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Description: Abstract 2431 Poster Board II-408 Nicotinamide (NAM), is a form of VitB3 that recognized and inhibits SIRT1, the human ortholog of the yeast Sir2 class III NAD+-dependent histone deacetylase. We have previously demonstrated that NAM inhibits in vitro differentiation and enhances expansion, migration, homing and NOD/SCID engraftment efficacy of cord blood (CB)-derived CD34+ cells cultured with cytokines. In the current study, the in vivo function of ex vivo cultured cells with NAM was tested in a congenic mice model (BALB/C, CD45.1/CD45.2) for BM transplantation. Purified CD117+ BM cells from BALB/C CD45.1 mice were cultured with a combination of 4 cytokines (FLT3, SCF, TPO, IL-6, 50 ng/ml each), with and without 0.5mM NAM for three weeks. Numbers of CFUc, CD117+ and CD117+Lin- cells were significantly (p 〈 0.05) higher in cultures treated with NAM as compared with cultured treated with cytokines alone. Non-cultured, freshly purified CD117+ cells (1000 and 2500 cells/mice) and their total progeny following expansion with or without NAM were transplanted into ablated (1000 Rad) CD45.2 mice (n = 10/cohort), 24h post irradiation (Fig 1). Three months post transplantation, all the mice in the control group (non-transplanted) died. The percent survival of mice transplanted with cells cultured with cytokines and NAM was remarkably higher over the survival of mice in the cohort transplanted with cells cultured with cytokines alone or non-cultured cells (Fig 1). FACS analysis (CD45.1-donor / CD45.2-host) of peripheral blood from mice transplanted with NAM cultured cells show 80% donor cell chimerism (CD45.1), 3 and 6 months post transplantation. Percent of donor derived Gr-1+ and CD3+ cells were similar in mice transplanted with non-cultured or NAM cultured cells. Percentages of donor cell chimerism (CD45.1) in secondary mice transplanted with total BM cells derived from primary recipients originally transplanted with non-cultured and NAM cultured cells were 47 and 73, respectively, 6 weeks after the secondary transplantation. In a different experiment, to follow time to engraftment during the first month post transplantation, mice transplanted with non-cultured cells or cells cultured with cytokines and NAM (n = 10/cohort) were bled at weekly intervals and peripheral blood samples were counted for WBC and analyzed by the FACS to determine donor cell chimerism and lineage engraftment. The results show accelerated engraftment (Fig 2) and higher levels of donor cell chimerism (Fig 3) in the cohort transplanted with NAM cultured cells relative to the cohort transplanted with non-cultured cells. Number of granulocytes, T, NK and B cells during the first month post transplant were also significantly (p

Description: Historical efforts at expansion of umbilical cord blood (UCB) derived CD34+ hematopoietic stem cells (HSCs) ex vivo with cytokines yielded large numbers of progenitors for transplantation but impaired their long-term engraftment ability. We used nicotinamide (NAM), an allosteric inhibitor of NAD-enzymes, to create omidubicel, an investigational cell therapy designed to improve the expansion of CD34+ HSCs for bone marrow transplant. A Phase 1/2 clinical study of omidubicel in patients with high-risk hematologic malignancies showed rapid neutrophil engraftment and a more favorable immune reconstitution profile in patients compared to historical controls.1 We hypothesized that NAM treatment maintains the stemness and engraftment potential of omidubicel, which is associated with clinical benefit.2 We performed transcriptome, transcription factor (TF), and pathway analysis by next generation sequencing (NGS) to discern the mechanism of action of NAM and to elucidate the pathways leading to the preservation of engraftment after ex vivo expansion of omidubicel compared to CD34+ cells grown in the absence of NAM. Transcriptome analysis revealed that treatment of CD34+ cells with cytokines alone (stem cell factor [SCF], thrombopoietin [TPO], IL-6, and FLT3 ligand) led to an increase in pathways responsible for cell proliferation and differentiation, apoptotic stress, and production of reactive oxygen species (ROS), and matrix metalloproteinases (MMPs), all of which were attenuated by NAM. TF enrichment analysis of NAM-upregulated genes and downregulated genes demonstrated that NAM modulated several TFs critically involved in pathways of HSC cell self-renewal, differentiation, apoptosis and migration. Specifically, NF-kB, C-Jun, LXR/RXR and PPARα/RXRα, and AMPK-mTor signaling were all reduced in NAM-treated CD34+ cells compared to controls. Reduced expression of key genes involved in the production of ROS and reactive nitrogen species (RNS) including NADPH-oxidase-related genes (CYBB, NCF2 and NCF4) and iNOS, suggested that NAM-expanded CD34+ cells were less exposed to oxygen and nitrogen free radical stress than controls. NAM also downregulated the expression of several matrix metalloproteinases (MMP) genes including MMP7, MMP9, MMP12 and MMP19. NAM-induced downregulation of MMPs may explain the increase in engraftment in patients receiving omidubicel. Pathway analysis of differentially expressed (DE) genes was conducted using ingenuity (IPA) software. IPA analysis of DE genes showed significant downregulation of growth factor activating pathways including SCF, TPO, FLT, and GM-CSF and Endothelin-1 and P2Y Purigenic Receptor, which was confirmed by a reduction in cell cycling rates of labeled cells. IPA analysis also pointed to genes in 3 key cellular pathways that were downregulated by NAM: stress induction of apoptosis, production of ROS and RNS, and production of MMPs. NAM treatment also uniquely upregulated genes linked to cellular metabolism including the Sirtuin family genes, TCA cycle genes, and HIF1a. Interestingly, NAM upregulated genes responsible for telomerase expression further validating our hypothesis that NAM preserves cell stemness. In summary, NGS transcriptome analysis revealed that ex vivo expansion of UCB derived CD34+ cells in the presence of NAM attenuated TFs responsible for proliferation and differentiation of stem cells. In addition, NAM treatment downregulated genes regulating the production ROS, RNS, and MMPs and upregulated genes controlling metabolism and senescence, thus allowing for the expansion of CD34+ cells with preserved function and long-term engraftment ability. Our gene expression data leads to a better understanding of the mechanisms by which NAM modulates CD34+ cells in omidubicel to preserve their function. These data provide further scientific rationale for the favorable clinical engraftment and patient outcomes observed in the Phase 1/2 clinical study of omidubicel.1 An international, randomized, multi-center Phase 3 study of omidubicel in patients with high-risk hematologic malignancies is underway.2 [1]Horwitz M.E., et. al., J Clin Oncol. 2019 Feb 10;37(5):367-374. [2] ClinicalTrials.gov identifier NCT02730299. Disclosures Lodie: Gamida Cell: Employment, Equity Ownership. Adams:Gamida Cell: Employment, Equity Ownership. Yackoubov:GAMIDA CELL: Employment, Other: unexecuted shares of the company . Peled:Gamida Cell: Employment, Equity Ownership.

Description: Nicotinamide (NA) is a non-competitive inhibitor of NAD(+)-dependent ADP-ribosyl transferases, of CD38 NADase (a major regulator of cellular NAD levels) and of Sir2 histone-deacetylase. These enzymes are playing a pivotal role in regulation of signal transduction pathways and gene expression. In the present study, we evaluated the effect of NA on the ex-vivo expansion of cord-blood (CB) derived CD34+ cells and their bone-marrow (BM) homing and engraftment potential. Culturing of CD34+ cells for three weeks in the presence of cytokines (SCF, TPO, IL-6, FLT3-ligand) only or cytokines + NA (5mM) resulted in similar expansion of CD34+ cells (40-fold relative to input). However, a remarkable increase in the fraction of CD34+ cells displaying an early progenitor cell phenotype (CD34+Lin−) was observed in the NA-treated cultures as compared with cytokines-only treated cultures (18.6 ± 3% and 0.7 ± 0.06%, n=6, p

Description: We found that nicotinamide (NAM), a form of VitB3 and a recognized inhibitor of SIRT1, the human ortholog of the yeast Sir2 class III NAD+-dependent histone deacetylase, inhibits in vitro differentiation and promotes expansion of hematopoietic progenitor cells. Cord blood (CB)-derived CD34+ cells cultured with cytokines (FLT3, TPO, IL-6, SCF; 50ng/ml) and NAM (2.5mM) (Sigma Aldrich, catalog number N5535) display enhanced in vitro migratory activity toward SDF-1 and home to the BM (24hr following infusion in vivo) with higher efficacy than cells cultured with cytokines only. The number of SCID-repopulating cells increased by 9- and 7.6-fold in cultures treated with NAM relative to non-cultured cells and cytokine only cultured cells, respectively. This net increase in repopulation potential was sustained in competitive transplant experiments where cultured cells were infused along with non-cultured competitor cells derived from the same CB unit. Several experimental clinical protocols of CB-derived expanded cells involve co-transplantation of cultured and non-cultured cells in a double CB transplantation (DCBT). We therefore sought to investigate the engraftment potential of NAM-treated cultured cells in a DCBT setting in NOD/SCID mice, using two CBUs marked as “unit-1” and “unit-2”. Two similar experiments were conducted, each experiment had 4 groups of mice (n=10/ experimental group): non-cultured cells cells cultured with NAM transplanted along with the CD34 negative cell fraction from the same unit that was kept frozen till the day of transplantation. groups a + b non-cultured cells from unit-1 transplanted along with non-cultured-cells from unit-2. Mice were transplanted with similar number of nuclear cells from the cultured or non-cultured units in the single or the DCBT groups. In Experiment-1, non-cultured cells were derived from one unit-1 and NAM-treated cultured cells were derived from another unit-2. In Experiment-2, we switched between the units (such an experiment was possible since our CBUs are frozen in several portions). Level of engraftment was evaluated two weeks post transplantation by FACS analysis of human CD45+ cells while the contribution of each unit to engraftment was measured by quantitative PCR for informative short tandem repeat (qSTR) regions that distinguished the units. The results show that in both experiments, the level of engraftment in the DCBT cohort of a cultured unit transplanted along with a non-cultured unit (12.8±1.8 %) was similar to the level of engraftment of the cultured unit when individually transplanted (15.4 % ±3, p〉0.05). This level of engraftment was 9.8-fold higher (p

Description: Abstract 4035 NK cells are cytotoxic lymphocytes that have drawn considerable attention in recent years as a promising tool for immunotherapy in patients with various refractory hematological malignancies and metastatic solid tumors. Clinical results of experimental protocols have shown only a partial response attributed mainly to the relatively low number of NK cells infused and their short in vivo persistence. An important challenge, therefore, in advancing the clinical applicability of NK cells is to expand ex vivo NK cells that display increased functionality upon in vivo infusion. In efforts to induce NK cell expansion, different combinations of cytokines have been studied. However, most reports show a modest expansion and demonstrate a need for additional stimuli. Nicotinamide (NAM) is a form of Vitamin B3 and a potent inhibitor of enzymes that use NAD for their activity. Hence, NAM is directly involved in the control of redox sensitive enzymes, mitochondrial functions, cell metabolism, the production of energy, and cell motility. Here we show that NAM (2.5–5 mM) enhances expansion (60-80 fold) of functional NK cells in feeder-free cultures stimulated with IL-2 and IL-15 for two weeks. This effect was observed in cultures initiated with purified CD56+ (CD56 enriched/CD3 depleted) or with CD3 depleted, peripheral blood and cord blood cells. Immunophenotyping of the cultured NK cells has so far revealed that NAM substantially modulates three cell surface receptors. CD200R and programmed death receptor-1 (PD-1) expressed on NK cells interact with their ligands on tumor cells which leads to a suppression in NK cell anti-tumor activity and tumor immunoevasion. These two receptors are down-regulated by NAM. CD62L (L-selectin) defines an NK subset with increased self-renewal capacity and its expression was reported to be pivotal for NK cells trafficking to lymphoid organs and their homeostatic proliferation. Following expansion in culture with IL-2, CD62L is down-regulated, whilst NAM increased its expression with a dose-dependent effect. Using a CFSE-based cytotoxicity assay we have demonstrated that NK cells cultured with NAM display higher cytotoxic activity against K562, BL2, NK-resistant COLO 205 cell lines and primary leukemia cells. In a Transwell migration assay, NK cells cultured with NAM demonstrated increased migration towards the CXCR4 ligand SDF-1. To test in vivo homing and retention, irradiated (350 RAD) NOD/SCID mice were transplanted with a similar number of cells (15–20×106 /mouse) derived from two week cultures treated with or without NAM. Mice were infused with 50μg/mouse IL-2 and 5μg/mouse IL-15 every other day. To test homing, mice were sacrificed 24 hour post infusion. Number of human NK cells (CD45+CD56+) detected in the spleen and BM were significantly (p〈 0.05) higher in the cohort of mice infused with NK cells cultured with NAM (7.9 and 1.39 respectively) compared to mice infused with NK cells cultured without NAM (4.13 and 0, respectively). In a different set of experiments, persistence of human NK cells was analyzed 4 and 12 days post infusion. Four days post infusion, the percentage of human NK cells in the spleen, BM, lung and liver were substantially higher in mice infused with NK cells cultured with NAM compared to mice infused with NK cells cultured without NAM (Fig 1). Even though 12 days post infusion, a decrease in the number of human NK cells was observed in comparison to day 4, still cell retention in the spleen, liver and lung was significantly greater in the cohort infused with NK cells cultured with NAM (13.45, 0.6, 9.21% Vs. 1.26, 0.12, 2.85%, (p