Yee, Karen

Abstract Background: Guadecitabine SC (SGI-110) is a dinucleotide next generation HMA resistant to degradation by cytidine deaminase resulting in extended in vivo exposure to its active metabolite decitabine. A Phase 1 established 60 mg/m2 QDx5 as the biologically effective dose (BED), and 90 mg/m2 QDx5 as the Maximum tolerated dose (MTD) in MDS patients given in 28-day cycles (Issa et al, 2015, Lancet Oncology). Phase 2 is conducted to evaluate dose response between the BED and MTD in both untreated MDS patients, and patients previously treated with other HMAs. M ethods: Int, or HR MDS, and CMML patients who were either treatment-naïve (TN) or relapsed/refractory to other HMAs (r/r) were randomized to either 60 mg/m2 or 90 mg/m2 QDx5 every 28 days. Efficacy was evaluated by the clinical responses of CR, PR, marrow CR (mCR), and Hematological Improvement (HI) based on the International Working Group Criteria 2006, as well as transfusion-independence, and overall survival (OS). Adverse events (AEs) were graded by the CTCAE v4 criteria. Results: The study completed target enrolment with 102 patients: 53 r/r MDS, and 49 TN MDS. Fifty three patients were randomized to 60 mg/m2 and 49 patients to 90 mg/m2 QDx5 with a median follow up of 3.2 years (IQR 2.8-3.5 years). Median age was 72 and 71 years for r/r and TN MDS respectively. Most baseline patient characteristics were well balanced between the 2 treatment dose groups except that more CMML patients were randomized to the 60 mg/m2 group (28%) vs. 14% in the 90 mg/m2 group, and more patients with baseline BM blasts >5% were in the 90 mg/m2 group (67%) vs. 38% in the 60 mg/m2 group. Most patients were RBC transfusion-dependent at baseline (57%). In the r/r MDS cohort, most patients (58%) received their last HMA treatment <3 month before enrolment, and most of them received ≥6 months of prior HMA treatment (77%). Median number of treatment cycles was 5 for both r/r and TN MDS (range 1-37 in r/r MDS and 1-49 in TN MDS). In the TN MDS cohort CR was achieved in 11 (22%) of patients with no major difference between the 2 dose groups (19% in the 60 mg/m2 group vs 27% in the 90 mg/m2 group). Overall CR+mCR was achieved in 18 patients (37%) in TN MDS patients and median OS was 23.4 months. In the r/r MDS cohort, CR was achieved in 4% of patients in each of the 2 dose groups. Overall CR+mCR in the r/r MDS cohort was achieved in 17 patients (32%), with a median duration of response of 7.9 months, and median OS of 11.7 months. No significant difference in response or OS between the 2 dose groups was observed. In patients who were RBC transfusion-dependent at baseline, transfusion independence for at least 8 weeks was achieved in 42% of TN MDS, and 15% in r/r MDS patients. In the overall population of 102 TN and r/r MDS patients there were no major differences in OS based on DNMT3A or TET2 mutation status while patients with TP53 mutations had worse median OS (7.4 months) compared to those without TP53 mutations (22.6 months). Other baseline prognostic factors for worse OS were BM blasts >5%; RBC transfusion-dependence; IPSS High Risk; and ECOG Performance Status of >1. Overall incidence of Grade ≥3 AEs regardless of relationship to treatment was reported in 83 vs. 96% for 60 and 90 mg/m2 dose groups respectively. There was a slightly higher but non-significant difference in Grade ≥3 thrombocytopenia (57 vs 41.5%); neutropenia (51 vs 39.6%); febrile neutropenia (43% vs 32%); and pneumonia (32.7 vs. 26.4%) for the 90 mg/m2 compared to 60 mg/m2 dose group. Early 30, 60, and 90-day all-cause mortality was observed in 0, 3.7%, and 5.7% in the 60 mg/m2 dose group respectively; and in 2%, 4%, and 12% in the 90 mg/m2 dose group respectively. Conclusions: Guadecitabine at both dose groups is a well-tolerated novel HMA with clinical activity in the treatment of both TN and r/r Int and HR MDS, and CMML patients. In TN MDS patient CR rate of 22% and median OS of 23.4 months compare well with first generation HMA efficacy (Fenaux et al, 2009, Lancet Oncology). Activity in r/r MDS who previously failed prior HMAs is particularly promising (CR+mCR in 32% of patients with median duration of response and overall survival of almost 8 and 12 months respectively). A phase 3 trial (ASTRAL-3) of guadecitabine vs Physician Treatment Choice in r/r MDS and CMML patients previously treated with azacitidine or decitabine is actively enrolling (ClinicalTrials.gov ID: NCT02907359). Disclosures Ritchie: NS Pharma: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Celgene: Consultancy, Other: Travel, Accommodations, Expenses, Speakers Bureau; Pfizer: Consultancy, Research Funding; ARIAD Pharmaceuticals: Speakers Bureau; Astellas Pharma: Research Funding. Savona:Boehringer Ingelheim: Consultancy; Celgene: Consultancy, 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. Kropf:Celegene: Consultancy; Takeda: Consultancy. Daver:Pfizer: Consultancy; Sunesis: Consultancy; Pfizer: Research Funding; ImmunoGen: Consultancy; ARIAD: Research Funding; Novartis: Research Funding; Incyte: Research Funding; Otsuka: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Alexion: Consultancy; Incyte: Consultancy; Karyopharm: Research Funding; BMS: Research Funding; Kiromic: Research Funding; Daiichi-Sankyo: Research Funding; Sunesis: Research Funding. Jabbour:Pfizer: Consultancy, Research Funding; Novartis: Research Funding; Abbvie: Research Funding; Takeda: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Yee:Celgene, Novartis, Otsuka: Membership on an entity's Board of Directors or advisory committees; Agensys, Astex, GSK, Onconova, Genentech/Roche: Research Funding. Stock:Jazz Pharmaceuticals: Consultancy. Griffiths:Alexion Inc.: Honoraria, Research Funding; Astex/Otsuka Pharmaceuticals: Honoraria, Research Funding; Celgene, Inc: Honoraria, Research Funding; Novartis, Inc.: Research Funding; Pfizer, Inc.: Research Funding. Podoltsev:Astex Pharmaceuticals: Research Funding; LAM Therapeutics: Research Funding; Sunesis Pharmaceuticals: Research Funding; Genentech: Research Funding; Boehringer Ingelheim: Research Funding; Daiichi Snakyo: Research Funding; Astellas Pharma: Research Funding; Pfizer: Research Funding; Celator: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. Berdeja:Genentech: Research Funding; Bluebird: Research Funding; Amgen: Research Funding; Novartis: Research Funding; Glenmark: Research Funding; Takeda: Research Funding; Bristol-Myers Squibb: Research Funding; Teva: Research Funding; Sanofi: Research Funding; Poseida Therapeutics, Inc.: Research Funding; Celgene: Research Funding; Janssen: Research Funding. Naim:Astex Pharmaceuticals, Inc.: Employment. Hao:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals, Inc.: Employment. Roboz:Orsenix: Consultancy; Roche/Genentech: Consultancy; Roche/Genentech: Consultancy; Otsuka: Consultancy; Bayer: Consultancy; Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy; Argenx: Consultancy; Sandoz: Consultancy; Celltrion: Consultancy; Bayer: Consultancy; Orsenix: Consultancy; Pfizer: Consultancy; Astex Pharmaceuticals: Consultancy; Daiichi Sankyo: Consultancy; Sandoz: Consultancy; Daiichi Sankyo: Consultancy; Novartis: Consultancy; Janssen Pharmaceuticals: Consultancy; Cellectis: Research Funding; Eisai: Consultancy; Celgene Corporation: Consultancy; Jazz Pharmaceuticals: Consultancy; Celgene Corporation: Consultancy; Janssen Pharmaceuticals: Consultancy; Eisai: Consultancy; Novartis: Consultancy; Otsuka: Consultancy; Argenx: Consultancy; Celltrion: Consultancy; Astex Pharmaceuticals: Consultancy; Aphivena Therapeutics: Consultancy; AbbVie: Consultancy; Aphivena Therapeutics: Consultancy; AbbVie: Consultancy; Cellectis: Research Funding.

Abstract Background SGI-110 is second generation HMA formulated as a dinucleotide of decitabine (DAC) and deoxyguanosine delivered as a small volume, pharmaceutically stable SQ injection allowing longer half-life and more extended decitabine exposure than DAC IV infusion. SGI-110 differentiated pharmacokinetic profile resulted in potent hypomethylation and clinical responses in previously treated MDS and AML patients in the phase 1 trial (Kantarjian et al. 2012). Methods In a randomized Phase 2 study, relapsed/refractory AML, or elderly treatment naïve AML patients who were not suitable for induction chemotherapy (poor major organ function; poor cytogenetics; or secondary AML) were randomized to one of two SQ doses – the biologically effective dose (BED) of 60 mg/m2 QDx5 or 90 mg/m2 QDx5. The primary endpoint of the phase 2 study is the overall remission rate (CR, CRi, and CRp) based on the International Working Group Criteria 2003. Safety findings based on adverse events (AEs) as graded by the CTCAE v4 criteria and pharmacodynamic data on Long Interspersed Nucleotide Element (LINE-1) DNA methylation (an index of global DNA methylation) activity were also assessed and reported. Results As of June 30, 2013, sixty-seven patients (50 relapsed/refractory AML, 17 treatment naïve elderly AML) were treated and had a minimum follow up of 3 months. Patients were randomized to either 60 mg/m2 dose (32 patients) or 90 mg/m2 dose (35 patients). The median age was 66 years (range, 22–84), 69% were male, and ECOG PS of 0/1/2 was reported in 11/47/9 patients respectively. Median number of prior regimens was 2 (range, 0–10). Patients’ characteristics were well balanced between the 2 dose groups. The primary endpoint of overall remissions (CR, CRp, or CRi) was observed in 17/67 patients (25% with 95% CI, 16–37%). There were 8 complete remissions (CR, CRp, or CRi) in 50 patients with relapsed/refractory AML (16% with 95% CI, 7-29%); and 9 complete remissions (CR, CRp, or CRi) in 17 treatment-naïve elderly AML patients (53% with 95% CI, 28-77%). Five patients (4 relapsed/refractory, and one treatment-naïve elderly AML) subsequently received a stem cell transplant. There was no difference in the complete remission rate between 60 and 90 mg/m2 doses (8 remissions in 32 patients at 60 mg/m2, and 9 remissions in 35 patients at 90 mg/m2). LINE-1 DNA methylation data before and after treatment was available in 50 (75%) patients enrolled. LINE-1 demethylation ≥ 10% post treatment was observed in 83% and 78% in the 60 mg/m2 and 90 mg/m2, respectively. The median maximum LINE-1 demethylation for responders is 25% as compared to 19% for non-responders. The most common adverse events (AEs) regardless of relationship to SGI-110 ≥ Grade 3 include febrile neutropenia, thrombocytopenia, anemia, leukopenia, neutropenia, and pneumonia. The 90 mg/m2 dose showed a greater frequency of Grade 3/4 related AEs ≥ 10% (anemia, febrile neutropenia, leukopenia, neutropenia, and thrombocytopenia) compared to the 60 mg/m2 dose. Conclusions SQ SGI-110 is a new HMA which is well tolerated and clinically active in the treatment of AML. Complete remissions and potent demethylation of ≥10% were equally observed at the 2 dose groups of 60 and 90 mg/m2. These data support further phase 3 investigation of this agent in the treatment of AML. Preliminary overall remission rate of 53% in treatment-naïve elderly AML seems to compare favorably with previous results reported for HMA treatment but this needs to be confirmed in a larger number of patients and randomized studies. Disclosures: Kantarjian: Astex Pharmaceuticals, Inc.: Research Funding. Jabbour:Astex Pharmaceuticals, Inc.: Research Funding. Yee:Astex Pharmaceuticals, Inc.: Research Funding. Kropf:Astex Pharmaceuticals, Inc.: Research Funding. O'Connell:Astex Pharmaceuticals, Inc.: Research Funding. Stock:Astex Pharmaceuticals, Inc.: Research Funding. Tibes:Astex Pharmaceuticals, Inc.: Research Funding. Rizzieri:Astex Pharmaceuticals, Inc.: Research Funding. Walsh:Astex Pharmaceuticals, Inc.: Research Funding. Griffiths:Astex Pharmaceuticals, Inc.: Research Funding. Roboz:Astex Pharmaceuticals, Inc.: Honoraria, Research Funding. Savona:Astex Pharmaceuticals, Inc.: Research Funding. Ervin:Astex Pharmaceuticals, Inc.: Research Funding. Podoltsev:Astex Pharmaceuticals, Inc.: Research Funding. Pemmaraju:Astex Pharmaceuticals, Inc.: Research Funding. Daver:Astex Pharmaceuticals, Inc.: Research Funding. Garcia-Manero:Astex Pharmaceuticals, Inc.: Research Funding. Borthakur:Astex Pharmaceuticals, Inc.: Research Funding. Wierda:Astex Pharmaceuticals, Inc.: Research Funding. Ravandi:Astex Pharmaceuticals, Inc.: Research Funding. Cortes:Astex Pharmaceuticals, Inc.: Research Funding. Brandwein:Astex Pharmaceuticals, Inc.: Research Funding. Odenike:Astex Pharmaceuticals, Inc.: Research Funding. Feldman:Astex Pharmaceuticals, Inc.: Research Funding. Chung:Astex Pharmaceuticals Inc.: Research Funding. Naim:Astex Pharmaceuticals, Inc.: Employment. Choy:Astex Pharmaceuticals, Inc.: Employment. Taverna:Astex Pharmaceuticals, Inc.: Employment. Hao:Astex Pharmaceuticals Inc.: Employment. Dimitrov:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals, Inc.: Employment. Issa:Astex Pharmaceuticals, Inc.: Consultancy, Research Funding.

Abstract Background SGI-110 is a second generation HMA formulated as a dinucleotide of decitabine (DAC) and deoxyguanosine. The compound is delivered as a small volume, pharmaceutically stable subcutaneous (SQ) injection which allows longer half-life and more extended DAC exposure than DAC intravenous infusion. This pharmacokinetic profile offers the potential for improved biological and clinical activity and safety over currently available HMAs (Kantarjian et al. ASH, 2012). Methods A randomized Phase 1-2 first-in-human PK/PD-guided, dose-escalation study was conducted in patients with relapsed or refractory intermediate or high-risk MDS or AML. Patients were initially randomized to one of two SQ regimens - Dailyx5 or Weeklyx3, for 28-day courses. Subsequently, a Twice Weeklyx3 regimen (Monday, Thursday) was added for evaluation based on emerging LINE-1 demethylation data from the Weeklyx3 regimen. Results 93 patients (74 AML, 19 MDS) were treated in the dose escalation phase: 44, 34, and 15 patients were treated in the Dailyx5, Weeklyx3, and the Twice Weeklyx3 regimens, respectively. Across the three regimens, median age was 70 years (range, 29–86), 68% male, and 87% had ECOG PS of 0-1. The median number of prior regimens was 3 (range, 1–9) and 68% of patients had prior HMA treatment (59% AML, and 100% MDS). Of the 74 AML patients treated, 31 (42%) had secondary AML including antecedent MDS. Patients received a median of 2 courses of SGI-110 (range, 1-20). LINE-1 demethylation data at the 2 highest dose levels which were well tolerated and evaluated for all 3 regimens (60 and 90 mg/m2) are shown in the figure below. The Dailyx5 regimen demonstrated the most potent average LINE-1 demethylation, while the Twice Weeklyx3 achieved the most prolonged LINE-1 demethylation. The least potent demethylation was seen with the Weeklyx3 regimen. There was no additional demethylation at the 90 mg/m2 dose compared to 60 mg/m2in all 3 regimens. Responses were reported according to the IWG Criteria 2006 (MDS)/2003 (AML). Complete remissions were observed in 5 AML patients (2CRs, 1CRp, and 2CRi). Clinical responses (2 mCR and 3 HI-E, 1 HI-N, 1 HI-P) were observed in 6 MDS patients, all of whom had been previously treated with HMA. All AML responses and both mCR in MDS patients achieved ≥10% LINE-1 demethylation. Safety is reported based on Adverse Events (AEs) as graded by the CTCAE v4 criteria. Across regimens, the Twice Weeklyx3 demonstrated an increased number of related AEs compared to the other regimens. The most commonly reported related AEs ≥ 10% in the Dailyx5 regimen (injection site pain, thrombocytopenia, neutropenia, anemia, fatigue), Weeklyx3 regimen (injection site pain and diarrhea), and Twice Weeklyx3 regimen (injection site pain, injection site reaction, fatigue, dizziness, febrile neutropenia, neutropenia, anemia, and thrombocytopenia). Conclusions SQ SGI-110 is a potent HMA using all 3 regimens evaluated. The most potent hypomethylation was achieved with Dailyx5 dosing and the most prolonged hypomethylation was achieved using the Twice Weeklyx3 regimen. All 3 regimens were well tolerated. Clinical responses were observed in heavily pretreated patients, including those with prior HMA exposure. These results support the ongoing Phase 2 expansion study investigating the Dailyx5 dosing schedule in patients with MDS and AML who are either HMA treatment naïve or previously treated with HMAs. Disclosures: Roboz: Astex Pharmaceuticals, Inc.: Honoraria, Research Funding. Issa:Astex Pharmaceuticals Inc.: Honoraria, Research Funding. Rizzieri:Astex Pharmaceuticals, Inc.: Research Funding. Stock:Astex Pharmaceuticals, Inc.: Research Funding. O'Connell:Astex Pharmaceuticals, Inc.: Research Funding. Yee:Astex Pharmaceuticals, Inc.: Research Funding. Tibes:Astex Pharmaceuticals, Inc.: Research Funding. Griffiths:Astex Pharmaceuticals, Inc.: Research Funding. Walsh:Astex Pharmaceuticals, Inc.: Research Funding. Feldman:Astex Pharmaceuticals, Inc.: Research Funding. Ritchie:Astex Pharmaceuticals, Inc.: Research Funding. Rao:Astex Pharmaceuticals, Inc.: Research Funding. Larson:Astex Pharmaceuticals, Inc.: Research Funding. Garcia-Manero:Astex Pharmaceuticals, Inc.: Research Funding. Ravandi:Astex Pharmaceuticals, Inc.: Research Funding. Jabbour:Astex Pharmaceuticals, Inc.: Research Funding. Cortes:Astex Pharmaceuticals, Inc.: Research Funding. Schimmer:Astex Pharmaceuticals, Inc.: Research Funding. Mesa:Astex Pharmaceuticals, Inc.: Research Funding. Blum:Astex Pharmaceuticals, Inc.: Research Funding. Chung:Astex Pharmaceuticals Inc.: Research Funding. Naim:Astex Pharmaceuticals, Inc.: Employment. Taverna:Astex Pharmaceuticals Inc.: Employment. Hao:Astex Pharmaceuticals Inc.: Employment. Choy:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals Inc.: Employment. Kantarjian:Astex Pharmaceuticals, Inc.: Research Funding.

Abstract Introduction: Guadecitabine (SGI-110) is a novel next-generation HMA administered as a small volume subcutaneous (SC) injection which results in extended decitabine exposure. Phase 2 studies have been conducted in TN-AML patients who were not candidates for intensive chemotherapy using two different doses and schedules of guadecitabine. We report here a comparative efficacy and safety analysis of the 5-day and 10-day regimens. Methods: TN-AML patients who were not candidates for intensive chemotherapy based on age (≥ 65 y), poor performance status (PS 2), comorbidities, or poor risk cytogenetics were enrolled in 2 separate treatment cohorts in the Phase 2 study. In the first cohort, patients were randomized (1:1) to either 60 mg/m2/d or 90 mg/m2/d on Days 1-5 (5-day regimen). In the second cohort, patients were treated with 60 mg/m2/d on Days 1-5 and Days 8-12 (10-day regimen) for up to 4 cycles, followed by 60 mg/m2/d Days 1-5 in subsequent cycles. Cycles were scheduled every 28 days for both regimes with dose reductions/delays allowed based on response and tolerability. Patients remained on treatment as long as they continued to benefit with no unacceptable toxicity. The primary endpoint was the composite Complete Response (CRc): Complete Response (CR) + CR with incomplete platelet recovery (CRp) + CR with incomplete neutrophil recovery (CRi) using modified International Working Group (IWG) criteria (Cheson et al, 2003). Secondary endpoints included overall survival (OS), and safety. Results: There was no difference in efficacy or safety between 60 and 90 mg/m2/d on the 5-day regimen (Yee et al, European Hematology Association meeting 2014, S647), so data are reported here for the two doses combined on the 5-day cohort. There were 51 patients treated in the 5-day regimen cohort and 52 treated with the 10-day regimen. There was no statistically significant difference in patient characteristics between the 2 regimens; median age 77.9 vs. 77.3 years ; male 59% vs. 65%; PS 2 or higher 35% vs. 40%; median BM blasts 40.0% vs. 49.5%; poor risk cytogenetics 46% vs. 43% for the 5-day and 10-day cohorts, respectively. Follow up of the 10-day cohort patients was shorter as it started after completion of enrolment of the 5-day cohort. The median follow up was 25.7 and 12.4 months and median number of cycles was 5 (range 1-26) and 3 (range 1-13) for the 5-day and 10-day cohorts, respectively. There was no significant difference in the primary efficacy endpoint, CRc, between the 2 regimens (p=0.43). CRc was achieved in 29/51 patients (57%) on the 5-day regimen (19 CR, 3 CRp, and 7 CRi) and in 25/52 patients (48%) on the 10-day regimen (16 CR, 5 CRp, and 4 CRi). Median OS was 10.5 and 8.7 months for the 5-day and 10-day cohorts, respectively (p=0.89). The 30, 60, and 90-day all-cause mortality rates were not statistically significant between the two cohorts: 5.9%, 15.7%, and 21.6% on the 5-day regimen and 1.9%, 17.3%, and 28.8% on the 10-day regimen. The most common Grade ≥3 AEs regardless of relationship to guadecitabine were: febrile neutropenia 59% vs. 60%, thrombocytopenia 47% vs. 38%, neutropenia 39% vs. 33%, anemia 27% vs. 19%, pneumonia 24% vs. 27%; and sepsis 12% vs. 19%, for the 5-day and 10-day cohorts respectively, none of which was statistically significant. Fifteen patients remain on treatment (5 from the 5-day cohort and 10 from the 10-day cohort). Conclusions: Guadecitabine is clinically active with a good safety profile in TN-AML patients not candidates for intensive chemotherapy. Unlike in relapsed/refractory AML, where the 10-day regimen of guadecitabine showed a trend toward improved efficacy (Roboz et al, Annals of Oncology 25 Supplement 4, 2014), there was no significant difference in either efficacy or safety between the 5-day and 10-day regimens in newly diagnosed AML patients. Guadecitabine 60 mg/m2/d SC Days 1-5 is currently being investigated in an 800-patient multicenter randomized phase 3 study in TN-AML patients unfit to receive intensive chemotherapy (ASTRAL-1 Phase 3 clinical trial: ClinicalTrials.gov reference NCT02348489). Disclosures Kropf: Teva Pharmaceuticals: Consultancy. O'Connell:Celgene: Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees. Griffiths:Astex: Research Funding; Alexion Pharmaceuticals: Honoraria; Celgene: Honoraria. Rizzieri:Teva: Other: ad board, Speakers Bureau; Celgene: Other: ad board, Speakers Bureau. Stock:Gilead: Membership on an entity's Board of Directors or advisory committees. Savona:Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; 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. Rosenblat:Astex Pharmaceuticals, Inc.: Research Funding. Berdeja:Celgene: Research Funding; Onyx: Research Funding; BMS: Research Funding; Abbvie: Research Funding; Array: Research Funding; Curis: Research Funding; Acetylon: Research Funding; MEI: Research Funding; Janssen: Research Funding; Novartis: Research Funding; Takeda: Research Funding. Wilson:Astex Pharmaceuticals, Inc.: Employment. Lowder:Astex Pharmaceuticals, Inc.: Employment. Taverna:Astex Pharmaceuticals, Inc.: Employment. Hao:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals, Inc.: Employment. Issa:Janssen: Consultancy; Astex Pharmaceuticals, Inc.: Consultancy.

Abstract Background: SGI-110 is a second generation HMA formulated as a dinucleotide of decitabine (DAC) and deoxyguanosine delivered as a small volume SC injection that yields longer half-life and more extended DAC exposure than DAC IV infusion. A phase 1 clinical trial of SGI-110 demonstrated a differentiated pharmacokinetic profile from DAC IV, potent hypomethylation, and clinical responses in previously treated patients with MDS and AML (Kantarjian et al. 2012). Phase 1 established 60 mg/m2 QDx5 as the biologically effective dose (BED), and 90 mg/m2QDx5 as the Maximum tolerated dose (MTD) in MDS patients given in 28-day cycles. Phase 2 is conducted to evaluate dose response between the BED and MTD in MDS patients. Methods: Int, or HR MDS, and CMML patients who were either treatment-naïve or previously treated were randomized to either 60 mg/m2 or 90 mg/m2QDx5 every 28 days. Efficacy was evaluated by the clinical responses of CR, PR, marrow CR (mCR), and Hematological Improvement (HI) based on the International Working Group Criteria 2006 as well as transfusion-independence. Adverse events (AEs) as graded by the CTCAE v4 criteria and pharmacodynamic biological activity as measured by Long Interspersed Nucleotide Element LINE-1 (an index of global DNA methylation) were also assessed. Patients are being followed for overall survival. Results: The study completed target enrolment with 102 patients: 53 who were refractory or have relapsed on prior treatment, and 49 previously untreated. Fifty three patients were randomized to 60 mg/m2 and 49 patients to 90 mg/m2 QDx5 with a median follow up of 8.2 months (range 1-21). Most baseline patient characteristics were well balanced between the 2 treatment arms with no significant differences in median age (71.7 vs. 72.5 y); male gender (70 vs. 61%); ECOG PS 2 (15 vs. 12%); HR MDS (28 vs. 37%); transfusion-dependence (57 vs. 55%), median baseline Hb (9.25 vs. 9.3 g/dL); platelets count (42.5 vs. 45 x109/L), and neutrophils count (1.19 vs. 1.16 x109/L) for the 60 and 90 mg/m2 QDx5 respectively. However, there were 15 CMML patients (28%) randomized to 60 mg/m2 vs. only 7 CMML patients (14%) randomized to 90 mg/m2(p=0.097). All but 2 patients in the previously treated group received one or more HMA. At the time of the data cutoff, 38 of 102 patients (37%) were still on treatment. Median number of treatment cycles was 4 for previously treated patients, and 5 for the treatment naïve group (range 1-22 cycles). CR+mCR were observed in 10/53 (19%), and 11/49 (22%) in the 60 and 90 mg/m2 arms respectively (p=0.8). CR was observed in 7/49 treatment naïve patients (14%) while CR+mCR were observed in 11/53 previously treated patients (21%) with no significant differences between 60 and 90 mg/m2 arms. Transfusion independence for at least 8 weeks was reported in 32% and 24% for platelets and RBCs respectively with no difference between the 2 treatment arms. Treatment naïve patients benefited from higher rate of transfusion-independence (58% and 46% for platelets and RBCs respectively). Potent demethylation was achieved in both treatment arms with a mean LINE-1 DNA demethylation of 27.3 and 30.5% for 60 and 90 mg/m2 respectively (p=0.12). Overall incidence of Grade ≥3 AEs regardless of relationship to treatment was reported in 81 vs. 88% for 60 and 90 mg/m2 treatment arms respectively (p=0.42).There was a slightly higher but non-significant difference in Grade ≥3 thrombocytopenia (51 vs 38%) and pneumonia (20 vs. 13%) for the 90 mg/m2 arm compared to 60 mg/m2. Early 8-week any-cause mortality occurred in 3/102 patients treated (3%), 2 at 60 and 1 at 90 mg/m2. Follow up for survival is still ongoing. Conclusions: SC SGI-110 is a well-tolerated novel HMA with biological and clinical activity in the treatment of Int and HR MDS, and CMML patients with particularly promising activity in patients previously treated with azacitidine or decitabine. Clinical responses, transfusion independence, DNA demethylation as assessed by LINE-1, and Safety did not significantly differ between the 2 treatment doses. Disclosures Tibes: Astex Pharmaceuticals, Inc.: Research Funding. Rosenblat:Astex Pharmaceuticals, Inc.: Research Funding. Yee:Astex Pharmaceuticals, Inc.: Research Funding. Griffiths:Astex Pharmaceuticals, Inc.: Research Funding. Issa:Astex Pharmaceuticals, Inc.: Consultancy, Research Funding. Naim:Astex Pharmaceuticals, Inc.: Employment. Taverna:Astex Pharmaceuticals, Inc.: Employment. Hao:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals, Inc.: Employment. Roboz:Astex Pharmaceuticals, Inc.: Consultancy.

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 Abstract 414 Background: SGI-110 is a dinucleotide of decitabine (DAC) and deoxyguanosine formulated as a low volume and pharmaceutically stable SQ injection allowing more extended decitabine exposure than DAC IV infusion. The anticipated differentiated PK profile offers the potential of improved biological and clinical activity and safety over currently available HMAs. Methods: A randomized Phase 1–2 FIH Pharmacokinetics/Pharmacodynamics (PK/PD)-guided, dose-escalation study has been conducted in patients with relapsed/refractory intermediate or high-risk MDS or AML. The objective of the first stage (dose escalation) is to determine safety and tolerability and to establish the Maximum Tolerated Dose (MTD) and Biologically Effective Dose (BED). Patients were randomized to one of two SQ regimens (dailyx5 or once weeklyx3, 28-day courses). PD is evaluated by LINE-1 global DNA hypomethylation. The second stage (dose expansion) is to determine the clinical activity and safety in AML and MDS using the established BED and MTD. We report here the results of the dose escalation phase which has completed enrolment. Results: 78 patients (64 AML, 14 MDS) were enrolled in the dose escalation phase: 44 patients in the dailyx5 regimen and 34 in the weeklyx3 regimen. Median age was 69 years (range 29–86), 65% were male, and 82% had ECOG PS of 0–1. Median number of prior regimens was 3 (range 1–9), 59% of patients had prior HMA treatment (50% of AML patients, and 100% of MDS patients). Six patients are still ongoing treatment. The PK profile demonstrated efficient conversion of SGI-110 to decitabine as predicted from the SGI-110 rational design, resulting in longer decitabine exposure window (beyond 8 hrs) compared to DAC IV (3–4 hrs). At SGI-110 dose range of 60–125 mg/m2, observed mean decitabine AUCs (88–231 ng*hr/mL) reach or exceed the therapeutic range seen with 20 mg/m2 DAC IV (115 ng*hr/mL) while achieving only a small fraction of the Cmax (26–64 ng/mL vs 146 ng/mL for DAC IV). The effective half-life for decitabine after SQ SGI-110 injection appeared to be prolonged (up to 4-fold or ∼2.4 hrs) compared to DAC IV (0.58 hrs). Decitabine exposures (AUC) increased in a dose-proportional manner regardless of the regimen and no accumulation was observed. Dose-related LINE-1 hypomethylation was observed in patients treated with the daily regimen between 18 and 60 mg/m2; a plateau in maximum average hypomethylation (∼25%) was evident at higher daily doses (90-125 mg/m2) and therefore the BED for the dailyx5 schedule is established at 60 mg/m2. The 25% average hypomethylation of LINE-1 compares favorably with that observed historically after DAC IV at the dose of 20 mg/m2 dailyx5. The extent of LINE-1 hypomethylation after weeklyx3 SGI-110 was inferior as the maximum average hypomethylation plateaued at ∼8% from baseline. Starting at 36 mg/m2 daily and 60 mg/m2 weekly (44 AML, and 7 MDS patients), clinical responses were observed: 2CRs, 1CRp, and 1CRi in heavily pretreated AML patients; 1 mCR and 1 HI in MDS patients previously treated with azacitidine. All responses were in patients who achieved >10% LINE-1 hypomethylation. The most common Adverse Events (AEs), regardless of relationship to SGI-110, were diarrhea (21%), febrile neutropenia (17%), fatigue/injection site pain/nausea at 15% each. The most common drug-related AEs were injection site pain (15%), fatigue (8%), nausea (6%), and thrombocytopenia (5%). MTD was not reached with the weekly regimen up to 125 mg/m2 weeklyx3. With the daily regimen, 125 mg/m2dailyx5 resulted in 2 Dose-Limiting Toxicities (DLTs) of febrile neutropenia in 3 MDS patients (1 associated with bacteremia, and the other with sepsis and thrombocytopenia Grade 4) while none of the 9 patients with AML had DLT at that dose. Conclusions: SGI-110 is well tolerated at doses higher than BED which is established at 60 mg/m2 dailyx5 where average hypomethylation of ∼25% was achieved. MTD estimated to be 90 mg/m2 dailyx5 for MDS and 125 mg/m2dailyx5 for AML patients. SQ administration of SGI-110 achieved efficient conversion to decitabine resulting in an improved PK profile over DAC IV. Clinical responses were observed in this heavily pretreated population and they seem to correlate with the extent of LINE-1 hypomethylation. Study is currently enrolling patients in the dose-expansion Phase 2 stage. Disclosures: Kantarjian: Astex Pharmaceuticals: Research Funding. Roboz:Astex Pharmaceuticals: Research Funding. Rizzieri:Astex Pharmaceuticals: Research Funding. Stock:Astex Pharmaceuticals: Research Funding. O'Connell:Astex Pharmaceuticals: Research Funding. Griffiths:Astex Pharmaceuticals: Research Funding. Yee:Astex Pharmaceuticals: Research Funding. Tibes:Astex Pharmaceuticals: Research Funding. Garcia-Manero:Astex Pharmaceuticals: Research Funding. Ravandi:Astex Pharmaceuticals: Research Funding. Walsh:Astex Pharmaceuticals: Research Funding. Feldman:Astex Pharmaceuticals: Research Funding. Ritchie:Astex Pharmaceuticals: Research Funding. Rao:Astex Pharmaceuticals: Research Funding. Decastro:Astex Pharmaceuticals: Research Funding. Schimmer:Astex Pharmaceuticals: Research Funding. Mesa:Astex Pharmaceuticals: Research Funding. Syed:Astex Pharmaceuticals: Research Funding. Choy:Astex Pharmaceuticals: Employment. Oganesian:Astex Pharmaceuticals: Employment. Taverna:Astex Pharmaceuticals: Employment. Azab:Astex Pharmaceuticals: Employment. Chung:Astex Pharmaceuticals: Research Funding. Issa:Astex Pharmaceuticals: Honoraria, Research Funding.

Abstract SGI-110 is a novel second generation HMA, formulated as a low volume SQ injection. It is designed as a dinucleotide incorporating decitabine and guanosine, to prolong in vivo exposure and potentially improve efficacy of its active component, decitabine by protecting decitabine from rapid deamination by cytidine deaminase. Preclinically, SGI-110 demonstrated potent activity in-vivo using different routes of administration. A randomized Phase 1-2 FIH PK/PD-guided, dose-escalation study is being conducted in subjects with relapsed/refractory intermediate or high-risk MDS or AML. The objective of the first stage of the study is to determine the safety and tolerability of SGI-110 and to establish the MTD and the biologically effective dose (BED). Subjects are randomized to one of two SQ regimens (daily x5 or once weekly x3, both given in 28-day courses). PD is evaluated by LINE-1 global DNA hypomethylation. The second stage of the study will be a randomized Phase 2 dose expansion, once the BED and MTD have been determined. Currently, 5 dose-cohorts have been fully enrolled, (n= 55) at doses ranging from 3mg/m2 to 60 mg/m2 daily x5, and 6mg/m2 to 90 mg/m2 weekly x3 but are not yet fully evaluable. PK guidance has allowed rapid dose escalation, and PD assessment of global hypomethylation has been correlated with increased dose and exposure levels. Apart from manageable local injection site pain, SGI-110 has been well tolerated. Other AE's were neutropenia, thrombocytopenia, or anemia. There have been 3 remissions in relapsed AML subjects: 1 CR with weekly (60mg/m2) and 1 PR and 1 CR with daily (36 and 60 mg/m2 respectively). The PK profile showed efficient conversion of SGI-110 to decitabine achieving exposures in the therapeutic range as predicted from the SGI-110 rational design, characterized by decitabine AUC in therapeutic range (cohorts 4-5), lower Cmax, and longer effective half life, as compared to historical data based on molar equivalent doses of IV decitabine. Dose-dependent hypomethylation induction in the first 5 cohorts was observed. The subject who achieved a CR had the highest degree of hypomethylation induction of all subjects tested to date, and also the highest decitabine AUC in the cohort. Updated efficacy, safety, PK, and PD data of both regimens will be presented. SGI-110 is safe and well tolerated to date; biologically effective and therapeutic dose levels have been achieved with little toxicity so far with both regimens. Preliminary efficacy (PR+CR) has been observed in relapsed AML subjects. The PK profile showed efficient conversion of SGI-110 to decitabine with achievable therapeutic exposures, longer apparent half life, and lower Cmax than predicted equivalent decitabine doses given IV. Global Hypomethylating effects were observed at all dose levels, evaluated to date with both regimens. The results justify the progress of the study to the second dose-expansion Phase 2 stage after establishing the BED and MTD. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-214. doi:1538-7445.AM2012-LB-214

Abstract In a randomized trial of therapy for FMS-like tyrosine kinase-3 (FLT3) mutant acute myeloid leukemia in first relapse, 224 patients received chemotherapy alone or followed by 80 mg of the FLT3 inhibitor lestaurtinib twice daily. Endpoints included complete remission or complete remission with incomplete platelet recovery (CR/CRp), overall survival, safety, and tolerability. Correlative studies included pharmacokinetics and analysis of in vivo FLT3 inhibition. There were 29 patients with CR/CRp in the lestaurtinib arm and 23 in the control arm (26% vs 21%; P = .35), and no difference in overall survival between the 2 arms. There was evidence of toxicity in the lestaurtinib-treated patients, particularly those with plasma levels in excess of 20μM. In the lestaurtinib arm, FLT3 inhibition was highly correlated with remission rate, but target inhibition on day 15 was achieved in only 58% of patients receiving lestaurtinib. Given that such a small proportion of patients on this trial achieved sustained FLT3 inhibition in vivo, any conclusions regarding the efficacy of combining FLT3 inhibition with chemotherapy are limited. Overall, lestaurtinib treatment after chemotherapy did not increase response rates or prolong survival of patients with FLT3 mutant acute myeloid leukemia in first relapse. This study is registered at www.clinicaltrials.gov as #NCT00079482.