Development of a Human Therapeutic L-Cyst(e)Ine-Degrading Enzyme for the Treatment of Hematological Malignancies

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1587-1587
Author(s):  
Giulia Agnello ◽  
Susan Alters ◽  
Joseph Tyler ◽  
Jinyun Liu ◽  
Peng Huang ◽  
...  

Abstract Cancer cells experience higher intrinsic oxidative stress than their normal counterparts and acquire adaptive antioxidant mechanisms to maintain redox balance. This increased antioxidant capacity has been correlated to malignant transformation, metastasis and resistance to standard anticancer drugs. This enhanced antioxidant state also correlates with cancer cells being more vulnerable to additional oxidative insults, therefore disruption of adaptive antioxidant mechanisms may have significant therapeutic implications. Hematological malignancies including Chronic Lymphocytic Leukemia (CLL), Acute Lymphocytic Leukemia (ALL), Acute Myeloid Leukemia (AML) and Multiple Myeloma (MM) are critically dependent on the cellular antioxidant glutathione (GSH), consistent with the higher intrinsic oxidative stress. L-cysteine is the rate-limiting substrate for GSH biosynthesis and adequate levels of cysteine are critical to maintain the intracellular homeostasis of GSH. CLL and a subset of ALL cells have been reported to rely on the stromal supply of cysteine to increase the synthesis of GSH in order to maintain redox balance, which in turn promotes cell survival and fosters drug resistance. One approach to target this cancer specific dependency is by therapeutic depletion of amino acids via enzyme administration; a clinically validated strategy for the treatment of ALL. Aeglea BioTherapeutics Inc. has developed a bioengineered cysteine and cystine degrading enzyme (Cyst(e)inase, AEB3103) and evaluated its therapeutic efficacy against hematological malignancies in in vitro, ex vivo and in vivo pre-clinical studies. The TCL1-TG:p53 -/- mouse model exhibits a drug resistant phenotype resembling human CLL with unfavorable cytogenetic alterations and highly aggressive disease progression. AEB3103 greatly decreased the viability of TCL1-TG:p53 -/- cells cultured in vitro, whereas the CLL therapeutic, fludarabine, showed minimal cytotoxic effects. In vivo treatment of TCL1-TG:p53 -/- mice with AEB3103 resulted in an increase in median survival time (7 months, p<0.0001) compared to the untreated control group (3.5 months, p<0.001) and a fludarabine treated group (5.3 months, p<0.001). These results indicate a superior therapeutic effect of AEB3103 compared to fludarabine. Additionally, evaluation of AEB3103 in in vitro 2D cultures of patient-derived CLL and MM cells, and in ex vivo 3D cultures of cells derived from ALL and AML PDx models resulted in significant cell growth inhibition with therapeutically relevant IC50 values. Collectively these results demonstrate the sensitivity of hematological malignancies to modulation of GSH levels via AEB3103-mediated cyst(e)ine depletion. Disclosures Agnello: Aeglea BioTherapeutics: Employment. Alters:Aeglea BioTherapeutics: Employment, Equity Ownership. Tyler:Aeglea BioTherapeutics: Employment, Equity Ownership. Huang:Aeglea BioTherapeutics: Research Funding. Stone:Aeglea Biotherapeutics: Consultancy, Equity Ownership, Research Funding; University of Texas at Austin: Employment, Patents & Royalties: I am an inventor of technology related to this abstract. Georgiou:Aeglea Biotherapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Lowe:Aeglea BioTherapeutics: Employment, Equity Ownership. Rowlinson:Aeglea BioTherapeutics: Employment, Equity Ownership.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 580-580
Author(s):  
Mark Wunderlich ◽  
Mahesh Shrestha ◽  
Lin Kang ◽  
Eric Law ◽  
Vladimir Jankovic ◽  
...  

Abstract Abstract 580 Generating a large number of pure, functional immune cells that can be used in human patients has been a major challenge for NK cell-based immunotherapy. We have successfully established a cultivation method to generate human NK cells from CD34+ cells isolated from donor-matched cord blood and human placental derived stem cells, which were obtained from full-term human placenta. This cultivation method is feeder-free, based on progenitor expansion followed by NK differentiation supported by cytokines including thrombopoietin, stem cell factor, Flt3 ligand, IL-7, IL-15 and IL-2. A graded progression from CD34+ hematopoietic progenitor cells (HSC) to committed NK progenitor cells ultimately results in ∼90% CD3-CD56+ phenotype and is associated with an average 10,000-fold expansion achieved over 35 days. The resulting cells are CD16- and express low level of KIRs, indicating an immature NK cell phenotype, but show active in vitro cytotoxicity against a broad range of tumor cell line targets. The in vivo persistence, maturation and functional activity of HSC-derived NK cells was assessed in NSG mice engineered to express the human cytokines SCF, GM-CSF and IL-3 (NSGS mice). Human IL-2 or IL-15 was injected intraperitoneally three times per week to test the effect of cytokine supplementation on the in vivo transferred NK cells. The presence and detailed immunophenotype of NK cells was assessed in peripheral blood (PB), bone marrow (BM), spleen and liver samples at 7-day intervals up to 28 days post-transfer. Without cytokine supplementation, very few NK cells were detectable at any time-point. Administration of IL-2 resulted in a detectable but modest enhancement of human NK cell persistence. The effect of IL-15 supplementation was significantly greater, leading to the robust persistence of transferred NK cells in circulation, and likely specific homing and expansion in the liver of recipient mice. The discrete response to IL-15 versus IL-2, as well as the preferential accumulation in the liver have not been previously described following adoptive transfer of mature NK cells, and may be unique for the HSC-derived immature NK cell product. Following the in vivo transfer, a significant fraction of human CD56+ cells expressed CD16 and KIRs indicating full physiologic NK differentiation, which appears to be a unique potential of HSC-derived cells. Consistent with this, human CD56+ cells isolated ex vivo efficiently killed K562 targets in in vitro cytotoxicity assays. In contrast to PB, spleen and liver, BM contained a substantial portion of human cells that were CD56/CD16 double negative (DN) but positive for CD244 and CD117, indicating a residual progenitor function in the CD56- fraction of the CD34+ derived cell product. The BM engrafting population was higher in NK cultures at earlier stages of expansion, but was preserved in the day 35- cultured product. The frequency of these cells in the BM increased over time, and showed continued cycling based on in vivo BrdU labeling 28 days post-transfer, suggesting a significant progenitor potential in vivo. Interestingly, DN cells isolated from BM could be efficiently differentiated ex vivo to mature CD56+CD16+ NK cells with in vitro cytotoxic activity against K562. We speculate that under the optimal in vivo conditions these BM engrafting cells may provide a progenitor population to produce a mature NK cell pool in humans, and therefore could contribute to the therapeutic potential of the HSC-derived NK cell product. The in vivo activity of HSC-derived NK cells was further explored using a genetically engineered human AML xenograft model of minimal residual disease (MRD) and initial data indicates significant suppression of AML relapse in animals receiving NK cells following chemotherapy. Collectively, our data demonstrate the utility of humanized mice and in vivo xenograft models in characterizing the biodistribution, persistence, differentiation and functional assessment of human HSC-derived cell therapy products, and characterize the potential of HSC-derived NK cells to be developed as an effective off-the-shelf product for use in adoptive cell therapy approaches in AML. Disclosures: Wunderlich: Celgene Cellular Therapeutics: Research Funding. Shrestha:C: Research Funding. Kang:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Law:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Jankovic:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Zhang:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Herzberg:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Abbot:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Hariri:Celgene Cellular Therapeutics: Employment, Equity Ownership, Patents & Royalties. Mulloy:Celgene Cellular Therapeutics: Research Funding.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3835-3835 ◽  
Author(s):  
Michael Fitzgerald ◽  
Yueying Cao ◽  
Bret Bannerman ◽  
Zhi Li ◽  
Olga Tayber ◽  
...  

Abstract Abstract 3835 Poster Board III-771 Introduction The first generation proteasome inhibitor VELCADE® (bortezomib) is indicated for the treatment of patients with multiple myeloma (MM), a form of plasma cell malignancy (PCM). MLN9708 is our novel proteasome inhibitor that selectively and reversibly binds to, and potently inhibits the b5 site of the 20s proteasome in preclinical studies. We have recently demonstrated that MLN9708 significantly prolongs tumor-free survival of double transgenic iMycCa/Bcl-XL mice, a genetically-engineered mouse model of de novo PCM. Here we describe the in vivo evaluation of cell lines derived from double transgenic iMycCa/Bcl-XL mice and the antitumor activity of MLN9708 in a disseminated mouse model of iMycCa/Bcl-XL PCM. Materials MLN9708 immediately hydrolyzes to MLN2238, the biologically active form, upon exposure to aqueous solutions or plasma. MLN2238 was used for all preclinical studies described below. Double transgenic iMycCa/Bcl-XL mice develop de novo PCM, in which neoplastic plasma cell development is driven by the targeted expression of the oncoprotein Myc and anti-apoptotic Bcl-XL (J. Clin. Invest. 113:1763-1773, 2004). DP54 and DP42 are plasma cell tumor cell lines isolated from the bone marrow and lymph nodes, respectively, of syngeneic mice previously inoculated with iMycCa/Bcl-XL tumors (Cancer Res. 67:4069-4078, 2007). In vitro, DP54 and DP42 cells express both the Myc and Bcl-XL transgenes, various plasma cell and B-cell markers including CD38, CD138 and B220, and have gene expression profiles very similar to human MM. Methods Cell viability studies were performed to determine the antiproliferative effects of MLN2238 in DP54 and DP42 cells in vitro. To evaluate DP54 and DP42 cells in vivo, these cells were aseptically inoculated into the tail vein of NOD-SCID mice. Progressions of the resultant PCM were monitored and tumor burdens were evaluated by magnetic resonance imaging (MRI), ex vivo mCT imaging, and histopathology. Mouse plasma samples were collected at the end of the studies and levels of immunoglobulin were assessed. To establish a preclinical disseminated mouse model of iMycCa/Bcl-XL PCM, freshly dissociated DP54-Luc cells (constitutively expressing firefly luciferase under a mouse Ig-k promoter) were aseptically inoculated into the tail vein of NOD-SCID mice. Once tumor growth has been established, mice were randomized into treatment groups and then treated with vehicle, bortezomib (at 0.7mg/kg intravenously [IV] twice weekly [BIW]) or MLN2238 (at 11 mg/kg IV BIW) for 3 consecutive weeks. Tumor burden was measured by bioluminescent imaging. Results In vitro, both DP54 and DP42 cells were sensitive to MLN2238 treatment (LD50 values of 14 and 25 nM, respectively). In vivo, NOD-SCID mice rapidly succumbed to PCM after being inoculated with DP54 and DP42 cells (25 and 14 days post-inoculation, respectively), where the disease was accompanied by marked elevation of plasma immunoglobulins. MRI scans revealed the presence of multiple lesions and several abnormalities were found including: cranial deformation, bowel distortion, splenomegaly and renal edema. Tumor infiltrates, ranging from minor to extensive, were identified in multiple organ compartments (brain<kidney<liver<lymph nodes<spleen<bone marrow) by histopathological analysis. Ex vivo mCT imaging has also revealed signs of bone erosion in the cranial sagittal sutures. Dissemination of DP54-Luc cells after tail vein inoculations was detected by in vivo bioluminescent and confirmed by ex vivo imaging where luminescent tumor nodules were identified in the spleen, kidneys, liver, intestine, lymph nodes, spinal bone and cranium. To assess the antitumor activity of MLN2238, an efficacy study was performed using the DP54-Luc disseminated model. Tumor burden (bioluminescence), skeletal malformation (mCT) and overall survival after treatment with bortezomib and MLN2238 will be presented. Conclusion The DP54-Luc disseminated mouse model of double transgenic iMycCa/Bcl-XL PCM recapitulated several key features of human MM and provided real-time assessment of novel MM therapy preclinically. MLN9708 is currently in human clinical development for both hematological and solid tumor indications. Disclosures: Cao: Milllennium: Employment, Equity Ownership. Bannerman:Milllennium: Employment. Li:Milllennium: Employment. Bradley:Milllennium: Employment, Equity Ownership, Research Funding. Silverman:Milllennium: Employment. Janz:Milllennium: Research Funding. Van Ness:Milllennium: Research Funding. Kupperman:Milllennium: Employment. Manfredi:Milllennium: Employment. Lee:Milllennium: Employment, Equity Ownership.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3059-3059 ◽  
Author(s):  
Dan T. Vogl ◽  
Anas Younes ◽  
Keith Stewart ◽  
Keith William Orford ◽  
Mark Bennett ◽  
...  

Abstract Background: Malignant cells alter metabolism in order to enable their highly anabolic state. In addition to a massive increase in glycolysis, malignant cells frequently become dependent on glutamine to feed the TCA cycle and provide key building blocks for cell growth and proliferation. CB-839 is a first-in-class potent and selective inhibitor of glutaminase (GLS), the first step in glutamine metabolism, that has broad in vitro and in vivo anti-tumor activity in solid and heme malignancies, including multiple myeloma. GLS inhibition with CB-839 induces apoptosis and/or growth arrest in multiple myeloma and lymphoma cell lines and is synergistic with pomalidomide and lenalidomide in vitro and as well as in multiple myeloma xenograft models in vivo. Methods: CX-839-002 is an ongoing Ph1 evaluation of escalating doses of CB-839 in patients with relapsed/refractory multiple myeloma (MM) or non-Hodgkins lymphoma (NHL) with the primary objective of assessing the safety profile and selecting a recommended Phase 2 dose (RP2D). Pharmacokinetics (PK) was monitored on Days 1 and 15. Initially, CB-839 was given three times daily (TID) without food, but based on PK and safety data generated across three Ph1 studies in patients with solid and heme malignancies, the drug is now being given twice daily (BID) with meals. Results: Safety data are available for a total of 14 patients (9 MM, 4 follicular lymphoma, 1 diffuse large B cell lymphoma) that have enrolled to date during the dose escalation (100-400 mg TID and 600 mg BID). The patients have received a median of 7 prior lines of systemic therapy. CB-839 has been well tolerated with only three subjects experiencing a Gr3/4 AEs considered possibly related to study drug and there have been no discontinuations due to AEs. A similar tolerability profile has been observed across three Ph1 studies for CB-839. With a total of 119 pts treated with CB-839 across the three studies, Gr3/4 drug-related AEs have occurred in 16 subjects (13%) and 4.3% of discontinuations were due to AEs. Reversible, asymptomatic elevations in transaminases have been the primary Gr3 AEs, occurring primarily on the TID schedule in 6/59 (10.2%) pts; only one occurred among 60 pts (1.7%) receiving the BID regimen. BID dosing with 600 mg was determined to be the RP2D and combination studies with pomalidomide and dexamethasone have been initiated. The half-life of CB-839 is ~4 hr, exposure increases with dose, and trough concentrations generally remain above the target threshold of 200 ng/mL for patients receiving the RP2D. Six of 8 MM pts that received ≥ 400 mg TID achieved steady state (D15) trough concentrations above the PK target threshold while 0 of 5 pts that received ≤ 250 mg TID achieved the PK threshold. Pharmacodynamic assessment of GLS activity in MM patients was consistent with a broader PK/PD assessment (across all 3 Ph1 studies), which established clear exposure-dependent inhibition of the target in peripheral blood platelets 4 hr after the first dose of CB-839, with >90% inhibition being maintained for most patients at the RP2D. Preliminary efficacy data include confirmed stable disease in 4 of 9 evaluable MM patients. Updated efficacy data and correlative studies on clinical samples will also be presented. The first pt treated with the combination of CB-839 and pomalidomide/dexamethasone (Pd) during dose escalation received 400 mg CB-839 BID, pomalidomide at 4 mg/day (D1-21) and dexamethasone at 40 mg on Days 1, 8, 15 and 22 of each 28-day cycle. This pt had a 71% decreased in urine M-protein and an 83% reduction in serum free light chain after the first 2 cycles of treatment. This pt had 11 prior lines of therapy but not pomalidomide and had two stem cell transplants and was progressing rapidly prior to study entry. The pt has tolerated the combination well and is continuing on study. Conclusions: CB-839 has been well tolerated at and above doses that produced robust inhibition of GLS in blood platelets and in tumors. Dosing BID with food has improved the PK profile and mitigated the frequency and severity of LFT elevations, which was the primary safety signal using TID dosing. Strong preclinical combination data, an excellent clinical safety profile, and initial data with CB-839 combined with Pd provide a strong rationale for continued development of CB-839 this combination in pts with relapsed/refractory multiple myeloma. Disclosures Vogl: Constellation Pharmaceuticals: Research Funding; Calithera Biosciences: Research Funding; Celgene Corporation: Consultancy; Acetylon Pharmaceuticals, Inc.: Research Funding; Millennium Pharmaceuticals: Research Funding; GSK: Research Funding. Younes:Celgene: Honoraria; Curis: Research Funding; Sanofi-Aventis: Honoraria; Seattle Genetics: Honoraria, Research Funding; Novartis: Research Funding; Janssen: Honoraria; Takeda Millenium: Honoraria; Bristol Meyer Squibb: Honoraria; Bayer: Honoraria; Incyte: Honoraria; Johnson and Johnson: Research Funding. Orford:Calithera Biosciences: Employment, Equity Ownership. Bennett:Calithera Biosciences: Employment, Equity Ownership. Siegel:Celgene Corporation: Consultancy, Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Novartis: Speakers Bureau; Merck: Speakers Bureau. Berdeja:Curis: Research Funding; Acetylon: Research Funding; Novartis: Research Funding; Janssen: Research Funding; Takeda: Research Funding; BMS: Research Funding; Array: Research Funding; MEI: Research Funding; Abbvie: Research Funding; Celgene: Research Funding; Onyx: Research Funding.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3914-3914
Author(s):  
Sriram Balasubramanian ◽  
Mint Sirisawad ◽  
Susanne Steggerda ◽  
Wangsen Cao ◽  
Charles Lowenstein ◽  
...  

Abstract Abstract 3914 Inhibitors of histone deacetylases (HDACs) are currently in clinical testing for treating various cancers, and two have been recently approved by the US FDA for treating cutaneous T-cell lymphoma. Here we describe novel anti-inflammatory properties of the HDAC inhibitor PCI-24781 which is in clinical trials for multiple indications including lymphoma (Evens et al., Blood 114: 2726, ASH 2009 Annual Meeting Abstracts). Cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a) have been shown to be involved in human inflammatory disorders, and an anti-IL-6 treatment was recently approved for rheumatoid arthritis (RA). Therefore, the effect of PCI-24781 on cytokine production by lipopolysaccharide (LPS)-stimulated human peripheral mononuclear blood cells (PBMC) as well as isolated monocytes was studied at the RNA expression level by microarrays and Taqman, and at the protein level by ELISA. PCI-24781 potently inhibits the production and secretion of several pro-inflammatory cytokines, including IL-6, TNF-a and interleukin-1beta (IL-1b), at both RNA and protein levels. In murine RAW macrophages as well, PCI-24781 inhibited LPS-stimulated IL-6 secretion at 20nM. PCI-24781 was most effective when given with or before LPS, but was still effective when given an hour after LPS. Similarly, PCI-24781 greatly attenuated in vivo pro-inflammatory cytokine production in LPS-treated Balb/c mice; the IC50 for IL-6 inhibition was < 5 mg/kg. Both the in vitro and in vivo IC50s for IL-6 inhibition are considerably less than the concentrations required to inhibit growth and induce apoptosis in tumor cells (0.2-0.5mM) and in xenograft models (60-80 mg/kg). The mechanism by which these cytokines are controlled involves attenuation of the LPS receptor TLR4 signaling at multiple levels, including acetylation of targets such as MKP-1 and NF-kB subunit p65 in the downstream MAPK and NF-kB pathways; other factors include reduced expression of proteasome, IKK and other NF-kB subunits. Interestingly, we observed a large reduction in levels of NOS2, which causes hypotension during sepsis by producing the inflammatory mediator nitric oxide (NO). Therefore the activity of PCI-24781 was tested in a model of sepsis where mice were treated with a lethal dose of 100 mg/kg LPS, an endotoxin known to be a major mediator of sepsis in humans. PCI-24781 was injected twice, first 16 h before LPS and then 2 h before LPS, in groups of 10 mice each. Control mice that did not receive any PCI-24781 all died within 2 days after LPS (mortality 100%). Pretreatment with PCI-24781 led to dose-dependent increase in survival with 60% of the mice surviving past 6 days with 2 doses of 50mg/kg PCI-24781. These data show that the HDAC inhibitor PCI-24781 protects mice from lethal endotoxemia. Thus, taken together, our data suggest that PCI-24781 has potent anti-inflammatory activities and may be useful to treat inflammatory disorders including RA and sepsis in humans. Disclosures: Balasubramanian: Pharmacyclics: Employment, Equity Ownership. Sirisawad:Pharmacyclics: Employment, Equity Ownership. Steggerda:Pharmacyclics: Employment, Equity Ownership. Cao:Pharmacyclics: Research Funding. Lowenstein:Pharmacyclics: Research Funding. Buggy:Pharmacyclics: Employment, Equity Ownership.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5106-5106
Author(s):  
Michel de Weers ◽  
Michael van der Veer ◽  
Berris van Kessel ◽  
Joost M Bakker ◽  
Shulamiet Wittebol ◽  
...  

Abstract Abstract 5106 Multiple myeloma (MM) represents an incurable malignancy of antibody-producing clonal plasma cells. Over the past decade significant progress has been made in MM treatment using novel immunomodulating agents such as lenalidomide (LEN) and bortezomib (BORT). Daratumumab (DARA) is a human CD38 antibody with broad spectrum killing activity. DARA mediates MM cell death via ADCC (antibody dependent cellular cytotoxicity), CDC (complement dependent cytotoxicity) and apoptosis. We are currently exploring the possibility to further improve MM therapy by combining novel MM therapeutics with DARA. Our initial in vitro work already showed significantly improved MM cell killing by combining DARA with LEN and BORT treatment, especially in patient samples which showed poor responses to the LEN-BORT combination. We now investigated whether DARA can also further improve therapy of lenalidomide or bortezomib in combination with corticosteroids. In ex vivo assays, which allow us to address MM cell lysis directly in BM-MNC isolated from MM patients, DARA significantly enhanced killing of MM cells that were treated with LEN or dexamethasone (DEX). Importantly, DARA was also able to enhance lysis of MM cells that were poor responders to the LEN-DEX combination. This suggests that patients might benefit from a DARA-LEN-DEX combination therapy. Experiments showing effects of DARA on killing of BORT-DEX treated cells are currently underway. The results of this study extend our previous results with LEN-BORT-DARA, showing that MM cells lysis is enhanced by DARA, especially in in samples from patients that are refractory or poorly responding to existing and novel emerging combination therapies. These results support the hypothesis that powerful and complementary effects may be achieved when DARA is combined with LEN and cortocosteroids in clinical MM studies. Disclosures: Weers: Genmab: Employment, Equity Ownership, Patents & Royalties. Veer:Genmab: Research Funding. van Kessel:Genmab: Research Funding. Bakker:Genmab: Employment, Equity Ownership. Parren:Genmab: Employment, Equity Ownership, Patents & Royalties. Lokhorst:Genmab: Membership on an entity's Board of Directors or advisory committees, Research Funding. Mutis:Genmab: Research Funding.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1476-1476
Author(s):  
Sachiko Kanaji ◽  
Taisuke Kanaji ◽  
My-Nuong Vo ◽  
Alessandro Zarpellon ◽  
Ryan Shapiro ◽  
...  

Abstract Aminoacyl-tRNA synthetases (aaRSs) are enzymes with a key role in the first step of protein synthesis by catalyzing the esterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. During evolution, eukaryotic aaRSs have acquired additional domains and motifs conferring non-canonical functions beyond translation, such as expressing multiple cytokine activities. Repurposing aaRSs often requires an activation step and the first reported example was for human tyrosyl-tRNA synthetase (YRS), which is abundant in platelets and released from their α-granules upon thrombin or arachidonic acid stimulation. As shown by previous work, activated YRS (YRSACT) - created by natural proteolysis, alternative splicing, or rational mutagenesis - can express the activity of different cytokines. In the current study, we demonstrate that recombinant YRSACT rendered active by the gain-of-function mutation Tyr341Ala exhibits a previously unrecognized role in megakaryocytopoiesis and thrombocytopoiesis. When administered in vivo in C57BL/6 wild type (WT) mice, recombinant YRSACT caused platelet increase both under baseline conditions as well as in a model of immune-mediated thrombocytopenia in which mice are made thrombocytopenic by injection of rat anti-mouse glycoprotein (GP) Ib monoclonal IgG. When WT mouse bone marrow (BM) cells were cultured ex vivo for 3 days, YRSACT treatment increased the number of megakaryocytes by 3.0-fold, particularly of megakaryocytes with 16N ploidy. This effect was independent of thrombopoietin (TPO) signaling because YRSACT could support the expansion of c-mpl-/- (TPO receptor knock-out) mouse megakaryocytes. YRSACT had no effect on purified mouse CD41+ or Sca1+ hematopoietic progenitor cells, indicating that YRS-dependent stimulation likely required the contribution of other cells present in BM cultures. When mouse BM cells were stimulated with different doses of YRSACT, the number of F4/80+ monocyte/macrophages as well as of megakaryocytes increased in a dose-dependent manner. Mechanistic analysis revealed YRSACT targets the Toll-like receptor (TLR) pathway signaling through MyD88 in monocyte/macrophages, thereby enhancing release of cytokines that influence megakaryocyte development. In vitro binding assay showed that YRSACT is capable of binding to TLR2 and TLR4. The effect of YRSACT was attenuated in the BM cells derived from TLR2-/- mice and was abolished in MyD88-/- mice. Among the cytokines with synthesis induced by YRSACT, IL-6 plays a pivotal role in megakaryocyte development. Thus, we tested the effect of YRSACT on megakaryocytes obtained by culturing BM cell derived from IL-6-/- mice and found that no effect was apparent. The stimulatory effect of YRSACT on megakaryocytopoiesis was confirmed with human CD41+ megakaryocyte progenitors differentiated from CD34+ hematopoietic stem cells derived from peripheral blood. In conclusion, we have documented a previously unrecognized activity of YRSACT that results in enhanced megakaryocytopoiesis and platelet production. These studies document a mechanistically distinct aaRS-directed hematological activity that highlights new potential approaches to stimulating platelet production for treating thrombocytopenia and for improving ex vivo preparation of platelet concentrates for transfusion. Disclosures Belani: aTyr Pharma: Consultancy, Equity Ownership, Patents & Royalties. Do:aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Yang:aTyr Pharma: Consultancy, Patents & Royalties, Research Funding. Schimmel:aTyr Pharma: Consultancy, Equity Ownership, Patents & Royalties, Research Funding.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5123-5123 ◽  
Author(s):  
Mark Joseph Axelrod ◽  
Peter Fowles ◽  
Jeff Silverman ◽  
Astrid Clarke ◽  
Jennifer Tang ◽  
...  

Abstract Background Entospletinib (GS-9973) selectively inhibits spleen tyrosine kinase (SYK), a critical signaling component of the BCR pathway that is expressed primarily in cells of hematopoietic lineage including normal and malignant B-lymphocytes. Entospletinib is currently in phase II clinical trials, where it has demonstrated both a high degree of safety as well as efficacy against chronic lymphocytic leukemia (Sharman, J., et al. Blood, 2015) and other B cell malignancies. Despite these successes, new therapeutic options, including combinations with standard of care agents, are needed in order to achieve the goal of curing disease through finite treatment. We show here that the combination of entospletinib and vincristine causes synergistic apoptosis in vitro in a broad panel of cell lines derived from hematological cancers including diffuse large B cell lymphoma (DLBCL), acute lymphocytic leukemia, follicular lymphom), multiple myeloma, and acute myelogenous leukemia. We also evaluated and compared the in vivo efficacy of entospletinib and vincristine as singe agents and in combination in a DLBCL tumor xenograft model using the SU-DHL-10 cell line. Methods In vitro growth inhibition of a panel of malignant hematological cell lines was assessed using CellTiter-Glo™ Assay (Promega) after 72h incubation with entospletinib or vincristine alone or in combination. Synergy was evaluated using the Bliss model of independence (Meletiadis, J., et al., Med Mycol, 2005). In vivo, SU-DHL-10 cells (5 x 106 cells) were implanted subcutaneously in the axilla in male SCID beige mice. All mice were sorted into study groups on Day 16 such that each group's mean tumor volume fell within 10% of the overall mean (197mm3). Dosing was initiated on Day 16 and animals were dosed for 17 days. Plasma concentrations of entospletinib and vincristine were assessed on Day 19, and the entospletinib 75 mg/kg dose was lowered on Day 22 to 50 mg/kg to approximate the human achievable SYK target coverage of EC80. Efficacy and tolerability were evaluated by tumor measurements and body weight monitored three times weekly. Tumor burden data were analyzed by the application of a two-way analysis of variance (ANOVA), with post-hoc analysis. Results In vitro combinations of entospletinib with low concentrations of vincristine resulted in marked inhibition of cell proliferation and induction of apoptosis in a broad panel of 19 tumor cell lines representing major B cell malignancies including DLBCL. The combination of entospletinib with vincristine had a profound inhibitory effect on proliferation in all subtypes of DLBCL. Entospletinib was evaluated at a concentration equivalent to the Cminof the clinical dose and vincristine was used at concentrations (≤ 10 nM) that had little to no significant single agent effect in these cell lines. In vivo in a SU-DHL-10 xenograft model, entospletinib dosed alone at 25 or 75/50 mg/kg significantly inhibited tumor growth, causing 39% and 20% tumor growth inhibition (TGI), respectively, compared to the vehicle-treated control group. Vincristine administered at either 0.15 and 0.5 mg/kg Q7D x 3 also resulted in significant TGI (42% and 85% TGI, respectively). The addition of entospletinib (75/50 mg/kg) to 0.5 mg/kg or 0.15 mg/kg vincristine resulted in a significant increase in TGI from 85% to 96% (p= 0.001) and 42% to 71% (p< 0.0001), respectively. The addition of entospletinib (25 mg/kg) to vincristine did not significantly increase the tumor growth inhibition. While the groups receiving either entospletinib or vincristine as single agents had no complete or partial tumor regression, 50% of the mice receiving the combination of 75/50 mg/kg entospletinib with 0.5 mg/kg vincristine had partial responses, 8% had complete regression and 8% were tumor free at the end of study (Figure 1). Conclusion Entospletinib and vincristine demonstrated efficacy and tolerability both alone and in combination in the SU-DHL-10 DLBCL cell line xenograft model in SCID beige mice. Vincristine combinations with entospletinib showed significantly greater efficacy than vincristine alone. These data support the further clinical development of entospletinib in combination with vincristine for the treatment of DLBCL. a ENTO: PO: Q12H x 2 (Day 16-32) b VCR: IV: Q7D x 3 (Days 18, 25, 32) Figure 1. Tumor Regressions in an Entospletinib/ Vincristine Treated Murine DLBCL Xenograft Figure 1. Tumor Regressions in an Entospletinib/ Vincristine Treated Murine DLBCL Xenograft Disclosures Axelrod: Gilead Sciences: Employment, Equity Ownership. Fowles:Gilead Sciences: Employment, Equity Ownership. Silverman:Gilead Sciences: Employment, Equity Ownership. Clarke:Gilead Sciences: Employment, Equity Ownership. Tang:Gilead Sciences: Employment, Equity Ownership. Rousseau:Gilead Sciences: Employment, Equity Ownership. Webb:Gilead Sciences: Employment, Equity Ownership. Di Paolo:Gilead Sciences: Employment, Equity Ownership.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3546-3546
Author(s):  
Stephen Bartelmez ◽  
Ashay Bhatwadekar ◽  
Patrick Iversen ◽  
Francis W Ruscetti ◽  
Maria Grant

Abstract Abstract 3546 Poster Board III-483 CD34+ cells from diabetic patients demonstrate reduced vascular reparative function due to decreased proliferation as well as diminished migration prowess which is largely due to lower levels of bioavailable nitric oxide (NO). We asked whether a transient TGF-β1 blockade in CD34+ cells from diabetics would improve their reparative ability given that TGF-β is a key factor modulating stem cell quiescence. Peripheral blood lin-CD34+ cells or lin-CD34+CD38+/− cells were treated ex vivo with antisense phosphorodiamidate morpholino oligomers (TGF-β1 -PMO), demonstrated to inhibit TGF-β1 protein expression in stem cells. Cells were then analyzed for cell surface TGF-β Receptor 2 (TGF-β R2) and CXCR4 expression, their ability to generate NO, their ability to migrate toward SDF-1, their ability to survive in the absence of added growth factors, and tested in vivo for their vascular reparative ability. After TGF-β1-PMO treatment, healthy and diabetic CD34+CD38+ and - cells downregulated TGF-βR2, upregulated CXCR4 expression, survived in the absence of added growth factors ex vivo and migrated more efficiently to SDF-1 compared to controls. TGF-β1-PMO treated diabetic CD34+ cells restored NO production to non-diabetic levels. In contrast, TGF-β1-PMO did not enhance NO generation in CD34+ cells from healthy subjects. Using an in vivo retinal ischemia reperfusion model, we observed that TGF-β1-PMO treatment increased the ability of both healthy and diabetic CD34+ cells to home to injured capillaries compared to control PMO treated cells. As also observed in our current study, a reduction of TGF-β1 levels in murine hematopoietic stem cells correlates with a reduction in TGF-βR2 expression which may induce proliferation in vivo. We also show that both diabetic and healthy lin-CD34+CD38+ cells express TGF-βR2 by FACS. In contrast, only healthy lin-CD34+CD38- cells expressTGF-βR2 while diabetic lin-CD34+CD38 - cells express essentially no cell surface TGF-βR2 (<5 % of cells are TGF-βR2+). Our results suggest that a transient blockade of TGF-β1 may represent a promising therapeutic strategy in restoring vascular reparative function in diabetic CD34+ cells. Disclosures: Bartelmez: BetaStem Therapeutics: Employment, Equity Ownership, Head, SRB, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Iversen:AVI-Biopharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4169-4169 ◽  
Author(s):  
Daniel W Pierce ◽  
Sabine Ponader ◽  
Kumudha Balakrishnan ◽  
Varsha Gandhi ◽  
William G. Wierda ◽  
...  

Abstract Introduction The B-cell receptor (BCR) and its downstream effectors have emerged as important therapeutic targets in B-cell malignancies. CC-292 is a novel, potent, covalent, and highly selective inhibitor of Btk (IC50apparent of 0.5 nM, kinact/KI ratio of 7.69 × 104 M-1s-1), that does not appreciably inhibit other kinases involved in BCR signaling (eg, IC50 Lyn kinase, 4401 nM) (Evans et al., J Pharmacol Exp Ther. 2013). Here, we report preclinical characterization and clinical data in CLL from a single-agent phase 1 dose-escalation trial of CC-292 in B-cell malignancies, with a focus on how target engagement and downstream events correlate with clinical activity. Results Pharmacodynamic effects of Btk inhibition by CC-292 can be monitored by occupancy of the Btk catalytic site, Btk autophosphorylation on Y223, and downstream phosphorylation of Plc-γ2 and Erk. We developed a sensitive (10 pg/mL lower limit of quantification) and quantitative assay to measure covalent binding of CC-292 to Btk (Evans et al., J Pharmacol Exp Ther. 2013), as well as Western and novel phos-flow assays to probe downstream signal transduction. These methods showed that CC-292 treatment blocks Btk autophosphorylation and downstream pathway activation in both tumor cells and human peripheral blood mononuclear cells (PBMCs). The extent of CC-292 binding to Btk correlated with its in vitro and in vivo effects. The occupancy assay demonstrated that CC-292 effectively targets Btk in tumor cell lines, PBMCs, spleen, and lymph nodes (LNs) in animal models, and in PBMC and lymph node samples from clinical trial subjects. In rats and non-human primates treated with CC-292, Btk occupancy in spleen and LNs was dose-dependent. Measured occupancy in rat spleen and axillary, mesenteric, and superficial cervical LNs was 94%, 92%, 90%, and 76% respectively, 4 hours (hrs) after a single 30-mg/kg dose. Interim data from the phase 1 CLL trial showed that PBMC Btk was completely occupied in the majority of subjects 4 hrs post-dose with both QD and BID dosing. Twenty-four hrs post-dose at 750 and 1000 mg QD, CC-292 exhibited 83% ± 17% Btk occupancy, whereas with BID dosing at 375 and 500 mg, occupancy was 94% ± 16% at the corresponding time point (12 hrs after the second dose). Thus, while both schedules achieved extensive and sustained Btk occupancy, residual free Btk levels were lower with the BID schedule, offering a rationale for an early trend towards more rapid nodal responses, lymphocytosis, and partial responses on the BID schedule observed to date in the phase 1 study. In the 10 clinical LN biopsies tested to date, no measurable levels of unoccupied Btk have been detected, although Btk protein was present as determined by Western blotting, showing that CC-292 was able to penetrate LNs and inhibit Btk in human subjects as it did in preclinical models. For monitoring downstream signal transduction, we developed reagents and assays including a phos-flow assay based on a novel rabbit monoclonal antibody to detect Btk pY223 levels in PBMC subsets. CC-292 effectively inhibited constitutive and induced phosphorylation of Btk and Plc-γ2 at low nanomolar concentrations. CC-292 also inhibited BCR activation and nurse-like cell–supported survival of CLL cells. Furthermore, CC-292 reduced CLL cell migration and actin polymerization in response to chemokines (CXCL12, CXCL13) and inhibited secretion of the chemokines CCL3 and CCL4 by CLL cells. These chemokines are essential for migration and retention of normal and neoplastic B cells in the marrow and secondary lymphatic tissues. Consistent with this preclinical data, CC-292 treatment resulted in rapid reductions in circulating CCL3 and CCL4 levels. In subjects treated at the 750 mg QD, 1000 mg QD, 375 mg BID, and 500 mg BID dose levels, plasma CCL3 was reduced from 99 ± 16 pg/ml before treatment to 28 ± 5 pg/ml (N = 48, mean ± SEM) at 24 hrs after the first dose, while CCL4 was reduced from 235 ± 59 pg/ml to 74 ± 16 pg/ml (N = 51). Conclusions These data demonstrate that CC-292 achieves significant and durable occupancy of Btk in vitro and in vivo, inhibits Btk-mediated downstream signaling events and chemokine production, and that these preclinical activities have translated into the clinic. Taken together, these results argue that Btk inhibition is necessary and sufficient for clinical activity in CLL. These emerging data support continued development of CC-292 for the treatment of B-cell malignancies. Disclosures: Pierce: Celgene: Employment, Equity Ownership. O'Brien:Genentech: Consultancy, Research Funding; Emergent: Consultancy, Research Funding; CLL Global Research Foundation: Membership on an entity’s Board of Directors or advisory committees; Celgene: Consultancy; Gilead Sciences: Consultancy, Research Funding; Infinity: Consultancy, Research Funding; MorphoSys: Research Funding; Pharmacyclics: Consultancy, Research Funding; Talon: Consultancy, Research Funding; Teva/Cephalon: Consultancy. Heise:Celgene: Employment, Equity Ownership. Nacht:Celgene: Employment, Equity Ownership. Aslanian:Celgene: Employment, Equity Ownership. Liu:Celgene: Employment, Equity Ownership. Hong:Celgene: Employment, Equity Ownership. Wu:Celgene: Employment, Equity Ownership. Zavodovskaya:Celgene: Employment, Equity Ownership. Marine:Celgene: Employment, Equity Ownership. Barnett:Celgene: Employment, Equity Ownership. Nava-Parada:Celgene: Employment, Equity Ownership. Mei:Celgene: Employment, Equity Ownership. Chopra:Celgene: Employment, Equity Ownership. Burger:Pharmacyclics: Research Funding; Gilead: Research Funding. Singh:Celgene: Employment, Equity Ownership.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5293-5293
Author(s):  
Sara Capolla ◽  
Riccardo Bomben ◽  
Sonia Zorzet ◽  
Ruben Spretz ◽  
Tiziana D'Agaro ◽  
...  

Abstract MicroRNAs are associated with prognosis, progression and drug resistance of Chronic Lymphocytic Leukemia (CLL). Among them, microRNA from the miR-17~92 family were demonstrated to affect CLL cells' growth and survival through the inhibition of the tumor suppressor PTEN and the proapoptotic protein Bim. Previous studies demonstrated the effect of an antagomiR17 in the reduction of leukemia cells' growth both in vitro and in vivo. However, despite these results, the in vivo clearance of antagomiR17 is strictly related to its small dimension which induced a rapid renal elimination preventing significant tumor accumulation and, as a consequence, antagomiR17 efficacy. To overcome this efficacy problem, antagomiR17 was loaded inside biodegradable and biocompatible nanoparticles (BNPs) composed on polyethylene glycol (PEG), polycaprolactone (PCL) and polylactic acid (PLA). The advantages of using BNPs include the significant reduction of toxicity; the potential to load different types of drugs; the improved bioavailability of the payload and cell internalization. Moreover, to ensure the specific binding to cancer B cells, BNPs were conjugated to the antiCD20 antibody Rituximab, targeting leukemia B-cells. Thus, antagomiR17-loaded BNPs efficacy was evaluated by in vitro and in vivo assays.Initially, studies made by quantitative PCR demonstrated that antagomiR17 was able to reduce miR-17 expression in two leukemia cell lines, EHEB and MEC1 cells. Comprehensively, EHEB represents p53wild type patient's derived cells, which developed an indolent model of CLL, while MEC1 represents p53mut/del cells, which usually develop an aggressive model of the disease. Both cell lines were incubated with antagomiR17-loaded BNPs and a significant reduction of miR-17 expression was detected after 24 hours with a complete depletion of miR-17 after 72 hours. Cells growth was also evaluated in vitro affirming that antagomiR17 decreased the proliferation of both MEC1 and EHEB cells in comparison to non-treated cells. Our data also demonstrated that antagomiR17 maintained activity even after encapsulation inside BNPs. For what concerns in vivo studies, a localized model of B-cell malignancy was induced injecting MEC1 cells subcutaneously into SCID mice, causing the formation of a localized tumor mass at the site of cell injection after 3-4 weeks. When the tumor mass reached 300mg in weight, animals were treated once with an intraperitoneal injection of BNPs containing 26μg of antagomiR17 with or without antiCD20 antibody on the BNP surface. The tumor mass dimension and mice's survival were evaluated. Specifically, the decreased in vivo growth of MEC1 cells was more evident after a treatment with antiCD20-conjugated BNPs in respect to unconjugated BNPs (2500 vs 3500 mg), confirming again the importance of the antiCD20 antibody in BNPs homing on B cells. Furthermore, the evaluation of mice survival also confirmed the data; mice treated with antiCD20-BNPs showed an increased survival in respect to mice injected with unconjugated BNPs (37 vs 21 days). In conclusion, our data confirms the efficacy of antiCD20 polymeric nanoparticles in the delivery of antagomiR17 into tumor B-cells. This new therapeutic approach allows to selectively restore miR17 levels and to reduce tumor cell growth, both in vitro and in vivo. Altogether, these results provide a new path for the specific delivery of small nucleic acids like miRNA, antagomiR or siRNA into tumor B-cells and offers the development of future drug combinations with standard therapeutic approach in the same targeted nanostructure. Disclosures Spretz: LNK Chemosolutions LLC: Employment, Equity Ownership. Larsen:LNK Chemosolutions LLC, Biotarget Inc.: Employment, Equity Ownership. Nunez:LNK Chemosolutions LLC, Biotarget Inc.: Employment, Equity Ownership.


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