ALBERT

Description: Abstract 3509 Mutations in the isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes are present in ∼16% of acute myeloid leukemia, and cause a neomorphic enzyme activity that results in the production of 2-hydroxyglutarate (2HG). Mutational and epigenetic profiling of a large patient cohort of acute myeloid leukemia (AML) has revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and an impaired hematopoietic differentiation. To further investigate the intrinsic effect of 2HG on hematopoietic proliferation and differentiation, we transfected an erythroleukemia cell line (TF-1) with either IDH1 or IDH2 mutant alleles. These cells overexpress the mutant enzyme, have high levels of 2HG, and exhibit GM-CSF independent growth. Consistent with clinical observations, overexpression of the IDH mutant proteins led to hypermethylation of both histones and DNA. These results suggest that mutations in IDH1/2 could lead to epigenetic rewiring of cells that could facilitate the gain of function phenotype. To gain a broader understanding of the biological consequence of the IDH1/2 gain of function mutations we have generated small molecules that are capable of selectively inhibiting IDHm enzymes. Upon compound treatment in vitro, we are able to reverse hypermethylation of both histones and DNA in Idhm expressing cells. These compounds are also suitable for use in vivo and upon compound treatment are able to lower 2HG by 〉90% in tumor xenograft models. These data suggest that an inhibitor of IDH1/2 mutations could correct the altered gene expression patterns seen in IDH1/2 mutant AML tumors and potentially lead to a profound effect on hematopoietic differentiation, proliferation and tumor growth. Disclosures: Yen: Agios Pharmaceuticals: Employment, Equity Ownership. Wang:Agios Pharmaceuticals: Employment, Equity Ownership. Schalm:Agios Pharmaceuticals: Employment, Equity Ownership. Hansen:Agios Pharmaceuticals: Employment, Equity Ownership. Straley:Agios Pharmaceuticals: Employment. Kernytsky:Agios Pharmaceuticals: Employment, Equity Ownership. Choe:Agios Pharmaceuticals: Employment, Equity Ownership. Liu:Agios Pharmaceuticals: Employment, Equity Ownership. Popovici-Muller:Agios Pharmaceuticals: Employment, Equity Ownership. Travins:Agios pharmaceuticals: Employment, Equity Ownership. Yang:Agios Pharmaceuticals: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals: Employment, Equity Ownership. Gross:Agios Pharmaceuticals: Employment, Equity Ownership. Dang:Agios Pharmaceuticals: Employment, Equity Ownership. Salituro:Agios Pharmaceuticals: Consultancy, Equity Ownership. Saunders:Agios Pharmaceuticals: Consultancy, Equity Ownership. Dorsch:Agios Pharmaceuticals: Employment, Equity Ownership. Agresta:Agios Pharmaceuticals: Employment. Schenkein:Agios Pharmaceuticals: Employment, Equity Ownership. Su:Agios Pharmaceuticals: Employment, Equity Ownership. Biller:Agios Pharmaceuticals: Employment, Equity Ownership.

Description: A failure of IL-2 transcription has been associated with tolerance induction. We hypothesized that inhibition of the NF-κB pathway in alloreactive T-cells, which is critical for IL-2 transcription, could lead to alloantigen-specific hyporesponsiveness and prevention of GVHD. PS1145, a potent inhibitor of IκB kinase, and hence NF-κB activation, was added to an MLR culture consisting of CD4+ T-cells and MHC class II-disparate stimulators. Inhibition of NF-κB activity was verified by EMSA and confocal microscopy. Global inhibition of cytokine production and T-cell hyporesponsiveness was observed which persisted after washing T-cells and re-exposure to alloantigen. Responses to non-specific mitogens remained largely intact and alloantigen hyporesponsiveness was reversed by exogenous IL-2. Treatment of T cells and stimulator cells with PS1145 was required for maximal effect. Depletion of CD4+CD25+ cells from the MLR indicated that these cells were not required for tolerance induction in this system. Using an MLR system containing alloreactive and non-alloreactive transgenic T cells indicated that PS1145 treatment increased the rate of T-cell apoptosis selectively in alloreactive cells. Data from each of 4 experiments showed that GVHD in recipients of ex vivo PS1145 treated cells was profoundly inhibited, whereas CD4+ T-cells recovered from a vehicle-treated 7-day MLR were uniformly fatal upon adoptive transfer into sublethally irradiated MHC class II-disparate recipients. Studies addressing non-alloreactive in vivo responses of PS1145 treated T cells will also be presented. Our studies indicate that the NF-κB pathway is a critical regulator of productive alloresponses and provide a novel ex vivo approach to induce alloantigen-specific tolerance as a means of preventing GVHD.

Description: BACKGROUND Pyruvate kinase (PK) deficiency is a congenital hemolytic anemia caused by deficiency of the glycolytic enzyme red cell PK (PK-R). AG-348 is an orally available, small molecule, allosteric activator of PK-R that activates wild-type and a range of mutated PK-R enzymes in vitro, and increases PK-R activity and restores adenosine triphosphate (ATP) levels in red blood cells from patients with PK deficiency ex vivo. AIMS To describe data from the ongoing DRIVE PK study (NCT02476916), an open-label, dose-ranging trial of AG-348 in transfusion-independent adults with PK deficiency. Early data from this study have been reported (Grace et al. EHA 2016, S466). METHODS After providing informed consent, patients are randomized to AG-348 50 mg or 300 mg orally twice daily (BID) for 6 months. Transfusion independence is defined as no more than 3 units of red blood cells transfused in the 12 months preceding first dose and no transfusions in the 4 months preceding first dose. Patients are followed weekly for Weeks 1-3, then every 3 weeks until Week 12, and then monthly until Week 24. Sex hormone levels and iron status are evaluated at Baseline, Week 12 and End of Study. RESULTS As of the data cutoff date of June 20, 2016, 25 patients have been enrolled and treated for ≥3 weeks. Adverse events (AEs) were mild to moderate. The most frequent AEs were nausea (n=11/25), headache, and insomnia (each n=8/25). One serious AE (Grade 2 osteoporosis) has been reported. Grade 3 AEs were hypertension (n=1), hypertriglyceridemia (n=1), insomnia (n=2), and anemia (n=1). One patient was discontinued from treatment because anemia worsened. There were no Grade 4 AEs and no deaths. Three patients had dose reductions because of headache, nausea, or insomnia. Serum levels of sex steroids were measured at baseline, 12 and 24 weeks; increases in free and total testosterone, and decreases in estradiol and estrone, indicate aromatase inhibition by AG-348, consistent with previously reported results. In 25 patients with ≥3 weeks on treatment, 13 patients (52%) showed a hemoglobin (Hgb) increase 〉1.0 g/dL (range: 1.2-4.9 g/dL; median: 3.40 g/dL). Three patients had dose reductions because of Hgb values exceeding the protocol-mandated maximum. Hgb responses were typically observed within 2 weeks of treatment and were stable with continued treatment. Two patients had dose increases because of insufficient response to 50 mg. Maximal change in Hgb from baseline according to genotype is shown in Figure 1. Of the 25 enrolled patients with ≥3 weeks on treatment, 6 (24%) had two non-missense mutations and none of these had an Hgb response 〉1.0 g/dL. Of the 19 patients with at least one missense mutation, 13 (68%) had an Hgb increase exceeding 1.0 g/dL. CONCLUSION AG-348 is a novel, first-in-class, PK-R activator in clinical testing as a disease-altering therapy to improve anemia in patients with PK deficiency. The ongoing DRIVE PK study has now enrolled over 25 patients, and data from additional patients will be available at the time of presentation. Daily dosing with AG-348 is well tolerated and has demonstrated clinically relevant durable increases in Hgb in the majority of the patients with at least 1 missense mutation. Out of the 19 patients with at least one missense mutation, 13 had an Hgb increase of 〉1.0 g/dL. These data highlight the potential of AG-348 as the first disease-altering treatment for patients with PK deficiency. Figure 1 Maximum hemoglobin (Hgb) increase by genotype Figure 1. Maximum hemoglobin (Hgb) increase by genotype Disclosures Grace: Agios Pharmaceuticals: Other: Scientific Advisor, Research Funding. Rose:Novartis: Honoraria; Celgene: Honoraria; Genzyme: Honoraria. Layton:Novartis: Other: Advisory board meeting; Alexion: Other: Advisory board meeting; GSK: Other: Advisory board meeting; Agios: Speakers Bureau. Yaish:Baxalta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer Healthcare: Consultancy; Octapharma: Consultancy. Barcellini:Agios: Consultancy. Kuo:Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals, Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Apotex: Other: Unrestricted education grant; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Silver:Agios Pharmaceuticals, Inc.: Consultancy. Merica:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Kung:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Cohen:Agios Pharmaceuticals, Inc.: Consultancy. Yang:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Hixon:Agios Pharmaceuticals, Inc.: Equity Ownership, Other: Employment (former); KSQ Therapeutics: Employment, Equity Ownership. Kosinski:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Dang:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Yuan:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Barbier:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Glader:Agios Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Description: MLN4924 is a potent and selective small molecule NEDD8-activating enzyme (NAE) inhibitor. In most cancer cells tested, inhibition of NAE leads to induction of DNA rereplication, resulting in DNA damage and cell death. However, in preclinical models of activated B cell–like (ABC) diffuse large B-cell lymphoma (DLBCL), we show that MLN4924 induces an alternative mechanism of action. Treatment of ABC DLBCL cells with MLN4924 resulted in rapid accumulation of pIκBα, decrease in nuclear p65 content, reduction of nuclear factor-κB (NF-κB) transcriptional activity, and G1 arrest, ultimately resulting in apoptosis induction, events consistent with potent NF-κB pathway inhibition. Treatment of germinal-center B cell–like (GCB) DLBCL cells resulted in an increase in cellular Cdt-1 and accumulation of cells in S-phase, consistent with cells undergoing DNA rereplication. In vivo administration of MLN4924 to mice bearing human xenograft tumors of ABC- and GCB-DLBCL blocked NAE pathway biomarkers and resulted in complete tumor growth inhibition. In primary human tumor models of ABC-DLBCL, MLN4924 treatment resulted in NF-κB pathway inhibition accompanied by tumor regressions. This work describes a novel mechanism of targeted NF-κB pathway modulation in DLBCL and provides strong rationale for clinical development of MLN4924 against NF-κB–dependent lymphomas.

Description: Pyruvate kinase (PK) deficiency is a glycolytic enzymopathy that causes lifelong chronic hemolytic anemia. AG-348 is an allosteric activator of the red cell isoform of pyruvate kinase (PK-R) that is in clinical development to treat PK deficiency. Phase 1 studies of AG-348 in healthy volunteers (NCT02108106, NCT02149966) have been completed, and a phase 2 study in patients with PK deficiency is in progress (DRIVE PK, NCT02476916). We have previously reported that in the healthy volunteer studies, AG-348 induced changes in levels of the metabolites adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) that are consistent with PK-R activation. A preliminary analysis of data showed that nine out of 18 DRIVE PK patients achieved a maximal increase in hemoglobin (Hb) levels of 〉1.0 g/dL. In this study, we characterize whole blood metabolism of healthy human subjects (from the multiple-ascending dose study NCT02149966) as well as PK-deficient patients (from DRIVE PK), before and after administration of AG-348, with a focus on the flux through the PK-R reaction. Whole blood taken from healthy subjects/DRIVE PK patients on each respective study was incubated with a stable isotope tracer, [U-13C6]-glucose. Glycolytic flux through PK-R was estimated by kinetic flux profiling based on the isotope labeling, as well as by the specific lactate production rate, with the two methods giving consistent results. Blood cells from healthy subjects exhibited classic red blood cell (RBC) metabolism, with the majority of glucose catabolized through glycolysis. AG-348 was shown to significantly increase the maximal PK-R protein activity in these subjects, and also to have metabolic effects consistent with PK-R activation, marked by decreased concentrations of glycolytic intermediates such as 2,3-DPG and phosphoenolpyruvate (PEP). Increases in ATP concentrations were also observed, with the magnitude and kinetics of the increase strongly suggesting enhanced adenosine salvage or synthesis. The overall glycolytic rates, however, did not change significantly after two weeks of AG-348 dosing, revealing the homeostatic regulation of RBC glycolysis in healthy blood. Five of the first 18 DRIVE PK patients underwent an extensive sampling protocol for metabolic analysis. This analysis revealed a number of distinct metabolic qualities in PK-deficient patients at baseline compared with healthy subjects. These included significantly reduced rates of lactate production and high concentrations of nucleotides, amino acids, and Krebs cycle intermediates. 13C labeling was observed in Krebs cycle intermediates, demonstrating significant respiratory metabolism in whole blood cells from PK-deficient patients, while incomplete labeling of glycolytic intermediates suggested the presence of a metabolically inactive cell subpopulation. These observations are most consistent with the hypothesis that PK-deficient whole blood is dominated metabolically by immature erythrocytes that retain residual mitochondrial activity. With AG-348 treatment, three of the five DRIVE PK patients had increases in Hb of 〉1.0 g/dL. In those three patients, we observed increased incorporation of 13C label into glycolytic intermediates such as 2,3-DPG, suggesting an increase in metabolically active erythrocytes. First order flux estimates based on either 2,3-DPG labeling kinetics or lactate production rates showed a 〉0.1 mmol/L/hr (〉50%) increase in glycolytic flux. Neither of the two DRIVE PK patients that did not have an Hb increase of 〉1.0 g/dL showed significant metabolic changes. In conclusion, metabolic profiling and stable isotope tracing experiments in blood from healthy subjects treated with AG-348 revealed strong homeostatic regulation of glycolysis even in the presence of activated PK-R. Analysis of data from a small number (n=5) of PK-deficient patients treated with AG-348 for two weeks showed that the three patients with Hb increases 〉1.0 g/dL also had increased glycolytic flux. While the small number of patients makes these results preliminary, it is the first demonstration of a direct link between increased red cell glycolysis induced by the PK-R activator AG-348 and the resulting hematological response as assessed by increases in Hb levels. Updated analyses including additional patients will be presented as more data are collected in the ongoing study. Disclosures Chubukov: Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Johnson:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Kosinski:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Clasquin:Agios Pharmaceuticals, Inc.: Other: former employee and stock holder; Pfizer, Inc.: Employment. Jha:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Kim:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Roddy:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Merica:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Barbier:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Dang:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Kung:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership.

Description: Pyruvate kinase deficiency (PKD) is an autosomal recessive enzymopathy that is the most common cause of hereditary nonspherocytic hemolytic anemia (HNSHA). PKD is a rare disease characterized by a life-long chronic hemolysis with severe co-morbidities. It is hypothesized that insufficient energy production to maintain red cell membrane homeostasis promotes the chronic hemolysis. Treatment is generally palliative, focusing on the resultant anemia, and there are no approved drugs that directly target mutated pyruvate kinase. Here, we describe the mechanism of action and cellular effects of AG-348, an allosteric activator of the red cell isoform of pyruvate kinase (PKR). Hundreds of mutant alleles of PKR have been identified and are known to have deleterious effects on catalytic activity, protein stability, or protein expression. We demonstrate that AG-348 can potently activate a spectrum of recombinantly expressed PKR mutant proteins, including mutations that span distinct subdomains of the enzyme. The R532W mutation is quite sensitive to AG-348 modulation, with over 4-fold activation of the enzyme activity, even as the mutation renders PKR insensitive to stimulation by its endogenous allosteric regulator fructose 1,6-bisphosphate (FBP) (Figure A). Crystallographic analysis reveals that very few mutations associated with PKD occur within the AG-348 binding pocket, accounting for its broad activity. The binding of AG-348 attenuates the thermostability defect of several mutant alleles of PKR, including the commonly observed R510Q mutant that has a half-life of ∼2% of the half-life of wild-type PKR when incubated at 53°C. Pre-incubation of the R510Q protein with AG-348 restores the half-life to ∼70% that of the wild-type enzyme (Figure B). PKD red cells are characterized by changes in metabolism associated with defective glycolysis, including a build-up of the PKR substrate phosphenolpyruvate (PEP) and deficiency in the PKR product adenosine triphosphate (ATP). PKD red cells from several patients with distinct compound heterozygous PKR mutations exposed to AG-348 had increased PKR enzyme activity (up to 4-fold over control) and showed consistent dose and time-dependent metabolic responses (Figure C), including sharp reductions in PEP (up to 70% compared to control) and increases in ATP levels (up to 100% over control). These responses were observed in patient samples harboring PKR mutations that we had studied biochemically (including R486W and R510Q), but also in an instance where the mutation had not previously been biochemically characterized (A495V). In these ex-vivo settings, ATP levels in AG-348 treated cells can reach levels that are typical of normal, non-PKD red cells. These data support the hypothesis that drug intervention with AG-348 may restore glycolytic pathway activity and normalize red cell metabolism in vivo. This therapeutic approach may be an effective way to correct the underlying pathology of PKD and, importantly, provide clinical benefit to patients. Disclosures: Kung: Agios Pharmaceuticals: Employment, Equity Ownership. Hixon:Agios Pharmaceuticals: Employment, Equity Ownership. Kosinski:Agios Pharmaceuticals: Employment, Equity Ownership. Histen:Agios Pharmaceuticals: Employment, Equity Ownership. Hill:Agios Pharmaceuticals: Employment, Equity Ownership. Si:Agios Pharmaceuticals: Employment, Equity Ownership. Kernytsky:Agios Pharmaceuticals: Employment, Equity Ownership. Chen:Agios Pharmaceuticals: Employment, Equity Ownership. DeLaBarre:Agios Pharmaceuticals: Employment, Equity Ownership. Clasquin:Agios Pharmaceuticals: Employment, Equity Ownership. Ho:Agios Pharmaceuticals: Employment, Equity Ownership. Salituro:Agios Pharmaceuticals: Employment, Equity Ownership. Popovici-Muller:Agios Pharmaceuticals: Employment, Equity Ownership. Agresta:Agios Pharmaceuticals: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals: Employment, Equity Ownership. Dang:Agios Pharmaceuticals: Employment, Equity Ownership.