Erba, Harry Paul

Abstract Background. Transfusion of blood products is an integral component of the management of patients with acute leukemias. However, high-quality evidence and clinical trial data to support specific practices of blood product transfusion in this population are limited. We hypothesized that there is wide variation in blood product transfusion practices among providers in North America who manage patients with acute leukemia. Methods. A 30-question web-based survey about transfusion practices was emailed to members of the Eastern Cooperative Oncology Group (ECOG)-ACRIN Cancer Research Group, Alliance for Clinical Trials in Oncology (Alliance), and the Southwest Oncology Group (SWOG), and the Cancer Trials Support Unit (CTSU) on 7/6/2015 with 4 subsequent weekly reminders. The distribution list included 9,859 recipients, of whom at least 741 were providers who treated patients with acute leukemia. Responses were anonymous, and the survey distribution was approved by the respective cooperative group chairs. Descriptive statistics were used to analyze the data. Results. Of 254 responses received, 113 were excluded as they were returned by recipients not directly treating patients with acute leukemia. Another 30 responses were excluded due to incomplete data, leaving 111 responses (43.7%) eligible for the primary analysis. Of those, 109 responders were from North America representing 83 institutions in 33 states and the province of Ontario. Eighty-four of the included responders (75.7%) were physicians, and 44 (39.6%) were females. Median age of responders was 44 years (range, 26-76). A hemoglobin (Hb) level of ≤7 g/dL was the most commonly used threshold (44%) for red blood cell (RBCs) transfusions to asymptomatic stable hospitalized patients, followed closely by 8 g/dL (38%) (Figure 1). In the outpatient setting, the most commonly reported threshold was 8 gm/dL (49%) (Figure 1). Most providers reported that they "always" use leukocyte-reduced (93%) and irradiated (79%) RBCs. A platelet level of 10,000/µL was the threshold for platelet transfusions in the stable non-bleeding hospitalized patients cited by the majority of responders (76%) (Figure 2). This platelet level remained the most common threshold for platelet transfusions for non-bleeding patients in the outpatient setting (49%), although 31% of responders reported a higher threshold of 20,000/µL. A preference for single-donor apheresis platelets was reported by 81% respondents, and 57% use these products exclusively. Most providers (70%) reported always using irradiated platelets. With respect to cryoprecipitate and plasma infusions, nearly half of the respondents reported a threshold fibrinogen level of 100 mg/dL as a trigger for administering a product to a stable non-bleeding patient (Figure 3). The most commonly reported platelet threshold for performing a bone marrow biopsy (BMB) was 10,000/μL (69% of responders), followed by 20,000 (21%), 50,000 (6%), and 30,000 (4%). Therapeutic anticoagulation was held by most responders (80%) before performing a BMB. Most responders (73%) reported a platelet level of 50,000/µL as the lowest level for performing a lumbar puncture (LP) without prophylactic platelet transfusion. Conclusions. This survey demonstrates wide variability in blood product transfusion patterns among providers who treat patients with acute leukemias. A platelet level of 10,000/µL is the most common trigger for platelet transfusions for stable non-bleeding patients in both inpatient and outpatient settings. This, along with a platelet threshold of 50,000/µL for performing an LP, appear to be most widely accepted practices. Our findings emphasize the need to obtain high-quality data to develop consensus evidence-based guidelines for transfusion practices in acute leukemia with the goal of limiting unnecessary transfusions without compromising patient outcomes. Figure 1. The most common reported hemoglobin level thresholds for red blood cell transfusions in the inpatient and outpatient settings. Figure 1. The most common reported hemoglobin level thresholds for red blood cell transfusions in the inpatient and outpatient settings. Figure 2. The most common reported platelet level thresholds for platelet transfusions in the inpatient and outpatient settings. Figure 2. The most common reported platelet level thresholds for platelet transfusions in the inpatient and outpatient settings. Figure 3. The most common reported fibrinogen level thresholds for cryoprecipitate or plasma transfusions in the inpatient and outpatient settings. Figure 3. The most common reported fibrinogen level thresholds for cryoprecipitate or plasma transfusions in the inpatient and outpatient settings. Disclosures Sekeres: TetraLogic: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Steensma:Onconova: Consultancy; Incyte: Consultancy; Amgen: Consultancy; Celgene: Consultancy. Prebet:CELGENE: Research Funding. Komrokji:Celgene: Consultancy, Research Funding; Incite: Consultancy; Novartis: Speakers Bureau; GSK: Research Funding. Stone:Merck: Consultancy; AROG: Consultancy; Celgene: Consultancy; Sunesis: Consultancy, Other: DSMB for clinical trial; Abbvie: Consultancy; Novartis: Research Funding; Juno: Consultancy; Amgen: Consultancy; Roche/Genetech: Consultancy; Celator: Consultancy; Agios: Consultancy; Karyopharm: Consultancy; Pfizer: Consultancy. Erba:GlycoMimetics; Janssen: Other: Data Safety & Monitoring Committees; Sunesis; Pfizer; Daiichi Sankyo; Ariad: Consultancy; Millennium/Takeda; Celator; Astellas: Research Funding; Seattle Genetics; Amgen: Consultancy, Research Funding; Novartis; Incyte; Celgene: Consultancy, Patents & Royalties. Barbarotta:Celgene, BMS, Novartis: Speakers Bureau. Gore:Celgene: Consultancy, Honoraria, Research Funding.

Abstract Background: Higher-risk MDS and CMML comprise a spectrum of disorders associated with cytopenias, high risk of transformation to acute myeloid leukemia (AML), and truncated survival. Initial treatment with a hypomethylating agent such as azacitidine (AZA) is considered standard of care. Whether addition of the histone deacetylase inhibitor vorinostat (VOR), which acts synergistically with AZA to reactivate epigenetically silenced genes, or addition of lenalidomide (LEN), which impacts the bone marrow microenvironment, improves response rates compared to AZA monotherapy is unknown. Methods: This Phase II study (ClinTrials.gov # NCT01522976) randomized higher-risk MDS (International Prognostic Scoring System (IPSS) Int-2 or High and/or bone marrow blasts >5%) and CMML patients (pts) with <20% blasts to receive AZA (75 mg/m2/d on d1-7 of a 28d cycle), AZA + LEN (10 mg/d on d1-21), or AZA + VOR (300 mg BID on d3-9). Eligibility criteria included: >18 years (yrs), no previous allogeneic transplant, no prior treatment with any of the study drugs, and adequate organ function; therapy-related (t)MDS was allowed. Pts continued treatment until disease progression, relapse, unacceptable toxicity, or lack of response. Dose reductions occurred for unresolved grade >3 adverse events (per NCI CTCAE) or delayed count recovery. The primary endpoint was improvement in overall response rate (ORR), by intention to treat and reviewed centrally, of one of the combination arms vs. AZA monotherapy per 2006 International Working Group MDS response criteria (complete response (CR) + partial response (PR) + hematologic improvement (HI)). Relapse-free survival (RFS) was from time of response. The study had 81% power to detect a 20% improvement in ORR from 35% to 55%. Results: Of 282 pts enrolled from 3/12–6/14, 276 are included in analyses (6 ineligible pts excluded): 92 on the AZA arm, 93 on AZA+LEN, and 91 on AZA+VOR. Baseline characteristics were well-balanced across arms (Table). Pts received a median of 23 weeks of therapy: 25 of AZA; 24 of AZA+LEN; and 20 of AZA+VOR and were followed for a median of 9 months (range: 0-26). Numbers of pts with notable adverse events >grade 3 for AZA:AZA+LEN:AZA+VOR included febrile neutropenia (10:13:13); gastrointestinal disorders (4:11:23); infections (2:3:3); and rash (2:12:1). Responses were assessable in 260 pts (94%). ORR for the entire cohort was 33%: 19% CR, 1% PR, and 13% HI, with a median RFS of 7 months. ORR was similar across study arms: 36% for AZA, 37% for AZA+LEN (p=1.0 vs. AZA), and 22% for AZA+VOR (p=.07 vs. AZA). CR/PR/HI rates across arms were also similar: 23%/0%/13% for AZA; 18%/1%/17% for AZA+LEN (CR p=.47 vs. AZA); and 14%/1%/7% for AZA+VOR (CR p=.18 vs. AZA); rates of bone marrow exams to assess response were 76%, 67%, and 73%, respectively. HI-P/HI-E/HI-N rates were 21%/15%/5% for AZA, 26%/14%/15% for AZA+LEN, and 12%/8%/4% for AZA+VOR. HI-N rates were higher in AZA+LEN vs. AZA (p=.05) but otherwise were similar across arms. Median time to best response across arms was 15 weeks in AZA, 16 weeks in AZA+LEN, and 16 weeks in AZA+VOR. ORR did not vary significantly across arms in subgroup analyses for tMDS, baseline red blood cell (RBC) transfusion dependence, and by IPSS risk group. ORR for CMML pts for AZA:AZA+LEN:AZA+VOR was 33%:53%(p=.15 vs. AZA):12%(p=.41 vs. AZA). Allogeneic transplantation rates were: 7 pts on AZA, 6 on AZA+LEN, and 9 on AZA+VOR. For AZA:AZA+LEN:AZA+VOR, median RFS was: 6:8:11 months (log-rank p=.3 for combination arms vs. AZA, Figure); and for pts on therapy >6 months, it was 7:7.5:13 months (log-rank p=.11 for AZA+VOR, .74 for AZA+LEN vs. AZA). Conclusions: In higher-risk MDS pts, ORR was similar for AZA monotherapy compared to AZA-containing combination arms, though some subgroups may have benefitted from combination therapy. Differences in types of response may have resulted from differential rates of follow-up bone marrow assessments. While a non-significant signal of a DFS advantage for combination therapy was observed, longer-term outcome data are being assessed. Table Table. Figure Figure. Disclosures Sekeres: Boehringer-Ingelheim: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Off Label Use: lenalidomide, vorinostat for higher-risk MDS. List:Celgene Corporation: Consultancy. Gore:Celgene: Consultancy, Research Funding. Attar:Celgene: Consultancy. Erba:Seattle Genetics: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Research Funding; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda Pharmaceuticals International Co.: Research Funding; Astellas Pharma: Research Funding; Celgene: Honoraria, Speakers Bureau.

Abstract Background: Pev (TAK-924/MLN4924), a novel investigational NAE inhibitor, enhances the anti-leukemic effects of aza in AML cell lines and murine xenografts (Smith et al, Blood 2011). Single-agent pev activity was confirmed in relapsed/refractory AML pts (Swords et al, Br J Haematol 2015). This open-label, multi-center, dose-escalation study (NCT01814826) investigated pev + aza in treatment-naïve older AML pts. Dose-limiting toxicities (DLTs)includedG2 hyperbilirubinemia and G4 AST elevation (n=1 each) at pev 30 mg/m2. The maximum tolerated dose (MTD) for the combination was pev 20 mg/m2 + aza 75 mg/m2 (Swords et al, ASH 2014).We present updated safety/efficacy results for the MTD cohort (fully enrolled). Methods: Primary objectives included safety and tolerability assessments of pev + aza in addition to defining the MTD. Secondary objectives included pharmacokinetics (PK) and disease response assessments. Treatment-naïve pts ≥60 yrs unlikely to benefit from standard induction therapy (defined by ≥1 of: antecedent hematologic disease; known adverse cytogenetic risk; ECOG PS 2; ≥75 yrs), received pev 20 or 30 mg/m2 IV on d 1, 3 and 5, + fixed-dose aza (75 mg/m2 IV/SC) on d 1-5, 8 and 9, every 28 d until disease progression or unacceptable toxicity. Adverse events (AEs) were assessed per NCI-CTCAE v4.03; response per IWG criteria for AML. Bone marrow samples were collected at screening to assess cytogenetic risk (CALGB) and mutation profile; serial samples for PK analysis were drawn in cycle 1. Results: Demographics:As of May 17 2016, 61 pts (median age 75 yrs [range 61-89]; 54% male; 77% ECOG PS 0/1, 23% ECOG PS 2; 57% de novo, 43% secondary AML; median marrow blasts 36% [range 5-92]) had received pev 20 mg/m2, of whom 48% had intermediate-, 30% adverse-, and 3% favorable-risk cytogenetics. Safety/PK: Pts received a median of 4 cycles (range 1-33), and 23/61 pts (38%) received ≥6 cycles of pev + aza. The most common AEs were constipation (46%), nausea (44%), fatigue (43%), and anemia (39%). Fifty pts (82%) experienced ≥G3 AEs; the most frequent (≥15%) were anemia, febrile neutropenia (each 28%), thrombocytopenia (21%), neutropenia (18%), and pneumonia (15%). ≥G3 AST/ALT elevations were reported in 5% of pts. Forty-one pts (67%) experienced serious AEs; the most frequent (≥10%) were febrile neutropenia, neutropenia (each 25%), and pneumonia (11%). Two pts discontinued due to pev related toxicity (G3 febrile neutropenia). There were 11 on-study deaths unrelated to study therapy. In the MTD expansion phase (n=55), 2 pts experienced DLTs of transient G3/4 transaminase elevations, and were successfully re-challenged following dose reduction to remain on study. Pev PK was not altered by the addition of aza. Responses: Overall response rate (ORR) in 52 response-evaluable pts was 60% (18CR, 5CRi, 8PR; Figure 1), with a median duration of remission of 8.3 mos (95% CI: 5.75, 12.06); 19/31 (61%) responses occurred within the first 2 cycles.Of the 23 pts with CR/CRi, 14 had responses lasting ≥4 cycles, 2 went on to have allogeneic stem cell transplant, 9 had intermediate-, 7 adverse-, and 1 favorable-risk cytogenetics. ORR was: 64% (14/22; 7CR, 3CRi, 4PR) vs 57% (17/30; 11CR, 2CRi, 4PR) for pts with low- (<30%) vs high- (≥30%) marrow blasts; 58% (18/31; 11CR, 3CRi, 4PR) vs 62% (13/21; 7CR, 2CRi, 4PR) for de novo vs secondary AML pts; 61% (14/23; 8CR, 1CRi, 5PR) vs 50% (8/16; 5CR, 2CRi, 1PR) for intermediate- vs adverse-risk cytogenetic pts; 83% (19/23; 14CR, 2CRi, 3PR) vs 41% (12/29; 5CR, 3CRi, 4PR) for pts who received ≥6 cycles vs <6 cycles of aza, respectively. Responses were seen in pts with typically refractory disease; 7/11 pts with TP53 mutations achieved either a CR/CRi (n=3) or PR (n=4); 4 stayed on study for >10 cycles. After a median follow-up of 16.4 mos, 6-mo survival was 52%. Median overall survival was: 7.0 mos for the MTD cohort; 8.5 vs 5.2 mos for pts with low- (<30%) vs high- (≥30%) marrow blasts (Figure 2); 5.6 vs 11.2 mos for de novo vs secondary AML pts (Figure 3); and 16.1 vs 5.3 mos for pts aged 65-74 vs ≥75 yrs, respectively. Conclusion: Pev + aza was well tolerated. Response rates and durable remissions were observed with limited additional toxicity beyond what is expected for aza alone. The timing and frequency of responses suggests benefit from the addition of pev compared to aza alone (Dombret et al, Blood 2015). At the time of writing, a randomized phase 2 study in low-blast AML/high-risk myelodysplastic syndromes is ongoing. Disclosures Coutre: Janssen: Consultancy; Pharmacylics, LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding. Zeidner:Tolero: Research Funding; Merck: Research Funding; Takeda: Research Funding; Otsuka: Consultancy; Agios: Honoraria. Foran:medscape: Honoraria; Millennium Pharmaceuticals, Inc.: Research Funding; novartis: Honoraria; pfizer: Honoraria; karyopharm: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding. Cruz:Millennium Pharmaceuticals, Inc.: Honoraria; Millennium Pharmaceuticals, Inc.: Speakers Bureau. Erba:Novartis: Consultancy, Speakers Bureau; Celator: Research Funding; Daiichi Sankyo: Consultancy; Celgene: Consultancy, Speakers Bureau; Juno: Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Pfizer: Consultancy; Seattle Genetics: Consultancy, Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Amgen: Consultancy, Research Funding; Agios: Research Funding; Sunesis: Consultancy; Gylcomimetics: Other: DSMB; Astellas: Research Funding; Ariad: Consultancy; Jannsen: Consultancy, Research Funding. Berdeja:Abbvie, Acetylon, Amgen, Bluebird, BMS, Calithera, Celgene, Constellation, Curis, Epizyme, Janssen, Karyopharm, Kesios, Novartis, Onyx, Takeda, Tragara: Research Funding. Tam:Millennium Pharmaceuticals, Inc.: Consultancy. Vardhanabhuti:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Dobler:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Faessel:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Dash:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Sedarati:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Dezube:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment, Equity Ownership. Savona:Takeda: Research Funding; Amgen Inc.: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Sunesis: Research Funding; Ariad: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: Retrospective analyses have demonstrated significantly improved survival for AYA ALL patients (pts) aged 16-21 years (yrs) when treated on pediatric versus adult U.S. NCI Cooperative group regimens where 2-yr event-free survivals (EFS) have been only 35-40%. The purpose of C10403, a large prospective US intergroup trial, was to evaluate the feasibility and effectiveness [with EFS as a primary endpoint), of treating AYA ALL pts (ages 16-39 yrs) using the standard arm of the successful Children's Oncology Group regimen (COG AALL0232) . Methods: Newly diagnosed AYA patients with B-precursor (B-ALL) or T-precursor (T-ALL) ALL were eligible to enroll on C10403. Burkitt type and Ph+ ALL were excluded. The regimen was identical to the Capizzi methotrexate arm of COG AALL0232 (Larsen E. JCO 2011; 29 suppl:3) and consisted of four intensive courses: remission induction, remission consolidation, interim maintenance, delayed intensification, and prolonged maintenance therapy. Pts with M2 marrow response (>5% but < 25% lymphoblasts) after remission induction received an extended remission induction course of therapy. Events were defined as induction failure (M3 [³25% blasts] day 29 of induction or M2 day 43 of extended induction), death, relapse, or second malignancy. Key correlative science studies in a subset of the total accrued population included assessment of Minimal Residual Disease (MRD) using quantitative real-time PCR of clonal IgH or TCR gene rearrangements as well as Low Density Microarray (LDA) assays designed to detect a previously validated gene expression profile (Harvey, R; ASH 2013, abstract 826) which can prospectively identify ALL pts with Ph-like (BCR-ABL1-like) ALL. Results: 318 pts were enrolled on C10403 from 11/2007 to 8/2012; 22 withdrew prior to therapy. Of 296 evaluable pts, the median age at diagnosis was 24 yrs (range: 17 to 39): 25% were 17-20 yrs, 53% were 21-29 yrs, and 22% were 30-39 yrs. The majority had B-ALL (76%) and were male ( 61%). Approximately 25% were non-Caucasian and 15% were Hispanic or Latino. 32% of pts were obese (BMI³30). There were 5 (2%) treatment-related deaths during protocol therapy: liver failure (n=2, both during induction), infection (1 in induction, 1 in consolidation), and ventricular arrhythmia (1 in induction). Overall, treatment toxicities were similar to those reported in the standard arm of COG AALL0232, with an increased thrombosis and early hyperbilirubinemia for C10403 pts, as reported previously (Advani A, ASH 2013, abstract 303). To date, 70 deaths have been reported and 87 pts remain on protocol therapy. With a median follow-up of 28 months for surviving pts, 105 events have been observed. The median EFS overall is 59.4 months (95% CI: 38.4 to NR) and the 2-yr EFS rate overall is 66% (95% CI: 60 – 72%) [Fig 1a] with similar 2-yr EFS rates for B and T- ALL pts (65%, and 68%). The 2-yr OS rate is 78% (95% CI: 72 – 83%)[Fig 1b], which is similar for B (78%, 95% CI: 72 – 84%) and T-ALL, (80%, 95% CI: 70 – 91%). These results allow rejection of the null hypothesis of this Phase II trial that the true median EFS is, at most, 32 months. In multivariable analysis of presenting clinical features, age > 20 years and initial WBC count ³ 30k/microliter were significantly associated with worse EFS and OS. Presence of MRD at day 28 following initiation of induction therapy and presence of a Ph-like gene expression signature were significantly associated with both worse EFS and OS. Notably, absence of detectable MRD noted in 22/58 [38%] evaluable pts at day 28 of induction was associated with 100% EFS (p=0.0006). The Ph-like like signature was detected in 28% of pts tested on C10403 and the 2 yr EFS for these patients was only 52%, compared to 81% for those without Ph-like disease (p = 0.04). Conclusions: This large prospective US adult intergroup trial (C10403) for pts 16-39 years old employing an intensive pediatric regimen demonstrates a significant improvement (compared to historical controls) in AYA EFS and OS and validates this approach for treatment of AYA with ALL by adult hematologists. The improved clinical outcomes and the predictive value of the correlative studies in this trial lay the foundation for the design of future trials, where incorporation of novel agents to eradicate MRD, and/or use of tyrosine kinase inhibitors to target the frequently detected Ph-like ALL in AYA pts may further improve survival for young adults with ALL. Figure 1a Figure 1a. Figure 1b Figure 1b. Disclosures Stock: Sigma-Tau: Membership on an entity's Board of Directors or advisory committees, Research Funding. Advani:Sigma Tau: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees. Liedtke:Onyx: Membership on an entity's Board of Directors or advisory committees. Larson:Novartis: Consultancy, Research Funding.

Abstract 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.

Abstract Background: Gilteritinib (ASP2215) is a novel, highly selective, potent oral FLT3/AXL inhibitor with preclinical activity against FLT3-ITD activating and FLT3-D835 resistance mutations. The objectives of this phase 1/2 study were to assess gilteritinib safety/tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) profiles after single- and multiple-day dosing, and antileukemic effects in patients with R/R AML. Methods: This open-label study (NCT02014558) enrolled patients (≥18 yr) into 1 of 7 dose-escalation cohorts (20-450 mg once daily [QD]) or concomitant dose-expansion cohorts. While confirmed FLT3 mutation was not an inclusion criterion, each expanded dose level enrolled ≥10 patients with FLT3 mutations (FLT3mut+); 120 and 200 mg dose levels were further expanded with ≥40 FLT3mut+ patients. The choice to expand these dose cohorts was based upon FLT3 inhibition in correlative assays and clinical activity seen during dose escalation. Safety and tolerability were primary endpoints; blood samples were drawn from patients in the dose-escalation cohorts to evaluate gilteritinib PK parameters and PD effects. Antileukemic response rates (eg, complete remission [CR], CR with incomplete platelet recovery [CRp], CR with incomplete hematological recovery [CRi], overall response rate [ORR]) were secondary endpoints. Results: Patients (N=252; 129M:123F, median age 62 yr [range: 21-90]) enrolled between October 2013 and August 2015 received ≥1 dose of gilteritinib. The study population was heavily pretreated: 70% (n=177) had ≥2 prior AML therapies, 29% (n=73) had a prior stem cell transplant, and 25% (n=63) had prior TKI treatment with sorafenib most commonly used. Across the study, 194 patients had a locally confirmed FLT3 mutation (ITD, n=159; D835, n=13; ITD-D835, n=16; other, n=6). For all enrolled patients, progressive disease (n=75), lack of efficacy (n=44), adverse events (n=34), and death (n=29) were the most common reasons for treatment discontinuation. Seven deaths were considered possibly/probably related to treatment: pulmonary embolism, respiratory failure, hemoptysis, intracranial bleed, ventricular fibrillation, septic shock, and neutropenia (all n=1). Maximum tolerated dose was determined to be 300 mg when 2 of 3 patients in the 450 mg cohort experienced diarrhea and/or hepatic transaminase elevation as dose-limiting toxicities. Diarrhea (16%) and fatigue (15%) were the most commonly reported treatment-related adverse events of any grade. Less than 5% of patients (11/252) had a maximum post-baseline QTcF interval >500 msec. Gilteritinib concentrations were generally dose proportional and showed both a long-elimination half-life (45-159 h) and substantial accumulation (3.2-10 fold) by day 15. An exposure-related increase in the inhibition of FLT3 phosphorylation with increasing doses of gilteritinib was also observed. Gilteritinib showed strong antileukemic activity in FLT3mut+ patients (ORR=49%); response was observed less frequently in patients with wild-type FLT3 (ORR=12%). While CR, CRi, and CRp occurred at all doses, responses were enriched among FLT3mut+ patients with gilteritinib steady-state trough concentrations ≥100 ng/mL, which correlated with potent FLT3 inhibition in PD assays and corresponded to doses ≥80 mg. The ORR in 169 FLT3mut+ patients receiving ≥80 mg was 52% (Table); median overall survival in this patient population was ~31 wk (range: 1.7-61; Figure) and median duration of response was 20 wk (range: 1.1-55). Clinical responses occurred in FLT3mut+ patients with -ITD, -D835, and both mutations (ORR: 55%, 17%, and 62%, respectively) as well as in FLT3mut+ patients with or without prior TKI treatment (ORR: 42% vs 56%, respectively). Conclusions: This PD-driven, first-in-human study shows that gilteritinib was well tolerated and generated frequent, prolonged, clinically important responses in FLT3mut+ patients with R/R AML. Antileukemic responses were enriched in FLT3mut+ patients treated at doses that consistently and potently inhibited FLT3 phosphorylation. The survival of these patients appears better than expected for this patient population when treated with standard therapy. Our data suggest that FLT3 inhibition may improve survival in patients with FLT3mut+R/R AML; as such, phase 3 testing of oral gilteritinib 120 mg QD in patients with FLT3mut+R/R AML after first-line therapy is underway (NCT02421939). Disclosures Perl: Astellas US Pharma Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Asana Biosciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Arog Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Actinium Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Altman:Janssen: Other: advisory board; BMS: Membership on an entity's Board of Directors or advisory committees; Spectrum: Other: advisory board; Ariad: Other: advisory board; Seattle Genetics: Other: advisory board; Syros: Other: advisory board. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. Smith:Astellas: Research Funding. Erba:Jannsen: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Agios: Research Funding; Juno: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Daiichi Sankyo: Consultancy; Ariad: Consultancy; Amgen: Consultancy, Research Funding; Astellas: Research Funding; Gylcomimetics: Other: DSMB; Seattle Genetics: Consultancy, Research Funding; Sunesis: Consultancy; Novartis: Consultancy, Speakers Bureau; Celator: Research Funding; Celgene: Consultancy, Speakers Bureau; Pfizer: Consultancy. Gill:Astellas: Employment. Goldberg:Bristol Myers Squibb, Novartis: Speakers Bureau; Novartis: Consultancy; COTA Inc: Employment; Pfizer: Honoraria; Neostem: Equity Ownership. Jurcic:Astellas: Research Funding. Larson:Astellas: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy. Liu:Astellas: Employment. 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. Schiller:Incyte Corporation: Research Funding. Strickland:Celator: Research Funding; Cyclacel: Research Funding; Karyopharm Therapeutica: Research Funding; GlaxoSmithKline: Research Funding; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; Ambit: Consultancy; Alexion Pharmaceuticals: Consultancy; Astellas Pharma: Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Sanofi: Research Funding. Wang:Incyte: Speakers Bureau; Immunogen: Research Funding. Stuart:Sunesis: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding; Agios: Research Funding; Incyte: Research Funding; Bayer: Research Funding; Celator: Research Funding; Astellas: Research Funding. Martinelli:Ariad: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; BMS: Speakers Bureau; Roche: Consultancy, Speakers Bureau; MSD: Consultancy; Genentech: Consultancy; Novartis: Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Bahceci:Astellas: Employment. Levis:Millennium: Consultancy, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Daiichi-Sankyo: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding.

Abstract Introduction: ASP2215 is a highly selective inhibitor of AXL and FMS-like tyrosine kinase-3 (FLT3) receptors. ASP2215 is active against both FLT3 internal tandem duplication [ITD] and D835 mutations. Prior analyses of an open-label, dose-escalation/dose-expansion study in subjects with relapsed or refractory acute myeloid leukemia (R/R AML) show ASP2215 was well tolerated from 20-300 mg and associated with antileukemic activity in FLT3 mutation-positive (FLT3+) patients at ≥80 mg with minimal activity observed in wild-type FLT3 subjects. Here we describe the tolerability and potent activity of ASP2215 in a large cohort of FLT3+ patients. Methods: Patients (≥18 years) with R/R AML were assigned to treatment in dose-escalation cohorts or were randomized to an open dose level in the dose-expansion cohorts. Although FLT3 mutation was not an inclusion criterion, each expanded dose level enrolled ≥10 FLT3+ subjects; 120 mg and 200 mg dose levels were further expanded with ≥40 FLT3+ subjects. Tolerability was assessed by adverse event (AE) monitoring. Response assessment was based on modified Cheson criteria and duration of response and overall survival were calculated using Kaplan-Meier estimates. Results: As of June 19, 2015,215 patients with a median age of 61 yr (range: 21-90) had received ≥1 dose of ASP2215 (safety population). Across the safety population, 65% of subjects received ≥2 prior lines of AML therapy, 29% had a hematopoietic stem cell transplant prior to ASP2215 treatment, and 23% had prior tyrosine kinase inhibitor (TKI) treatment. Approximately 73% of patients were FLT3+, of which 137 had FLT3-ITD mutation, 7 were FLT3-D835+, and 9 had both FLT3-ITD and D835. Treatment-related AEs of all Grades, reported in ≥10% of the safety population were diarrhea (16%), fatigue (13%), and increased AST (11%); <2% of subjects reported a Grade ≥3 QTc prolongation. Activity was assessed in the 133 FLT3+ patients treated with ASP2215 ≥80 mg. Overall response rate (ORR; composite complete [CRc] plus partial remission [PR]) for all FLT3+ subjects was 55% (Table). Median overall survival for FLT3+ patients receiving ASP2215 ≥80 mg was ~29 weeks (95% CI: 22-32) and was similar for patients who achieved CRc or PR (Figure). Treatment with ≥80 mg ASP2215 was associated with an ORR of 60% in FLT3-ITD subjects; ORR for the other FLT3 populations was 29% (Table). No difference was observed in median ORR of ASP2215 (≥80 mg) in TKI-naïve patients (55%) and patients with prior TKI treatment (55%). Conclusions: ASP2215, a novel AXL/FLT3 TKI, was well tolerated in subjects with R/R AML and demonstrated a strong antileukemic activity in FLT3+ subjects. Importantly, the ASP2215 response rate in these FLT3+ patients was independent of prior TKI treatment. Even in this heavily pretreated population, the survival of R/R FLT3+ AML patients who received ≥80 mg ASP2215 was longer than prior reports of cytotoxic chemotherapy or other FLT3 inhibitors. Table. ASP2215 Response Assessment 80 mg 120 mg 200 mg 300 mg 450 mg Total All FLT3+ Subjects Population, n 12 52 57 10 2 133 CRc, n (%) 5 (42) 25 (48) 28 (49) 3 (30) 0 61 (46) PR, n (%) 3 (25) 3 (6) 3 (5) 3 (30) 0 12 (9) ORR, n (%) 8 (67) 28 (54) 31 (54) 6 (60) 0 73 (55) Subjects with FLT3-ITD Only Population, n 10 46 50 8 0 114 CRc, n (%) 4 (40) 23 (50) 26 (52) 3 (38) 0 56 (49) PR, n (%) 3 (30) 3 (7) 3 (6) 3 (38) 0 12 (11) ORR, n (%) 7 (70) 26 (57) 29 (58) 6 (75) 0 68 (60) Subjects with FLT3-D835 and Subjects with FLT3-ITD and FLT3-D835 Population, n 2 5 5 1 1 14 CRc, n (%) 1 (50) 1 (20) 2 (40) 0 0 4 (29) PR, n (%) 0 0 0 0 0 0 ORR, n (%) 1 (50) 1 (20) 2 (40) 0 0 4 (29) CRc, composite complete remission (complete remission + complete remission with incomplete platelet recovery + complete remission with incomplete hematologic recovery); ORR, overall response rate; PR, partial response. NR, no response. Subjects with non-evaluable data (N=8) were not included in this curve. Figure 1. Overall Survival by Best Overall Response Achieved with ASP2215 ≥80 mg Across All FLT3+ Subjects Figure 1. Overall Survival by Best Overall Response Achieved with ASP2215 ≥80 mg Across All FLT3+ Subjects Disclosures Altman: BMS: Other: Advisory board; Novartis: Other: Advisory board; Spectrum: Other: Advisory board; Ariad: Other: Advisory board; Seattle Genetics: Other: Advisory board; Astellas: Other: Participation in an advisory board December 2013. Off Label Use: ASP2215 is currently under investigation for the treatment of AML and is not yet approved.. Perl:Arog Pharmaceuticals: Consultancy; Asana Biosciences: Consultancy; Actinium Pharmaceuticals: Consultancy; Ambit/Daichi Sankyo: Consultancy; Astellas US Pharma Inc.: Consultancy. Cortes:Pfizer: Consultancy, Research Funding; BerGenBio AS: Research Funding; Novartis: Consultancy, Research Funding; Teva: Research Funding; BMS: Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Ambit: Consultancy, Research Funding; Arog: Research Funding; Celator: Research Funding; Jenssen: Consultancy. Levis:Arog: Research Funding; Ambit: Research Funding; Takeda: Research Funding; Astellas: Consultancy. Smith:Plexxikon: Research Funding; Astellas: Research Funding. Claxton:NCI: Research Funding; Medimmune, Inc: Research Funding; Ambit Biosciences Corp: Research Funding; Incyte Corporation: Research Funding; Merck Sharp & Dohme Corp: Research Funding; Astellas Pharma: Research Funding. Erba:Seattle Genetics: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Ariad: Consultancy; Celgene: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; GlycoMimetics: Other: Data Safety and Monitoring Committees ; Jannsen (J&J): Other: Data Safety and Monitoring Committees ; Seattle Genetics: Consultancy, Research Funding; Millennium/Takeda: Research Funding; Amgen: Consultancy, Research Funding; Celator: Research Funding; Millennium/Takeda: Research Funding; Astellas: Research Funding; Sunesis: Consultancy; Celator: Research Funding; Pfizer: Consultancy; Astellas: Research Funding; Daiichi Sankyo: Consultancy; Sunesis: Consultancy; Ariad: Consultancy; Pfizer: Consultancy; GlycoMimetics: Other: Data Safety and Monitoring Committees ; Jannsen (J&J): Other: Data Safety and Monitoring Committees ; Daiichi Sankyo: Consultancy. Gill:Astellas Pharma US, Inc: Employment. Goldberg:Cyclacel: Research Funding; Celetor: Research Funding; Pfizer: Research Funding; Ambit: Research Funding; Astellas: Research Funding. Jurcic:Astellas Pharma: Research Funding. Larson:Astellas: Consultancy, Research Funding. Lui:Astellas Pharma US, Inc: Employment. Ritchie:Incyte: Speakers Bureau; Novartis: Speakers Bureau; Ariad: Other: Advisory Board; Celgene: Speakers Bureau; Onyx: Speakers Bureau. Sargent:Astellas Pharma US, Inc: Employment. Schiller:Sunesis: Honoraria, Research Funding. Strickland:Sunesis Pharmaceuticals: Other: Steering Committee and Advisory Board Participation; Alexion Pharmaceuticals: Other: Advisory Board Particpation; Amgen: Other: Advisory Board Particpation; Daiichi-Sankyo: Other: Advisory Board Particpation; Boehringer-Ingelheim: Other: Advisory Board Particpation. Wang:Immunogen: Research Funding. Stuart:Sunesis: Honoraria, Other: Advisory Board, Research Funding; Astellas Pharma, Inc: Research Funding. Baldus:Novartis: Research Funding. Martinelli:MSD: Consultancy; ARIAD: Consultancy; BMS: Speakers Bureau; Pfizer: Consultancy; Novartis: Speakers Bureau; Roche: Consultancy. Bahceci:Astellas Pharma Global Development: Employment.

Abstract Background: Treatment of elderly AML patients considered unfit for conventional chemotherapy is inadequate and hypomethylating agents are commonly used alternatives. In the case of azacitidine, responses are typically seen after 3–6 cycles of therapy, and a recent large randomized trial in elderly unfit patients reported a complete response (CR)/CR with incomplete blood count recovery rate of 28% (Dombret et al, EHA 2014). Pevonedistat (MLN4924) is an investigational, first-in-class NEDD8-activating enzyme (NAE) inhibitor. A phase 1 trial previously reported pevonedistat single-agent clinical activity in relapsed/refractory AML patients. Preclinical studies of pevonedistat and azacitidine identified synergistic lethality in AML cell lines and murine xenografts. The current phase 1b dose-escalation study evaluated the safety and tolerability of pevonedistat combined with azacitidine in elderly AML patients considered unfit for conventional chemotherapy. Methods: The primary objective was to assess the safety and tolerability of pevonedistat combined with azacitidine. Secondary objectives included assessment of pevonedistat pharmacokinetics (PK) and clinical activity. Treatment-naïve AML patients aged ≥60 years who were considered unfit for standard induction therapy received pevonedistat via 1-hour IV infusion on days 1, 3, and 5 of 28-day cycles. Dose escalation began at 20 mg/m2 and used an adaptive Bayesian continual reassessment method. Azacitidine 75 mg/m2 was administered (IV or SC) on days 1–5 and 8–9. Patients were treated until disease progression or unacceptable toxicity. Adverse events (AEs) were graded per NCI-CTCAE v4.03. Responses were assessed according to International Working Group response criteria for AML. Serial blood samples were obtained for PK analysis following dosing on days 1 and 5 of cycle 1. Results: As of May 30, 2014, 25 patients (median age 75.0 years [range 63–85]; 16 [64%] male) had received pevonedistat 20 mg/m2 (n=22) and 30 mg/m2 (n=3). Primary diagnoses were 16 (64%) de novo AML and 9 (36%) secondary AML. Fourteen (56%) patients had intermediate- and 6 (24%) had adverse-risk cytogenetics (5 [20%] undetermined). During dose escalation, dose-limiting toxicity (DLT) at the 30 mg/m2 pevonedistat dose level included reversible grade 2 increased bilirubin (n=1) and grade 3/4 increased transaminases (n=1) without clinical sequelae. In 1 of the 22 patients treated at the maximum tolerated dose (20 mg/m2 pevonedistat plus 75 mg/m2 IV/SC azacitidine), 1 additional DLT (grade 4 AST/ALT elevation) was seen in the expansion cohort. This patient was successfully re-challenged with a reduced pevonedistat dose. The most common all-grade AEs are shown in table 1. Twelve (48%) patients experienced drug-related grade ≥3 AEs (table 1). The nature and frequency of the reported toxicities (excluding DLTs) were similar to previous reports for azacitidine alone. Preliminary PK data showed that addition of azacitidine did not alter the known PK profile of single-agent pevonedistat. In the 18 response-evaluable patients, there were 6 (33%) CRs and 4 (22%) PRs (table 2), for an overall response rate of 56%. Nine of the 10 responses occurred within the first two cycles of therapy and included 1 patient with bone marrow blasts >80%. Conclusions: Combination therapy with pevonedistat and azacitidine was generally well-tolerated. The characteristics of the observed responses suggest added benefit from the addition of pevonedistat compared with azacitidine alone. Table 1 Common all-grade AEs n (%) Most frequent (≥10%) drug-related grade ≥3 AEs n (%) Febrile neutropenia 9 (36) Febrile neutropenia 4 (16) Constipation 8 (32) Thrombocytopenia 3 (12) Decreased appetite 7 (28) – – Thrombocytopenia 7 (28) – – Table 2 Responders* Tumor Type Cytogenetic Risk Group Current Status Response Molecular CR 1st Response 1st CR 1 De novo AML Adverse C12 C4 – – 2 Undetermined C4† C1 C1 Y 3 Adverse C9 C1 C1 Y 4 Undetermined C5‡ C1 C2 Y 5 Intermediate C5† C1 C2 N 6 Intermediate C7 C1 C4 Y 7 Intermediate C2 C2 – – 8 Secondary AML Undetermined C4 C2 C2 – 9 Normal C4 C1 – – 10 De novo AML – C1 C1 – – Molecular CR, complete remission confirmed by molecular studies *All received 20 mg/m2 pevonedistat except #4, who started on 30 mg/m2 and had a dose reduction to 20 mg/m2. †Patient off study ‡Patient off treatment and in follow-up Disclosures Swords: Novartis: Consultancy; KaloBios Pharmaceuticals, Inc.: Consultancy; Millennium: The Takeda Oncology Company: Consultancy. Savona:Novartis: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences, Inc.: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Karyopharm Pharmaceuticals: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Erba:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Research Funding; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda Pharmaceuticals International Co.: Research Funding; Astellas Pharma: Research Funding; Celgene: Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding. Foran:Takeda Pharmaceuticals International Co.: Research Funding. Hua:Takeda Pharmaceuticals International Co.: Employment. Faessel:Takeda Pharmaceuticals International Co.: Employment, Equity Ownership. Dash:Takeda Pharmaceuticals International Co.: Employment. Sedarati:Takeda Pharmaceuticals International Co.: Employment. Dezube:Takeda Pharmaceuticals International Co.: Employment. Medeiros:Millennium: The Takeda Oncology Company: Consultancy, Honoraria; Takeda Pharmaceuticals International Co.: Research Funding.

Abstract Abstract 788 FLT3 mutations are common in AML and are associated with poor prognosis. Lestaurtinib is a multi-targeted kinase inhibitor with potent activity against FLT3. In an attempt to definitively establish whether or not there is clinical benefit for FLT3 inhibition in the relapse setting, we conducted a randomized trial of chemotherapy followed by lestaurtinib for patients with FLT3 mutant AML in first relapse. Patients were randomized to receive either chemotherapy alone, consisting of mitoxantrone, etoposide, and cytarabine (MEC) or high-dose cytarabine (HiDAc) depending on the duration of CR1) or chemotherapy followed by 80 mg lestaurtinib orally BID. Patients on the chemotherapy only arm were eligible for crossover if they were refractory to therapy. Patients on the lestaurtinib arm received the drug for up to 112 days on study (they could continue to receive the drug through a separate extension protocol). The primary objective was complete remission (CR/CRp). Secondary objectives included overall survival (OS), safety, and tolerability. From January 2004 through December 2008, 224 patients at 52 different centers were enrolled and randomized, with 220 patients actually receiving therapy. Blood samples from patients on the lestaurtinib arm were obtained at baseline, on Day 15, and on Day 42 for pK studies and for determination of in vivo FLT3 inhibition and measurement of plasma FLT3 ligand (FL) and alpha-1 acid glycoprotein (AGP) levels. The median age for all patients enrolled was 55 years (53.5 in the control arm, 58.5 in the lestaurtinib arm), with 88% having FLT3/ITD mutations, 8% having D835 mutations, and 4% having both. The duration of CR1 was less than 6 months in 47% of patients in each arm. On the lestaurtinib arm, 107 patients received at least 1 week of lestaurtinib (mean 60.1 days, range 8-418), with 17 of these patients receiving drug on the extension protocol. On the chemotherapy only arm, 7 patients crossed over to receive lestaurtinib, and 31 patients went on to receive lestaurtinib on the extension protocol after outcome evaluation. Lestaurtinib was generally well tolerated following chemotherapy, with 104 Grade 3/4 adverse events in the lestaurtinib arm versus 99 in the control arm. There were 61 serious adverse events in the lestaurtinib arm versus 49 in the control arm. Early death (by Day 42) occurred in 22 lestaurtinib patients (2 progressive leukemia, 14 infectious, 6 organ failure) and16 control patients (6 progressive leukemia, 5 infectious, 5 organ failure). By intention to treat analysis, there were 29 CR/CRp in the lestaurtinib arm and 23 in the control arm (26% versus 21%; p = 0.35), with no difference in OS (4.73 months versus 4.57 months) between the two arms. Blood samples from 79 of the 107 lestaurtinib-treated patients obtained on Day 15 were analyzed for FLT3 inhibitory activity (plasma inhibitory activity [PIA] assay), as well as FLT3 ligand (FL), lestaurtinib, and AGP concentrations. Mean lestaurtinib plasma concentration was 12 uM at Day 15 and fell to 7.5 uM on Day 42. Mean lestaurtinib concentration at Day 15 was 13.3 uM in patients achieving CR/CRp and 11.5uM in non-responders. A target of >85% inhibition of FLT3 maintained at trough (pre-dose) was defined from previous studies. Of the 79 patients tested, 46 (58%) achieved this degree of FLT3 inhibition on Day 15. FL concentrations rose from baseline (15.6 pg/mL) to Day 15 (1148 pg/mL), and AGP concentrations rose by an average of 52% over the same period, both of which may have reduced the degree of FLT3 inhibition. Of the 46 patients with target FLT3 inhibition on Day 15, 18 (39%) achieved CR/CRp, while only 3 (9%) of the 32 patients with below target FLT3 inhibition achieved CR/CRp. Thus, in patients with FLT3 mutant AML at first relapse, pharmacokinetic factors and possible physiologic factors (FL and AGP) limit lestaurtinib's ability to effectively inhibit FLT3. FLT3 inhibition by lestaurtinib, when achieved, correlates with better CR rates, but in this trial that benefit was negated by a poor CR rate in those patients for whom the drug did not reach the target level of FLT3 inhibition. Overall, lestaurtinib treatment following re-induction chemotherapy failed to increase response rates or prolong survival of patients with FLT3 mutant AML in first relapse. Disclosures: Levis: Cephalon: Clinical Advisory Board member. Ravandi:Cephalon: Honoraria, Member, clinical advisory board, Research Funding. Erba:Cephalon: Research Funding, Speakers Bureau. Baccarani:Novartis Pharma, Bristol Myers Squibb, Merck Sharp & Dome, Pfizer: Consultancy, Speakers Bureau. Stone:Cephalon: ad hoc consultancy; Novartis: Research Funding, ad hoc consultancy. Advani:Cephalon: Research Funding. Douer:Cephalon: Honoraria, Research Funding, Speakers Bureau. Litzow:Cephalon: Research Funding. Tremmel:Cephalon: Employment, Equity Ownership. Bensen-Kennedy:cephalon: Employment. Smith:Cephalon: Research Funding.

Abstract BACKGROUND: Chronic lymphocytic leukemia (CLL) is one of the most common lymphoid malignancies, accounting for ~11% of all hematologic neoplasms. Over the last 15 years, a series of phase 3 trials have established that chemoimmunotherapy (CIT) with fludarabine, cyclophosphamide, and rituximab (FCR) improves both progression free survival (PFS) and overall survival (OS) compared with chemotherapy alone. FCR is the gold standard for young fit patients with treatment naïve CLL. In parallel with the advances in CIT, a profound increase in the understanding of CLL B-cell biology led to new therapeutic approaches.1 Among these, ibrutinib (an irreversible inhibitor of Bruton's Tyrosine Kinase [BTK]) has had the largest impact on clinical practice to date. Initial trials of ibrutinib demonstrated robust and durable efficacy in patients with relapsed/refractory disease. Subsequent phase 3 trials showed improved PFS and OS with ibrutinib relative to chlorambucil in previously untreated, older CLL patients. Despite these advances, the efficacy of ibrutinib as a first-line treatment for younger CLL patients (i.e. <70) relative to the most efficacious CIT regimens, such as FCR, is unknown. METHODS: Eligible patients were treatment-naive individuals with CLL who were age <70 and required therapy. Patients with deletion 17p- were excluded from participating given the poor response of these patients to FCR therapy. Participants were randomly assigned in a 2:1 ratio to receive ibrutinib (420 mg/day until disease progression) and rituximab (50 mg/m2 on day 1 of cycle 2; 325 mg/m2 on day 2 of cycle 2; 500 mg/m2 on day 1 of cycles 3-7) or six courses of intravenous fludarabine (25 mg/m2 ) and cyclophosphamide (250 mg/m2) days 1-3 with rituximab (50 mg/m2 on day 1 of cycle 1; 325 mg/m2 on day 2 of cycle 1; 500 mg/m2 on day 1 of cycles 2-6) every 28-days. The planned accrual was 519 patients. Hematologic toxicity was graded according to the 2008 IWCLL Working Group scale. All other adverse events were graded according to the NCI Common Toxicity Criteria (version 4). The primary endpoint was PFS with a secondary endpoint of overall survival (OS). Analysis was by intention to treat. The first planed interim analysis for PFS was scheduled to occur 24-27 months after full accrual with the first interim analysis for OS scheduled to occur if the boundary for PFS was crossed. The primary analysis was a stratified logrank test applied to all patients as randomized. Treatment effect p-values are one-sided. The study was approved by the Central Institutional Review Board for the National Cancer Institute, conducted in accordance with the principles of the Declaration of Helsinki, and registered with ClinicalTrials.gov (NCT02048813). RESULTS: A total of 529 patients were accrued between January 31, 2014 and June 9, 2016. 354 patients were assigned to ibrutinib and rituximab (IR) and 175 to FCR. Nineteen patients did not start protocol therapy. The first interim analysis was performed September 2018. With median follow-up of 33.4 months, we observed 77 PFS events and 14 deaths. The hazard ratio (HR) for PFS favored IR over FCR (HR=0.352; 95% CI 0.223-0.558; p<0.0001) which crossed the pre specified boundary. The HR for OS also favored the IR arm (HR=0.168, 95% CI 0.053-0.538; p=0.0003, pre-specified boundary for superiority p=0.0005). Kaplan-Meier estimates for PFS and OS are shown in Figure 1A and 1B. In subgroup analysis for PFS, IR was superior to FCR independent of age, sex, performance status, disease stage or the presence/absence of del11q23. With current follow-up, IR was also superior to FCR for IGHV unmutated patients (HR=0.262; 95% CI 0.137-0.498; p<0.0001) but not IGHV mutated patients (HR=0.435; 95% CI 0.140-0.1350; p=0.07). Grade 3 and 4 treatment-related adverse events were observed in 58% of IR and 72% of FCR treated patients (p=0.0042). Specifically, FCR was more frequently associated with grade 3 and 4 neutropenia (FCR: 69 [44%] of 158 vs. IR: 80 [23%] of 352; p<0·0001) and infectious complications (FCR: 28/158 [17.7%] vs. IR: 25/352 [7.1%]; p<0.0001). CONCLUSIONS: The combination of ibrutinib and rituximab provides superior PFS and OS relative to FCR for patients with previously untreated CLL age <70. These findings have immediate practice changing implications and establish ibrutinib-based therapy as the most efficacious first-line therapy for patients with CLL. Disclosures Shanafelt: Mayo Clinic: Patents & Royalties: Physician Well-being Index, Medical Student Well-being Index, Well-being index; Celgene: Research Funding; GlaxoSmithKline: Research Funding; Genentech: Research Funding; Abbvie: Research Funding; Pharmacyclics: Research Funding; Janssen: Research Funding. Kay:Janssen: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees. O'Brien:Amgen: Consultancy; Astellas: Consultancy; Celgene: Consultancy; GlaxoSmithKline: Consultancy; Janssen: Consultancy; Aptose Biosciences Inc.: Consultancy; Vaniam Group LLC: Consultancy; Abbvie: Consultancy; Alexion: Consultancy; Kite Pharma: Research Funding; Regeneron: Research Funding; Acerta: Research Funding; Gilead: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding. Barrientos:Pharmacyclics/AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Erba:Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy, Other: grant; Novartis: Consultancy, Speakers Bureau; Pfizer: Consultancy, Other: grant; Pfizer: Consultancy, Other: grant; Incyte: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Astellas: Research Funding; Janssen: Research Funding; Janssen: Research Funding; Amgen: Research Funding; Amgen: Research Funding; Novartis: Consultancy, Speakers Bureau; Astellas: Research Funding; Incyte: Consultancy, Speakers Bureau; Astellas: Research Funding; Pfizer: Consultancy, Other: grant; Novartis: Consultancy, Speakers Bureau; Juno: Research Funding; Juno: Research Funding; Novartis: Consultancy, Speakers Bureau; MacroGenics: Consultancy; MacroGenics: Consultancy; Amgen: Research Funding; Takeda/Millenium: Research Funding; Amgen: Research Funding; Takeda/Millenium: Research Funding; Seattle Genetics: Consultancy, Research Funding; Jazz: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Jazz: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy, Speakers Bureau; Takeda/Millenium: Research Funding; Immunogen: Consultancy, Research Funding; Takeda/Millenium: Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Celgene: Consultancy, Speakers Bureau; MacroGenics: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; MacroGenics: Consultancy; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Daiichi Sankyo: Consultancy, Research Funding; Juno: Research Funding; Juno: Research Funding; Agios: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Jazz: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Jazz: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy, Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Daiichi Sankyo: Consultancy, Research Funding. Stone:Juno: Consultancy; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; FujiFilm: Consultancy; Sumitomo: Consultancy; Ono/Theradex: Consultancy; Otzuka/Astex: Consultancy; Pfizer: Consultancy; Roche: Consultancy; AbbVie: Consultancy, Research Funding; Actinium: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; Argenx: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy; Celator / Jazz: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cornerstone: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Tallman:ADC Therapeutics: Research Funding; Daiichi-Sankyo: Other: Advisory board; BioSight: Other: Advisory board; AbbVie: Research Funding; Cellerant: Research Funding; AROG: Research Funding; Orsenix: Other: Advisory board.