Foran, James M.

Abstract Background: Large case-control studies have identified common epidemiologic exposures associated with risk of AML development, including obesity [BMI ≥30 kg/m2] associated with 2-fold increase risk. However it is not known whether individual risk factors are associated with unique AML genetic lesions. We have recently identified a significant association of some common exposures including obesity with unique disease cytogenetic subgroups in a cohort of n=295 consecutive AML patients diagnosed and treated at Mayo Clinic [Cancer Epidemiol 39:1084, 2015]. Aberrant DNA methylation is a hallmark of cancer and has been reported in AML, and we therefore performed an analysis of global DNA methylation in patients in this cohort to determine whether specific epidemiologic exposures are associated with a unique pattern of DNA methylation. Methods: Patients in the initial cohort were previously reported. An available baseline AML bone marrow cytogenetic pellet from diagnosis was identified for n=148 patients (50.2%). Following IRB approval and using previously reported techniques [Leukemia 24:1283, 2010], leukemia DNA was isolated from the remnant diagnostic cytogenetic samples and processed on the HumanMethylation450 BeadChip array (Illumina). Individual CpG dinucleotides were assigned a Beta value (i.e. methylation value) ranging from 0 (unmethylated) to 1 (methylated). We excluded those with minor methylation changes (<0.2 between any two samples), resulting in 383,524 CpG's. For the purposes of this first analysis we have focused only on CpG's with an inter-quartile range (IQR, i.e. difference between 75th and 25th percentiles) of greater than 0.25, comprising a total of 39,657 CpG's. An unsupervised cluster analysis of differential methylation was generated ("Heatmap", Figure). Univariate and multivariable analyses were performed adjusting for age as a continuous variable to determine the association of individual exposures with unique methylation clusters (primary endpoint), and we also evaluated the association of clinical characteristics and clinical outcomes after therapy (secondary endpoint). The median age of patients was 69 yrs (range 19-89), male 65%, and Caucasian 89%. The median BMI was 27.2 (range 16.9-59.9), and n=47 patients (32%) had BMI ≥30. Standard cytogenetic risk groups were applied [favorable (n=8), normal (n=61), intermediate abnormal (n=32) and poor (n=47)]. Results: We identified 4 distinct methylation clusters (Figure: Cluster #1, Black horizontal bar; Cluster #2, Green; Cluster #3, Blue; and Cluster #4, Red). Multivariate analysis of select variables is shown in Table. Patients in cluster #1 were significantly more likely to have a BMI ≥30 [Odds Ratio (OR) 2.49, p=0.017] and more likely to have favorable risk cytogenetics although this was not statistically significant [OR 6.71, p=0.088], while those in cluster #2 were significantly more likely to be have a history of regular NSAID use [OR 3.26, p=0.03] and less likely to have normal [OR 0.40, p=0.044] and possibly intermediate abnormal cytogenetics [OR 0.34, p=0.051]. Those in cluster #3 were significantly younger [median age 48 yrs, p<0.001] and were also more likely to have prior history MDS although this was not statistically significant [OR 3.7, p=0.082]. Cluster #4 was not correlated with any distinct exposure apart from possible decreased alcohol use [OR 0.3, p=0.079]. History of past or current tobacco use, regular acetaminophen use, documented myelotoxin exposure, family history, and secondary AML did not correlate with a unique methylation cluster. There was no independent association of methylation cluster with overall survival (p=0.46), although among patients receiving intensive therapy cluster #2 was associated with lower complete remission rate [OR 0.28 (95% CI 0.09-0.86), p=0.026]. Conclusion: This first analysis of AML molecular epidemiology and clinical outcome suggests that specific disease risk factors (esp. obesity and age) are associated with unique leukemia DNA methylation clusters. In addition, aberrant methylation is associated with some clinical features and with outcome after therapy, suggesting that epidemiologic risk factors may have a prognostic impact. This provides novel insight into leukemogenesis, and will guide prospective studies of AML epidemiology and outcome. Figure. Figure. Disclosures Foran: medscape: Honoraria; pfizer: Honoraria; Millennium Pharmaceuticals, Inc.: Research Funding; novartis: Honoraria; karyopharm: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding.

Abstract Background Myeloid neoplasms (MN) occurring secondary to treatment of non-malignant disease, especially autoimmune diseases (AID), and the overlap between them, is an increasing clinically important observation. Confounding variables for myeloid transformation include the nature of autoimmune disease as an incessant, chronically activated inflammatory cascade that has been associated with an increased risk of myeloid malignancy, and disease modifying therapies, often with cytotoxic and immunosuppressive drugs. Thus, the addition of therapeutic agents for treatment of AID theoretically amplifies the opportunity for MN to develop in genetically susceptible individuals. To our knowledge, there is no large study evaluating a comprehensive primary AID population that developed MDS or AML with detailed assessment of therapeutic interventions for AID. The presented study queries the association of cytotoxic, anti-inflammatory, and immune-modulating agents to treat AID as risk factors for developing myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML). Methods In a 10-year period from 2004-2014, a total of 40,011 patients with an ICD-9 coded diagnosis of AID were seen at Mayo Clinic Arizona and Florida campuses; 311 patients from this population had a concomitant coded diagnosis of MDS and/or AML. In an IRB approved, retrospective chart review, we confirmed 86 cases meeting strict inclusion criteria for AID and confirmed MDS or AML. We performed a case-control match from the same primary autoimmune population for age, gender, and autoimmune specific diagnosis at a 2:1 ratio querying for therapeutic interventions. Results Myeloid neoplasm specifics in our case cohort of 86 patients were 55 MDS, 21 de novo AML, and 10 AML with history of MDS. Average age was 72 years with a slight male predominance (57%). Rheumatoid arthritis (26.4%), psoriasis (20.7%), systemic lupus (13.8%), was the most common autoimmune profiles. Median onset of autoimmune disease to diagnosis of myeloid neoplasm was 6 years (range 1-54 years). Up to 26% controls documented no systemic agent for treatment of autoimmune disease and similarly 12.8% of the case cohort (p=0.142). Case and control populations treated with systemic therapies had similar exposures by category for immune-modulating agents (33.7% and 37.8% respectively) and cytotoxic therapies (47.7 and 44.8% respectively). A total of 57/86 cases (66.3%) received either a cytotoxic or immune-modulating agent. In comparison, 105/172 (61.1%) controls received either agent; p=0.495. Azathioprine was the only statistically significant agent exposure observed more frequently in the study cohort than controls with an OR of 7.05 (p= < 0.001). There was no increased incidence of MDS or AML in TNF-antagonist treated patients. No significant correlation for duration of agent exposure by drug category was observed. Discussion In a large primary AID population, azathioprine exposure was associated with a 7 fold risk of MDS or AML (p=< 0.001). Notable, but not statistically significant case cohort trends among cytotoxic agents was exposure to cyclophosphamide (OR 3.58) followed by mitoxantrone (OR 2.73). Methotrexate, mercaptopurine, and mycophenolate had favorable odd ratios, but these were not statistically significant. No association was found for TNF-inhibitory agents. Finally, there was no association of drug exposure time to the incidence in development of MDS or AML. Disclosures Dueck: Bayer: Honoraria. Mesa:Gilead: Research Funding; Novartis: Consultancy; Celgene: Research Funding; Incyte Corporation: Research Funding; Galena: Consultancy; Ariad: Consultancy; CTI: Research Funding; Promedior: Research Funding. Al-Kali:Onconova Therapeutics, Inc.: Research Funding; Celgene: Research Funding. Foran:Millennium Pharmaceuticals, Inc.: Research Funding; novartis: Honoraria; karyopharm: Honoraria; medscape: Honoraria; pfizer: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding.

Abstract Background: International Working Group (IWG) has set criteria in 2003 for response assessment in patients with AML; at which time intensive chemotherapy was the main therapy (Cheson, JCO 2003). Hypomethylating agents (HMA) were approved shortly after for the treatment of elderly AML (Fenaux, JCO 2009; Dombret et al Blood 2015). Although few patients achieve a deep response, the majority will have stable disease (SD), some of which could last several months while patients continue to receive HMA and gain clinical benefit. We hereby describe outcomes for patients who achieve SD with HMA for the treatment of elderly unfit AML patients. Methods: A total of 56 AML patients' data from Feb 2007 to June 2015 at Mayo Clinic were reviewed after appropriate IRB approval was obtained. All cases had their bone marrow slides reviewed at our institution. Patients were considered for our study if they received HMA as frontline therapy for their AML. Patients who received HMAs after induction chemotherapy failure or for their MDS were excluded. Response was identified based on 2003 IWG AML response criteria. Patients with SD were categorized into short-lasting (<6 cycles of HMA, cohort 1) or long-lasting (≥6 cycles of HMA, cohort 2) SD.Prognostic factors were analyzed by univariate and multivariate analyses. Survival estimates were calculated using Kaplan-Meier curves and univariate and multivariate analyses was based on log-rank testing using JMP software version 10. Results: i) Characteristics: Fifty six AML patients were treated with HMA as frontline therapy with median age of 76 years (range, 59-91), 68% of which were males. Therapy related AML (T-AML) was seen in 2% of the cases. Cytogenetics were favorable risk in 2%, intermediate in 62%, and poor in 36%. Complete remission (CR) was found in 10 (18%) patients, CR with incomplete count recovery in 3 (5%), partial remission (PR) in 3 (5%) patients. Forty patients were non-responders (SD). ii) Characteristics of HMA SD cohorts: Upon comparison of cohort 1 versus cohort 2 there was no statistical significance in median age, white blood count, absolute neutrophil count, platelets, peripheral blood and bone marrow blasts, bone marrow cellularity and sex. Median number of cycles was expectedly higher in cohort 2 vs 1 (9 vs 2, p<0.0001). Intermediate cytogenetic risk was more common in cohort 2 vs 1 (90% vs 43%, p=0.006), while poor risk was more common in cohort 1 vs 2 (57% vs 10%, p=0.006). Only 10% had complex karyotype in cohort 2 compared to 50% in cohort 1 (p=0.017). NPM1 mutation was absent in all cases, while FLT3 mutation was present 30% in cohort 1 and 25% in cohort 2 (p = 0.9). Decitabine was more commonly given in cohort 1 vs cohort 2 (80% vs 50%, p =0.07). iii) Clinical outcome of HMA SD cohorts : Median overall survival was higher in long-lasting SD patients (cohort 2) vs short-lasting SD (18 vs 4 months, p = 0.0002). Upon multivariate analysis, both age (p <0.0001) and long-lasting SD (p =0.01) were statistically significant for overall survival but not cytogenetics risk grouping nor type of HMA administered. Conclusions: Standard response criteria for AML by IWG were developed for intensive chemotherapy and do not apply to newer agents, specifically HMA. Stable disease (SD) could be meaningful to some elderly AML patients when treated with HMA. Intermediate cytogenetics and azacitidine use were more frequent in patients with long-lasting SD. Long-lasting SD did confer a survival benefit in elderly AML patients. Newer response criteria for assessing novel agents' efficacy are needed in this population. Figure Figure. Disclosures Tibes: Italfarmaco S.p.A.: Consultancy, Honoraria. Foran:pfizer: Honoraria; Millennium Pharmaceuticals, Inc.: Research Funding; medscape: Honoraria; karyopharm: Honoraria; novartis: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding. Al-Kali:Novartis: Research Funding; Celgene: Research Funding.

Abstract Background: Persistence of minimal residual disease (MRD) after induction, consolidation and salvage therapies is an independent poor prognostic marker in AML. The bone marrow (BM) microenvironment is a protective niche that promotes chemotherapy resistance of leukemia cells. This residual subset of chemotherapy-resistant cells present during remission eventually contributes to the leukemia relapse/persistence. Adhesion of AML cells to BM stroma is dependent on the CXCR4 receptor binding to its ligand CXCL12. High levels of CXCR4 expression correlate with poor survival in AML. It is postulated that blocking the CXCL12/CXCR4 axis will dislodge AML cells from the protective microenvironment and, when combined with chemotherapy, may improve the response to therapy. BL-8040 (BKT140) is a short peptide which inhibits the binding of CXCR4 to CXCL12, resulting in mobilization of leukemic blasts from the BM to the peripheral blood (PB). BL-8040 has strong affinity for the CXCR4 receptor with long receptor occupancy and as a single agent induces differentiation and apoptosis of leukemia cells in preclinical models. A clinical trial assessing the safety and efficacy of BL-8040 in combination with cytarabine (Ara-C) for the treatment of relapsed/refractory AML patients was recently completed (NCT01838395). Here we report results from correlative studies done on samples from patients who participated in this trial. Objective: To assess BL-8040 single agent anti leukemia effects in relapsed/refractory AML. Method: Patients received a once daily SC dose of BL-8040 monotherapy on days 1-2 followed by the same dose of BL-8040 plus Ara-C (1.5g/m2 for patients ≥60; 3g/m2 for patients <60) per day on days 3-7. Six dose levels of BL-8040 (0.5 - 2.0 mg/kg) were tested. PD parameters such as mobilization of leukemic blasts and induction of differentiation and apoptosis were assessed after monotherapy with BL-8040 using frequent PB sampling and BM aspirates at baseline and on day 3 prior to Ara-C administration. Results: 45 patients (including 3 receiving compassionate use BL-8040) with a median age of 61 yrs were treated. The majority of patients had poor risk disease with 24% secondary AML and 17% with prior allogeneic stem-cell transplantation. Most patients were heavily pretreated with 19% relapsing after a short first remission (CR1 ≤12 months), 17% had ≥2 relapses and 45% refractory to 1-2 inductions. The CR+CRi rate was 38% in subjects receiving BL-8040 dose ≥1.0 mg/kg (n=39). Ongoing follow-up (FU) of responding patients (expansion phase; N=19) shows median EFS of 9.3 months (range 4.3-12.8 months). At the time of this analysis 10/19 patients are alive with a FU range of 0.96 - 12.8 months. FACS analysis revealed that BL-8040 monotherapy triggered an average 4.3-fold increase of immature AML blasts (CD45+Low/CD34+/CD117+/HLA-DR+) in PB (i.e., mobilization). Response to treatment was associated with more robust mobilization of AML blasts following BL-8040 monotherapy (responders 9.5 vs non-responders 1.7 fold median). Preferential mobilization of AML blasts over normal cells (4.7 fold vs. 1.4 fold, respectively) was confirmed by FISH analysis in a subset of patients with informative cytogenetic abnormalities. Induction of granulocytic differentiation of immature leukemia progenitors (2.5 fold) in the BM following BL-8040 monotherapy was noted. Finally, induction of AML blasts apoptosis (40% increase) by BL-8040 alone was evident by FACS in day 3 (pre-araC) bone marrow biopsies. Conclusions: The data demonstrate that sustained blockade of the CXCR4-CXCL12 axis with BL-8040 is safe and well tolerated and when given in combination with Ara-C improves the response rate achieved historically with Ara-C alone. In addition, treatment with BL-8040 as a single agent rapidly and efficiently induces mobilization, differentiation and cell death of AML blasts. This selective effect on chemotherapy-resistant cells may be translated into reduction of residual disease arguing for incorporation into front-line trials and such studies are ongoing. Disclosures Foran: Millennium Pharmaceuticals, Inc.: Research Funding; medscape: Honoraria; karyopharm: Honoraria; pfizer: Honoraria; novartis: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding. DiPersio:Incyte Corporation: Research Funding. Peled:Biokine Therapeutics: Employment. Abraham:Biokine Therapeutics Ltd: Employment. Pereg:BioLineRx Ltd: Employment. Vainstein:BioLineRx Ltd.: Employment. Oberkovitz:BioLineRx Ltd.: Employment. Aharon:BioLineRx Ltd.: Employment. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding.

Background: Although 5-azacitidine (5-AZA) is the standard of care for patients with higher-risk patients with Myelodysplastic Syndrome (MDS) almost all patients will fail 5-AZA therapy with the majority of patients progressing within 2 years. Two-year survival for MDS patients refractory to 5-AZA is only 15%. There is a need for more effective therapies for these 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, supporting potential as therapeutic targets. SMAC (second mitochondrial activator of caspases) is an IAP antagonist, resulting in caspase activation, inhibition of the pro-survival transcription factor NF-kB and increased apoptosis leading to tumor cell death. Birinapant is a potent bivalent SMAC mimetic in clinical development for the treatment of several cancers. Pre-clinical data support its investigation in myeloid malignancies, specifically MDS. Methods: This Phase 1b study was designed 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 to or have relapsed or are refractory to 5-AZA. Secondary objectives included determining the clinical activity of the combination of birinapant plus 5-AZA, and assessing the pharmacokinetics (PK) and exploratory biomarkers. Results: Twenty-one patients were enrolled, of whom 15 had high/very high risk MDS, with median IPSS score of 3 (range, 1.5-8). Median age (range) was 73 years (48-84 years). Eight patients were therapy-naïve. All patients received 5-AZA, administered either intravenous (IV; 13 patients) or subcutaneous (SC; 8 of whom 4 later switched to IV), 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) at 13 mg/m2 for either 3 of 4 weeks (15 patients; Cohort 1 and Expansion Cohort) or 4 of 4 weeks (6 patients; Cohort 2) in 28-day cycles. No cycle 1 dose-limiting toxicities were observed. Adverse events ≥Grade 3 observed in two or more patients were thrombocytopenia (9 patients); pneumonia (including fungal pneumonia; 8); anemia (8); leukopenia (7); febrile neutropenia (7) neutropenia (5); fatigue (4); respiratory failure (3); cellulitis or soft tissue necrosis (3); and nausea, vomiting, or hypoxia (2 patients each). SAEs seen in more than one patient included pneumonia (6 patients, including fungal pneumonia); febrile neutropenia (4); sepsis (3) and cellulitis or soft tissue necrosis (3). Grade 3 abdominal soft tissue necrosis occurred in the area of subcutaneous injections of 5-AZA, and two events of Grade 3 cellulitis were judged related to treatment. These local injection site reactions were more severe than expected with SC 5-AZA, and were not observed with subsequent IV administration. These events were not considered DLTs. Treatment-related suppression of NF-k B activity was evident in circulating blast cells from patients in Cohort 1 suggesting pharmacodynamic activity of birinapant at this dose and schedule. Based on this, the Phase 2 dosing regimen has been recommended 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 IV daily for 7 days of a 28-day cycle. Although not a primary endpoint, evidence of clinical activity, as demonstrated by significant reduction in marrow blast percentages, was seen, including 3 patients considered relapsed or refractory to prior therapy. Nine patients of 20 evaluable (45%) demonstrated either a ≥50% decrease in marrow blast count, or a blast count of ≤5% at the end of Cycle 1 or 2. Two additional patients (10%) demonstrated hematological improvement in one or more peripheral cell lineages without transfusions. In addition, 2 patients, one of whom had previously received 5-AZA, could be bridged to stem cell transplant subsequent to response with birinapant plus 5-AZA. Several patients remain in active follow-up. Conclusion: This Phase 1b trial confirms the acceptable safety profile of the combination of birinapant administered with IV 5-AZA. Evidence of clinical activity in both 5-AZA naïve and refractory patients provide the rationale for an ongoing global randomized, blinded Phase 2 study comparing birinapant in combination with 5-AZA vs. 5-AZA alone in patients with higher-risk MDS in the front-line setting. Disclosures Wang: Immunogen: Research Funding. Rakkar:TetraLogic Pharmaceuticals: Research Funding. Minderman:TetraLogic Pharmaceuticals: Research Funding. Burns:TetraLogic Pharmaceuticals: Employment. Tibes:TetraLogic Pharmaceuticals: Research Funding.

Abstract Background: Current tumor profiling analytics provide some insight into the various molecular abnormalities and their individual consequences on oncogenic signaling. However, these analyses are limited by their lack of integration where the combined effect of individual mutations, gene copy number variations and chromosomal aberrations are not consolidated to create the global molecular architecture that supports neoplastic growth, particularly in the context of drug resistance. Consequentially, identities of the preferential oncogenic pathway(s) tumor cells employ to oppose the effects of targeted therapies remain cryptic and unactionable. Here we present a simulation-based method, which not only replicates the molecular architecture of ibrutinib-resistant Waldenstroms Macroglobulinemia (WM, for which ibrutinib is the only FDA-approved agent) in silico, but also predicts cell sensitivity towards existing drugs, which we validated experimentally for potential clinical translation. Materials: We used the newly established human WM cell line, RPCI-WM1/IR, as a surrogate model of ibrutinib-refractory WM. Genomic data including whole exome sequencing (WES) and copy number analysis (CNA) was utilized for the creation of an avatar of RPCI-WM1/IR, which through simulation identified the salient and prominently dysregulated cellular pathways. Importantly, illustrating these pathways highlights common convergence points on increased proliferation and viability. These convergence points were then directly and indirectly targeted by simulated testing of a library of FDA approved drugs and those impacting these dysregulated pathways were nominated. Importantly, this simulation avatar approach not only looks for agents acting on the specific gene mutation, but also predicts the convergence points to be attacked. The personalized simulation avatar technology is a comprehensive functional proteomics representation of the WM physiology network. A standardized library of equations models all the biological reactions such as enzymatic reactions, allosteric binding and protein modulation by phosphorylation, de-phosphorylation, ubiquitination, acetylation, prenylation and others. Results: Several genomic aberrations were used to create the RPCI-WM1/IR simulation avatar. Functional activity (based on mutation or copy number alteration) of several ibrutinib targets or transcription factors associated with BTK activity such as FYN, SP1, BMX and FRK were predicted to be lost. Increased expression of CAV1, which also inhibits BTK mediated signaling, was increased. An increase in CSNK2B, which activates PU.1- a transcriptional target of BTK, was also observed. Of note, no CXCR4 mutations, which have been shown to impact ibrutinib response, were observed. Next, the cytotoxic potential of over 150 FDA approved drug (and some in experimental stages) were simulated individually and in combination on the RPCI-WM1/IR avatar. In silico modeling predicted aberrant activity of aurora kinase A (AURKA) and its associated signaling partners, which could be disrupted with the (AURKA) inhibitor, tozasertib. AURKA activation was predicted as upregulated due to alterations in several genes: RASA1 loss and SOS1 increase --> increased ERK --> increased ETS1 --> increased AURKA. High beta-catenin signaling (high CTNNB1 and FZD1/4 and low AXIN1 and GSK3B) was also shown to increase AURKA. The simulation predictions were experimentally validated in vitro where AURKA inhibition with tozasertib significantly inhibited proliferation of RPCI-WM1/IR cells (IC50~14nM) as well as inducing apoptosis (48hr, 20nM treatment) and cell-cycle arrest. Conclusions: Our data demonstrates the potential of in silico modeling in predicting novel drug targets, allowing guidance in 1.) Delineating operational oncogenic circuits in an ibrutinib-resistant state by reanimation of the molecular architecture in silico, 2.) Calculating the impact of individual genomic abnormalities and their collective influence on maintaining tumor survival and 3.) Performing a rapid in-silico drug-sensitivity screen directed by the pathway analyses, which can be validated experimentally using standard assays. This novel approach holds tremendous potential in creating highly personalized therapies for ibrutinib-refractory WM patients based on unique genetic signatures. Disclosures Vali: Cellworks Group, Inc.: Employment, Equity Ownership. Kumar:Cellworks Group, Inc.: Employment. Singh:Cellworks Group, Inc.: Employment. Abbasi:Cellworks Group, Inc.: Employment, Equity Ownership.

Abstract Background: The bone marrow (BM) niche protects acute myeloid leukemia (AML) cells from chemotherapy. BM homing of AML cells is dependent on CXCR4 and its ligand CXCL12; high levels of CXCR4 expression correlate with poor survival in AML. It is postulated that blocking the CXCL12/CXCR4 axis with a potent CXCR4 antagonist will disrupt the interaction of the leukemic blasts with the BM and augment the anti-leukemic effect of chemotherapy. BL-8040 (BKT140) is a short synthetic peptide which inhibits the binding of CXCR4 to CXCL12, resulting in the mobilization of leukemic blasts from the bone marrow to the peripheral blood. BL-8040 also inhibits CXCR4/CXCL12 mediated pro-survival ERK/Akt signaling and alters balance of pro/anti-apoptotic Bcl-2 proteins. BL-8040 has strong affinity for the CXCR4 receptor with long receptor occupancy, and, in contrast to other CXCR4 inhibitors, as a single agent induces apoptosis of leukemia cells ex-vivo in clinical samples. A clinical trial assessing the safety and efficacy of BL-8040 in combination with cytarabine (Ara-C) for the treatment of adult relapsed/refractory AML patients is currently ongoing (NCT01838395). Objective: To assess the safety, efficacy and pharmacodynamics/pharmacokinetic parameters of BL-8040 in combination with Ara-C in first or second relapse and refractory AML patients. Method: The study includes a dose escalation phase (3+3 design) followed by an expansion phase. Each patient receives a once daily SC dose of BL-8040 monotherapy on days 1-2 followed by the same dose of BL-8040 plus Ara-C (1.5 g/m2 for patients ≥60; 3 g/m2 for patients <60) on days 3-7. Five dose levels of BL-8040 (0.5, 0.75, 1, 1.25 and 1.5 mg/kg) have been tested. Extensive pharmacodynamic parameters such as CXCR4 expression on the leukemic cells, receptor occupancy, mobilization of leukemic cells and induction of apoptosis are being assessed after monotherapy with BL-8040 using peripheral blood sampling (PB) and BM aspirates at baseline and on day 3 prior to Ara-C administration. Clinical response to treatment is evaluated by BM biopsy on day 30 (-/+ 2). Results: Twenty two patients (median age, 61 y; range, 43-74 y) with relapsed/refractory AML were treated during the escalation phase. BL-8040 was escalated up to 1.5 mg/kg (recommended phase 2 dose) without reaching the MTD. Combination of BL-8040 with Ara-C was safe and well tolerated at all doses tested. Only one SAE (Sweet Syndrome) was reported as possibly related to study drug. The primary treatment related AEs were transient injection site and systemic reactions. The composite complete remission including complete remission (CR) and complete remission with incomplete blood count recovery (CRi) rate was 38% in subjects receiving BL-8040 doses of 1 mg/kg and higher (n=16). Two days of BL-8040 monotherapy triggered an average 40.2-fold (range 1.0-350.9) mobilization of immature AML progenitors (CD45+Low/CD34+/CD117+/HLA-DR+) from the BM to the PB. Moreover, a significant apoptotic effect on the immature leukemia progenitors in the BM following 2 days of BL-8040 monotherapy was noted. Flow cytometric evidence of apoptosis by BL-8040 was corroborated by an increase in cleaved caspase 3 positive blasts in day 3 bone marrow biopsies. In addition, BL-8040 treatment resulted in a median decrease of 57.7% (range, -10.4% to -96.2%) in the number of BM Leukemia progenitor cells (CD45+Low/CD34+/CD117+/HLA-DR+ out of total CD45+/CD34+ normal/progenitor cells) compared with the baseline biopsy. This decrease was accompanied with a 3.1 fold increase in granulocytes in the day 3 BM biopsy supporting differentiation effect. Finally, long receptor occupancy (up to 24 hours post dosing) was confirmed by FACS analysis measuring surface CXCR4 staining. Pharmacokinetics analysis confirmed dose incremental BL-8040 exposure with a short plasma half-life. Conclusions: The current data demonstrate that sustained blockade of the CXCR4-CXCL12 axis with BL-8040 has potent anti leukemic activity and in combination with Ara-C may improve the response typically achieved in this advanced AML population. Mechanistically, BL-8040 was able to induce apoptosis of leukemic progenitor cells, overcoming the stroma protection, inducing mobilization and differentiation. Disclosures Rowe: BioLineRx Ltd.: Consultancy; Amgen: Consultancy; BioSight Ltd.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Uy:Novartis: Research Funding. Altman:Seattle Genetics: Consultancy; Novartis: Consultancy; Spectrum: Consultancy; Astellas: Consultancy; Ariad: Consultancy; BMS: Consultancy. Peled:Biokine Ltd.: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; BiolineRX: Consultancy, Research Funding. Pereg:BioLineRx: Employment. Vainstein:BioLineRx: Employment. Aharon:BioLineRx: Employment. Pemmaraju:Stemline: Research Funding; Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; LFB: Consultancy, Honoraria. Cortes:Teva: Research Funding; Pfizer: Consultancy, Research Funding; BMS: Consultancy, Research Funding; BerGenBio AS: Research Funding; Novartis: Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Ambit: Consultancy, Research Funding; Arog: Research Funding; Celator: Research Funding; Jenssen: Consultancy.

Abstract Introduction: DLBCL is an aggressive mature B-cell neoplasm with a low incidence in African Americans and other minority groups. The differences in outcomes based on DLBCL Cell of Origin(COO) immunophenotypic subtypes as defined by the Hans algorithm using CD10, Bcl-6, and MUM1 namely germinal center B-cell (GCB) and non-GCB have been based on predominantly Caucasian patients (pts) and their impact on outcomes in AA patients have not been well studied. Material and Methods: A retrospective review of clinicopathologic data from patients diagnosed and treated for DLBCL at UAB between 2002-2011 was conducted following IRB approval .The data collected included patient demographics (age, sex, self identified race), DLBCL subtype (GCB vs. non-GCB based on the Hans algorithm), disease stage, first line therapy regimens and patient outcomes. We analyzed group differences in both C and AA pts with GCB and non-GCB subtypes of DLBCL in all the parameters mentioned above using the chi square test for categorical variables,. In addition, OS was examined using Kaplan Meier curves and the log rank test. We performed univariate and multivariate analyses to examine the effects of variables of interest on OS. All results were considered statistically significant at α=0.05 level. Results: We included a total of 259 pts in our analysis after excluding patients with missing demographics, disease related data, primary mediastianal DLBCL, missing first line therapy data and outcomes data as well as race identified as other than C or AA. 45 patients (17.4%) of patients self identified as AA and 214 (82.6%) self identified as Caucasian. The mean age of presentation for AA pts was 52 yrs compared to 58 years for C patients (p=0.045) and 28 (62.2%) AA patients presented with advanced Stage III and IV disease compared to 89 (44.6%) of C patients (P=0.04) both being statistically significant. Based on COO characterization using immunophenotype by Hans algorithm, 27 AA pts (60%) and 145(67%) of C pts were GCB by immunophenotype(p=0.317). 95% of all patients received R-CHOP as first line therapy , 3.5% received R-CVP and the remaining received a combination of Rituximab alone, FCR or radiation therapy .On analyzing OS based on COO, AA patients did not demonstrate a significant difference in OS based on COO with both GCB and non-GCB groups having a median OS of 84 months ( p=0.74)( 95% CI 72-121 months). However, the median OS for C pts with GCB phenotype was 104 months compared to 25 months for the non-GCB phenotype and the median OS was 55 months +/-12.6 months for the C pt group as a whole( p<0.001 by log rank test )which was highly statistically significant.Multivariate analyses of different factors affecting OS showed only COO (p<0.001), age(p=0.07) and stage of DLBCL at presentation(p=0.027) to affect OS significantly.Race,Gender and IPI score did not appear to impact OS significantly. Conclusion: Our study aimed to study the impact of COO and Race on OS in DLBCL especially in AA pts where this has not been well characterized. Our results show that as expected the incidence of DLBCL is lower in AA patients compared to C pts. However, DLBCL presents at younger age and with more advanced stage in AA than in C patients. Although distribution of COO is similar in AA and C patients, our findings suggest that COO may not have the same effect on prognosis among AA pts as it does among the C pt population where we see non-GCB patients do significantly worse than their GCB counterparts. This may reflect a different disease biology in AA patients that has yet to be understood. Our study limitations include not taking into account disease relapse, second line therapy and effect of autologous bone marrow transplantation on overall survival. Figure 1. Figure 1. Figure 2. Figure 2. Figure 3. Figure 3. Disclosures No relevant conflicts of interest to declare.

Abstract Background In the U.S. over 14,000 new cancer cases occur annually in people under 21 years of age; approximately 21% of cases are acute lymphoblastic leukemia (ALL) and ∼ 30% classify as Burkitt lymphoma (BL). Most cases of ALL and BL are due to malignant B-cells that have acquired disease-defining oncogenic lesions that facilitate their rapid proliferation. To maintain a state of homeostasis, the malignant cells rely heavily on the ability of the internal degradation and recycling systems to match the high rate of protein turnover. As such, the ubiquitin proteasome system (UPS) is central in this operation where it prevents buildup of misfolded proteins while also regulating the availability of anti-apoptotic proteins such as BCL2 and MCL1. These observations coupled with the observation that UPS disruption leads to cellular demise have resulted in the development of several proteasome inhibitors (PI). These PI have primarily been examined in adult B-cell malignancies. The feasibility of a bortezomib-containing regimen for use in pediatric malignancies has been examined by the TACL consortium and demonstrated a 73% response rate in relapsed/refractory ALL patients. However, a major limitation of bortezomib-based therapy is an increased incidence of peripheral neuropathy (PN), which was also noted in the TACL study. As such, more potent and reportedly less toxic PI have been developed that seem to carry considerably lower risk for development of PN. Such agents that maintain a high response rate and carry reduced long-term adverse effects are highly desirable in pediatric age patients. Aim Investigation of the novel proteasome inhibitors carfilzomib and MLN9708 (Millennium Pharmaceuticals) in preclinical models of pediatric B-lymphocytic cancer. Methods Representative preclinical models of BL (Raji cell line) and B-ALL (ALL-1 cells) were used in this study. Proteasomal activity was measured using synthetic fluorogenic peptide substrates. Cell viability was measured by MTS assay. Apoptosis was determined by annexin-v/PI staining and mitochondrial membrane permeability (MOMP) was assessed using TMRM followed by flow cytometry. Protein profiling was performed via immunoblot. Results In an effort to understand the effect of carfilzomib and MLN9708 in our pediatric cancer models, we first assessed their ability to inhibit proteasomal activity. While chymotrypsin-like activity, which is the target of both PIs, is inhibited by more than 90% in both cell lines, inhibition (∼ 35%) of caspase-like function conferred by the b1 subunit was more significantly pronounced in MLN9708 treated Raji and ALL-1 cells. Next we performed an MTS assay to determine the growth inhibitory effects of these PI in vitro. Both PI inhibited the growth of the Raji and ALL-1 cells in a dose dependent manner. Carfilzomib showed a more potent effect (IC50 ∼1nM in both cell lines) as compared to MLN9708 (IC50 ∼30nM in ALL-1 cells and ∼50nM in Raji cells). To further understand mechanisms of growth inhibition we examined both tumor cell lines for induction of apoptosis along with corresponding markers. As compared to Raji cells, we observed ALL-1 cells to be more sensitive to the effects of both PI, albeit with MLN9708 (50nM) inducing more cell death (65%) as compared to carfilzomib (10nM, 50% cell death). Further, we observed altered MOMP, cleavage of caspases 9, 3 and PARP-1 were found to occur in both cell lines in presence of carfilzomib or MLN9708. These changes indicate the apoptotic effects of novel PI in ALL-1 and Raji cells are via mitochondrial destabilization and caspase activation. As inhibition of the UPS aids NOXA and BIM (pro-apoptotic BCL2 proteins) mediated cell death, we examined the expression of BCL2 family proteins changes in Raji and ALL-1 cells in response to novel PI. Indeed protein levels of both BCL2 and MCL1 were reduced in carfilzomib and MLN9708 treated cells. Reduced BCL2 expression was more pronounced in ALL-1 cells as compared to Raji cells and downregulation was noted to be dose-dependent. Summary Our data show that both carfilzomib and MLN9708 potently inhibit the viability of malignant ALL and BL cells in vitro. We conclude that PI are promising anti-neoplastic therapeutics that target not only the UPS but also modulate the expression of critical anti-apoptotic proteins. Data from mechanistic studies conducted herein underscore the need for further research in in vivo models of these diseases. Disclosures: Foran: Celgene: Research Funding.

Abstract Abstract 2686 Background: DLBCL is the most commonly occurring form of non-Hodgkin lymphoma and is a highly curable disease, but one that is universally fatal if untreated or improperly treated. In a series of studies, we have reported racial disparities in the clinical presentation and the treatment outcomes for patients (pts) with DLBCL in the United States (Shenoy Cancer 2010; Flowers CEBP 2012). These studies showed that black pts with DLBCL are diagnosed at an age a decade younger than whites, are more likely to have advanced stage disease, and are less likely to survive 5 years. One explanation is that black patients in the US less often receive standard of care therapy (Flowers CEBP 2012). However, in a cohort study of 533 white and 144 black patients with DLBCL managed at Emory and University of Alabama-Birmingham (UAB) black race predicted worse overall survival (OS) even when black and white pts received the same therapy (CHOP; Hazard ratio [HR] 1.8, p<0.001) suggesting a biological basis for some disparities(Flowers Leuk Lymph 2012). To address these findings, we examined whether known prognostic biological variants within DLBCL [germinal center B-cell-like (GCB) and activated B-cell like (ABC)] occurred differentially between black and white pts. Methods: DLBCL pts within our Emory-UAB cohort study provided formalin fixed material available for construction of tissue microarrays (TMAs). All pts were diagnosed with DLBCL from 1990–2010 and met the following criteria: age ≥18 years at diagnosis and available information on demographics, race, gender, initial clinical features at presentation, treatment, and treatment outcomes. H&E slides from each block for each case were reviewed to identify the appropriate zone(s) for cores. Sections placed in TMAs underwent immunohistochemistry (IHC) staining with BCL6, GCET1, CD10, FOXP1, and LMO2 antibodies. The percentages of positive cells were scored in 10% increments for each antibody, and recorded for each case by 3 hematopathologists blinded to the clinical and demographic data. The Choi algorithm was used to classify all patients into ABC and GCB subsets; other IHC algorithms were used as a backup. Descriptive statistics for the baseline characteristics of black and white pts were compared using Chi-square tests. Kaplan–Meier estimation was used to evaluate OS for the two groups and compared with the log-rank test. To evaluate prognostic factors and the effects of treatment on OS, Cox proportional hazards models were used controlling for age, sex, stage, LDH, performance status, presence of B-symptoms, race, treatment (R-CHOP vs. other), and ABC subtype. Results: Tissues for 26 black pts and 63 white pts meeting all eligibility criteria were evaluated in the TMA. There were significant differences in baseline characteristics between the two groups; 23% of black pts vs. 46% of whites were > 60 years of age (p=0.04), 73% had stage III/IV disease vs. 56% (p=0.03), and 77% had an LDH>ULN vs. 51% (p=0.04). There were no significant differences between the two racial groups in terms of sex, ECOG PS, presence of B-symptoms (38% vs. 29%p=0.46), extranodal sites (50% vs. 78% ≤ 1, p=0.27), IPI risk, or treatment received (RCHOP 46% vs. 40% p=0.93). By the Hans, Natkunam, Tally, and Choi algorithms black patients more commonly presented with the poor-risk ABC/non-GCB subtype (by Choi black 64% ABC vs. white 37%; p= 0.01, Table). After controlling for clinical confounders including age, sex, stage, LDH, performance status, presence of B-symptoms, race, treatment (RCHOP vs. other), and ABC subtype, being >60 years of age [HR 3.1 95% CI 1.3–7.2], being black (HR 3.5 95% CI 1.5–8.2), and receiving treatment other than RCHOP (HR 12.8, 95% CI 3.2–50.6) were associated with inferior OS. Conclusions: The rate of ABC DLBCL is significantly higher in black pts compared to white pts in this university-based cohort from the Southern United States. Additional studies confirming these findings in larger populations and examining the mutations associated with these differences are underway to address biological differences intrinsic to DLBCL that may in part explain comparatively adverse features and outcomes for black pts with DLBCL. Disclosures: Flowers: Celgene, Spectrum, Millennium, Gilead, Janssen: Research Funding; Genentech/Roche (unpaid), Millennium (unpaid), Celgene: Consultancy. Bernal-Mizrachi:Empire Genomics (not related to current work): Patents & Royalties. Sinha:Celgene: Research Funding. Jaye:Millenium Pharmaceuticals (For single lecture on immunohistochemical subtyping of large B cell lymphomas): Honoraria.