Tibes, Raoul

Abstract Background CD19, a B cell-specific marker, is expressed in the majority of patients with B-lineage leukemia and non-Hodgkin lymphoma. SGN-CD19A is a novel antibody-drug conjugate (ADC) composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl linker. Methods This first-in-human, phase 1, open-label, dose-escalation study is investigating the safety, tolerability, pharmacokinetics, and antitumor activity of SGN-CD19A in adult and pediatric patients with relapsed or refractory B-cell leukemia or highly aggressive lymphoma (NCT 01786096). Eligible patients must have B-cell acute lymphoblastic leukemia (B-ALL) or lymphoma (B-LBL), Burkitt leukemia or lymphoma, and be relapsed or refractory to at least 1 prior systemic regimen. A modified continual reassessment method is used for dose allocation and maximum tolerated dose (MTD) estimation for both pediatric and adult patients. The study is evaluating 2 schedules of IV SGN-CD19A administration: weekly (Days 1 and 8 of 21-day cycles; 0.3-4.5 mg/kg) or every 3weeks (q3week; 0.5-6 mg/kg). Results To date, 49 patients with relapsed or refractory leukemia (n=40) or lymphoma (n=9) have been treated. Median age of adult (n=38) and pediatric patients (n=11) was 37 and 11 years (range, 18-74 and 1-16), respectively. Patients received a median of 2 prior therapies (range 1-9); 14 patients (29%) previously received an allogeneic stem cell transplant. On the weekly schedule, 39 patients (28 adult, 11 pediatric) have been treated, and the median number of cycles is 2.5 (adults; range, 1-12) or 1 (pediatric; range, 1-4). On the q3week schedule, 10 adult patients have been treated, and the median number of cycles is 2.5 (range, 1-4) to date. Six patients remain on study treatment (3 on each schedule), and enrollment is ongoing. The toxicity profiles were similar across both dosing schedules (0.3-2.3 mg/kg weekly and 4-5 mg/kg q3week) and across adult and pediatric patients. The most frequently reported drug-related AEs included pyrexia, nausea, chills, vomiting, blurred vision, and dry eye. Frequent infusion-related reactions were observed early in the study, and recommendation for premedication was instituted. Ocular events were also observed and treated with ophthalmic steroids; steroid eye drop prophylaxis was instituted with each dose. Corneal findings consistent with superficial microcystic keratopathy were observed in 13 adult patients (34%) and in 1 pediatric patient (9%). Grade 3/4 corneal AEs have been observed in 4 adult patients; the majority of these events have resolved or improved to Grade 1 or 2. Steroid eye drop prophylaxis has reduced the incidence of Grade 3/4 events at this interim analysis. Three DLTs were observed: acidosis in a pediatric patient at 1 mg/kg weekly, cytokine release syndrome in an adult patient at 2 mg/kg weekly, and asymptomatic Grade 4 AST elevation in an adult patient at 5 mg/kg q3week. MTD has not yet been determined. SGN-CD19A ADC pharmacokinetic profiles indicate target-mediated drug disposition in patients with leukemia. Plasma ADC exposures generally increased with doses and were lower than those in patients with lymphoma. To date, no objective responses were observed in 9 efficacy-evaluable pediatric patients or in 3 adult patients with Burkitt lymphoma/leukemia. However, in efficacy-evaluable adult patients with B-ALL/B-LBL, objective responses were observed in 6 of 25 patients treated on the weekly schedule (3 CR, 2 CRp, 1 PR), and in 4 of 8 patients treated on the q3week schedule (2 CR, 2 CRp). Of 8 B-ALL patients with CR/CRp, 6 were MRD negative. Conclusions MTDs have not yet been identified, and dose escalation continues on weekly and q3week schedules. SGN-CD19A has been generally well tolerated. At this interim analysis, objective responses were observed in 30% (10 of 33) of heavily pretreated adult B-ALL/B-LBL patients dosed weekly or q3week. Evidence of activity in relapsed/refractory patients and lack of overlapping toxicities suggest opportunities for combination with conventional anti-leukemic therapies in lymphoblastic malignancies. Disclosures Fathi: Ariad: Consultancy; Exelixis: Research Funding; Takeda pharmaceuticals International Co.: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding. Off Label Use: SGN-CD19A is an investigational agent being studied in patients with B-cell malignancies. SGN-CD19A is not approved for use. . Chen:Seattle Genetics, Inc.: Consultancy, Research Funding, Speakers Bureau, Travel expenses Other. Trippett:OSI Pharmaceuticals: Research Funding; Seattle Genetics, Inc.: Research Funding. O'Brien:Seattle Genetics, Inc.: Research Funding. DeAngelo:Seattle Genetics, Inc.: Research Funding. Shah:Pharmacyclics: Consultancy; SWOG: Consultancy; Celgene: Consultancy, Speakers Bureau; NCCN: Consultancy; Seattle Genetics, Inc.: Research Funding; Janssen: Consultancy. Cooper:Seattle Genetics, Inc.: Research Funding. Foran:Seattle Genetics, Inc.: Research Funding. Hale:Seattle Genetics, Inc.: Research Funding. Pressey:Seattle Genetics, Inc.: Research Funding. Silverman:Seattle Genetics, Inc.: Research Funding. Tibes:Seattle Genetics, Inc.: Research Funding. Kim:Bayer: Consultancy; Eli Lily: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding. Albertson:Seattle Genetics, Inc.: Employment, Equity Ownership. Sandalic:Seattle Genetics, Inc.: Employment, Equity Ownership. Zhao:Seattle Genetics, Inc.: Employment, Equity Ownership. Borate:Genoptix: Consultancy; Seattle Genetics, Inc.: Research Funding.

Abstract Introduction: Proteasome inhibition is the backbone of various Multiple Myeloma (MM) treatment regimens, leading to durable responses and high quality remissions. However, under prolonged therapy patients eventually develop drug resistance and the underlying mechanisms have been poorly understood. Proteasome inhibitor resistant cell lines were generated by continuous exposure to proteasome inhibiting drugs. In these cell line models a number of variants within the PSMB5 gene were observed. This includes single point mutations, leading to conformational changes of the _5 subunit within the 20S proteolytic core of the proteasome, impairing its chymotryptic catalytic function and the binding of inhibitory drugs. However, no PSMB5 mutations could, so far, be identified in human disease, leaving the functional relevance of such mutations to be determined. Methods: We applied the MM Mutation Panel (M3P) and used the Personal Genome Machine (Life Technologies) to sequence CD138+ purified bone marrow plasma cells and peripheral blood germ line control from a MM patient in third relapse that had been previously treated by various proteasome inhibitor containing therapies (VTD-PACE, VCD, PAD-Rev). This patient was subsequently treated with a pomalidomide, bortezomib, adriamycin and dexamethasone combination therapy (Pom-PAD) and achieved a partial remission after 4 cycles of therapy. When being exposed to VCD at earlier relapse a complete remission was induced within 6 cycles of therapy, demonstrating excellent response to proteasome inhibition at this earlier disease stage. Results: We identified clonal missense mutations in this patient at known NRAS hotspot location (p.Gln61Arg) and in MAX (p.Arg35His). Most notably we found and validated four subclonal single point mutations in PSMB5, each of them in subclonal frequencies with variant reads (VR) ranging from 1.9%- 5.9% (average read depth 750X). All PSMB5 mutations occurred in a highly conserved region in exon 2 of the gene (p.Cys122Tyr, p.Met104Ile, p.Ala86Pro, p.Ala79Thr), with three of them being located within the proteasome inhibitor drug binding site. Our 400bp amplicon design allowed us to observe that each mutation identified in PSMB5 is exclusively present on a different sequencing read and no reads are shared between the mutations. This implies that the mutations are present on different subclones of the tumor, which means that, despite low VR frequencies of the single mutation, in sum more than a quarter of the whole tumor might be affected by mutated PSMB5. At a disease stage when the patient was well responsive to proteasome inhibitor treatment (at diagnosis and at first relapse), of note, none of the mutations in PSMB5 is detectable. Conclusion: Here we report the first in human PSMB5 mutation in a MM patient. These mutations evolved in parallel within different subclones of the disease under the selective pressure of bortezomib- containing treatment regimens, representing branching evolution. It is to speculate whether previous investigations negating the existence of PSMB5 mutations in proteasome inhibitor treated patients might not have sequenced deep enough or did set up a sensitivity cut-off too rigid to detect such subclonal mutations. Our finding suggests that the mutations identified may contribute to the development of proteasome inhibitor resistance, emphasizing the need for more detailed genomic characterization of tumors, including minor subclonal mutation detection. Functional analysis of the mutations is ongoing and results will be presented at the meeting. Figure Figure. Disclosures No relevant conflicts of interest to declare.

Abstract 5-azacitidine (5-AZA) is standard of care in the first-line setting for higher-risk patients with Myelodysplastic Syndrome (MDS). However, 40-50% of patients are refractory to 5-AZA and most responders ultimately demonstrate disease progression within 2 years, often progressing to AML. For patients refractory to 5-AZA, 2-year survival probability is low (15%). Thus, there is a need for more effective initial and second-line therapies for patients with higher-risk MDS. The Inhibitors of Apoptosis (IAP) Proteins are a family of molecules that suppress apoptotic cell death. Expression of IAPs is dysregulated in MDS, suggesting a potential path for therapeutic intervention. SMAC (second mitochondrial activator of caspases) is an IAP antagonist, resulting in caspase activation, inhibition of NF-kB and increased apoptosis. Birinapant is a potent bivalent SMAC mimetic with improved tolerability and therapeutic index compared to other SMAC mimetics. This Phase Ib/2a study was designed primarily to determine the MTD and recommended Phase 2 dose and schedule of birinapant in combination with 5-AZA in patients with higher-risk MDS who are naïve or have relapsed or are refractory to 5-AZA. To date, 11 patients have been enrolled in the Phase 1b portion of the study, including 7 with IPSS classification high-risk MDS (5 male, 2 female; median age 75, range 64-82) and 4 with intermediate-risk MDS (2 male, 2 female; median age 72.5, range 65-84). All patients received standard 5-AZA, administered via either intravenous (IV) or subcutaneous (SC) routes, at 75 mg/m2 for 7 days of a 28-day cycle in combination with birinapant. Birinapant was administered IV twice weekly (Days 1 and 4) for either 3 of 4 weeks or 4 of 4 weeks per 28-day cycle at a dose of 13 mg/m2. No cycle 1 dose-limiting toxicities have been observed. Adverse events ≥ Grade 2 observed in two or more patients and judged to be related to treatment were rash/pruritis (Grade 2, 2 patients), thrombocytopenia (Grade 4, 2 patients) and neutropenia (Grade 4, 1 patient; Grade 3, 1 patient). Two SAEs, Grade 3 abdominal soft tissue necrosis with abdominal pain in the area of subcutaneous injections of 5-AZA, and Grade 3 cellulitis were judged to be related to treatment. These local injection site reactions/cellulitis were more severe than usually expected with SC 5-AZA, suggesting an on target pharmacodynamic (TNF mediated) localized synergistic effect in skin, but were not observed with IV administration. Both occurred after cycle 1 and were not considered DLTs. Data showing inhibition of NF-kB, a downstream pro-survival molecule activated by IAPs, in circulating blast cells from patients treated with birinapant at a dose of 13 mg/m2 twice weekly for 3 weeks out of 4, suggests that birinapant is pharmacologically active at this dosing schedule. Based on these and other pharmacodynamic data, despite not determining the formal MTD, the Phase 2 dosing regimen has been established as birinapant administered at 13 mg/m2 IV twice weekly for 3 weeks of a 28-day cycle in combination with 5-AZA at 75 mg/m2 by IV infusion for 7 days of a 28-day cycle. Although not a primary endpoint, evidence of clinical activity in 5-AZA resistant/refractory patients was observed in 2 of 11 patients to date, with an additional good clinical response in a 5-AZA naive high-risk MDS/CMML patient. One patient with prior 5-AZA-refractory MDS (cytogenetics: hypodiploid and +11q) showed bone marrow (BM) blast count reduction from 25% to 2% after 1 cycle of 5-AZA/birinapant treatment. Another patient with MDS (cytogenetics: +X; +19; +21) refractory to single-agent 5-AZA showed BM blast count reduction from 21% to 7% after 2 cycles. A third patient with treatment-naïve MDS/CMML-2 (cytogenetics: 46, XY, inv(6)(p11.2q15), t(6;21)(q21;q22) ) who had received prior hydroxyurea demonstrated BM blast count reduction from 17% to 2% after 3 cycles and underwent hematopoietic stem cell transplant. Several patients remain on study and are in active follow-up. This Phase 1b trial provide data for an acceptable safety profile of the first combination of a SMAC mimetic (birinapant) administered with IV 5-AZA. Early signs of clinical activity including in 5-AZA naïve and refractory patients were observed. These results provide rationale for a randomized Phase 2 study comparing birinapant in combination with 5-AZA against 5-AZA alone in the first-line setting for patients with higher-risk MDS. Disclosures Borthakur: Tetralogic Pharmaceuticals: Research Funding. Foran:TetraLogic Pharmaceuticals: Research Funding. Wang:Tetralogic Pharmaceuticals: Research Funding. Rakkar:Tetralogic Pharmaceuticals: Research Funding. Hager:Tetralogic Pharmaceuticals: Research Funding. Frey:Tetralogic Pharmaceuticals: Research Funding. Andreeff:TetraLogic Pharmaceuticals: Research Funding. Carter:Tetralogic Pharmaceuticals: Research Funding. Minderman:Tetralogic Pharmaceuticals: Research Funding. Russell:Tetralogic Pharmaceuticals: Employment. Tibes:Tetralogic Pharmaceuticals: Research Funding.

Abstract Background: A cancer diagnosis results in a multitude of health care decisions that require adequate patient understanding to navigate the health care system. Understanding the type and degree of information needs of cancer patients is imperative to instructing effective and pertinent patient education. This study sought to evaluate the impact of a patient centered cancer symposium on knowledge level, knowledge needs and symptom burden in a cancer patient population. Methods: Surveys were distributed to attendees of the Mayo Clinic "Living with and Surviving Cancer" patient symposium in January 2016. A follow up survey was sent to participants 3 months after the symposium. Surveys included demographic data, questionnaire evaluating disease comprehension and information assessment, symptom burden, desired information and quality of life assessment. Responses were compared between patients with hematologic and solid tumor malignancies by chi-square test. Pre and post comparisons were done in patients completing both surveys by McNemar test. Results: Demographics: 150 patients completed the pre-intervention survey. Average age of participants 67.5 years. Some patients reported more than 1 malignancy. Disease types represented included hematologic malignancies (N=60), specifically multiple myeloma (N=23), lymphoma (N=26), leukemia (N=8) and MPNs (N=3) as well as solid tumor malignancies (N=90). Most patients were diagnosed with cancer at least 1 year prior to the intervention (N=137). Patients with hematologic malignancies were more likely to be on active treatment at the time of the convention (N=35, 58%) compared to solid tumor malignancies (N=37,41%). Baseline Knowledge: Most patients reported an adequate level of knowledge defined as the proportion of participants reporting "quite a bit" or "very much understanding" on the topic of disease understanding (76%). Lowest levels of knowledge were legal issues (18%), pain management (31%), disease relapse symptoms(46%), fatigue management (48%), end of life decision making (50%) and financial management (50%). Patients with hematologic malignancies were more likely to report understanding of fatigue management (N=36, 60%) but less like to report understanding disease risk factors (N=20, 33%), or increased nutritional interest following diagnosis (N=32, 53%) compared to solid tumor malignancy (N=33,37%) (N=55,61%)(N=70,78%), respectively (all p <0.05). The EORTC-INFO25 at baseline revealed hematologic patients had received less information on sexual side effects of treatments (N=7, 14%) compared to solid tumor patients (N=30, 35%; p=0.004), and reported a lower score of treatment information (50 vs 59; p=0.04). Pre and Post Analysis: Of the 150 initial participants, 81 completed the pre and post-convention surveys (54%). Post-symposium, significant improvement defined as the proportion of participants reporting "quite a bit" or "very much" understanding was noted of disease (pre 75% vs post 89%), stress management (pre 56% vs post 69%), maintain relationships (pre 60% vs post 75%) and pain management (pre 33% vs post 51%)(p-value<0.05). The desire for increased information decreased post-symposium regarding all 9 topics, with significant decreases noted in disease, treatment options and side effects, legal issues and stress management. The EORTC INFO25 analysis revealed a decrease in the reported desire for more information (mean; pre 70 vs post 53, p-value <0.05) Discussion: Cancer patients have a variety of information needs. A patient centered educational conference was able to produce significant improvement in understanding in 4 of 17 topics (24%), including general disease, stress and pain management, and relationship maintenance that was durable at 3 months. At least some improvement in understanding was noted in 10 of 17(59%) additional topics. Knowledge deficit improved in all 9 topics assessed, significantly in five. Cancer patient knowledge needs are varied, and likely evolve over time as a patient progress through stages of disease and treatment. Education should re-evaluate and redistribute information to cancer patients over the course of treatment and survivorship. Disclosures Mikhael: Abbvie: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Onyx: Research Funding. Dueck:Bayer: Honoraria. Mesa:Novartis: Consultancy; Ariad: Consultancy; Promedior: Research Funding; Galena: Consultancy; Incyte: Research Funding; Celgene: Research Funding; CTI Biopharma: Research Funding; Gilead: Research Funding.

Abstract Introduction/Background Recurrent deletions of chromosome 5 and 7 are characteristic of the myeloid malignancies MDS and AML, determine prognosis and influence therapeutic decision. The pathogenetic contribution of individual genes to MDS/AML development has been shown for several of these genes. However, how and if these genetic losses may relate to therapeutic interventions or represent haploinsufficient targets has remained elusive for the most part. We hypothesized that genes found within the commonly deleted regions (CDRs) of chromosome 5/7 (chr 5/7) represent targetable vulnerabilities in malignant myeloid cells. Therefore we generated a custom RNAi library to functionally interrogate these genomic regions alone or under 5-Azacitidine (5-Aza) treatment, to identify individual genes whose silencing modulate 5-Aza responsiveness. Methods/Materials Custom siRNA plates against ~270 genes (3x sequences/gene, Qiagen) on CDRs of chr 5/7 were assembled. Genes were silenced by siRNA for 48 hours followed by 48-72 hour 5-Aza treatment after which cell viability was determined. Four cell lines (TF1, THP1, MDS-L and HEL) were investigated in parallel with combined siRNA/5-Aza incubations and appropriate 5-Aza and siRNA only control. Hits were selected as > 2 standard deviation changes in viability from the median log2 value of the ratio [(siRNA + 5-Aza)/(siRNA only)], normalized per plate and across the entire screen. Duplictae RNAis screens were performed. Synergy between 5-Aza and the SMO inhibitors LDE225 (Sonidegib) and GDC0449 (Vismodegib) was assessed with CalcuSyn in a panel of AML cell lines. Ex vivo viability and clonogenic re-population experiments in primary patient derived AML and MDS cells were performed with Sonidegib. Results Several genes within the Hedgehog (HH) pathway emerged as sensitizers to 5-Aza when silenced by siRNA in three of four cell lines examined. Specifically Shh siRNA sensitized to 5-Aza in both TF-1 and THP-1 cells, SMO in HEL and GLI3 in THP-1 cells. Shh silencing alone (siRNA only) resulted in reduction of viability only in TF-1 cells but not in THP-1 cells, while SMO and GLI3 siRNA alone did not result in significant reductions in viability but sensitized to 5-Aza, indicating true sensitization and an interactions between the HH pathway and 5-Aza treatment. The SMO inhibitor Vismodegib synergized with 5-Aza in drug dose response assays in a panel of four AML cell lines (TF-1, THP-1, ML-2, HL-60) with Combination Index (CI) values of around 0.6 or lower at low doses of both drugs. Similar results were also observed with Sonidegib in vitro in 5 molecularly heterogeneous AML cell lines. Given stem cell modulation capacity of SMO inhibition, we examined ex vivo proliferation and more importantly clonogenic growth capacity. Highly interesting, ex vivo viability was reduced and synergy observed by the Sonidegib/5-Aza combination to a much greater extend in CD34+ selected primary MDS and AML cells as compared to bulk or CD34 depleted (normal) MNCs. Clonogenic growth was reduced in the combination over single agent 5-Aza or Sonidegib in ~ 50% of samples assessed to date. No direct correlations to cytogenetics were observed. A clinical Phase 1b trial was designed based on these results and is currently accruing in the first cohorts. Conclusions RNAi screening of CDRs of chr 5/7 yielded potential targetable therapeutic vulnerabilities with several genes within the HH pathway sensitizing to 5-Aza. SMO inhibitors pharmacologically validate this concept in vitro and ex vivo with the potential to more selectively affect leukemia stem/progenitor cells. Clinical data will show if this is a specific effect involving chr 5/7 or a general concept in malignant myeloid cells. Thus, SMO inhibition in combination with 5-Aza may be a novel rational combination in AML and MDS. Disclosures Off Label Use: LDE225/Sonidegib on a clinical trial. Mesa:Incyte, CTI, NS Pharma, Inc., Gilead, Celgene: 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 Hypomethylating agents have changed treatment and outcomes in MDS and are active in AML patients. However a significant number of patients do not respond to 5-Azacytidine or Decitabine and there is no clinically validated assay that predicts response to 5-Azacytidine (5-Aza) or Decitabine (DAC). Clinical parameters and recently TET2 mutations have been identified as genetic predictors of response to 5-Aza. Several recent papers report on the possible predictive value of anti-apoptotic proteins, for example BCL2L10. In previous genome-scale RNA-interference (RNAi) screens anti-apoptotic BCL-2 family members, most potently BCL-XL, were identified as top targets whose down-regulation sensitize to 5-Aza. Results were confirmed with the BCL-XL and BCL-2 inhibitor ABT-737, as well as the BCL-2-specific inhibitor ABT-199, both of which sensitized myeloid cells to 5-Aza. Although it is expected that interfering with anti-apoptotic genes would sensitize to hypomethylating similar to cytotoxics, few of the other >900 genes from our RNAi sensitizer screens, including few of the 571 kinases, sensitized to 5-Aza as potently as inhibition of BCL-XL. Thus BCL-2 family members constitute an especially potent context to modulate the activity of 5-Aza. To assess if protein expression of the top targets BCL-XL, BCL-2 or MCL-1 correlate with and may explain a preferential sensitization, 577 primary AML samples were examined by Reverse Phase Protein Array (RPPA). There was substantial overlap of expression across and within FAB subgroups and cytogenetics, and expression of neither of these genes/proteins could explain the observed effects. This may be expected due to functional redundancies amongst the different anti-apoptotic BCL-2 family members, as well as distinct, yet overlapping binding affinities between anti- and pro-apoptotic BCL-2 proteins and BH3 peptides. Thus, we next aimed to functionally interrogate the overall balance of pro- and anti-apoptotic BCL-2 family members, also described as “primedness” by BH3 profiling. This assay uses peptides derived from pro-apoptotic BH3-only proteins to determine the capacity of cells to initiate apoptosis in response to pro-apoptotic BH3 molecules [anti-apoptotic BCL-2 molecules like BCL-XL and BCL-2 bind and inhibit BH3-only molecules]. This assay is a broad functional readout that incorporates many parameters including the consequences of varying BCL2L10 expression. To establish a proof-of-concept that the functional interrogation of specific apoptotic thresholds may be an optimal readout for 5-Aza response, we first assessed a broad panel of 13 AML-derived cell lines by BH3 profiling and in parallel 5-Aza drug dose response experiments. Several BH3 profiling metrics, including NOXA plus BIM, significantly correlated with 5-Aza sensitivity in vitro (Figure 1). Next, to correlate actual clinical responses to 5-Aza with BH3 profiling, specimens from 28 AML, MDS and MDS/MPN overlap patients treated with 5-Aza or DAC-based regimens and for whom clinical outcome was available, were assayed in BH3 assays. In the clinic, the best BH3 metrics were combined values from NOXA and BIM peptides similar to cell lines. NOXA plus BIM discriminated clinical responses defined as achieving any response (sensitive) versus a patient being resistance/refractory to 5-Aza/DAC based regimens with statistical significance (Mann-Whitney two-tailed p = 0.001). This was true for the entire group of patients (5-Aza- and DAC- regimens) with a Receiver Operating Characteristic (ROC) of an AUC=0.875, with a further increase for patients treated only with 5-Aza based regimens with an AUC=0.95.Figure 1BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM).Figure 1. BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM). In conclusion, due to significant expression overlap and functional redundancies of the BCL-2 family proteins, expression does not correlate with 5-Aza clinical or in vitro responses. However, BH3 profiling as a general functional readout of apoptotic primedness, significantly discriminated responses in patients as well as in vitro. Thus, BH3 profiling incorporates the entirety of pro- and anti-apoptotic molecules (including BCL2L10) and is promising to predict responses to hypomethylating agents. We propose to prospectively validate BH3 profiling as a predictive biomarker assay for 5-Aza or DAC based regimens. Disclosures: Pierceall: Eutropics: Employment, Equity Ownership. Lena:Eutropics: Employment, Equity Ownership. Cardone:Eutropics: Employment, Equity Ownership. Elashoff:Eutropics: Employment. Blake:Noel Blake: Employment, Equity Ownership.

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 Background: Approximately 1,000 acute promyelocytic leukemia (APL) patients are diagnosed in the US annually. APL has the highest cure and early mortality rates of all acute leukemias. The availability of all trans-retinoic acid (ATRA) in 1995 and arsenic trioxide in 2000 has further improved the overall survival (OS). However, whether there is uniform improvement in OS across demographic subgroups and if sooner time-to-treatment (TTT) reduces early mortality are unknown. We used the National Cancer Data Base (NCDB), a nationwide oncology registry covering 70% of the US cancer population to answer these questions. Methods: We identified patients with APL diagnosed from 1998-2011 using ICD-O-3 code 9866. Survival functions were estimated using the Kaplan-Meier method and 30-day mortality was estimated as 1-survival at 30 days. We compared OS according to demographic subgroups (gender, age [18-40, 41-64, and >65 years], race [White, Black, Native American, Asian/Pacific Islander, and other], and ethnicity) across years of diagnosis (Period [P] 1: 1998-2001, P2: 2002-2006, and P3: 2007-2011). For 30-day mortality, we compared the rates according to demographic subgroups and time periods and determined the effect of TTT (days from APL diagnosis to ATRA and/or chemotherapy). For this analysis we included only patients treated within 30 days of diagnosis and those diagnosed from 2003 to 2011. TTT was grouped as 0, 1, 2, or >3 days. We used mixed-effects logistic regression model to obtain odds ratio comparing treatment delays. Our model accounted for multiple subjects per facility with a random intercept and was adjusted for gender, Charlson-Deyo score, and year of diagnosis. Results: Characteristics: There were 8,084 APL patients in our study. The median age at diagnosis was 51 (24% were older than 65) years and 50% were females. White race (85%) was the most common, followed by black (11%) and Asian (3%). Twelve percent were Hispanic in origin. Slightly more patients (54.8%) were treated in academic centers. Thirty seven percent had either Medicaid or Medicare insurance. OS: Race had no impact on OS, although Asians had a trend towards improved OS (P=0.06). Both females and young age affected OS favorably (P <0.0001). In general, OS improved over the three time periods (P=0.002). Across Periods 1-3, we observed significant improvement in OS among the males (P=0.03), 18-40 (P=0.035) and 41-64 (P=0.005) age groups, Whites (P=0.012), and non-Spanish/Hispanics (P=0.002), but not among their counterparts. 30-day mortality rate: Age above 65 years was associated with highest 30-day mortality (33%). Similarly male gender had statistically significant higher 30-day mortality (shown in the Figure). There was no statistically significant difference among Periods 1-3. As expected, untreated patients had an increased risk of death versus treated (HR=1.9, confidence interval 1.7-2.1). TTT: A third (33.5%) of the patients was treated within two days of APL diagnosis. TTT was not independently associated with lower 30-day mortality rate (shown in the Table). Presence of disseminated intravascular coagulopathy (DIC) data was not available to analyze. Conclusions: From 1998-2011, the OS of APL continued to improve but not uniformly across demographic subgroups. In contrast, the 30-day mortality did not improve in the same time period. Both Age above 65 and male gender predicted worse 30-day mortality and OS. Our study did not find a favorable association between shorter TTT and lower 30-day mortality rate. Our study was not able to study these findings among different risk groups. Disclosures Al-Kali: Celgene: Research Funding. Tibes:TetraLogic Pharmaceuticals: Research Funding.

Abstract Introduction: Successful treatment of AML remains dependent upon cytotoxic chemotherapy. However, traditional regimens are not well tolerated by older patients who are at highest risk of disease, and salvage rates after relapse are low, necessitating novel therapeutic strategies. Our groups identified Wee1 as a potential therapeutic target in AML, particularly in the context of concomitant treatment with cytarabine (Tibes et al, Blood, 2012; Porter et al, Leukemia, 2012). Wee1 inhibits CDK1&2 via phosphorylation thereby stalling cell cycle progression. One consequence of Wee1 inhibition/CDK1 activation is impairment of DNA repair via homologous recombination (Krajewska et al, Oncogene, 2013). Cells in which HR is impaired are dependent upon Parp1/2 function, and HR deficient cells are particularly sensitive to Parp1/2 inhibition. Therefore, we hypothesized that combined Wee1 and Parp1/2 inhibition may result in greater inhibition of AML cell proliferation and survival than either alone. Methods: Human AML cell lines, MV4-11 and Molm-13, and a mouse AML that expresses MLL-ENL/FLT3-ITD were cultured with various concentrations of a Wee1 inhibitor (AZ1775) and a Parp1/2 inhibitor (olaparib) and counted 72 hours later by propidium iodide exclusion and flow cytometry. In some experiments, cells were split into fresh media to recover for 72 more hours. Combination Index (CI) values were calculated by the method of Chou and Talalay. Apoptosis was measured using Annexin V/7AAD and flow cytometry. Western blots were used to confirm inhibition of CDK1/2 phosphorylation and to measure DNA damage induction (gamma-H2AX). Results: Combined inhibition of Wee1 and Parp1/2 was synergistic, as measured by cell numbers at 72 hours, in all 3 cell lines tested, with combination index values ranging from 0.3 to 0.9. When cells were allowed to recover after treatment, those treated by single agents were able to continue proliferating. However, those treated with the combination did not recover as well or at all, indicating greatly impaired proliferative capacity. Combined inhibition of Wee1 and Parp1/2 also resulted in a significant increase in apoptosis greater than either drug alone. Western blots for gamma-H2AX confirmed that the combination of Wee1 and Parp1/2 resulted in more DNA damage than either drug alone. Discussion: Combined inhibition of Wee1 and Parp1/2 results in greater inhibition of AML cell proliferation, DNA damage and apoptosis than either drug alone. Future studies will include experiments with primary patient samples, as well as in vivo trials combining Wee1 inhibition with Parp1/2 inhibition. These preliminary studies raise the possibility of rational combinations of targeted agents for leukemia in those for whom conventional chemotherapeutics may not be well tolerated. Disclosures No relevant conflicts of interest to declare.