NPM1mut who relapsed had co-occurring ASXL1mut and NRASmut at screening. In previously treated AML (treated sAML and R/R AML, n=52), the CR/CRi rate in NPM1mut pts was 60% (n=10), in IDH1/2mut pts was 50% (n=8), and in TP53mut pts was 21% (n=14, Table 2). The median OS for NPM1mut pts was NR, for IDH1/2mut pts was 7.8 mo, and for TP53mut pts was 4.5 mo. The median DOR for NPM1mut pts was NR, for IDH1/2mut pts was NR, and for TP53mut pts was 3.2 mo (Table 2). The only grade 4 TLS event occurred in a pt with NPM1mut and IDH2mut and baseline WBC of 28x109/L. 2 other pts with high % of PB blasts and FLT3mut experienced grade 3 TLS. Among 15 pts with FLT3-ITD/TKD, 8 pts received sorafenib, 5 pts received midostaurin, and 2 pts did not receive FLT3i (1 insurance non-approval and 1 very low ITD ratio). Among ND FLT3mut AML pts (n=7), the CR/CRi rate was 100% (n=5) in pts receiving FLT3i with negative MRD by flow cytometry (FCM) in 80% pts, with median OS of 8.8 mo and median DOR not reached (Table 1). Of the 2 FLT3-ITD pts not receiving FLT3i, 1 pt with FLT3-ITD of 0.47 did not respond, and 1 pt with low FLT3-ITD of 0.02 achieved CR MRD-. Among previously treated FLT3mut pts (n=8), all received FLT3i with a CR/CRi rate of 38% (n=5) and negative MRD by FCM in 75% pts tested (3/4). The median OS was 6.4 mo and the median DOR was 6.6 mo (Table 2). 2 pts had received prior FLT3i, 1 pt achieved morphologic leukemia-free state (MLFS), and the other pt did not respond. 1 pt with new t(9;22) identified at 4th relapse achieved a MLFS after 1 cycle with addition of ponatinib and transitioned to allogeneic transplant. Overall, pts with durable CR/CRi/MLFS sustained without relapse till data cut-off, had significantly higher proportion of mutations in NPM1 and DNA methylation pathways (DNMT3A, TET2, IDH1/2) compared to pts refractory to, or relapsing after DEC10-VEN (Table 3, Fig. 1). Pts with relapsed or refractory disease to DEC10-VEN had significantly higher frequency of N/KRASmut, ASXL1mut, and TP53mut compared to pts with durable CR/CRi/MLFS (Table 3, Fig. 1). TP53mut associated with worse OS on multivariable analysis (HR 2.9, 95% CI 1.4-5.7, p=0.003). Conclusion: DEC10-VEN is an effective regimen for AML. Addition of FLT3i to DEC10-VEN was safe and may improve upon responses in FLT3mut pts. Mutations in NPM1 and DNA methylation pathways were associated with more durable responses while mutations in ASXL1, RAS and TP53 were associated with refractory disease or relapse. Disclosures Maiti: Celgene: Other: research funding. Cortes:BiolineRx: Consultancy; Forma Therapeutics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Sun Pharma: Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Merus: Consultancy, Honoraria, Research Funding; Biopath Holdings: Consultancy, Honoraria. Pemmaraju:samus: Research Funding; celgene: Consultancy, Honoraria; abbvie: Consultancy, Honoraria, Research Funding; incyte: Consultancy, Research Funding; mustangbio: Consultancy, Research Funding; cellectis: Research Funding; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; novartis: Consultancy, Research Funding; plexxikon: Research Funding; Daiichi-Sankyo: Research Funding; sagerstrong: Research Funding; affymetrix: Research Funding. Daver:Servier: Research Funding; Agios: Consultancy; Abbvie: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Agios: Consultancy; Celgene: Consultancy; Hanmi Pharm Co., Ltd.: Research Funding; Forty-Seven: Consultancy; Forty-Seven: Consultancy; Immunogen: Consultancy, Research Funding; Immunogen: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Astellas: Consultancy; BMS: Consultancy, Research Funding; Astellas: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz: Consultancy; Jazz: Consultancy; NOHLA: Research Funding; Karyopharm: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Servier: Research Funding; Genentech: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Karyopharm: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Glycomimetics: Research Funding; Sunesis: Consultancy, Research Funding; Otsuka: Consultancy; NOHLA: Research Funding; Celgene: Consultancy; Otsuka: Consultancy; Glycomimetics: Research Funding; Novartis: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Hanmi Pharm Co., Ltd.: Research Funding; Pfizer: Consultancy, Research Funding. Ravandi:Cyclacel LTD: Research Funding; Macrogenix: Consultancy, Research Funding; Xencor: Consultancy, Research Funding; Menarini Ricerche: Research Funding; Selvita: Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Garcia-Manero:Amphivena: Consultancy, Research Funding; Helsinn: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Celgene: Consultancy, Research Funding; Astex: Consultancy, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Merck: Research Funding. Borthakur:Cyclacel: Research Funding; AbbVie: Research Funding; Eli Lilly and Co.: Research Funding; Xbiotech USA: Research Funding; Merck: Research Funding; Bayer Healthcare AG: Research Funding; Agensys: Research Funding; Janssen: Research Funding; NKarta: Consultancy; BioTheryX: Membership on an entity's Board of Directors or advisory committees; Arvinas: Research Funding; Incyte: Research Funding; Tetralogic Pharmaceuticals: Research Funding; Strategia Therapeutics: Research Funding; Oncoceutics: Research Funding; BioLine Rx: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncoceutics, Inc.: Research Funding; GSK: Research Funding; BMS: Research Funding; Cantargia AB: Research Funding; FTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Argenx: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Consultancy; Novartis: Research Funding; Eisai: Research Funding; Polaris: Research Funding; AstraZeneca: Research Funding. Short:Takeda Oncology: Consultancy, Research Funding; AstraZeneca: Consultancy; Amgen: Honoraria. Alvarado:Jazz Pharmaceuticals: Research Funding; Abbott: Honoraria. Kadia:AbbVie: Consultancy, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Bioline RX: Research Funding; BMS: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Takahashi:Symbio Pharmaceuticals: Consultancy. Jain:Janssen Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, an AbbVie company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Verastem: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Biosciences: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Sasaki:Otsuka: Honoraria; Pfizer: Consultancy. Andreeff:NIH/NCI: Research Funding; CPRIT: Research Funding; Breast Cancer Research Foundation: Research Funding; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eutropics: Equity Ownership; Aptose: Equity Ownership; Reata: Equity Ownership; 6 Dimensions Capital: Consultancy; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; AstaZeneca: Consultancy; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Cancer UK: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; BiolineRx: Membership on an entity's Board of Directors or advisory committees. Bose:CTI BioPharma: Research Funding; Promedior: Research Funding; NS Pharma: Research Funding; Incyte Corporation: Consultancy, Research Funding, Speakers Bureau; Celgene Corporation: Consultancy, Research Funding; Blueprint Medicine Corporation: Consultancy, Research Funding; Kartos: Consultancy, Research Funding; Constellation: Research Funding; Pfizer: Research Funding; Astellas: Research Funding. Jabbour:Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Cyclacel LTD: Research Funding; BMS: Consultancy, Research Funding. Thompson:AbbVie: Research Funding; Amgen: Consultancy, Research Funding; Pfizer: Research Funding; Pharmacyclics: Research Funding; Genentech: Consultancy, Honoraria; Gilead: Consultancy, Honoraria. Zhang:The University of Texas M.D.Anderson Cancer Center: Employment. Kantarjian:Daiichi-Sankyo: Research Funding; BMS: Research Funding; Cyclacel: Research Funding; Ariad: Research Funding; AbbVie: Honoraria, Research Funding; Takeda: Honoraria; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Jazz Pharma: Research Funding; Immunogen: Research Funding; Amgen: Honoraria, Research Funding; Astex: Research Funding; Agios: Honoraria, Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees. Konopleva:Genentech: Honoraria, Research Funding; Ascentage: Research Funding; Kisoji: Consultancy, Honoraria; Reata Pharmaceuticals: Equity Ownership, Patents & Royalties; Ablynx: Research Funding; Astra Zeneca: Research Funding; Eli Lilly: Research Funding; Cellectis: Research Funding; Amgen: Consultancy, Honoraria; F. Hoffman La-Roche: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Forty-Seven: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Agios: Research Funding. DiNardo:agios: Consultancy, Honoraria; medimmune: Honoraria; notable labs: Membership on an entity's Board of Directors or advisory committees; syros: Honoraria; jazz: Honoraria; abbvie: Consultancy, Honoraria; celgene: Consultancy, Honoraria; daiichi sankyo: Honoraria. OffLabel Disclosure: FLT3 inhibitors, used in combination with decitabine and venetoclax

Abstract: INTRODUCTION: Mutations in TP53 can be detected in up to 16-19% patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). TP53 mutations confer adverse prognosis irrespective of currently available therapies. The clinical impact of the type, clonality and number of TP53 abnormalities is unclear. Preclinical data suggests some TP53 mutations may be associated with additional transactivation activity and increased oncogenicity. METHODS: We evaluated 1401 patients with previously untreated AML or MDS treated at The University of Texas MD Anderson Cancer Center from 2012 to 2016. Sequencing data was obtained by use of a 28 or 53-gene targeted PCR-based next generation sequencing platform. The following mutations in TP53 where defined as GOF based on available in vitro data: R172H, R175H, R270H, G245S, R248W, G248Q and R273H. Response was defined following 2003 IWG criteria for patients with AML and 2006 revised IWG criteria for patients with MDS. Generalized linear models were used to study the association of overall response (OR), complete response (CR) and risk factors. Kaplan-Meier produce limit method was used to estimate the median overall survival (OS). RESULTS: A total of 593 (42%) patients had MDS and 808 (56%) had AML. In a total of 984 (70%) patients, data on therapy with sufficient follow up and response evaluation was available, with 494 (35%) patients receiving therapy with hypomethylating agents (HMAs) and 373 (27%) with chemotherapy regimens. Among evaluated MDS pts, based on the Revised-IPSS prognostic model, 62 (11%) had very-low risk, 149 (25%) had low, 121 (20%) intermediate, 109 (18%) high and 152 (26%) very-high risk. A total of 167 (28%) pts with MDS and 223 (26%) pts with AML had complex karyotype. A total of 405 mutations in TP53 were detected among 151 (26%) and 161 (20%) patients with MDS and AML, respectively. Mutations included 332 (82%) missense, 26 (6%) nonsense, 34 (8%) frameshift insertions or deletions and 13 (3%) splice-site mutations. The most prevalent mutation was R273H (MDS: n=10, AML: n=9) followed by R248W (MDS: n=8, AML: n=8), Y220C (MDS: n=7, AML: n=8) and R175H (MDS: n=7, AML: n=6). Median variant allele frequency (VAF) of TP53 mutations was 39% (range 1-94). Among patients with TP53-mutant disease: 1 TP53 mutation was identified in 105 (70%) and 126 (78%) MDS and AML pts respectively, 2 in 44 (29%) and 34 (21%) and 3 in 2 (1%) and 1 (1%) respectively. The median difference in VAF among detectable mutations in pts with 2 TP53 mutations was 3.9% [95% CI 4.9-14%]. Among double TP53-mutant pts, known GOF mutations where always found in association with a LOF mutation with no pts having 2 detectable GOF mutations. Additionally, 66 (11%) MDS and 105 (13%) AML patients had TP53 deletions evidenced by presence of monosomy 17 or del(17p). Presence of a TP53 mutation was associated with loss of TP53 locus by cytogenetic abnormality (r=0.492, p 〈 0.001). However, patients with multiple detectable TP53 mutations were less likely to have co-occurring chr17 abnormalities (79% vs 21%, OR 0.48, CI 0.29-0.81, p=0.01). Sequential bone marrow sequencing through the course of disease evolution was available in 75 pts. Dynamics of TP53 VAF at time or response and subsequent relapse in evaluable pts is shown in Figure A. Median follow up was 10.4 months (range 0-167 months) for MDS pts and 7.8 months (range 0-50) in AML pts. Presence of TP53 mutations with high VAF (defined as VAF 〉 median VAF) was associated with significantly worse median OS (Figure B). Presence of more than 1 TP53 abnormality was not associated with worse OS, LFS or PFS in pts with MDS but predicted for shorter OS in pts with AML (Figure C). In addition, GOF were associated with worse OS than LOF mutations in pts with AML (Figure D), but not in MDS. Presence and number of TP53 mutations did not predict for response to HMAs. In addition, clearance of mutation at the time of response was associated with improved OS (HR 0.26, 95% CI 0.08-0.78, p=0.016). CONCLUSION: Presence of multiple TP53 abnormalities can be observed in up to 13% of patients with MDS or AML. The number of TP53 abnormalities does not seem to affect the survival of patients with MDS, but is associated with worse OS in AML. In addition, although GOF mutations do not seem to affect outcome of pts with MDS, these mutations were associated with worse OS than LOF in pts with AML. Clonal size of TP53 mutations as well as their clearance in therapy correlate with survival outcomes. Figure Figure. Disclosures Sasaki: Otsuka Pharmaceutical: Honoraria. Kadia:Jazz: Consultancy, Research Funding; Jazz: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Celgene: Research Funding; Amgen: Consultancy, Research Funding; Novartis: Consultancy; Abbvie: Consultancy; Pfizer: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Abbvie: Consultancy; Takeda: Consultancy; Novartis: Consultancy; BMS: Research Funding; BMS: Research Funding; Celgene: Research Funding; Takeda: Consultancy. Ravandi:Astellas Pharmaceuticals: Consultancy, Honoraria; Abbvie: Research Funding; Jazz: Honoraria; Abbvie: Research Funding; Bristol-Myers Squibb: Research Funding; Jazz: Honoraria; Macrogenix: Honoraria, Research Funding; Sunesis: Honoraria; Sunesis: Honoraria; Orsenix: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Research Funding; Macrogenix: Honoraria, Research Funding; Bristol-Myers Squibb: Research Funding; Astellas Pharmaceuticals: Consultancy, Honoraria; Xencor: Research Funding; Orsenix: Honoraria; Xencor: Research Funding. Cortes:novartis: Research Funding. Daver:Novartis: Research Funding; Incyte: Consultancy; Karyopharm: Research Funding; Pfizer: Consultancy; ImmunoGen: Consultancy; Daiichi-Sankyo: Research Funding; Otsuka: Consultancy; BMS: Research Funding; Sunesis: Research Funding; Sunesis: Consultancy; Alexion: Consultancy; Novartis: Consultancy; Incyte: Research Funding; Kiromic: Research Funding; ARIAD: Research Funding; Karyopharm: Consultancy; Pfizer: Research Funding. DiNardo:Karyopharm: Honoraria; Medimmune: Honoraria; Bayer: Honoraria; Celgene: Honoraria; Agios: Consultancy; Abbvie: Honoraria. Jabbour:novartis: Research Funding. Pemmaraju:daiichi sankyo: Research Funding; samus: Research Funding; cellectis: Research Funding; abbvie: Research Funding; stemline: Consultancy, Honoraria, Research Funding; Affymetrix: Research Funding; novartis: Research Funding; plexxikon: Research Funding; celgene: Consultancy, Honoraria; SagerStrong Foundation: Research Funding. Konopleva:cellectis: Research Funding; Immunogen: Research Funding; Stemline Therapeutics: Research Funding; abbvie: Research Funding. Colla:Abbvie: Research Funding. Andreeff:Eutropics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy; Aptose: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Patents & Royalties: MDM2 inhibitor activity patent, Research Funding; United Therapeutics: Patents & Royalties: GD2 inhibition in breast cancer ; Reata: Equity Ownership; Celgene: Consultancy; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Research Funding; Amgen: Consultancy, Research Funding; SentiBio: Equity Ownership.

Abstract: Introduction: Dasatinib monotherapy has demonstrated clinical activity in CML-LBC, however with limited duration of response and median overall survival (OS) & lt;6 months (mos) (Cortes et al 2008 Leukemia). Outcome of Ph-positive ALL has dramatically improved with hyper-CVAD (HCVAD) in combination with tyrosine kinase inhibitors (TKIs, Ravandi et al Cancer 2015). The aim of this study is to report on the outcome of patients (pts) with CML-LBC who received HCVAD plus dasatinib (HCVAD+Dasa) therapy, and compare it with the outcome of pts with Ph-positive ALL who received the same therapy. Methods: We reviewed 81 pts (CML-LBC, N=19 and newly diagnosed Ph-positive ALL, N=62) who were treated with HCVAD+Dasa at our institution between 9/2006 and 3/2016. De novo CML-LBC cases without prior CML or relapsed CML-LBC cases were excluded. HCVAD+Dasa therapy consisted of 4 alternating cycles of HCVAD and high-dose methotrexate (MTX) / cytarabine (AraC) with 8 intrathecal injections of MTX/AraC. Dasa was administered 100mg daily on days 1-14 for course 1, and 70mg daily on courses 2 and onwards. The maintenance phase consisted of vincristine and steroids in addition to Dasa. Pts with CD20-positive disease received additional rituximab. Allogeneic stem cell transplant (allo-SCT) was offered at physician's discretion if matched donor was available. Complete cytogenetic remission (CCyR) was defined as the absence of Ph by karyotyping. Major molecular response (MMR) was defined as BCR-ABL1 transcripts & lt;0.1%, and complete molecular response (CMR) as the absence of BCR-ABL1 transcripts with a sensitivity of 0.01%. OS was calculated from the start date of treatment to the date of death, or last follow-up. Progression-free survival (PFS) was calculated from the start date of treatment to the date of disease progression, or last follow-up. Results: Among pts with CML-LBC, median age was 49 years (yrs) (range, 26-76). Initial CML diagnosis was as chronic phase (N=17, 89%), accelerated phase (N=1, 5%), or myeloid blast phase (N=1, 5%). Median time from initial CML diagnosis to LBC was 9.5 mos (range, 3-257). Seventeen (89%) pts were previously treated with TKIs (9 [47%] imatinib, 6 [32%] nilotinib, 1 [5%] imatinib and nilotinib, 1 [5%] imatinib and bosutinib), of which 7 (41%) were refractory to TKIs. The median duration of TKI therapy was 8.3 mos (range, 3.2-37). Two (11%) pts had not received any TKIs. One had undergone allo-SCT. At the time of CML-LBC, 9 (47%) pts were on imatinib, 7 (37%) with nilotinib, and 1 (5%) with bosutinib. At CML-LBC, 11 (58%) had abnormal karyotype, all with additional cytogenetic abnormalities (ACAs) in addition to Ph. ABL1 mutations were detected in 8 of 14 (57%) tested-pts, none with T315I. BCR-ABL1 transcript was p210 in all pts. In pts with Ph-positive ALL, 52 (84%) had abnormal karyotype, of which 10 (19%) had Ph only and 41 (79%) had Ph with ACAs. p210 and p190 were detected in 13 (21%) and 48 (77%) pts, respectively. Morphologic response (CR or CRi) rates were similar between pts with CML-LBC (90%) and Ph-positive ALL (96%), whereas pts with CML-LBC were less likely to obtain deeper molecular remission. CCyR was achieved in 94% vs 95% of pts with CML-LBC vs Ph-positive ALL, respectively (p = 1). MMR was achieved in 68% vs 95% of pts with CML-LBC vs Ph-positive ALL, respectively (p = 0.006). CMR was achieved in 53% vs 74% of pts with CML-LBC vs Ph-positive ALL, respectively (p = 0.093, Table 1). Nineteen pts received allo-SCT (CML-LBC, N=8 [42%]; Ph-positive ALL, N=11 [18%] ). With a median follow-up of 133 mos (95% CI: 115-137), 20 (25%) pts relapsed and 50 (62%) died. Pts with CBL-LBC had similar survival outcome compared with pts with Ph-positive ALL (5-yr PFS 50% vs 44% [p = 0.75], 5-yr OS 61% vs 48% [p = 0.74] , Figure 1). The 5-yr OS rates were 88 % and 37% for pts with CML-BC with or without allo-SCT (p = 0.019). In pts with Ph-positive ALL, there was no difference in outcome based on allo-SCT (p = 0.252, Figure 2). In pts with Ph-positive ALL, outcome was predicted by the achievement of CMR. The 5-yr OS rates were 63% and 25% (p = 0.002) for pts with CMR and MMR, respectively (Figure 3). By MVA, allo-SCT seemed to predict better OS in CML-LBC (HR 0.20, p = 0.057), whereas CMR predicted better OS in Ph-positive ALL (HR 0.37, p = 0.015) (Table 2). Conclusions: Outcome of CML-LBC has improved with HCVAD+Dasa therapy, particularly in pts who received subsequent allo-SCT. Further improvement can be obtained by the use of novel TKI and targeted agents. Disclosures Kantarjian: Oxford Biomedical: Honoraria; Janssen: Honoraria; Delta Fly: Honoraria; BioAscend: Honoraria; Aptitute Health: Honoraria; Abbvie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Jazz: Research Funding; Immunogen: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; BMS: Research Funding; Ascentage: Research Funding; Amgen: Honoraria, Research Funding; Adaptive biotechnologies: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Research Funding; Pfizer: Honoraria, Research Funding. Ravandi:Macrogenics: Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; Xencor: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding. Sasaki:Novartis: Consultancy, Research Funding; Otsuka: Honoraria; Pfizer Japan: Consultancy; Daiichi Sankyo: Consultancy. Jain:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aprea Therapeutics: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Pfizer: Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Konopleva:Ablynx: Research Funding; Ascentage: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; Genentech: Consultancy, Research Funding; Amgen: Consultancy; Agios: Research Funding; AbbVie: Consultancy, Research Funding; Eli Lilly: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Forty-Seven: Consultancy, Research Funding; Sanofi: Research Funding; AstraZeneca: Research Funding; Rafael Pharmaceutical: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Kisoji: Consultancy; F. Hoffmann La-Roche: Consultancy, Research Funding. Short:Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy. DiNardo:Syros: Honoraria; MedImmune: Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; ImmuneOnc: Honoraria; Jazz: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Takeda: Honoraria. Kadia:Abbvie: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Astellas: Research Funding; JAZZ: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Pulmotec: Research Funding; Incyte: Research Funding; Celgene: Research Funding; Cellenkos: Research Funding; Cyclacel: Research Funding; BMS: Honoraria, Research Funding; Astra Zeneca: Research Funding; Amgen: Research Funding; Ascentage: Research Funding; Novartis: Honoraria. Garcia-Manero:Merck: Research Funding; H3 Biomedicine: Research Funding; AbbVie: Honoraria, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Amphivena Therapeutics: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Novartis: Research Funding. Daver:Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Issa:Celegene: Research Funding; Syndax: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Cortes:Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sun Pharma: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Telios: Research Funding; Astellas: Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; Merus: Research Funding; Immunogen: Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding. Jabbour:Pfizer: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding.

Abstract: Background: An inflammatory bone marrow microenvironment with overactive immune stimulation mediated by cytotoxic T cells and defective T regulatory cells contribute to acquired bone marrow failure (BMF) syndromes, including aplastic anemia (AA), primary myelofibrosis (PMF) and hypoplastic myelodysplasia (MDS). Adoptive therapy with allogeneic cord blood (CB) T-regulatory (Treg) cells has shown safety in humans and clinical benefit in graft vs. host disease. Derived from CB, these Treg cells enjoy immune privilege, demonstrate high proliferative index, lack plasticity, and have been shown to consistently suppress inflammation. Therefore, we hypothesized that adoptive therapy with CB Tregs can be utilized as treatment for the inflammatory BMF disorders. Study Design and Methods: This is a phase I clinical trial examining the role of a single infusion of CK0801, an allogeneic, fresh CB Treg product for the treatment of BMF. CK0801 was produced utilizing novel process development that consists of well-defined qualification criteria for the starting material (CB units), parameters for manufacturing and culture-expansion; and well-defined analytic testing and lot release criteria. Three dose-levels were examined: i) 1x106 cells/kg; ii) 3x106 cells/kg and iii) 10x106 cells/kg (NCT03773393). No immune suppression or lymphodepletion was administered. Patients were allowed to continue their ongoing treatment at stable doses. The study follows 3+3 phase I design. Patients aged ≥ 18 yrs with aplastic anemia, myelodysplastic syndrome or myelofibrosis, and available (HLA 3 out of 6) matched CB unit were eligible. The primary endpoint is to determine the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) of the Treg infusion defined as any of the 3 events: i) severe (grade 3 or 4) infusion toxicity within 24 hours (NCI-CTCAE V4.0), ii) regimen related death within 30 days, or iii) severe (grade 3 or 4) cytokine release syndrome (CRS) within 30 days. Secondary endpoints include exploration of efficacy, PB and BM immune reconstitution, and inflammatory cytokines. Results: Six patients (Pts) have been treated, with a median age of 54 (range, 20-74). Four pts (67%) had a diagnosis of PMF and 2 patients (33%) had a diagnosis of AA. Overall, the patients had received a median of 4 prior therapies (2-5). There were no infusion related reactions and not DLTs in any of the patients. The patient characteristics and outcomes are summarized in Table 1. Three patients were treated at dose level 1 where the clinical effect was measured at day 30 post CK0801 infusion: Pt#1 (PMF): decrease in JAK2 mutant allele burden; Pt#2 (Triple negative PMF): improvement in MPN symptom burden and improved BM cellularity; and Pt#3 (AA): improvement in blood and platelet transfusion requirement and resolution of BM dysplasia. Additional three patients were treated at dose level 2, where the clinical effect was measured at day 30 post CK0801 infusion: Pt#4 (AA): improvement in blood and platelet transfusion requirement and resolution of BM dysplasia; Pt#5 (PMF): improvement in chronic pain; Pt#6 (PMF) improvement in blood and platelet transfusion requirement and decrease in JAK2 mutant allele burden. The durability of the clinical effect was variable, ranging from 1 month to 9 months. No DLTs were encountered and the MTD has not been reached. Enrollment on dose level 3 has started. Conclusion: This is the first study to show that a single infusion of allogeneic CB derived Treg cells (CK0801) is well tolerated, feasible, and may be associated with clinical improvement in patients with immune related bone marrow disorders. Determining the optimal dose and schedule of the Treg cell infusion is ongoing. Table Disclosures Kadia: Amgen: Research Funding; Novartis: Honoraria; Pfizer: Honoraria, Research Funding; Celgene: Research Funding; Cyclacel: Research Funding; Ascentage: Research Funding; Cellenkos: Research Funding; Astra Zeneca: Research Funding; Astellas: Research Funding; Pulmotec: Research Funding; BMS: Honoraria, Research Funding; Incyte: Research Funding; Abbvie: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding. Pemmaraju:Daiichi Sankyo: Research Funding; Cellectis: Research Funding; AbbVie: Honoraria, Research Funding; Samus Therapeutics: Research Funding; MustangBio: Honoraria; Blueprint Medicines: Honoraria; DAVA Oncology: Honoraria; LFB Biotechnologies: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Celgene: Honoraria; Incyte Corporation: Honoraria; Novartis: Honoraria, Research Funding; Plexxikon: Research Funding; Affymetrix: Other: Grant Support, Research Funding; Pacylex Pharmaceuticals: Consultancy; SagerStrong Foundation: Other: Grant Support; Roche Diagnostics: Honoraria. Yilmaz:Pfizer: Research Funding; Pint Pharma: Honoraria; Daicho Sankyo: Research Funding. Parmar:Cellenkos Inc.: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. DiNardo:Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Jazz: Honoraria; Novartis: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; MedImmune: Honoraria; Calithera: Research Funding; Takeda: Honoraria; ImmuneOnc: Honoraria; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Syros: Honoraria; Agios: Consultancy, Honoraria, Research Funding. Daver:Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding. Issa:Novartis: Membership on an entity's Board of Directors or advisory committees; Syndax: Research Funding; Celegene: Research Funding. Jabbour:AbbVie: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. Borthakur:Oncoceutics: Research Funding; Novartis: Research Funding; BioTherix: Consultancy; FTC Therapeutics: Consultancy; Curio Science LLC: Consultancy; Jannsen: Research Funding; Argenx: Consultancy; BioLine Rx: Consultancy; BioLine Rx: Research Funding; Cyclacel: Research Funding; GSK: Research Funding; Polaris: Research Funding; AstraZeneca: Research Funding; BMS: Research Funding; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; Abbvie: Research Funding; PTC Therapeutics: Research Funding; Incyte: Research Funding; Xbiotech USA: Research Funding; PTC Therapeutics: Consultancy. Verstovsek:Incyte Corporation: Consultancy, Research Funding; PharmaEssentia: Research Funding; AstraZeneca: Research Funding; ItalPharma: Research Funding; Protagonist Therapeutics: Research Funding; Celgene: Consultancy, Research Funding; Roche: Research Funding; CTI Biopharma Corp: Research Funding; Genentech: Research Funding; Sierra Oncology: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Blueprint Medicines Corp: Research Funding; Gilead: Research Funding; NS Pharma: Research Funding; Promedior: Research Funding.

Abstract: Acute myeloid leukemia (AML) patients with any history of cigarette smoking have worse survival outcomes compared to patients that have never smoked. The molecular basis of cigarette smoking or cigarette smoke exposure (CSE) impacting AML progression or treatment response is unknown. Altered DNA methylation from smoking persists decades after quitting and has been followed in peripheral blood mononuclear cells (PBMCs) but have not been evaluated in the context of AML. Smoking also causes oxidative stress in PBMCs, but this has yet to be studied in AML patients with a history of smoking. To model how smoking worsens AML progression, we created a CSE model using a cigarette smoking robot where NOD-SCID mice received 2 hours of CSE 5 days/week or air alone. After 2 weeks of CSE, 100,000 luciferase-tagged, human AML cells were injected via tail-vein and leukemic burden was monitored by bioluminescent imaging. Two cell lines, MOLM13 and MOLM14 carrying the oncogenic fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation, when introduced into CSE mice had enhanced leukemic progression within one week (p-value & lt;0.0001 and & lt;0.001 respectively). MOLM14-bearing mice showed increased leukemic burden 24 days post injection (p-value & lt;0.05). DNA methylation was evaluated by bisulfite sequencing of splenocytes from CSE mice, which was mapped to the human (AML) or mouse (host) genome. Over 200 significant changes in DNA methylation of gene promoters was seen, including hypomethylation of aryl-hydrocarbon receptor repressor (AHRR), an established hallmark of smoking in humans. Indicating that our CSE model recapitulates DNA methylation from smoking in humans. Additionally, GATA-2, a critical protein for hematopoietic differentiation known to be frequently mutated in AML, was also amongst the top hypomethylated genes. We quarried TCGA to understand the implications of altered DNA methylation in AML patients. In AML patients, low GATA-2 methylation showed decreased survival compared to those with high GATA-2 methylation (N=42/group, p-value: 0.000138). The discovery of GATA-2 methylation in smoking models and its attribution as a poor prognostic indicator in AML is novel, which underscores a need to understand the role of GATA-2 methylation in AML. Reactive oxygen species (ROS) have been implicated in AML progression, drug resistance, and are elevated in otherwise healthy smokers. No significant differences were seen in intracellular ROS in spleen or PBMCs of CSE mice; however, we found more than a two-fold increase of heme oxygenase 1 (HO-1) (p-value:0.0505), a protein involved in antioxidant responses and AML treatment resistance. There was also increased BCL-2 protein expression and a decrease in AHRR expression (p-value: 0.0098) in CSE mouse samples. This suggests that CSE causes oxidative stress and increases pro-leukemic signaling. To address if CSE impacted treatment efficacy, we treated mice with daunorubicin (2 mg/kg, twice weekly via tail-vein) once evidence of engraftment was detected. We found a trend towards increased leukemic burden compared to non-smoking mice which approached statistical significance. To study the direct impact of CSE on AML, without exposure to the tumor environment, AML cells were treated in vitro with a commercially available cigarette smoke condensate (CSC) that contains the chemicals from cigarette smoke. To mimic the in vivo CSE, MOLM13 cells received two weeks of CSC treatment before being injected into mice. At 3, 10, and 17 days post injection, mice with CSC-treated AML had enhanced leukemic burden (p-value & lt;0.0001, & lt;0.0001, and & lt;0.001). This model revealed that chemicals in cigarette smoke can directly promote AML. On day 14 of CSC treatment, mirroring when the cells were injected into mice, both FLT3-ITD cell lines had increased ROS levels and or glutathione as measured by flow cytometry; this is indicative of CSC-induced oxidative stress. Cumulatively, these data define novel changes in DNA methylation and redox from smoking or tobacco products with strong potential to drive AML progression and therapy resistance. Future studies will determine if blocking these redox or methylation events can reverse the accelerated AML growth and will aid in the creation of a tailored treatment strategy for AML patients with any history of smoking. Disclosures Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Konopleva: Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; AstraZeneca: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; KisoJi: Research Funding; Stemline Therapeutics: Research Funding; Agios: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; Cellectis: Other: grant support; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. DiNardo: Novartis: Honoraria; Agios/Servier: Consultancy, Honoraria, Research Funding; Forma: Honoraria, Research Funding; Foghorn: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria, Research Funding; Takeda: Honoraria; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding.