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Background: The curative potential of allogeneic hematopoietic stem cell transplant (SCT) for acute myeloid leukemia (AML) depends in part on the graft-versus-leukemia (GVL) cellular immune response. Mechanisms of resistance to GVL and methods to overcome post-SCT relapse are a critical focus of research. AML blasts can inhibit activation and proliferation of immune cells in culture. We hypothesized that irradiating AML blasts would diminish their immune suppressive capacity while maintaining antigen presentation, leading to higher activation of CD8+ T cells among peripheral blood mononuclear cells (PBMC) in co-culture. Furthermore, we investigated the capacity of live and irradiated AML blasts to induce expression of immune checkpoints on CD8+ T cells in co-culture, focusing on Lymphocyte-activation gene 3 (LAG3) which interacts with class II MHC. Methods: PBMC were isolated from healthy donors in compliance with an IRB-approved protocol. PBMC were co-cultured with live human AML K-1 cells (CRL-2724) and irradiated K-1 cells (40 Gy) at the following ratios: 1:1, 1:2, 1:4 and 1:8. Cells were cultured in RPMI complete media supplemented with 10% FBS and IL-2 20 IU/ml. On day 3 of co-culture, immunophenotypic characterization of T cells was performed on an Attune NxT flow cytometer using the following antibody markers: CD3, CD4, CD8, CD25, CD137, CD154, PD-1, TIM3, TIGIT, and LAG3. PBMC were fixed and permeabilized prior to intracellular staining of IFNg and FOXP3. Regulatory T cells (Tregs) were identified as CD4+ CD25+ FOXP3+. To correlate the expression of the genes encoding for IFNg, LAG3, PD1, and antigen presentation molecules in the tumor microenvironment, we analyzed RNA sequencing data from The Cancer Genome Atlas (NCI TCGA) AML database. Associations were determined by Spearman's correlation and K-means clustering. Results: PBMC co-cultured with irradiated AML K-1 showed significant higher IFNg expression (11.8% ± 3.1 v. 7% ± 3.3; n=7, P=0.012) and higher CD137 (4-1BB) expression (9.3% ± 1.21 v. 5.7% ± 3.4; n=7, P Conclusion: In our in vitro model, LAG3 upregulation correlates with decreased activation of CD8+ cells and higher Tregs when healthy donor PBMC are co-cultured with AML K-1 cells. Antibody-mediated blocking of LAG3 may potentially reverse the suppression of CD8+ T cells by AML K-1 cells and produce fewer Tregs. Bioinformatic analysis of TCGA database confirmed a positive correlation between LAG3 transcript levels and expression of both immune activation and antigen presentation genes. LAG3 transcript levels are higher in unfavorable-risk AML. Figure. Figure. Disclosures Lin: Jazz Pharmaceuticals: Honoraria.

Introduction: Gilteritinib is a novel, potent, highly-selective oral fms-like tyrosine kinase 3 (FLT3)/AXL inhibitor. Once-daily single-agent gilteritinib doses of ≥80 mg/day elicited antileukemic responses in FLT3 mutation-positive (FLT3mut+) subjects with relapsed/refractory AML (Perl AE, et al. Lancet Oncol. 2017). We examined the safety/tolerability and antitumor activity of gilteritinib plus front-line intensive chemotherapy in newly diagnosed AML patients. Methods: This ongoing open-label, dose-escalation/expansion phase 1 study (NCT02236013) assesses the safety/tolerability and antitumor effects of gilteritinib combined with 7+3 induction and high-dose cytarabine consolidation, and as single-agent maintenance therapy in subjects aged ≥18 years with newly diagnosed AML (excluding core-binding factor translocations). Dose escalation followed a 3+3 design; successive cohorts of 3-6 subjects received 40, 80, 120, or 200 mg/day gilteritinib. Subjects received ≤2 cycles of a 7+3 induction regimen (cytarabine 100 mg/m2/day, Days 1-7 plus idarubicin 12 mg/m2/day, Days 1-3 [dose-escalation and dose-expansion cohorts], and once-daily gilteritinib on Days 4-17 [Schedule 1]). After completion of the dose-expansion cohort using Schedule 1, a new cohort of patients were enrolled. In this cohort of six patients, gilteritinib administration was changed to Days 8-21 (Schedule 2) in preparation for phase 3 studies and daunorubicin 90 mg/m2/day, administered on Days 1-3, was used as an alternative anthracycline to idarubicin. During consolidation, subjects received cytarabine (1.5 g/m2 every 12 hours, Days 1, 3, and 5) and once-daily gilteritinib (Days 1-14) at the induction dose for ≤3 cycles. Subjects in the dose-expansion cohort received gilteritinib at the recommended expansion dose established during dose escalation. Transplantation was allowed for responding subjects. After consolidation or transplantation with stable engraftment, subjects received maintenance therapy with once-daily gilteritinib (28-day cycles; ≤26 cycles). Results: As of July 2, 2018, 62 subjects have been enrolled; 60 are included in the safety analysis set. Most subjects were male (66.7%; median age, 59.5 years [range, 23-77]) and 32 (53.3%) had FLT3 mutations (FLT3-ITD, n=23). During dose-escalation, two subjects in the 40 mg/day cohort who had received gilteritinib on Days 1-14 experienced dose-limiting toxicities (DLTs; neutropenia, thrombocytopenia, decreased ejection fraction). After the gilteritinib induction schedule change, no more DLTs occurred at this dose. Two subjects in the 200 mg/day cohort experienced DLTs (neutropenia, neutropenic enterocolitis). The maximum tolerated dose and the recommended expansion dose were established at 120 mg/day. Grade ≥3 adverse events (AEs) in ≥10% of patients were febrile neutropenia (63.3%), thrombocytopenia (18.3%), decreased platelet count (16.7%), neutropenia (15.0%), bacteremia (10.0%), sepsis (10.0%), and decreased white blood cell count (10.0%). Serious drug-related AEs in >1 subject were febrile neutropenia (n=9), small intestinal obstruction, lung infection, sepsis, and decreased ejection fraction (all n=2). The end-of-treatment investigator-reported rate of composite complete remission (CRc) for response evaluable FLT3mut+ subjects receiving gilteritinib 120 mg on Schedule 1 (n=17) was 100%. The CRc rate in FLT3mut+ subjects receiving Schedule 2 induction with daunorubicin was also 100% (Table). Enrollment in the Schedule 2 cohort receiving idarubicin is ongoing; the two subjects in this cohort have not been assessed for response. Among subjects who received ≥80 mg/day gilteritinib (n=47), CRc rates for FLT3mut+ subjects were 88.9% (n=24/27). Median overall survival has not been reached. Median disease-free survival was 297 days (95% CI: 112, not reached). Assessment of minimum residual disease in FLT3-ITD patients using a next-generation sequencing-based assay is ongoing; results will be available at the time of presentation. Conclusions: Gilteritinib can be safely combined with intensive chemotherapy, and given as single-agent maintenance therapy in subjects with newly diagnosed AML. Treatment was well tolerated. High response rates were observed in FLT3mut+ subjects after treatment with either idarubicin or daunorubicin in combination with two different gilteritinib administration schedules. Disclosures Pratz: Millenium/Takeda: Research Funding; AbbVie: Consultancy, Research Funding; Agios: Research Funding; Astellas: Consultancy, Research Funding; Boston Scientific: Consultancy. Altman:Astellas Pharma: Other; Agios: Other: Payment to the institution to conduct the trial ; Epizyme: Other: payment to the institution to conduct clinical trial work; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: payment to the institution to conduct clinical trial work; Cyclacel: Other: payment to the institution to conduct clinical trial work; Celator: Other: payment to the institution to conduct clinical trial work; Ariad: Other: payment to the institution to conduct clinical trial work; Bayer: Other: payment to the institution to conduct clinical trial work; Genetech: Other: Payment to the institution to conduct clinical trial work; FujiFilm: Other: payment to the institution to conduct clinical trial work; Incyte: Other: payment to the institution to conduct clinical trial work; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: payment to the institution to conduct clinical trial work; Boeringer Ingelheim: Other: payment to the institution to conduct clinical trial work; Syros: Membership on an entity's Board of Directors or advisory committees; GSK: Other: payment to the institution to conduct clinical trial work; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Immune Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Cruz:Takeda: Speakers Bureau. Jurcic:Kura Oncology: Research Funding; Forma Therapeutics: Research Funding; Celgene: Research Funding; Daiichi-Sankyo: Research Funding; Incyte: Consultancy; Actinium Pharmaceuticals, Inc: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Syros Pharmaceuticals: Research Funding; Genetech: Research Funding; AbbVie: Consultancy, Research Funding; Astellas: Research Funding. Lin:Jazz Pharmaceuticals: Honoraria. Perl:AbbVie: Membership on an entity's Board of Directors or advisory committees; Actinium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy; NewLink Genetics: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy. Podoltsev:Pfizer: Membership on an entity's Board of Directors or advisory committees; Astellas Pharma: Research Funding; LAM Therapeutics: Research Funding; Astex Pharmaceuticals: Research Funding; Genentech: Research Funding; Boehringer Ingelheim: Research Funding; Sunesis Pharmaceuticals: Research Funding; Daiichi Snakyo: Research Funding; Celator: Research Funding; Celgene: Research Funding; Pfizer: Research Funding. Schiller:bluebird bio: Research Funding; Astellas Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding. Liu:Astellas Pharma: Employment. Bahceci:Astellas Pharma: Employment.

Patients with acute leukemia harbor chemotherapy-resistant leukemia stem cells (LSC) which ultimately lead to disease relapse in many patients. Clinical trial design of LSC targeted therapy is a challenge. The majority of leukemia cells are differentiated leukemia cells, with LSC comprising Citation Format: Tara L. Lin, John M. Perry, Xi He, Gregory Reed, Na Zhang, Scott Weir, Joseph P. McGuirk, Linheng Li. Biomarkers of response to leukemia stem cell targeted therapy with low dose daunorubicin in relapsed/refractory acute 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 CT137.

Introduction: Targeted therapy for KMT2A (mixed lineage leukemia [MLL]) rearranged acute leukemia (AL) is lacking. KMT2A regulates leukemic stem cell transcription factors HOXA9 and MEIS1. Spleen tyrosine kinase (SYK) signaling induces MEIS1 in conjunction with HOXA9. We hypothesize that this regulatory loop may be sensitive to SYK inhibition with Entospletinib (ENTO) a highly selective, oral SYK inhibitor. In this analysis, we evaluate the efficacy of ENTO in patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) with t(v;11q23.3) KMT2A/MLL gene rearrangements. Methods: Patients with KMT2A rearranged AL in two different clinical trials were included. AML patients (NCT02343939) received ENTO 400mg BID monotherapy for up to 14 days prior to and with induction chemotherapy (cytarabine 100 mg/m2 for 7 days plus daunorubicin 60 mg/m2 for 3 days) if previously untreated, or ENTO monotherapy alone if relapsed/refractory (R/R). R/R B-ALL patients received ENTO monotherapy for 7 days prior to and with vincristine and dexamethasone in a phase 1 study (NCT02404220). Results: 18 patients with KMT2A rearranged AL were treated. Untreated AML (n=10) patients had a median age of 49 years. One patient was in a morphologic leukemia-free state after ENTO monotherapy (before chemotherapy). After induction chemotherapy plus ENTO, seven patients had morphologic (CR) and cytogenetic (CRc) remission, but two of them had incomplete count recovery (CRi). The composite CR rate (CR/CRi/CRc) was 90%: 5 CRc, 3 CRi (CR/CRc with incomplete count recovery), and 1 CR. Six patients underwent allogeneic stem cell transplantation (SCT) in CR1. After median follow-up of 9.9 months one patient who achieved CR relapsed, with persistence of t (6;11) and an NRAS mutation. Median overall survival and event-free survival have not been reached. In R/R AML (n=6), patients had a median age of 48 years, with 2 median prior therapies. One had CR and one had CRi (but normal cytogenetics) and both received SCT. In all, 3 AML patients (1 newly diagnosed, 2 R/R) responded to ENTO monotherapy alone. In R/R ALL (n=2), median age was 59 years. Both patients had t (4;11) along with other cytogenetic abnormalities with 2 prior therapies. Both patients achieved CR with loss of KMT2A on cytogenetic testing, and one patient received SCT. Overall, ENTO was safe and well tolerated, even in combination with chemotherapy. Conclusions: KMT2A rearranged AL is sensitive to ENTO with CR observed on monotherapy in AML and high response rates in AL patients treated with combination therapy. This represents the first documentation of CR with small molecule monotherapy (n=3) in this genetic subgroup, which typically portends a poor prognosis. Correlative biomarker studies evaluating HOXA9/MEIS1 in patients with t(v;11q23.3) KMT2A rearranged leukemia treated with ENTO are pending. Citation Format: Alison R. Walker, John C. Byrd, William Blum, Tara Lin, Howland E. Crosswell, Danjie Zhang, Jie Gao, Arati V. Rao, Mark D. Minden, Wendy Stock. High response rates with entospletinib in patients with t(v;11q23.3);KMT2A rearranged acute myeloid leukemia and acute lymphoblastic 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 819.

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.

7040Background: CPX-351, a liposomal encapsulation of cytarabine (C) and daunorubicin (D) at a synergistic ratio, is approved in the US for treatment of adults with newly diagnosed therapy-related ...

Background: Gilteritinib is a novel, potent, highly-selective oral fms -like tyrosine kinase 3 (FLT3)/AXL inhibitor with clinical activity in relapsed/refractory (R/R) AML with activating FLT3-ITD and -TKD mutations. In such patients, once-daily gilteritinib ≥80 mg/day, as a single agent, elicited a response rate of 52% and median overall survival (OS) of 31 weeks (Perl AE, et al. Lancet Oncol . 2017.). Here we examined the safety/tolerability and antitumor activity of gilteritinib combined with front-line intensive chemotherapy in newly diagnosed AML patients. Methods: The primary objective of this open-label, dose-escalation/expansion Phase 1 study (NCT02236013) was to assess the safety/tolerability profile (including dose-limiting toxicities [DLTs] and maximum tolerated dose [MTD]) of gilteritinib when combined with 7+3 induction and high-dose cytarabine (HiDAC) consolidation, and administered as single-agent maintenance therapy in subjects aged ≥18 years with newly diagnosed AML. Assessment of antitumor effects of this combination therapy was an exploratory objective. Dose escalation followed a 3+3 design where successive cohorts of 3-6 subjects received gilteritinib doses of 40, 80, or 120 mg/day. Dose-escalation decisions were made based on DLTs that occurred during remission induction. A DLT was defined as any grade ≥3 non-hematologic or extramedullary toxicity (with exceptions) or hematologic toxicity that occurred after the first gilteritinib dose and did not resolve by Day 42 of the last induction cycle or before initiation of consolidation therapy. Subjects received up to 2 cycles of a 7+3 induction regimen (cytarabine 100 mg/m2/day, days 1-7 plus idarubicin 12 mg/m2/day, days 1-3) plus once-daily oral gilteritinib, which was initially administered on days 1-14 but was subsequently changed to administration on days 4-17 at the designated dose. During consolidation, subjects received cytarabine (1.5 g/m2 every 12 hours, days 1, 3, and 5) and once-daily gilteritinib (days 1-14) at the induction dose, for up to 3 cycles. Subjects in the dose-expansion cohort, received gilteritinib at the recommended expansion dose established during dose escalation. After consolidation, subjects received maintenance therapy with once-daily gilteritinib (28-day cycles; up to 26 cycles). Results: As of July 9, 2017, 50 subjects had been enrolled (n=17, dose-escalation cohort; n=33, dose-expansion cohort); 49 had received at least 1 dose of gilteritinib. Most subjects were male (67.3%; n=33); median age was 59 years (range, 23-77 years). Of the 48 subjects with known FLT3 mutation status, 23 (47.9%) were FLT3mut+, of whom 15 (65.2%) had internal tandem duplications. During dose-escalation, 2 subjects in the 40 mg/day cohort who had received gilteritinib on days 1-14 experienced DLTs (neutropenia, thrombocytopenia, and decreased ejection fraction). After gilteritinib induction schedule modification, no additional DLTs were observed. The MTD was not reached; gilteritinib 120 mg/day was chosen as the recommended expansion dose. Grade ≥3 treatment-emergent adverse events (TEAEs) occurring in ≥10% of subjects were febrile neutropenia (53.1%), thrombocytopenia (18.4%), neutropenia (16.3%), decreased platelet count (12.2%), sepsis (10.2%), and decreased white blood cell count (10.2%). Serious drug-related TEAEs occurring in >1 subject were febrile neutropenia (16.3%), sepsis (6.1%), and decreased ejection fraction (4.1%). The end of treatment investigator-reported composite complete remission (CRc) rate for all subjects was 71.4% and 57.1% achieved complete remission (Table). In FLT3mut+ and FLT3 mutation-negative (FLT3mut−) subjects, end-of-treatment CRc rates were 91.3% and 56%, respectively. Among subjects who received ≥80 mg/day gilteritinib (n=40), end-of-treatment CRc rates were 90% (n=18/20) for FLT3mut+ and 60% (n=12/20) for FLT3mut− subjects. Median OS and duration of response have not been reached. For the total study population, median event-free survival (EFS) was 327 days and median disease-free survival (DFS) was 297 days; FLT3mut+ subjects had a longer median EFS (327 days) and DFS (134 days) than FLT3mut− subjects (EFS, 80 days; DFS, not estimable). Conclusions: In subjects with newly diagnosed AML, gilteritinib combined with intensive chemotherapy was well tolerated (MTD >120 mg/day) with seemingly high response rates in FLT3mut+ subjects. Disclosures Cherry: Pfizer: Membership on an entity's Board of Directors or advisory committees; Astellas: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees; Ariad: Membership on an entity's Board of Directors or advisory committees. Altman: NCCN: Other: Educational speaker; Syros: Consultancy; BMS: Consultancy; Celgene: Consultancy; Astellas: Consultancy; Ceplene: Consultancy; Janssen Pharmaceuticals: Consultancy; Novartis: Consultancy; ASH: Other: Educational speaker. Cooper: Novartis: Research Funding. Jurcic: Syros Pharmaceuticals: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy; Kura Oncology: Research Funding; Incyte: Consultancy; Genentech: Research Funding; Forma Therapeutics: Research Funding; Celgene: Research Funding; Alexion Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Research Funding; Actinium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi-Sankyo: Research Funding; Astellas Pharma, Inc: Research Funding; Amgen: Consultancy. Levis: Astellas Pharma Us: Consultancy, Research Funding; Daiichi Sankyo, Inc.: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Research Funding; FujiFilm: Research Funding. Lin: Jazz Pharmaceuticals: Consultancy. Perl: Arog Pharmaceuticals: Consultancy; Asana Biosciences: Other: Scientific advisory board; Astellas: Consultancy; Daiichi Sankyo: Consultancy; Pfizer: Other: Advisory Board; Novartis: Other: Advisory Board; Actinium Pharmaceuticals: Other: Scientific Advisory Board; Seattle Genetics: Other: Advisory board. Podoltsev: Alexion: Consultancy; CTI biopharma/Baxalta: Consultancy; Incyte: Consultancy; Ariad: Consultancy. Schiller: Celator/Jazz: Research Funding. Liu: Astellas Global Pharma, Inc.: Employment. Bahceci: Astellas Pharma Global Development: Employment.

Background: Older patients with acute myeloid leukemia (AML) who are ineligible for intensive chemotherapy are unlikely to achieve remission with available therapy and have unacceptably short survival. Venetoclax (VEN) is a small molecule inhibitor of BCL-2 that achieved remission rates of >60% combined with low-dose cytarabine (LDAC). Presented are long-term outcomes, including 1-year overall survival (OS) and biomarker analyses. Methods: This phase 1b/2, open-label study (NCT02287233) evaluates the safety and preliminary efficacy of orally administered VEN combined with LDAC in patients ≥65 years with previously untreated AML (except for hydroxyurea). Patients were ineligible for intensive chemotherapy because of comorbidity or other factors and had an ECOG performance score of 0-2, with adequate hepatic and renal function. Exclusion criteria were acute promyelocytic leukemia, active CNS involvement with AML, concominant use of moderate or strong CYP3A inhibitors, or prior treament with cytarabine for a preexisting myeloid disorder. Prior treatment for myelodysplastic syndrome (MDS) was allowed. In cycle 1, VEN was started at 50 mg/day PO and increased over a 5-day ramp-up to reach the designated cohort dose of 600 or 800 mg/day on day 6, which was continued through day 28. In subsequent cycles, the desingated dose of VEN 600 or 800 mg/day was administered on days 1-28. LDAC 20 mg/m2/day SQ was given on days 1-10 of each cycle. Preliminary efficacy was assessed as the overall response rate (ORR, which included complete remission [CR], CR with incomplete blood count recovery [CRi], and partial remission [PR]). Adverse events (AEs) and laboratory values were monitored. Exploratory analysis of biomarkers (eg, cytogenetics, molecular markers) was performed to identify potential predictors of clinical outcomes. Results: Data cutoff was May 30, 2017. All 71 patients were enrolled ≥1 year prior (46 [65%] male; median age, 74 years [range, 66-87 years]): 10 received VEN 800 mg and 61 received VEN 600 mg, the recommended phase 2 dose. Thirty-three patients (47%) had a history of antecedent hematologic disorder (AHD), most commonly MDS. Among 61 patients given VEN 600 mg, median time on VEN treatment was 6 months (range, Conclusions: The safety profile of VEN 600 mg/day plus LDAC was acceptable for elderly patients with treatment-naive AML who were ineligible for intensive chemotherapy. After ≥1 year of follow-up, the observed median OS was 11.4 months. This cohort included 44% (27/61) of patients with AHDs. Corelations of specified AML mutations with response and duration should be confirmed in later trials. Due to the observced CR/CRi rate of 62%, extended duration of response, and encouraging OS in a cohort of patients with particularly poor-risk features, the 600-mg dose of VEN combined with LDAC is being tested in an ongoing phase 3 study. Figure Figure. Disclosures Wei: AbbVie, Celgene, Novartis, Amgen, Servier: Honoraria; AbbVie, Celgene, Servier: Research Funding; AbbVie, Celgene, Novartis, Amgen, Servier: Membership on an entity's Board of Directors or advisory committees. Strickland: Boehringer-Ingelheim: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Novartis: Consultancy; Tolero: Consultancy; Astellas: Consultancy; CTI BioPharma: Consultancy; Baxalta: Consultancy. Roboz: AbbVie, Agios, Amgen, Amphivena, Array Biopharma Inc., Astex, AstraZeneca, Celator, Celgene, Clovis Oncology, CTI BioPharma, Genoptix, Immune Pharmaceuticals, Janssen Pharmaceuticals, Juno, MedImmune, MEI Pharma, Novartis, Onconova, Pfizer, Roche Pharmace: Consultancy; Cellectis: Research Funding. Hou: Teva Oncology, Seattle Genetics: Speakers Bureau. Fiedler: Amgen, Pfizer: Research Funding; Amgen, Gilead, GSO, Teva, Jazz Pharmaceuticals: Other: Support for meeting attendance; Amgen: Patents & Royalties; Amgen, ARIAD/Incyte: Membership on an entity's Board of Directors or advisory committees. Lin: Jazz Pharmaceuticals: Consultancy. Walter: ADC Therapeutics: Research Funding; Aptevo Therapeutics: Research Funding. Chyla: Abbvie: Employment, Equity Ownership. Popovic: AbbVie: Employment, Equity Ownership. Fakouhi: AbbVie: Employment, Equity Ownership. Shah: AbbVie: Employment, Equity Ownership. Dunbar: AbbVie: Employment, Equity Ownership. Xu: AbbVie: Employment, Equity Ownership. Mabry: AbbVie: Employment, Equity Ownership. Hayslip: AbbVie: Employment, Equity Ownership.

The cancer stem cell (CSC) hypothesis suggests that clonogenic growth potential within an individual tumor is restricted to a specific and phenotypically defined cell population. Evidence for CSC in human tumors initially arose from studies of AML, but functionally similar cell populations have been identified in an increasing number of malignancies. Despite these findings, controversy surrounds the CSC hypothesis, especially the generalization that clonogenic tumor cells are rare. Nevertheless, efforts to define the cellular processes regulating self-renewal and resistance to anticancer therapeutics, two of the major properties ascribed to CSC, are likely to provide useful insights into tumor biology as a whole. BMT has been at the forefront of clinically translating basic stem cell concepts starting with the original hypothesis that normal hematopoietic precursors could rescue patients from myeloablative doses of radiation or chemotherapy. Even today, a better understanding of CSC may enhance ongoing efforts to induce specific and effective anti-tumor immune responses in both the allogeneic and autologous setting. It is also likely that new clinical research approaches will be required to accurately evaluate novel CSC-targeting strategies. Owing to the capacity to produce remissions in most diseases, SCT may provide the ideal clinical platform to carry out these investigations by studying the ability of anti-CSC agents to prolong relapse free and overall survival.

Misfolded or unfolded proteins are often refolded with the help of chaperones or degraded by the 26S proteasome. An alternative fate of these proteins is the aggresome pathway. The microtubule-organizing center (MTOC) transports unfolded proteins to lysosomes and are degraded through autophagy. Histone deacetylase 6 (HDAC6) deacetylates alpha-tubulin, which is thought to be a component of the MTOC. Recently, two small molecule inhibitors of the aggresome pathway and HDAC6 have been described. One inhibitor, tubacin, prevents deacetylation of alpha-tubulin and produces accumulation of polyubiquitinated proteins and apoptosis. Tubacin acts synergistically with the proteasome inhibitor, bortezomib, to induce cytotoxicity in one type of hematologic malignancy, multiple myeloma. The other, LBH589, is a pan HDAC inhibitor and hydroxamic acid derivative that induces apoptosis of multiple myeloma cells resistant to conventional therapies. In this review, we summarize recent reports on targeting the aggresome pathway and HDAC6 in hematologic malignancies.

Misfolded or aggregated proteins have two fates: they are either refolded with the help of chaperones or degraded by the proteasome. Cells also have an alternative pathway that involves intracellular “storage bins” for misfolded intracellular proteins known as aggresomes. Aggresomes recruit motor proteins that transport misfolded or aggregated proteins to chaperones and proteasomes for subsequent destruction. There is emerging evidence that inhibiting the aggresome pathway leads to accumulation of misfolded proteins and apoptosis in tumor cells through autophagy. We discuss the role of aggresomes in cancer and the potential to target this pathway for therapy. [Cancer Res 2008;68(8):2557–60]

Despite extensive study in many malignancies, maintenance therapy has clinically benefited only two diseases: acute lymphocytic leukemia (ALL) and acute promyelocytic leukemia (APL). ALL maintenance therapy utilizes low-dose 6-mercaptopurine (6MP) and methotrexate (MTX), while maintenance in APL primarily consists of all-trans-retinoic acid (ATRA). 6MP and MTX as used in ALL are also now usually added to maintenance ATRA for APL, based on data suggesting an improved disease-free survival. Although the mechanism of action of MTX and 6MP as maintenance is unknown, low-dose cytotoxic agents are potent inducers of differentiation in vitro. Thus, we studied whether maintenance therapy in ALL, like ATRA in APL, may be inducing terminal differentiation of ALL progenitors. The APL cell line NB4, the ALL cell lines REH and RS4;11, and patients' ALL blasts were incubated with ATRA, 6MP, and MTX in vitro. All three drugs inhibited the clonogenic growth of the APL and ALL cell lines without inducing immediate apoptosis, but associated with induction of phenotypic differentiation. The three drugs similarly upregulated lymphoid antigen expression, while decreasing CD34 expression, on patients' ALL blasts. These data suggest that induction of leukemia progenitor differentiation plays an important role in the mechanism of action of maintenance therapy in ALL.

Extracorporeal photopheresis (ECP) is a commonly used treatment for severe graft-versus-host-disease (GVHD). We sought to evaluate the effects of ECP over a prolonged period on forced expiratory volume in 1 s (FEV1) in patients with pulmonary GVHD. We identified eight patients who developed new airflow obstruction following allogeneic stem cell transplantation and a substantial decline in FEV1 despite receiving corticosteroids and standard therapy for pulmonary GVHD. Those eight patients were treated with ECP for a period of 1 year, with a primary endpoint of FEV1 change during this treatment period. Over the first 3 months of ECP, there was no further decline in FEV1 in seven of the eight patients. However, over the 1 year period, only two of the eight patients had stability in FEV1. The rate of FEV1 decline was substantially less once ECP was initiated, though the median FEV1 continued to decline over 1 year of therapy. All patients survived through the first year of ECP therapy. There was a significant decrease in the median dose of prednisone per patient throughout the 12 months of ECP treatment. ECP shows promise in slowing rate of decline of FEV1 in pulmonary GVHD, though the effects may not be long lived. J. Clin. Apheresis 31:347-352, 2016. © 2015 Wiley Periodicals, Inc.

Background Invasive fungal infections remain problematic in immunosuppressed allogeneic stem cell transplant recipients and the use of corticosteroids for the treatment of graft-versus-host-disease can increase the risk threefold. Although antifungal prophylaxis has been shown to decrease the incidence of infection, the optimal antifungal prophylactic regimen in this patient population has yet to be identified. Since early diagnosis of fungal infections might not be possible and the treatment of established fungal infections might be difficult and associated with high infection-related mortality, prevention has become an important strategy in reducing overall morbidity and mortality. While triazoles are the preferred agents, some patients are unable to tolerate them and an alternative drug is warranted. Objectives To assess the tolerability of once weekly liposomal amphotericin B as a prophylactic strategy in patients undergoing stem cell transplantation by evaluating any adverse events leading to its discontinuation. In terms of efficacy, to also compare the outcome and incidence of invasive fungal infections in patients who received amphotericin B, triazoles, and echinocandins. Results A total of 101 allogeneic transplant recipients receiving corticosteroids for the treatment of graft-versus-host-disease and antifungal prophylaxis were evaluated from August 2009 to September 2012. Liposomal amphotericin B 3 mg/kg intravenous once weekly was found to be well tolerated. The incidence of invasive fungal infections was 19%, 17%, and 7% in the liposomal amphotericin B, echinocandin, and triazole groups, respectively. Two deaths occurred in the liposomal amphotericin B group and one death occurred in the echinocandin group. None of the deaths were fungal infection related. Conclusion Antifungal prophylaxis with liposomal amphotericin B was well tolerated, but the incidence of invasive fungal infections in patients receiving liposomal amphotericin B was higher than other antifungal agents in this study. The optimal dose and schedule of liposomal amphotericin B for antifungal prophylaxis in this patient population are still not known and considering its broad spectrum activity, prospective trials in comparison to triazoles are warranted.

Survival rates for all stages of non-small-cell lung cancer (NSCLC) are dismal. Despite complete resection of early-stage NSCLC, many patients have recurrence at distant metastatic sites, reinforcing the need for effective systemic adjuvant therapy. Chemotherapy, and more recently, targeted therapies, have been evaluated in the adjuvant setting. Although initial trials did not suggest improved survival, a 1995 meta-analysis favored adjuvant cisplatin-based chemotherapy. The recently published International Adjuvant Lung Trial confirms this finding and suggests a new standard of care. In this paper we review data on adjuvant chemotherapy and limitations of recent clinical trials, including those with targeted therapies. We also address the most effective and least toxic regimens for adjuvant chemotherapy and the subsets of patients likely to derive the most benefit.

e19001 Background: Surveillance scans performed after autologous stem cell transplant (AutoSCT) for patients with relapsed/refractory (RR) diffuse large B Cell lymphoma (DLBCL) have no proven survival benefit. We studied survival differences among patients with RR DLBCL post AutoSCT whose recurrences were detected on clinical history and exam, versus those detected on routine surveillance scan. Methods: We retrospectively identified 139 patients from our institutional database with DLBCL who underwent AutoSCT from 2000 to 2014. All patients had surveillance scans performed at days 100, 180 and at 1-year post AutoSCT. Results: Among the 139 patients with RR DLBCL that underwent AutoSCT, 37 relapsed, of which 21 were clinical and 16 radiological. There were no statistically significant differences in patient characteristics, although more patients in the clinical cohort had extra-nodal and bulky disease (Table 1). The median time to progression was 167 days for the clinical cohort and 565 days for the radiological cohort (p= 0.03). Median follow-up was 587 days for the clinical cohort and 1503 days for the radiological cohort (p=0.002). Median overall survival (OS) was 587 days for the clinical cohort, and was not reached for the radiological cohort (p=0.006). Conclusions: In our review, most patients with relapsed DLBCL after AutoSCT were diagnosed clinically. Patients whose relapse was diagnosed clinically were likely to be detected earlier and have a shorter OS. Our data indicates that patients with aggressive disease may be detected when clinically relevant, regardless of scanning. Given the known risks of excess radiation exposure, our data suggests that routine scanning may not be necessary in the majority of patients with DLBCL following AutoSCT. [Table: see text]

e18507 Background: FLT3+ AML patients (pts; 20%-30% of AML pts) often have rapid post-induction relapse, highlighting the need for therapies that improve the bridge to SCT. CPX-351 is a liposomal formulation that delivers a synergistic 5:1 molar ratio of cytarabine (C) and daunorubicin (D). CPX-351 demonstrated efficacy versus 7+3 in a randomized, open-label, controlled phase III trial in pts aged 60-75 years with newly diagnosed, high-risk AML; our analysis investigated outcomes in the subset of FLT3+ pts. Methods: Pts were randomized 1:1 to induction with 1-2 cycles of CPX-351 (100 u/m2 [C 100 mg/m2 + D 44 mg/m2] on Days 1, 3, and 5 [2nd induction: Days 1 and 3]) or 7+3 (C 100 mg/m2/day x 7 days [2nd induction: x 5 days] + D 60 mg/m2on Days 1, 2, and 3 [2nd induction: Days 1 and 2]). Pts with complete remission (CR) or CR with incomplete platelet or neutrophil recovery (CRi) could receive up to 2 consolidation cycles. Results: Of the pts who had FLT3 mutations assessed and received study treatment, 22/138 (16%) pts in the CPX-351 arm and 20/136 (15%) pts in the 7+3 arm had baseline FLT3 mutations. AML subtypes in FLT3+ pts were: tAML (19%); AML after MDS with (38%) or without (10%) prior hypomethylating agents; AML after CMMoL (12%); and de novo AML with MDS karyotype (21%). In FLT3+ pts, median OS was longer with CPX-351 (10.25 mo) versus 7+3 (4.55 mo; HR = 0.57 [95% CI: 0.24, 1.33]; P= 0.093) and the rate of CR+CRi was higher (68% vs 25%). A greater number of FLT3+ pts treated with CPX-351 were able to undergo SCT (n = 10/22 [45%]; 4 pts were alive as of this analysis, after a median post-SCT follow up of 692 days [range: 96-769]) compared with 7+3 (n = 2/20 [10%]; neither pt still alive). The on-study safety profile of CPX-351 in FLT3+ pts was comparable to 7+3 and consistent with the overall study population. Serious adverse events were experienced by 7 (32%) FLT3+ pts in the CPX-351 arm and 10 (50%) in the 7+3 arm. Conclusions: CPX-351 demonstrated numerical improvement in median OS in older pts with newly diagnosed, FLT3+ high-risk AML and allowed more pts to undergo SCT. The analysis was limited by small number of pts. Clinical trial information: NCT01696084.

Acquired von Willebrand Syndrome (AVWS) is a rare bleeding disorder associated with hematoproliferative disorders, autoimmune conditions, neoplasia, and cardiovascular disorders that often presents a diagnostic challenge. Monoclonal gammopathy of undetermined significance (MGUS) is one of the most common causes of AVWS that typically presents later in life with mucocutaneous or postsurgical bleeding and multimers consistent with type I or II von Willebrand Disease (VWD). Here we present the case of a patient with a 32 year history of type III VWD that was ultimately found to be AVWS related to an IgG MGUS. In this case report, we highlight the diagnostic challenges of AVWS to ensure proper identification and potentially lifesaving treatment of this rare disorder.

High-dose chemotherapy and autologous hematopoietic cell transplantation (Auto-HCT) is an established therapy for patients with multiple myeloma and lymphomas. Post-transplant complications during the neutropenia phase include pancytopenia requiring transfusions and G-CSF support, mucositis and infectious complications. Previously, we have demonstrated that hyperbaric oxygen therapy (HBO) given day 0 prior to transplant reduced erythropoietin (EPO) levels and improved engraftment in umbilical cord blood transplantation. Subsequently, we conducted a pilot trial to study HBO effects EPO levels and engraftment in Auto-HCT setting. Herein, we review HBO effects on Auto-HCT post-transplant complications. Methods: Charts of patient who underwent HBO treatment prior to Auto-HCT on our pilot study and matched historic controls were retrospectively reviewed for post-transplant transfusion requirements, G-CSF support, mucositis and infectious complications Results: Nineteen patients completed HBO therapy and were compared to 118 patients in our historic cohort. Basic patient characteristics are listed in table-1. Average days of G-CSF use was 6.2 days in our HBO cohort compared to 9.16 days in the historic cohort (P=0.0007). Average number of transfused packed red cells was 2.1 and 2.58 units (P=0.22), while average number of platelet unit transfusions was 2.5 and 3.2 (P=0.17) in the HBO and historic cohorts, respectively. Mucositis incidence was 26.3% in the HBO cohort compared to 59.3% in controls (P=0.008). Similarly, the rate of neutropenic fever was 47% in the HBO cohort vs. 65% in controls (P=0.11). The rate of admissions, on the other hand, was 31.5% in the HBO cohort compared to 23.7% in controls (P=0.31) with an average length of hospital stay of 6.6 days in the HBO cohort compared to 7.68 days in controls (P=0.31). Conclusions: HBO therapy prior to Auto-HCT is associated with lower G-CSF use and lower incidence of mucositis in our retrospective study. Prospective studies are needed to determine HBO effects on Auto-HCT post-transplant complications. Disclosures Ganguly: Onyx: Speakers Bureau; Seattle Genetics: Speakers Bureau; Janssen: Research Funding.

Background: A majority of younger pts with AML receive initial therapy with a 7+3 scheme. Escalated doses of daunorubicin (dauno) in combination with standard doses of ara-C may lead to improved outcomes (Fernandez; NEJM 2009). A phase II trial of idarubicin and high-dose ara-C (IA) in combination with the histone deacetylase inhibitor vorinostat (IA+V) resulted in historically high response rates compared to IA or 7+3 (Garcia-Manero; JCO 2011). SWOG 1203 tested whether a high-dose ara-C induction with or without vorinostat could result in improved outcomes for younger AML pts compared to 7+3. Methods: The primary endpoints were comparison of event-free survival (EFS) of 7+3 vs IA vs IA+V and evaluating the frequency of allogeneic hematopoietic cell transplantation. Secondary endpoints included toxicity, remission rate, relapse-free survival (RFS), and overall survival (OS) according to treatment arm, and by cytogenetic and molecular subgroups. Because of the historical trend of cured pts in S0106, EFS was modeled with an exponential cure model, and it was assumed IA or IA+vorinostat increased the proportion of pts cured from 35% to 45% and increased median EFS among those not cured from 4.7 months to 7.1 months. Main inclusion criteria included a diagnosis of previously untreated non-APL AML by WHO criteria, age 15 to 60 years, and preserved cardiac function but no severe comorbidities. Pts with known CBF rearranged or FLT3 mutant leukemias were eligible if no other alternative clinical trials existed. Treatment was as follows: Induction: 7+3 arm: dauno 90 mg/m2 IV QD x 3 on days 1-3 with ara-C CI 100 mg/m2 QD x 7 days on days 1 to 7. IA arm: ida 12 mg/m2 QD x 3 on days 1 to 3 with 24 hours CI ara-C 1.5 gm/m2 QD for 4 days on days 1 to 4. IA+vorinostat was as IA but with vorinostat 500 mg orally TID for 3 days on days 1 to 3. Consolidation: 7+3 arm: standard high-dose ara-c at 3 gm/m2 over 3 hrs q12 hours x 6 doses for 1 to 4 cycles depending on transplant availability. IA arm: idarubicin 8 mg/m2 IV QD x 2 days on days 1 to 2 with ara-C 0.75 gm/m2 CI for 3 days on days 1 to 3 for 4 cycles. The number of consolidation cycles depended on transplant indication; a secondary aim of the study was to transplant all cytogenetically-determined high risk pts (presented in a different abstract). Results: Of 754 pts randomized, 738 were eligible (261 to 7+3, 261 to IA, and 216 to IA+V). Baseline characteristics were well balanced among all three groups. Most (75%) pts were between 40 and 60 years, 51% were male, median (range) WBC and platelets were 10.8 (0.3-800) and 49 (3-3900), respectively; marrow blast percentage was 60% (0%-100%); cytogenetics were favorable in 13% of pts, intermediate in 63%, and high-risk in 22%; FLT-3 was mutated in 21% and unknown in 31%; NPM1 was mutated in 20% and was unknown in 37%. Complete remission (CR) rates were 75% for 7+3, 79% for IA, and 77% for IA+V (p=0.58). Significantly more pts received reinduction with 7+3 (24%) versus 11% with IA and 9% with IA+V (p=0.001). 48% of intermediate and unfavorable risk pts received transplant in CR1, with no significant differences among arms (p=0.44). There were no significant differences in EFS, RFS or OS among all three arms (Figure 1, all p>0.5). By cytogenetic or molecular group, there were no differences in outcome for any standard risk subset (FLT-3, NPM1, or CEBPα or cytogenetic subset), although pts with favorable cytogenetics had significantly better EFS, RFS and OS with 7+3 therapy compared to IA or IA+V (Figure 2, all p≤0.015). 30% of pts received 1 consolidation cycle, 18% 2, 16% 3, and 37% 4 cycles. Grade 5 induction toxicity rates were 4% (7+3), 8% (IA), and 9% (IA+V) by arm (p=0.07), and for toxicities related to therapy, 2%, 7%, 8%, respectively (p=0.01). Grade 4 induction toxicity rates were similar across arms (p=0.38). Conclusion: Treatment with IA is not more effective than 7+3 in younger pts with AML. Outcomes with IA or IA plus vorinostat are similar. In pts with favorable cytogenetics, outcomes were inferior with IA or IA+V when compared to 7+3, perhaps related to use of lower doses of ara-C during consolidation. Clinical Trials Registry: NCT #0180233 Support: NIH/NCI grants CA180888, CA180819, CA18020, CA180821, CA180863, CA077202; CCSRI grant #021039 Disclosures Othus: Glycomimetics: Consultancy; Celgene: Consultancy. Radich:Novartis: Consultancy, Research Funding; Ariad: Consultancy; BMS: Consultancy. Strickland:Alexion Pharmaceuticals: Consultancy; Astellas Pharma: Research Funding; Baxalta: Consultancy; Cyclacel: Research Funding; Celator: Research Funding; Abbvie: Research Funding; Ambit: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Savoie:Novartis: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria; Pfizer: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Jazz: Consultancy; Lundbeck: Consultancy. Sekeres:Millenium/Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Stone:Amgen: Consultancy; Karyopharm: Consultancy; Juno Therapeutics: Consultancy; Roche: Consultancy; Pfizer: Consultancy; Agios: Consultancy; Jansen: Consultancy; Xenetic Biosciences: Consultancy; Celator: Consultancy; Merck: Consultancy; Abbvie: 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; Novartis: Consultancy; ONO: Consultancy; Seattle Genetics: Consultancy; Sunesis Pharmaceuticals: Consultancy. Erba:Sunesis: Consultancy; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy, Speakers Bureau; Gylcomimetics: Other: DSMB; Ariad: Consultancy; Astellas: Research Funding; Gylcomimetics: Other: DSMB; Amgen: Consultancy, Research Funding; Pfizer: Consultancy; Gylcomimetics: Other: DSMB; Astellas: Research Funding; Astellas: Research Funding; Amgen: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Celgene: Consultancy, Speakers Bureau; Juno: Research Funding; Seattle Genetics: Consultancy, Research Funding; Jannsen: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy; Sunesis: Consultancy; Millennium Pharmaceuticals, Inc.: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Agios: Research Funding; Celator: Research Funding; Ariad: Consultancy; Agios: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Jannsen: Consultancy, Research Funding; Juno: Research Funding; Agios: Research Funding; Jannsen: Consultancy, Research Funding; Novartis: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Incyte: Consultancy, DSMB, Speakers Bureau; Juno: Research Funding; Pfizer: Consultancy; Millennium Pharmaceuticals, Inc.: Research Funding; Celator: Research Funding; Daiichi Sankyo: Consultancy; Agios: Research Funding; Celator: Research Funding; Daiichi Sankyo: Consultancy; Millennium Pharmaceuticals, Inc.: Research Funding; Pfizer: Consultancy; Celator: Research Funding; Jannsen: Consultancy, Research Funding; Sunesis: Consultancy; Seattle Genetics: Consultancy, Research Funding; Astellas: Research Funding; Ariad: Consultancy; Ariad: Consultancy; Millennium Pharmaceuticals, Inc.: Research Funding; Seattle Genetics: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Sunesis: Consultancy; Pfizer: Consultancy; Juno: Research Funding; Celgene: Consultancy, Speakers Bureau; Gylcomimetics: Other: DSMB.

Introduction CPX-351 (Vyxeos), a liposomal formulation of cytarabine and daunorubicin encapsulated at a 5:1 molar ratio, has shown enhanced efficacy compared with standard induction in older adults with high-risk AML in phase II clinical trials. Presented here are pre-specified secondary subgroup results from a phase III randomized, open-label study of CPX-351 versus 7+3 (cytarabine plus daunorubicin) in newly diagnosed patients with high-risk features, focusing on efficacy results stratified by age group. Methods Eligible patients were aged 60 to 75 years and had secondary AML, either therapy-related or an antecedent myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia, or AML with World Health Organization-defined MDS-related cytogenetic abnormalities. Patients were randomized 1:1 to receive CPX-351 induction (100 units/m2 [100 mg/m2 cytarabine + 44 mg daunorubicin mg/m2] on days 1, 3, and 5 [first induction only]) or 7+3 induction (cytarabine 100 mg/m2/day x 7 days plus daunorubicin 60 mg/m2 on days 1, 2, and 3 [first induction] or x 5 days [reinduction/consolidation] plus daunorubicin 60 mg/m2 on days 1 and 2). A dynamic allocation procedure was performed to stratify patients by age group (60-69 or 70-75 years) for each arm of the study. The distribution of overall survival (OS) by treatment arm was estimated using the method of Kaplan-Meier. Efficacy for each age group was reported in terms of median OS in months and percentage of patients with a morphologic complete remission (CR) or CR with incomplete platelet or neutrophil recovery (CRi) according to International Working Group criteria. Results Three hundred and nine patients were enrolled from December 2012 to November 2014 at 39 US and Canadian sites, with 153 patients randomized to the CPX-351 arm and 156 to the 7+3 arm. Among patients aged 60-69 years, there were 96 patients in the CPX-351 arm and 102 in the 7+3 arm; for patients aged 70-75 years, there were 57 and 54 patients in each arm, respectively. Demographic data for these age subgroups were similar between the CPX-351 and 7+3 arms of the study. The CR+CRi rates for patients aged 60-69 years were 50.0% for patients in the CPX-351 arm and 36.3% in the 7+3 arm, with an odds ratio (OR) of 1.76 (95% confidence interval [CI], 1.00-3.10); for patients aged 70-75 years, the rates of CR+CRi were 43.9% and 27.8%, respectively, with an OR of 2.03 (95% CI, 0.92-4.49). Kaplan-Meier curves for OS by age group are shown in the Figure. Median OS in months for patients aged 60-69 years was 9.63 in the CPX-351 arm and 6.87 in the 7+3 arm, with a hazard ratio of 0.68 (95% CI, 0.49-0.95); for patients aged 70-75 years these were 8.87 for the CPX-351 arm and 5.62 for the 7+3 arm, with a hazard ratio of 0.55 (95% CI, 0.36-0.84). The allogeneic hematopoietic cell transplant (HCT) rate in patients aged 60-69 years was 37.5% in the CPX-351 arm and 32.4% in the 7+3 arm, with an OR of 1.25 (95% CI, 0.70-2.25). For patients aged 70-75 years, the allogeneic HCT rates were 28.1% and 11.1%, respectively, with an OR of 3.12 (95% CI, 1.12-8.72). Incidence of grade 3-5 adverse events were virtually equal (92% vs 91%) and were similar in frequency and severity in both arms. The most common grade 3-5 nonhematologic adverse events (>10% overall) were febrile neutropenia (CPX-351: 68%; 7+3: 71%), pneumonia (CPX-351: 20%; 7+3: 15%), and hypoxia (CPX-351: 13%; 7+3: 15%). Conclusions This subgroup analysis of patients aged 60-69 and 70-75 years with untreated secondary AML demonstrated that CPX-351 treatment had substantially greater median OS and higher CR+CRi rates than standard 7+3 (cytarabine and daunorubicin) in both age groups. In addition, somewhat more patients in each age group in the CPX-351 arm received allogeneic HCT compared with the 7+3 arm, with the greatest difference in the older age group. Future studies with larger patient groups are warranted. Support: Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc. Disclosures Medeiros: Agios: Consultancy, Research Funding; Amgen: Consultancy; ARIAD: Consultancy; Celgene: Consultancy, Other: Travel, Accomodations, Expenses, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy; Roche/Genentech: Consultancy, Research Funding; Celator: Other: Travel, Accomodations, Expenses, Research Funding; MEI Pharma: Research Funding; Merck/Schering Plough: Research Funding. Lancet:Celgene: Consultancy, Research Funding; Quantum First: Consultancy; Kalo Bios: Consultancy; Pfizer: Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy; ERYtech: Consultancy; Biopath Holdings: Consultancy; Karyopharm: Consultancy; Boehringer-Ingelheim: Consultancy; Seattle Genetics: Consultancy; Baxalta: Consultancy; Amgen: Consultancy. Cortes:ARIAD: Consultancy, Research Funding; Bristol-Myers Squib: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. Ritchie:Celgene: Consultancy, Other: Travel, Accomodations, Expenses, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Ariad: Speakers Bureau; Pfizer: Consultancy, Research Funding; Astellas Pharma: Research Funding; Bristol-Meyers Squibb: Research Funding; NS Pharma: Research Funding. Stuart:Astellas: Research Funding; Incyte: Research Funding; Agios: Research Funding; Sunesis: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding; Bayer: Research Funding; Celator: Research Funding. Strickland:Sunesis Pharmaceuticals: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy, Research Funding; Celator: Research Funding; Astellas Pharma: Research Funding; Alexion Pharmaceuticals: Consultancy; Sanofi: Research Funding; CTI Biopharma: Consultancy; Karyopharm Therapeutica: Research Funding; Baxalta: Consultancy; Daiichi Sankyo: Consultancy; Ambit: Consultancy; Abbvie: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding. Hogge:Sanofi: Consultancy; Roche: Other: Travel, Accomodations, Expenses. Stone:ONO: Consultancy; Xenetic Biosciences: Consultancy; Seattle Genetics: Consultancy; Amgen: Consultancy; Agios: Consultancy; Karyopharm: Consultancy; Abbvie: 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; Novartis: Consultancy; Juno Therapeutics: Consultancy; Celator: Consultancy; Roche: Consultancy; Sunesis Pharmaceuticals: Consultancy; Merck: Consultancy; Pfizer: Consultancy; Jansen: Consultancy. Kolitz:Gliead Sciences: Consultancy; Seattle Genetics: Consultancy; Pharmacyclics: Consultancy. Schiller:Celator: Research Funding. Ryan:AbbVie: Equity Ownership; U of Rochester: Patents & Royalties. Chiarella:Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc.: Employment, Equity Ownership. Louie:Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc.: Employment, Equity Ownership. Uy:Glycomimetics: Consultancy; Boehringer Ingelheim: Consultancy.

Background: Multiple studies have demonstrated the modest efficacy of low-dose cytarabine (LDAC) in older patients (≥65 years) with Acute Myeloid Leukemia(AML) who are unlikely to benefit from an anthracycline and cytarabine intensive induction [CR/CRi rates of 10 - 26%; (CRi = complete remission with incomplete marrow recovery)]. Venetoclax, a selective BCL-2 inhibitor has demonstrated single-agent activity in patients with relapsed and refractory AML [Konopleva et al., ASH 2014]. When administered with LDAC, the recommended phase 2 dose (RP2D) of venetoclax was 600 mg daily [Lin et al., ASCO 2016 (abstract 7007)]. Here we present the safety and efficacy data at RP2D of venetoclax from the dose escalation and expansion phases of the study (NCT02287233). Methods: Patients enrolled as of 15DEC2015 are included in this analysis with a data cut-off date of 31MAR2016. Patients were eligible if considered unfit for intensive chemotherapy, had an ECOG performance status of 0-2 and adequate renal and liver function. Patients treated with cytarabine for a pre-existing myeloid disorder, or those with acute promyelocytic leukemia or active CNS involvement with AML were excluded from the study. Venetoclax 600 mg was administered orally once daily on days 2 - 28 of Cycle 1 and days 1 - 28 of subsequent cycles. A 5-day dose ramp-up schedule was followed to reach the 600 mg dose. LDAC 20 mg/m2 was administered s.c. daily on days 1-10 in 28-day cycles. To mitigate the potential risk of tumor lysis syndrome (TLS), all patients were hospitalized and received prophylaxis commencing 48 hours prior to venetoclax during Cycle 1. Adverse events (AEs) were graded by NCI CTCAE Version 4.0. Results: Twenty patients were enrolled in the study (escalation, n=8; expansion, n=12). The median age was 74 years (range: 66 - 87). 8/20 (40%) patients had an antecedent hematologic disorder. Median time on venetoclax was 147.5 days (range: 8 - 455). Grade 3/4 AEs (≥10% patients) excluding cytopenias were febrile neutropenia (35%), hypertension (20%), hypophosphatemia (20%), decreased appetite, increased blood bilirubin, hyponatremia, hypoxia, hypotension, pneumonia, sepsis, syncope, urinary tract infection, and vomiting (10% each). No events of TLS occurred. Venetoclax exposures on Cycle 1 Day 10 (with LDAC) vs. Cycle 1 Day 18 (venetoclax alone) were comparable. The mean ± SD of maximum observed concentration (Cmax, µg/mL/mg) were 2.04 ± 1.45 vs. 2.92 ± 2.15, respectively. The mean ± SD of area under the curve (AUC24, µg*hr/mL) were 33.3 ± 27.5 vs. 46.1 ± 36.8, respectively. Similarly, co-administration of venetoclax did not markedly affect LDAC exposures. The mean ± SD of Cmax (ng/mL) of LDAC on Cycle 1 Day 1 (LDAC alone) vs. Cycle 1 Day 10 (with venetoclax) were 158.89 ± 79.08 vs 166.49 ± 32.06, respectively. Similarly, the mean ± SD of AUCinf (ng*hr/mL) were 170.64 ± 102.86 vs 246.51 ± 93.41, respectively. 15/20 (75%) patients achieved an objective response (CR+CRi+PR). Of them, 14/20 (70%) patients had a CR+CRi; all 14 patients belonged to a subset of 18 patients with no prior myeloproliferative neoplasm (MPN). 16/19 (84%) patients with available data had their bone marrow blast percentage reduced to below 5%. The 12-month overall survival (OS) estimate for all patients was 74.7% (95% CI=49.4 - 88.6) and that for the responders (n=15) was 86.7% (95% CI=56.4 - 96.5). The overall response rates and 12-month OS estimates for patients with or without prior hypomethylating agent (HMA) and with or without MPN are summarized in Table 1. A Kaplan-Meier curve showing OS for responders vs. non-responders is shown in Figure 1. The median time to best response was 30 days (range: 23 - 169). Only 2/14 patients who achieved CR/CRi have died [disease progression (n=1), acute hepatic failure (n=1)]. Conclusions: Venetoclax (600 mg RP2D) plus LDAC demonstrated an acceptable safety and pharmacokenitic profile in patients aged ≥65 years with treatment-naive AML who are not eligible for an intensive anthracycline-containing induction chemotherapy. Clinical remission was achieved in the majority of patients. The median OS has not been reached. A substantially better survival in responders as compared to non-responders suggests that the improvement is likely due to treatment with venetoclax plus LDAC. Updated responses and survival estimates for all patients, including those in dose expansion phase that were enrolled after the preliminary data cut, will be presented. Disclosures Wei: Novartis: Honoraria, Research Funding. Strickland:Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sanofi: Research Funding; Sunesis Pharmaceuticals: Consultancy, Research Funding; Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding. Roboz:Agios, Amgen, Amphivena, Astex, AstraZeneca, Boehringer Ingelheim, Celator, Celgene, Genoptix, Janssen, Juno, MEI Pharma, MedImmune, Novartis, Onconova, Pfizer, Roche/Genentech, Sunesis, Teva: Consultancy; Cellectis: Research Funding. Fiedler:Amgen: Consultancy, Other: Travel, Patents & Royalties, Research Funding; Kolltan: Research Funding; Novartis: Consultancy; Teva: Other: Travel; Ariad/Incyte: Consultancy; Gilead: Other: Travel; Pfizer: Research Funding; GSO: Other: Travel. Martinelli:MSD: Consultancy; Celgene: Consultancy, Speakers Bureau; Ariad: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Genentech: Consultancy; BMS: Speakers Bureau; Novartis: Speakers Bureau; Roche: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau. Fakouhi:AbbVie Inc.: Employment, Other: may own stock. Darden:AbbVie Inc.: Employment, Other: may own stock. Dunbar:AbbVie Inc.: Employment, Other: may own stock. Zhu:AbbVie Inc.: Employment, Other: may own stock. Agarwal:AbbVie Inc.: Employment, Other: may own stock. Salem:AbbVie Inc.: Employment, Other: Stocks or options. Mabry:AbbVie Inc.: Employment, Other: May own stock. Hayslip:AbbVie Inc.: Employment, Other: May own stock.

Introduction: The optimal treatment of older patients with Acute Myeloid Leukemia (AML) is unclear. Traditional induction chemotherapy is less effective in older patients and often more toxic. Clinical trials for elderly AML patients feature inclusion/exclusion criteria based on "fitness" for chemotherapy that often include subjective assessments and variable enrollment criteria. Determining "fitness" remains controversial, and there are few validated objective markers to assist in determining whether a patient is "fit" or "unfit" for intensive induction chemotherapy. Previously published work identified a Short Physical Performance Battery (SPPB) score < 9 and a Modified Mini-Mental Status (3MS) score Methods: Beginning December 2015, patients age ≥ 60 who presented with new or relapsed AML were evaluated using the 3MS and SPPB tests. To increase objectivity, the 3MS and SPPB tests were performed by a non-treating provider when possible. Patients who were determined to be a fall risk by history had their SPPB test performed by a specially trained physical therapist. Scores were made immediately available to the treating physician and were used as a guide to determine if the patient was "fit" for intensive therapy or "unfit". If "unfit" the patient was evaluated for a clinical trial for "unfit" patients, hypomethylating agents or best supportive care (BSC). Scores were taken into context with age and comorbidities for treatment decisions. Results: Testing was feasible using the SPPB and 3MS and easy to implement, with testing taking approximately 15 minutes. A total of 21 new or relapsed AML patients have been evaluated. The median age was 72, ranging from age 60-83. There were10 male and 11 female patients. Three patients had relapsed disease. Fifteen patients had evaluable data >60 days. Seven were determined "fit" for intensive chemotherapy. Median SPPB and 3MS scores were 9 and 95, respectively. Six achieved remission following intensive induction therapy. One patient underwent allogeneic stem cell transplant and remains in remission. Three relapses occurred at days 44, 50 and 54 from initial induction therapy. Two deaths occurred from relapsed disease at days 148 and 175 from initial induction and one death from infection at day 54 during consolidation therapy. Eight patients were determined to be "unfit" for intensive chemotherapy. Median SPPB and 3MS scores were 5 and 93, respectively. Two patients received BSC based on clinical judgement and died at days 32 and 50 from initial diagnosis. Both were the only patients of 21 evaluated to have a 3MS score < 77. Four patients were eligible for clinical trials at our institution. Two deaths occurred 95 and 52 days from initiation of clinical trial, and 2 remain on trial at 61 and 65 days from initial therapy with one in complete remission. Two patients were given decitabine. One died at 34 days from initial therapy due to infectious complications and the other remains on treatment. Conclusion: Performance of the SPPB and 3MS tests on patients age ≥ 60 is feasible and should be considered at diagnosis for elderly AML patients. Our group found that the use of objective measures was most helpful in identifying the two patients who had impaired cognition at baseline with 3MS scores < 77. The use of a second provider as an examiner allowed for thoughtful discussion regarding choice of initial therapy. Based on this pilot, further investigation and validation of SPPB and 3MS testing for "fitness" prior to determining choice of therapy in patients with new or relapsed AML age ≥ 60 should be pursued. Disclosures No relevant conflicts of interest to declare.

Introduction Intensive induction chemotherapy for acute myeloid leukemia (AML) in patients aged 60 years or older has lower remission rates with increased induction mortality compared with younger patients. CPX-351 (Vyxeos) is a liposomal formulation of cytarabine and daunorubicin encapsulated at a 5:1 molar ratio. Previously reported results from a phase III, randomized, open-label study of CPX-351 versus 7+3 (cytarabine and daunorubicin) in newly diagnosed older patients with secondary AML suggested superior survival in those randomized to CPX-351. We conducted an exploratory analysis of patients who received allogeneic hematopoietic cell transplantation (HCT) after induction treatment, to determine the effect of HCT on outcome by arm, as few patients in this age range can be cured with chemotherapy alone. Methods This phase III trial was a randomized, open-label, parallel-arm, standard therapy-controlled study. Eligible patients were aged 60 to 75 years with newly diagnosed secondary AML defined as having a history of prior cytotoxic treatment, antecedent myelodysplastic syndrome (MDS) (± prior treatment with hypomethylating agents), or AML with World Health Organization-defined MDS-related cytogenetic abnormalities. Patients were randomized 1:1 to CPX-351 induction (100 units/m2 [100 mg/m2 cytarabine + 44 mg daunorubicin mg/m2] on days 1, 3, and 5 [first induction only]) or 7+3 induction (cytarabine 100 mg/m2/day x 7 days plus daunorubicin 60 mg/m2 on days 1, 2, and 3 [first induction] or x 5 days [reinduction/consolidation] plus daunorubicin 60 mg/m2 on days 1 and 2). The distribution of overall survival (OS) after HCT in each treatment arm was estimated using the Kaplan-Meier method, and Cox regression hazard ratio and OS rates, along with corresponding confidence intervals, are reported. Results Three hundred and nine (309) patients were enrolled from December 2012 to November 2014 at 39 US and Canadian sites, with 153 patients randomized to the CPX-351 arm and 156 to the 7+3 arm. Patients in either arm responding to induction with a complete response (CR) or a CR with incomplete platelet or neutrophil recovery (n=125) were considered for allogeneic HCT when possible. In total, 91 patients were transplanted: 52 (34%) from the CPX-351 arm and 39 (25%) from the 7+3 arm. Patient and AML characteristics were similar according to randomized arm, including percentage of patients in each arm that underwent transplant in CR/CRi status (Table); however, the CPX-351 arm contained a higher percentage of older patients (age ≥ 70) who were transplanted (CPX-351, 31%; 7+3, 15%). Mortality at 100 days after transplant was 9.6% for patients in the CPX-351 arm and 20.5% in the 7+3 arm patients. Causes of death Conclusions An exploratory analysis from this phase III study demonstrated that CPX-351, compared with standard cytarabine and daunorubicin, resulted in better outcomes after allogeneic HCT in older patients with high-risk AML, including 53% fewer deaths within 100 days of transplant. These results suggest that CPX-351 may provide an effective bridge to successful transplant for a very poor-risk subgroup of AML patients. Support: Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc. Disclosures Uy: Boehringer Ingelheim: Consultancy; Glycomimetics: Consultancy. Cortes:ARIAD: Consultancy, Research Funding; Bristol-Myers Squib: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. Ritchie:Astellas Pharma: Research Funding; Ariad: Speakers Bureau; Celgene: Consultancy, Other: Travel, Accomodations, Expenses, Speakers Bureau; Pfizer: Consultancy, Research Funding; Incyte: Consultancy, Speakers Bureau; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; NS Pharma: Research Funding; Bristol-Meyers Squibb: Research Funding. Stuart:Celator: Research Funding; Incyte: Research Funding; Astellas: Research Funding; Sunesis: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding; Agios: Research Funding; Bayer: Research Funding. Strickland:Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Hogge:Sanofi: Consultancy; Roche: Other: Travel, Accomodations, Expenses. Stone:Sunesis Pharmaceuticals: Consultancy; Xenetic Biosciences: Consultancy; Agios: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celator: Consultancy; Roche: Consultancy; Seattle Genetics: Consultancy; Juno Therapeutics: Consultancy; Jansen: Consultancy; Merck: Consultancy; ONO: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy. Kolitz:Gliead Sciences: Consultancy; Pharmacyclics: Consultancy; Seattle Genetics: Consultancy. Schiller:Celator: Research Funding. Ryan:AbbVie: Equity Ownership; U of Rochester: Patents & Royalties. Chiarella:Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc.: Employment, Equity Ownership. Louie:Celator Pharmaceuticals, Inc., a subsidiary of Jazz Pharmaceuticals plc.: Employment, Equity Ownership. Medeiros:MEI Pharma: Research Funding; Merck/Schering Plough: Research Funding; Celgene: Consultancy, Other: Travel, Accomodations, Expenses, Research Funding; ARIAD: Consultancy; Celator: Other: Travel, Accomodations, Expenses, Research Funding; Roche/Genentech: Consultancy, Research Funding; Pfizer: Consultancy; Novartis: Consultancy, Research Funding; Agios: Consultancy, Research Funding; Amgen: Consultancy.

Introduction: Multiple Myeloma (MM) is an incurable cancer characterized by a pre-malignant clonal phase of disease called monoclonal gammopathy of undetermined significance (MGUS). Most patients with MGUS do not develop overt MM and the biology underlying this potential transformation is unclear. Investigations to prevent the development of MM from MGUS are limited by the relative infrequency of MGUS progression. Unfortunately, MGUS cells have historically proven difficult to grow in vitro because of slow rates of proliferation and difficulty in sustaining cell cultures. We present evidence of an in vitro model that generates MM-like plasma cells from patients diagnosed with only MGUS. We further present gene expression patterns of primary patient cells versus the induced MM cells to provide guidance as to important initiating events within our model. Methods: We collected a CD38+ cell fraction and a mononuclear (CD38-) fraction from 4 patients with MGUS using a Miltenyl Biotec column Separator. The CD38- fraction was grown in RPMI with 10% FBS and 1% sodium pyruvate with or without a polyglycolic acid/ poly L-lactic acid 90/10 (PLGA) copolymer scaffold to create 3D culture conditions. The mononuclear layer from healthy donors and the MM cell line, U266, were grown as controls. We then analyzed the initial CD38+ fraction, the initial CD38- fraction, and the CD38- fraction grown in media or 3D co-culture by flow cytometry for expression of kappa, lambda, CD38, CD138, CD45, CD19, and CD56. Gene expression analysis was performed using RNA-sequencing data from the CD38+, CD38-, cultured CD38-, and control cells. Expression of the top 100 ranked differentially expressed genes, which demonstrated the largest variation, were further analyzed using the nCounter® Analysis System (NanoString Technologies). Results: The CD38- fraction from MGUS patients grew into an adherent layer of elongated cells, consistent with bone marrow stromal cells. After several months, the stromal cells were noted to change shape and new, round cells were observed budding off from the stromal layer. Over time, the stromal layer disappeared and the round plasmacytoid cells remained. Characterization of these round cells revealed them to be plasma cells by IHC and flow cytometry. When comparing these in vitro generated cells to the initial CD38+ fraction removed from patients, the new cells showed the re-emergence of CD38 and CD138, increased expression of CD56 and CD19, and decreased expression of CD45. Gene expression analysis revealed 3 distinct populations of cells. The initial CD38- fraction separated with the healthy mononuclear layer. The initial CD38+ fraction clustered independently while the grown plasma cells clustered with the U266 cells. Analysis of the differential gene expression patterns revealed differences in the expression of immunoglobulin genes, as well as alterations in expression of extracellular matrix and cell adhesion markers including PAI-1, MMP2, COL1A2, and GREM1; and alterations in expression of mitochondrial genes. Conclusion: To our knowledge, this is the first in vitro simulation of disease progression from MGUS to MM. Our model induced the growth of plasma cells with an aggressive phenotype as assayed by flow cytometry. The gene expression profile further demonstrates gene expression patterns from our induced plasma cells consistent with MM versus MGUS. The alterations in extracellular matrix proteins as seen in our induced plasma cells are consistent with an epithelial to mesenchymal type transition implicated in disease progression, metastasis, and bone lesions. Additionally, the alterations in mitochondrial gene expression have been implicated in early disease progression in colon cancer and MM. These findings provide further evidence that our model simulates disease transformation and the expression data suggest possible pathways that may be important in myeloma disease progression that can be further evaluated in vivo. Disclosures No relevant conflicts of interest to declare.

Background: Adult acute myeloid leukemia (AML) patients with high-risk cytogenetics have a significantly worse survival compared to similarly treated intermediate- or favorable-risk patients. Although prior studies suggest better outcome in high-risk AML patients in first complete remission (CR1) who undergo allogeneic hematopoietic cell transplantation (HCT) compared with consolidation chemotherapy, only 40% of patients proceed to HCT. The lack of a matched sibling donor (available in about 33%) should not be a barrier to HCT since alternative donors are available for the large majority of high-risk AMLpatients and recent data suggest outcomes after allogeneic HCT from fully matched unrelated donors are similar to those following matched related donor transplantation. We sought to determine if a prospective organized effort could rapidly identify alternative donors to improve the historical 40% allogeneic HCT rate in high-risk CR1 AML patients ≤ age 61. Secondly, we hypothesized that transplanting significantly more adults with high-risk AML in CR1 would lead to an improved outcome compared with the historical relapse-free survival (RFS) of 22%. Patients and Methods: Adult patients between ages 18 and 60 years with untreated AML were randomized to receive induction therapy with standard cytarabine plus daunorubicin (7+3; n=261), idarubicin with high-dose cytarabine (IA; n=261), or IA with vorinostat (IA+V; n=216). Conventional cytogenetics were obtained at time of enrollment and used to determine risk classification by standard criteria. All patients with high-risk cytogenetics underwent expedited HLA-typing. High-risk patientswere encouraged tobe referred for consultation with a transplant team with the goal of conducting an allogeneic HCT in CR1. Results: Of 738 eligible patients (median age, 49 years; range, 18-60), 159 (22%) had high-risk cytogenetics, of whom 60 (38%), 61 (38%), and 38 (24%) received induction with 7+3, IA, or IA+V, respectively. A total of 107 of the 159 high-risk patients achieved CR/CRi (67%). HCT was performed in 317 of all 738 patients (43%) and 68 (64%) of the high-risk patients received a transplant in CR1 (p Conclusions: In newly diagnosed adults with AML age 18-60, early cytogenetic testing with an organized effort to identify a suitable allogeneic HCT donorled to a CR1 transplant rate of 64% in the high-risk group, which in turn led to a significant improvement in RFS over historical controls. Better outcomes in poor prognosis AML patients may be achieved simply by rapidly finding unrelated donors and performing allogeneic HCT in CR1 as soon as possible. Clinical Trials Registry: NCT #0180233; Support: NIH/NCI grants: CA180888, CA180819, CA18020, CA180821, CA180863, CA077202; CCSRI #021039 Figure 1 Overall Survival (OS) among all patients in the high-risk cohort, all high-risk patients achieving CR1, and in those high-risk patients transplanted in CR1. Figure 1. Overall Survival (OS) among all patients in the high-risk cohort, all high-risk patients achieving CR1, and in those high-risk patients transplanted in CR1. Disclosures Othus: Glycomimetics: Consultancy; Celgene: Consultancy. Radich:Novartis: Consultancy, Other: laboratory contract; ARIAD: Consultancy; Pfizer: Consultancy; TwinStrand: Consultancy; Bristol-MyersSquibb: Consultancy. Strickland:Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Savoie:AbbVie: Consultancy; Lundbeck: Consultancy; BMS: Consultancy, Honoraria; Velgene: Consultancy; Pfizer: Consultancy; Amgen: Consultancy; Novartis: Consultancy, Honoraria; Jazz: Consultancy. Sekeres:Millenium/Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Stone:Amgen: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Xenetic Biosciences: Consultancy; Jansen: Consultancy; Pfizer: Consultancy; ONO: Consultancy; Juno Therapeutics: Consultancy; Merck: Consultancy; Roche: Consultancy; Seattle Genetics: Consultancy; Sunesis Pharmaceuticals: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy; Novartis: Consultancy; Celator: Consultancy; Karyopharm: Consultancy. Erba:Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy; Jannsen: Consultancy, Research Funding; Juno: Research Funding; Celator: Research Funding; Ariad: Consultancy; Agios: Research Funding; Amgen: Consultancy, Research Funding; Novartis: Consultancy, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Gylcomimetics: Other: DSMB; Sunesis: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Research Funding.

Introduction The vascular disrupting agent OXi4503 induces apoptosis in malignant myeloblasts by removing endothelial cell protection and sensitizing blasts to the cytotoxic effects of cytarabine by inducing them into the cell cycle (PMID 26898708). Cogle et al confirmed the safety and feasibility of single agent intravenous (IV) OXi4503 up to doses of 7.81 mg/m2 (maximum tolerated dose [MTD] not reached) in patients with relapsed/refractory acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Based on these data and pre-clinical evidence of synergy in vitro, a Phase 1b dose-finding study was initiated to evaluate the safety and tolerability of combined therapy with OXi4503 and cytarabine for a similar patient population. Methods The primary objective of this study (NCT02576301) was to determine the MTD of OXi4503 in combination with cytarabine in patients with relapsed/refractory AML or MDS. Pharmacokinetic (PK)/pharmacodynamic (PD) studies and a preliminary assessment of efficacy were secondary endpoints. Escalating doses of OXi4503 (in 5 cohorts starting from 3.75 mg/m2 and ending at 9.76 mg/m2) were administered IV over 10 minutes on Days 1 and 4. Fixed dose cytarabine (1 g/m2/day) was administered IV over 2 hours on Days 1-5 and on Days 1 and 4 cytarabine was administered 4 hours after the end of OXi4503 infusion. Cycles were repeated every 28 days for up to 4 cycles. Results A total of 22 patients (18 currently evaluable) with relapsed/refractory AML were enrolled, with Cohort 5 (9.76 mg/m2) in active treatment at time of writing. Median age was 61 years (range 26 - 77) and 67% were male; 83% of subjects had ECOG status 1 and 17% had ECOG status 2. Subjects had failed a median of 3 (range: 1-8) prior therapies and all had intermediate or poor-risk cytogenetics. Most patients (61%) received 1 cycle of investigational therapy while 39% of patients received 2 or more cycles. 11 of 18 patients (61%) withdrew from the study for progressive disease (PD), 4 of 18 patients (22%) withdrew with persistent AML, and 3 of 18 evaluable patients (17%) achieved a complete remission (CR). An additional 3 patients experienced reduction in bone marrow blasts but did not achieve a CR. CRs were durable for 12 months, 5 months, and one patient remains in ongoing remission for 5 months as of July 2017. One patient in the 3.75 mg/m2 cohort experienced a dose-limiting toxicity of hypofibrinogenemia, but with no clinical evidence of bleeding. Following correction with cryoprecipitate, fibrinogen returned to normal and remained normal unsupported. The most common Grade 3/4 treatment-related adverse events included neutrophil count decreased (28%), platelet count decreased (28%), febrile neutropenia (22%), anemia (17%), and WBC count decreased (11%). Adverse Events of all Grades are presented in Figure 1. Changes in coagulation parameters were common, with 14 of 18 (78%) patients experiencing one or more of: increase in D-Dimer, decrease in fibrinogen, INR or PTT increased. Clinically significant bleeding was not observed. The MTD has not yet been reached on this study. Conclusions The vascular disrupting agent OXi4503 in combination with cytarabine (1 g/m2/day) is well tolerated with preliminary evidence of activity in heavily pretreated, relapsed and refractory AML patients, including those with poor risk cytogenetic profiles. This Phase 1b study at time of writing showed evidence of activity at doses from 3.75 to 9.76 mg/m2 with 17% of patients achieving CR, suggesting a re-sensitizing effect to cytarabine. Additional studies of Oxi4503 in well-controlled clinical trials to further characterize the initial safety and efficacy of this novel agent are warranted. Disclosures Watts: Jazz Pharmaceuticals: Consultancy, Speakers Bureau. Cogle: Celgene: Other: Membership on Steering Committee for Connect MDS/AML Registry. Schiller: bluebird bio: Research Funding; mateon therapeutics: Research Funding. Lin: Jazz Pharmaceuticals: Consultancy.

Gastrointestinal ischemia following allogeneic bone marrow transplantation is a rare complication not well-described in the literature. Herein, we retrospectively review charts offour patients that developed intestinal ischemia following allogeneic bone marrow transplantation atour institution. The patients were found to be predominately younger males that presented with nonspecific abdominal pain. Graft versus host Disease was a common finding among all patients. Laboratory values suggestive of microangiopathy were present in two patients. Obesity and hypertriglyceridemia were of the cardiovascular risk factors that were found in patients. The development of intestinal thrombotic microangiopathy and cardiovascular risk factors after allogeneic bone marrow transplant may predispose patients to gastrointestinal ischemia and may portend a poor prognosis.

Bendamustine is an alkylating agent currently used in the treatment of lymphoproliferative disorders. Many adverse effects, including a rare case of reversible neurotoxicity, have been reported in association with bendamustine. Herein, we report the first case of irreversible ascending paralysis related to bendamustine.

7048Background: Umbilical cord blood (UCB) transplantation has a major drawback related to delayed or failed engraftment which increases post-transplant mortality. In a pilot clinical trial, we hav...

7000Background: Older patients with secondary AML have poor outcomes following first-line cytarabine and anthracycline-based treatment. CPX-351 is a liposomal formulation of cytarabine and daunorubicin encapsulated at a 5:1 molar ratio with enhanced efficacy among poor risk AML patients. We report final results from a randomized open-label study of first-line CPX-351 in patients with high-risk sAML (NCT01696084). Methods: Patients 60-75 years of age with untreated AML with a history of prior cytotoxic treatment, antecedent MDS or CMML (+/- prior hypomethylator treatment), or AML with WHO-defined MDS-related cytogenetic abnormalities were eligible. 300 patients were to be randomized 1:1 to CPX-351 (100 units/m2, days 1, 3, 5) or 7+3 (cytarabine 100 mg/m2/day x 7 days, daunorubicin 60 mg/m2 days 1, 2, 3) induction therapy. Endpoints included: overall (OS, 1o) and event free survival (EFS) assessed by stratified log rank analysis, independent blinded assessment of CR+CRi, and 60-day mortality. Patient enroll...

e18518Background: Insights into the biology of chemotherapy resistance may suggest novel strategies to treat Acute Myeloid Leukemia (AML). We examined the role of hyperbaric oxygen (HBO) in AML sen...

e19004Background: High-dose chemotherapy and autologous hematopoietic cell transplantation (Auto-HCT) is associated with neutropenia, anemia and thrombocytopenia in the post-transplant period. The ...

7007Background: Treatment options for older patients (pts) with acute myelogenous leukemia (AML) unfit for intensive chemotherapy are limited. Expected complete remission rates for low-dose cytarabine (LDAC) are about 10% in this population. Targeting the pro-survival molecule BCL-2 has demonstrated clinical efficacy as a therapeutic strategy in various hematologic malignancies. Venetoclax (VEN), a selective BCL-2 inhibitor, shows synergy with cytarabine in several AML cell lines and primary samples. Methods: This is a non-randomized, open-label phase 1/2 dose-escalation/expansion study of VEN + LDAC, in treatment-naive AML pts ≥ 65 years not eligible for intensive chemotherapy. Pts receive oral VEN once daily (QD) on days 1‒28 and subcutaneous LDAC 20 mg/m2 QD on days 1‒10 of each 28-day cycle. VEN dose escalation follows a 3 + 3 design; dose-limiting toxicities (DLTs: grade 4 toxicity, platelet count < 25,000/μL, or absolute neutrophil count < 500/μL within 14 days of last VEN dose) areassessed during c...

Emerging laboratory and clinical investigations demonstrate that Hedgehog signaling (Hh) represents a novel therapeutic target in various human cancers. This conserved signaling pathway precisely regulates self-renewal and terminal differentiation in embryonic development, but is typically silenced in adult tissues, with reactivation usually only during tissue repair. Aberrant Hh pathway signaling has been implicated in the pathogenesis, self-renewal, and chemotherapy resistance of a growing number of solid and hematologic malignancies. Major components of the Hh pathway include the Hh ligands (Sonic, Desert, and Indian), the transmembrane receptor Patched, the signal transducer Smoothened (Smo), and transcription factors Gli1-3 which regulate the transcription of Hh target genes. Mutations in Hh pathway genes, increased Hh signaling in tumor stroma, and Hh overexpression in self-renewing cells (cancer stem cells) have been described, and these different modes of Hh signaling have implications for the design of Hh pathway inhibitors and their integration into conventional treatment regimens. Discovery of a naturally-occurring Smo inhibitor, cyclopamine, and the identification of Hh pathway mutations and over expression in cancer cells prompted the development of several cyclopamine derivatives. Encouraging laboratory and in vivo data has resulted in Phase I and II clinical trials of Smo inhibitors. In this review, we will discuss the current understanding of Hh pathway signaling in malignancy and Smo antagonists in development. Recent data with these agents shows that they are well-tolerated and may be effective for subsets of patients. Challenges remain for appropriate patient selection and the optimal combination and sequence of these targeted therapies into current treatment paradigms.

Follicular lymphoma (FL) comprises nearly 25% of non-Hodgkin lymphoma cases and is clinically characterized by initial sensitivity to chemotherapy followed by relapse. FL stroma contains a special type of stromal cell found in the germinal centre of lymph nodes-the follicular dendritic cell (FDC). We first isolated tumourigenic cells from the FL cell line FLK-1 by side population (SP) technique, and found that SP cells, which express ABCG2, were enriched by chemotherapy and radiation treatments. In vitro, SP cells were attracted by and adhered to FDCs through chemokine (C-X-C motif) ligand 12/chemokine (C-X-C motif) receptor 4 (CXCL12/CXCR4) signalling. In vivo, limiting dilution assays showed SP cells were highly enriched in cancer stem cells (CSC), but required FDC for tumour formation in non-obese diabetic/severe combined immunodeficiency mice. Treatment with AMD3100, a specific CXCL12/CXCR4 inhibitor, eliminated tumour growth. These findings were then verified with FL cells isolated from an FL patient's ascitic fluid (FLA-1). Finally, we detected the ABCG2 expressing lymphoma cells in FL clinical specimens. Thus, we found that the highly tumourigenic FL cells having CSC-like activities (FL-SC) interact with FDCs in a CXCL12/CXCR4 dependent manner to resist chemotherapy. Our results indicate the importance of FL-SC and niche cell signalling in maintaining tumourigenicity. These signals represent novel targets for CSC eradication.

Background Limitations in umbilical cord blood (UCB) transplantations result from decreased cell numbers available for infusion at time of transplant. Delayed engraftment and higher rates of engraftment failure subsequently increase the need for post-transplant growth factor use and transfusion support. Hyperbaric oxygen (HBO) has been shown to improve engraftment in an animal model of UCB transplantation. These experiments proved sufficient to initiate a first-in-human trial of HBO for UCB transplantation. Objectives This study compared growth factor use and time to packed red blood cell (PRBC) and platelet transfusion independence between the HBO study population and historical UCB cases from the same institution. The effects of conditioning regimen and the number of cord units infused at time of transplant were analyzed. Study Design Subjects underwent HBO therapy at the University of Kansas Medical Center after reduced intensity conditioning (RIC) (n=9) or myeloablative conditioning (MAC) (n=6) regimens. Six hours following HBO therapy, they received single (n=8) or double (n=7) UCB units. Charts of HBO-treated patients and historical controls (n=44) were reviewed for post-transplant growth factor use and transfusion requirements. These were further stratified by preparative regimen and number of UCB units infused. Kaplan-Meier curves were compared between HBO and control subjects using log-rank tests as some observations were right-censored if the patient experienced relapse or expired within the first 100 days post-transplant. A small quantity was imputed to values of 0 to facilitate including these subjects in the analyses. Results By days +66 and +74 post-transplant, 100% of HBO-patients were PRBC and platelet independent, respectively. This compares to incomplete platelet (88.63%) and PRBC (86.36%) independence in the control cohort at day 100. Though time to transfusion independence (TTI) for PRBCs was consistently shorter in the HBO cohort, it was only statistically significant in the RIC setting and approached significance in the single cord setting (Table-1). TTI for platelets was shorter for the HBO cohort and approached statistical significance in the single cord setting. Similarly, the consecutive days of filgrastim support post-transplant were consistently fewer for HBO patients, with values approaching statistical significance in the MAC and single cord settings. Conclusions In vitro data with HBO and UCB showed improved rates of engraftment in animal models. Similarly, data in this small pilot study suggests that HBO facilitates less growth factor use and shorter TTI. However, these effects did not reach statistical significance in all settings, most likely due to small sample size of the HBO cohort. Further studies are needed to examine the effect of HBO on growth factor use, PRBC and platelet independence post-UCB transplantation. Table 1. A comparison of supportive transfusion means, between standard and HBO-UCB transplant recipients. These data are segregated for conditioning regimens and units of UCB infused for transplant. Group PRBC Units Platelet Units Days G-CSF Support TTI - PRBC TTI - Platelets HBO-total (n=15) 9 (p=0.30) 16.35 (p=0.31) 29.4 (p=0.08) 32.87 (p=0.07) 33.53 (p=0.11) Standard-Total (n=44) 9.29 17.14 35.02 56.09 54.8 HBO-Ablative (n=6) 5.43(p=0.23) 7.86 (p=0.16) 26.63 (p=0.07) 24 (p=0.53) 25.5 (p=0.45) Standard-Ablative (n=23) 11.93 22.29 35.65 66.13 67.78 HBO-RIC (n=9) 6.13 (p=0.66) 11.89 (p=0.78) 31.67 (p=0.44) 22.56 (p=0.02) 25.56 (p=0.11) Standard-RIC (n=21) 7.52 13.71 34.33 45.09 40.57 HBO-Single UCB (n=8) 5.43 (p=0.19) 7.87 (p=0.26) 26.63 (p=0.06) 24 (p=0.06) 25.5 (p=0.06) Standard-Single UCB (n=4) 10.25 24 36.2 74.4 70.2 HBO-Double UCB (n=7) 12.57 (p=0.87) 24.86 (p=0.95) 33.57 (p=0.70) 43 (p=0.74) 42.71 (p=0.95) Standard-Double UCB (n=40) 9.19 16.19 34.87 53.74 52.82 Disclosures No relevant conflicts of interest to declare.

Introduction: Patients with relapsed/refractory acute lymphoblastic leukemia (ALL) have a poor prognosis and limited treatment options. Blinatumomab was approved in 2014 for the treatment of relapsed/refractory Philadelphia chromosome-negative B-cell ALL. The largest published study of 189 patients with relapsed/refractory B-ALL showed a complete remission/complete remission without hematologic recovery of 43%. Here we report our single center experience in 7 patients with relapsed/refractory B-ALL treated with blinatumomab. Methods: We reviewed the charts of 7 adult patients with relapsed/refractory ALL. All patients were treated with blinatumomab 9 mcg daily as a continuous infusion on days 1-7, followed by 28 mcg daily as a continuous infusion on days 8 - 28 of a 6 week cycle. For cycle 2, 28 mcg daily as continuous infusion was given on days 1 - 28 of a 6 week cycle. Patients: The median age was 48 (range 23-70) and included 5 males/2 females. One patient had persistent disease after two cycles of induction (pt 4), 6 had relapsed B-ALL, and 4/6 had prior allogeneic stem cell transplant (SCT). Results: Two patients (28.6%) had complete remission and received allogeneic SCT in CR, 3 received additional therapy, 2 patient expired soon after blinatumomab. Three of 7 patients (42.9%) were unable to complete 2 cycles: patient 1 for progressive disease on cycle 1 day 13; patient 2 for trismus on cycle 2 day 17; patient 7 on cycle 2 day 8 for mental status changes which recurred after re-challenge. Other toxicities were relatively minor (rigors,headache). One patient (pt 7) developed a venous thromboembolism during the 2 week break period between cycles 1 and 2. Five patients are alive: three in CR post-SCT, one in CRi to other salvage therapy, and one on active therapy in a clinical trial. Conclusion: The observed response rates in our single center experience are not as high as reported in the clinical trials of blinatumomab in relapsed/refractory B-ALL. We saw responses in patients with MRD as well as one patient who had received 5 lines of prior therapy. It is not uncommon to see responses in clinical practice lower than those observed in a clinical trial. Studies are ongoing to determine the benefit of blinatumomab in other B-ALL settings. Our observed rates of CRS and neurologic toxicity were lower than those previously reported, and our experience suggests that it is relatively well-tolerated. Blinatumomab may be beneficial for some patients with B-ALL and provide a bridge to SCT for those who respond. Table 1. Pt Sex Age Prior treatments Prior SCT Bone marrow blast % prior tx # of cycles &Reason for discontinuation Toxicity Bone marrow blast % after tx Outcome 1 M 70 1 4 cycles of hyperCVAD, achieved CR Relapse at 9 months post-tx N 74% < 1 Stopped for progressive disease Grade 1 CRS 99% blasts in peripheral blood on day 13 Other salvage chemotherapy Expired 2 F 62 4 Allogeneic SCT in CR1 Relapse 3.5 years post-SCT Y 70% Disclosures No relevant conflicts of interest to declare.

Introduction: CPX-351 is a liposomal formulation of cytarabine and daunorubicin encapsulated at a fixed 5:1 molar ratio. It is highly effective in patients with high-risk acute myeloid leukemia (AML). This study evaluated the impact of CPX-351 (100 units/m2) on cardiac repolarization. Methods: This open-label, Phase II, pharmacokinetic (PK) and pharmacodynamic (PD) study entered AML and acute lymphocytic leukemia (ALL) patients with good risk hepatic function (Child-Pugh scores 480 ms were never observed and no consistent QTcF intervals >450 ms were noted. Absolute QTcF increases between 30 and 60 ms were present in 4 of 25 patients and no changes >60 ms were observed. CPX-351 plasma concentration vs. time curves for day 1 and 5 exhibited a volume of distribution approximately equal to the plasma volume with prolonged single-exponential elimination half-lives for cytarabine and daunorubicin of ≥24 hours. The PK of CPX-351 was independent of renal function. Patients with moderately impaired (eGFR=30-59 mL/min/1.73m2) renal function exhibited similar drug exposure as those with mild and normal renal function. | Analyte | Renal Function | | Cmax (ng/mL) | AUClast (ng*hr/mL) | AUCinf (ng*hr/mL) | T1/2 (hr) | | -------------- | -------------- | ----- | ------------ | ------------------ | ----------------- | --------- | | Cytarabine | Normal (n=3) | Mean | 59333 | 2893146 | 2902641 | 42.5 | | %CV | 28.7 | 68.8 | 69 | 34.1 | | Mild (n=7) | Mean | 58071 | 3599512 | 3606695 | 41.0 | | %CV | 31.9 | 52.4 | 52.4 | 21.8 | | Moderate (n=3) | Mean | 57333 | 3149303 | 3156738 | 38.0 | | %CV | 46.6 | 50.7 | 50.6 | 21.9 | | Daunorubicin | Normal (n=3) | Mean | 25967 | 754646 | 870861 | 24.9 | | %CV | 23.1 | 63 | 65.3 | 56.0 | | Mild (n=7) | Mean | 28686 | 865034 | 1021420 | 30.5 | | %CV | 43.9 | 43.5 | 43.6 | 25.3 | | Moderate (n=3) | Mean | 21933 | 671542 | 814732 | 35.4 | | %CV | 50.9 | 35.9 | 33.5 | 31.2 | Table 1. Impact of renal function impairment on Day 5 CPX-351 PK parameters (mean, %CV): Table 2 summarizes response and transplant outcomes. One of two ALL patients achieved CR and was transplanted. Among AML patients there were 7 CR and 2 CRi of which three went on to transplant. An additional four patients became morphologically leukemia free (MLF) and were transplanted before full documentation of CR was achieved. A large majority of patients given first-line treatment with CPX-351 responded or became suitable for transplant (10/13, 77%). | Diagnosis | n | Response CR/CRi | Transplanted in CR/CRi | Induced MLF and Transplanted | No Response | | ---------------------- | -- | ---------------------- | ---------------------- | ---------------------------- | ----------- | | ALL-Relapsed | 2 | 1/0 | 1/0 | | 1 | | AML-First Line de novo | 8 | 5/0 | | 1 | 2 | | AML-First Line sAML | 5 | 1/2 | 1/1 | 1 | 1 | | AML-Salvage | 11 | 1/0 | 1/0 | 2 | 8 | Table 2. 206 Study Efficacy Conclusions: Clinically relevant prolongation of QTcF is not a feature of CPX-351 treatment. CPX-351 exposure was independent of renal function, indicating no need for dose adjustment when renal function is impaired. The high rate of complete remission and referral for transplant corroborate the high level of efficacy observed in earlier studies with CPX-351. Disclosures Stuart: Sunesis: Honoraria, Other: Advisory Board, Research Funding; Astellas Pharma, Inc: Research Funding. Michaelis: Incyte: Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Wyeth: Membership on an entity's Board of Directors or advisory committees; Pfizer: Equity Ownership. Pentikis: Celator Pharmaceuticals: Consultancy. Alvarez: Celator Pharmaceuticals, Inc.: Employment, Equity Ownership. Mayer: Celator Pharmaceuticals, Inc.: Employment, Equity Ownership. Louie: Celator Pharmaceuticals, Inc.: Employment, Equity Ownership.

Background and objective: Acute myeloid leukemia (AML) develops from leukemia stem cells (LSCs), a small subset of leukemia cells possessing both self-renewal and multilineage differentiation potential similar to normal hematopoietic stem cells. The stem cell niche of the bone marrow microenvironment protects LSCs from chemotherapy, resulting in subsequent leukemia relapse. The study of AML LSCs in vitro is limited because of the lack of an ideal culture system mimicking the protective bone marrow microenvironment. The bone marrow stem cell niche is mainly composed of stromal cells, soluble cytokines and growth factors, as well as extracellular matrix (ECM). We therefore developed a 3-dimensional ECM model using decellularized Wharton's jelly from human umbilical cords to better characterize AML LSCs in vitro. Previously we have shown that leukemia cells grown in DWJM changed morphology to become spindle shaped and maintained viability but had decreased proliferation as measured by Alamar blue assay. Herein, we further characterize leukemia cells cultured in DWJM. Methods: Wharton's jelly decellularization process included multiple osmotic shock cycles using hypertonic and hypotonic solutions, a non-ionic detergent Triton-x, an anionic detergent sodium lauroyl succinate, and an enzyme digestion with recombinant endonuclease Benzonase™. We examined three human leukemia cell lines: HL60, Kasumi I and MV411. We characterized leukemia cell proliferation by CellTrace proliferation assay and phenotype by flow cytometry for stem cell markers. Serial colony forming unit (CFU) assays were used to test the self-renewal of leukemia cells. Results: CellTrace proliferation assay showed that, compared to cells in suspension, cells cultured in DWJM divided less frequently. To assess for LSCs properties, we measured the ALDH+ population by Aldefluor assay and found that the ALDH+ cells from Kasumi I and HL60 increased significantly in DWJM compared to suspension (p Conclusion: Decellularized Wharton's jelly matrix may serve as a practical in vitro ECM model to enrich for LSCs and study the ECM-LSC interactions. Disclosures No relevant conflicts of interest to declare.

Introduction: Chemotherapy resistance remains a significant challenge in the treatment of adults with Acute Myeloid Leukemia (AML). Although new targets and novel agents are under clinical investigation, the majority of AML patients are treated with conventional induction chemotherapy consisting of an anthracycline and cytarabine, with little modification in over 40 years. Insights into the biology of resistance to cytarabine and anthracyclines may suggest novel strategies in the treatment of AML. Hyperbaric oxygen (HBO) treatment is commonly used in the treatment of decompression sickness from scuba diving, wound healing and infections. 100% oxygen is administered at increased pressure. Limited published data suggest a role for HBO to cause in vitro apoptosis of leukemia cell lines, but no mechanism has been described. We examined the role of HBO in AML sensitivity to chemotherapy, reactive oxygen species (ROS) generation, glycolytic pathway activation and gene expression. Methods: Human AML cell lines HL-60 and MV-411 were treated with escalating doses of cytarabine or daunorubicin as single agents followed by HBO treatment for 2 hours or normobaric conditions. HBO treatment consisted of exposure to 100% oxygen at 2.5 atmosphere absolutes for a total of 2 hours in a specifically designed in vitro HBO chamber. At 24 hours after chemotherapy dosing, leukemia cells were analyzed for proliferation using Cell Titer 96 Aqueous MTS assay (Promega). Apoptosis was measured using Annexin V-FITC and analyzed by flow cytometry. In order to understand potential mechanisms of HBO activity on leukemia cells, studies of HBO-treated cells without use of chemotherapy were also performed. CellROX Oxidative Stress assay (Life Technologies) was performed at 24 hours. CellROX Green and Deep Red reagents measured ROS level in the DNA and cytoplasm. RNA was isolated and real-time PCR was performed using CFX384 Real-time PCR system using primer sets specific for human hexokinase2 and phosphofructokinase to examine the effects of HBO on glycolysis. Gene expression profiling was performed using the Human Transcriptome Array 2.0 (Affymetrix) and examined differences in gene expression following HBO treatment of HL-60 cells and bone marrow from an AML patient. Results: HBO-treated leukemia cells had increased sensitivity to cytarabine (Table 1, Figure 1) (MV411 response to cytarabine: IC50 2649nM without HBO treatment, 1921nM with HBO, p=0.02; HL60 response to cytarabine: linear response without HBO, IC50 1625nM with HBO, p Conclusions: HBO treatment significantly increases the sensitivity to cytarabine AML cell lines in vitro. Increased ROS, upregulation of glycolysis-related enzymes and changes in gene expression profiling provide insight into the potential mechanisms of HBO enhanced chemotherapy sensitivity. Given the safety and commonplace use of HBO for other indications, and the significant challenge of chemotherapy resistance, it is important to pursue further studies to understand the biology of HBO treatment in AML. Table 1. IC50 (nM) of chemotherapy agents in AML cell lines with and without co-treatment with HBO. Cytarabine Daunorubicin no HBO HBO p-value no HBO HBO p-value MV411 2649 1921 0.0214 709.1 641.1 ns HL60 * 1625 0.0346 639 406.5 ns * linear response, no IC50 available Figure 1. Increased sensitivity to cytarabine in AML cell lines following treatment with HBO. Figure 1. Increased sensitivity to cytarabine in AML cell lines following treatment with HBO. Disclosures No relevant conflicts of interest to declare.