scholarly journals The Role and Mechanism of Upregulation of HO-1 Expression By Activating of Adenosine-2a Receptor in the Tumor Immune Microenvironment with Diffuse Large B-Cell Lymphoma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2948-2948
Author(s):  
Chanjuan Wang ◽  
Jishi Wang
Keyword(s):  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Cells ◽  
Cell Lines ◽  
B Cell Lymphoma ◽  
Receptor Activation ◽  
Tumor Growth Inhibition ◽  
Immune Microenvironment ◽  
Positive Correlation ◽  
Tumor Immune Microenvironment

Abstract Objective: In the previous study, we found a high proportion expression of HO-1 and Foxp3 in tumor tissues of patients with DLBCL result in a poor prognosis, and there is a positive correlation between HO-1 and Foxp3. Activation of A2aR not only increases the number of Treg cells but also directly enhances their immunosuppression to tumor cells. on the other hand, A2aR on the surface of tumor cells was also induced, considering a positive correlation between HO-1 and Foxp3, it is hypothesized that activation of A2aR in tumor cells results in upregulated HO-1 expression. And HO-1 play a crucial role in the maintenance and survival of tumor cells in the tumor immune microenvironment, so this study aimed to prove that adenosine activates the A2aR receptor of tumor cells to upregulate the expression of HO-1. Further investigating the regulation and mechanism of the interaction between A2aR and HO-1, elucidating the role of A2aR receptor activation in the immune microenvironment of patients with DLBCL. Methods: Multi-color immunohistochemical staining (mIHC) was performed on paraffin sections of clinical cases with DLBCL to make a quantitative analysis the expression of biomarkers of the immune microenvironment, K-M survival curve and Log-Rank test were used for statistical analysis. Oci-ly10 and Oci-ly19 cell lines were used as the DLBCL cell model, were treated with A2aR receptor agonist, adenosine and NECA. NECA-pretreated cells were treated by anticancer drugs Cisplatin and Vincristine (VCR). Western blot, CCK8 test and FACS were performed on measure the expression of HO-1, cell viability and apoptosis, respectively. NOD-SCID mouse bearing Oci-ly10 cells were established in to investigate the effect of induced HO-1 by A2aR activation on tumor growth inhibition and drug-resistance in vivo. Results: The results of multicolor immunohistochemistry showed that lower expression of HO-1, Foxp3 and PD-L1 and higher expression of CD8 obtained a higher overall survival(p<0.05). There was no significant difference in the OS with CD4 and CD68 (p>0.05). There was a positive correlation between the HO-1 and Foxp3 cells among the tumor microenvironment markers (p<0.05). Western blotting results showed that both NECA and adenosine induced the upregulation expression of HO-1 through the activation of A2aR receptors in Oci-ly10 and Oci-ly19 cell lines in a concentration- and time-dependent manner (p<0.05). 0.5μmol of the inhibitor preladenant inhibited the activation of HO-1 expression mediated by A2aR receptor activation (p<0.05). The knockdown A2aR expression by si-A2aR resulted in the above induction. siRNA rescue experiments showed that the cells regained the ability of NECA to induce HO-1 upregulation by reset the A2aR expression. Pretreatment with NECA reduced the sensitivity of cells to cisplatin or VCR, and the concentration of IC50 increased significantly (p<0.05). However, the above changes were not significant after preladenant-pretreatment. FACS results showed that NECA significantly increased anti-apoptotic ability of cisplatin in Oci-ly10 cells, but preladenant-pretreatment blocked the enhancement of anti-apoptotic effect (p<0.05). When HO-1 was knockdown, NECA activation of A2aR receptor could not induce HO-1 up-regulation, and the apoptosis rate was not significantly different from that of cisplatin-treated group (p>0.05) NECA further phosphorylated p38 MAPK through activation of A2aR. Downstream transcription factors regulate the induction of HO-1 expression. The results showed that the tumor growth of cisplatin and preladenant combination group was the most significantly inhibited (p<0.05), while cisplatin had limited effects in inhibiting tumor growth. In addition, tumor growth inhibition was significantly reduced (p<0.05) by NECA-pretreatment. The positive rates of HO-1 and Foxp3 cells in the cisplatin plus NECA group were significantly higher than those in the cisplatin group after NECA stimulation of the A2aR receptor (p<0.05). In contrast, after the inhibition of A2aR receptor activation, the positive rate of HO-1 cells in the cisplatin plus preladenant group was lower than that in the cisplatin group (p<0.05). Conclusion: It is essential for the maintenance and survival of tumor cells in the tumor immune microenvironment. Upregulation of HO-1 by A2aR receptor activation plays an important role in the immune microenvironment of DLBCL tumors. Disclosures No relevant conflicts of interest to declare.

scholarly journals Close Interactions between Mesenchymal Stem Cells and Neuroblastoma Cell Lines Lead to Tumor Growth Inhibition

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e48654 ◽  
Author(s):  
Giovanna Bianchi ◽  
Fabio Morandi ◽  
Michele Cilli ◽  
Antonio Daga ◽  
Chiara Bocelli-Tyndall ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Tumor Growth ◽  
Growth Inhibition ◽  
Cell Lines ◽  
Neuroblastoma Cell ◽  
Tumor Growth Inhibition ◽  
Neuroblastoma Cell Lines

scholarly journals Highly Differentiated Anti-CD47 Antibody, AO-176, Potently Inhibits Hematologic Malignancies Alone and in Combination

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1844-1844
Author(s):  
John Richards ◽  
Myriam N Bouchlaka ◽  
Robyn J Puro ◽  
Ben J Capoccia ◽  
Ronald R Hiebsch ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Combination Therapy ◽  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Cells ◽  
Tumor Growth Inhibition ◽  
Employment Equity ◽  
Equity Ownership

AO-176 is a highly differentiated, humanized anti-CD47 IgG2 antibody that is unique among agents in this class of checkpoint inhibitors. AO-176 works by blocking the "don't eat me" signal, the standard mechanism of anti-CD47 antibodies, but also by directly killing tumor cells. Importantly, AO-176 binds preferentially to tumor cells, compared to normal cells, and binds even more potently to tumors in their acidic microenvironment (low pH). Hematological neoplasms are the fourth most frequently diagnosed cancers in both men and women and account for approximately 10% of all cancers. Here we describe AO-176, a highly differentiated anti-CD47 antibody that potently targets hematologic cancers in vitro and in vivo. As a single agent, AO-176 not only promotes phagocytosis (15-45%, EC50 = 0.33-4.1 µg/ml) of hematologic tumor cell lines (acute myeloid leukemia, non-Hodgkin's lymphoma, multiple myeloma, and T cell leukemia) but also directly targets and kills tumor cells (18-46% Annexin V positivity, EC50 = 0.63-10 µg/ml) in a non-ADCC manner. In combination with agents targeting CD20 (rituximab) or CD38 (daratumumab), AO-176 mediates enhanced phagocytosis of lymphoma and multiple myeloma cell lines, respectively. In vivo, AO-176 mediates potent monotherapy tumor growth inhibition of hematologic tumors including Raji B cell lymphoma and RPMI-8226 multiple myeloma xenograft models in a dose-dependent manner. Concomitant with tumor growth inhibition, immune cell infiltrates were observed with elevated numbers of macrophage and dendritic cells, along with increased pro-inflammatory cytokine levels in AO-176 treated animals. When combined with bortezomib, AO-176 was able to elicit complete tumor regression (100% CR in 10/10 animals treated with either 10 or 25 mg/kg AO-176 + 1 mg/kg bortezomib) with no detectable tumor out to 100 days at study termination. Overall survival was also greatly improved following combination therapy compared to animals treated with bortezomib or AO-176 alone. These data show that AO-176 exhibits promising monotherapy and combination therapy activity, both in vitro and in vivo, against hematologic cancers. These findings also add to the previously reported anti-tumor efficacy exhibited by AO-176 in solid tumor xenografts representing ovarian, gastric and breast cancer. With AO-176's highly differentiated MOA and binding characteristics, it may have the potential to improve upon the safety and efficacy profiles relative to other agents in this class. AO-176 is currently being evaluated in a Phase 1 clinical trial (NCT03834948) for the treatment of patients with select solid tumors. Disclosures Richards: Arch Oncology Inc.: Employment, Equity Ownership, Other: Salary. Bouchlaka:Arch Oncology Inc.: Consultancy, Equity Ownership. Puro:Arch Oncology Inc.: Employment, Equity Ownership. Capoccia:Arch Oncology Inc.: Employment, Equity Ownership. Hiebsch:Arch Oncology Inc.: Employment, Equity Ownership. Donio:Arch Oncology Inc.: Employment, Equity Ownership. Wilson:Arch Oncology Inc.: Employment, Equity Ownership. Chakraborty:Arch Oncology Inc.: Employment, Equity Ownership. Sung:Arch Oncology Inc.: Employment, Equity Ownership. Pereira:Arch Oncology Inc.: Employment, Equity Ownership.

Anti-Tumor Activity of the Aurora a Inhibitor MLN8237 in Diffuse Large B-Cell Lymphoma Preclinical Models.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1592-1592 ◽  
Author(s):  
Jessica J Huck ◽  
Mengkun Zhang ◽  
Marc L Hyer ◽  
Mark G Manfredi
Keyword(s):  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Model ◽  
B Cell Lymphoma ◽  
Tumor Growth Inhibition ◽  
Aurora A ◽  
Hct 116 ◽  
Xenograft Models

Abstract Aurora A kinase is a serine/threonine protein kinase that is essential for normal transit of cells through mitosis. In many tumor types the Aurora A gene is amplified and/or the protein is over-expressed. The Aurora A small-molecule inhibitor MLN8237 demonstrated robust tumor growth inhibition in xenograft models of solid tumors grown subcutaneously (S.C.) in immunocompromised mice. Here we explored the antitumor activity of MLN8237 in models of diffuse large B-cell lymphoma (DLBCL) both in vitro and in vivo. In vivo three established DLBCL xenograft models (OCI-Ly7, OCI-Ly19, and WSU-DLCL2; all cells expressing luciferase) and a primary DLBCL tumor model PHTX-22-06 were tested using MLN8237 at different doses. Rituximab, an anti-CD20 monoclonal antibody that is active against CD20+ malignant B cells and is a standard of care agent was used for comparison. Using these model systems, tumor cells were injected either I.V. (to evaluate disseminated disease), or S.C. in severe combined immunodeficient mice (SCID). Animals were dosed orally for 21 days with MLN8237 (QD or BID) at various doses, or Rituximab dosed at 10mg/kg IV (once/week) and tumor growth inhibition was monitored using either bioluminescent imaging for the disseminated models or vernier calipers for the S.C. models. Tumor growth inhibition by MLN8237 was dose dependent with 20 mg/kg bid being the most efficacious dose (TGI&gt;100% in both disseminated OCI-Ly19 and WSU models). All animals in the OCI-Ly19 disseminated model 20 mg/kg BID treatment group demonstrated regressions and remained disease free until the end of the study, day 65. In this study the Rituximab treated animals were euthanized on day 31 due to a high level of tumor burden. In the primary tumor model, PHTX-22-06, MLN8237 dosed at 20 mg/kg BID was also the most efficacious with a TGI of 95%. Moreover, tumor growth inhibition was durable as determined by prolonged tumor growth delay (&gt;50 days). Significant efficacy was achieved in all models tested, whether grown as disseminated or subcutaneous models. A noted increase in durability of response was observed with MLN8237 treatment when compared with previous data from solid tumor models. In vitro, MLN8237 treatment increased levels of apoptosis in the OCI-Ly19 cells in comparison to the solid tumor cell line HCT-116 (colon). Greater Annexin V positive cells and greater cleaved PARP and Caspase-3 signals were detected in the MLN8237 treated OCI-Ly19 cells when compared to HCT-116 cells. The demonstration of robust and durable anti-tumor activity in preclinical models treated with MLN8237 provides the basis for its clinical evaluation as a treatment option for DLBCL. MLN8237 is currently in multiple Phase I clinical trials.

Imatinib Mesylate Reduces Rituximab-Induced Tumor Growth Inhibition In Vivo on EBV-Associated Human B-Cell Lymphoma.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2360-2360
Author(s):  
Fariba Némati ◽  
Claire Mathiot ◽  
Isabelle Grandjean ◽  
Olivier Lantz ◽  
Vincent Bordier ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Growth Inhibition ◽  
B Cell ◽  
Nk Cells ◽  
Imatinib Mesylate ◽  
Kinase Inhibitor ◽  
B Cell Lymphoma ◽  
Tumor Growth Inhibition ◽  
Immunodeficient Mice

Abstract We previously reported an increase of tumor growth inhibition following chemotherapy combined with concomitantly administration of imatinib mesylate [Decaudin D, et al. Int J Cancer2005;113:849–856; Decaudin D, et al. Anti-Cancer drugs2006;17:685–696; Decaudin D, et al. Impact of STI571 on the pharmacokinetics of etoposide and / or ifosfamide in mice. Cancer Res (AACR Annual Meeting) 2006;abstr:5154]. Inversely, combination of imatinib and rituximab was reported in very few cases of patients and remains controversial. In order to explore this particular combination of targeted therapies, we therefore investigated the in vivo impact of rituximab plus imatinib on a B-cell lymphoproliferation. Combination of the tyrosine kinase inhibitor imatinib mesylate (STI571) and the anti-CD20 monoclonal antibody rituximab was evaluated on an EBV-associated B-cell lymphoproliferative disorder xenografted into SCID or Rag2/gc −/− (B-, T-, and NK-) mice. Using SCID mice, we found that STI571 diminished the efficacy of rituximab to inhibit tumor growth in vivo (Figure 1A). Using alymphoid Rag2/gc −/− mice, we showed that the effect of STI571 was not dependent on the presence of NK cells (Figure 1B). In contrast, serum complement administered after STI571 treatment reversed this inhibitory effect. Finally, using non immunodeficient mice, we observed an in vivo decrease of CD4-positive T-cells and mature B-cell lymphocytes after imatinib administration. We found that STI571 decreased the in vivo efficacy of rituximab via serum protein components that could influence complement-dependent cytotoxicity. In contrast, this effect was not dependent on the presence of NK cells. Figure Figure

Intratumoral exposure levels of pentaglutamated pemetrexed following treatment with LEAF-1401 and pemetrexed.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 3524-3524
Author(s):  
Gwangseong Kim ◽  
Angelique Nyinawabera ◽  
Zhenghong (Hannah) Xu ◽  
Jason DeFuria ◽  
Alvin Sezibera ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Cells ◽  
Xenograft Model ◽  
Fold Increase ◽  
Drug Candidate ◽  
Tumor Growth Inhibition ◽  
Intracellular Enzyme ◽  
Exposure Levels

3524 Background: The activity of pemetrexed is highly dependent on the intracellular enzyme folypolyglutamate synthase (FPGS) which adds glutamates to pemetrexed and yields very potent pemetrexed polyglutamates. Pemetrexed pentaglutamate (tetraglutamated pemetrexed) is 80-fold more potent than pemetrexed in inhibiting thymidylate synthase. Yet it is a poor drug candidate because it cannot readily cross the negatively charged cell membrane due to its own negative charge. We are developing LEAF-1401, a novel nanoliposomal encapsulation of gamma L-pentaglutamated pemetrexed. Because liposomes can readily be taken up by tumor cells, for its anti-tumor effect, LEAF-1401 can directly deliver pentaglutamated pemetrexed into tumor cells, bypassing the need for transmembrane folate carriers and FPGS which are both downregulated in resistant tumors. Methods: To measure drug levels in tumor, blood and various tissues (biodistribution), in vivo testing of LEAF-1401 and pemetrexed was conducted in a CT-26 murine colorectal carcinoma xenograft model. Animals were treated with a single dose of either LEAF-1401 (80mg/kg; equivalent to 32 mg/kg pemetrexed) or pemetrexed (118mg/kg). Tumor growth inhibition and clinical assessments were conducted. Animals were sacrificed: 5 mice per timepoint in each group and tumor, blood, liver, spleen and other tissues were harvested. Pentaglutamated pemetrexed levels were quantitatively analyzed by LC/MS/MS. Results: Compared to pemetrexed, LEAF-1401 treatment resulted in a 19-fold increase in exposure levels of pentaglutamated pemetrexed in the tumor and significant tumor growth inhibition. Plasma levels of pentaglutamated pemetrexed were high with LEAF-1401, but undetectable with pemetrexed. Like other liposomes, LEAF-1401 also resulted in accumulation of pentaglutamated pemetrexed in the liver and spleen (See Table below). Treatment appeared to be generally well tolerated. Conclusions: LEAF-1401, given at approximately a quarter of the equivalent pemetrexed dose, resulted in a 19-fold increase in pentaglutamate pemetrexed in tumor tissue compared to regular pemetrexed. LEAF-1401 represents a promising new class of novel nanoliposomal antifolates, that enhance the intratumoral delivery of potent polyglutamate antifolates, and improve antitumor activity while retaining an acceptable safety profile. [Table: see text]

scholarly journals The Anti-Tumor Effect of the Ubiquitin-Activating Enzyme (UAE) Inhibitor TAK-243 on Pre-Clinical Models of Multiple Myeloma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3296-3296 ◽  
Author(s):  
Junling Zhuang ◽  
Hans Lee ◽  
Isere Kuiatse ◽  
Hua Wang ◽  
Fazal Shirazi ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Drug Resistance ◽  
Tumor Growth ◽  
Growth Inhibition ◽  
Er Stress ◽  
Cell Lines ◽  
Caspase 3 ◽  
Tumor Growth Inhibition ◽  
Xenograft Models

Abstract Background: The ubiquitin-proteasome system (UPS) has been validated as a target in multiple myeloma (MM) through the success of proteasome inhibitors such as bortezomib, but drug resistance is an emerging challenge. Targeting some of the upstream components of the UPS, such as the E1 ubiquitin activating enzyme (UAE), could therefore be a promising alternative. TAK-243 (MLN7243) specifically blocks the ubiquitin conjugation cascade through the formation of a TAK-243-ubiquitin adduct, thereby inhibiting the UAE. Our aim was to explore the effectiveness of TAK-243 against pre-clinical myeloma models, and to understand some its mechanisms of action. Methods: We performed pre-clinical studies in myeloma cell lines and mouse models using TAK-243. Downstream effects were evaluated using viability, apoptosis assays, western blotting, gene expression profiling (GEP), and Reverse Phase Protein Array (RPPA) techniques. Results: MM1.S and MOLP-8 TP53 wild-type cell lines were sensitive to TAK-243, with median inhibitory concentrations (IC50) of 25 nM at 24 hours based on viability assays. In otherwise isogenic cell lines in which TP53 was suppressed using genome editing techniques, the IC50 was ~40 nM, but higher TAK-243 concentrations of 100 nM overcame resistance due to TP53 inactivation. Similarly, TAK-243 was able to overcome resistance to both conventional (dexamethasone) and novel (bortezomib, lenalidomide) drugs in paired sensitive and resistant cell line models. After treatment with TAK-243, Annexin V and TO-PRO3 staining determined that viable MM1.S cells were induced into early or late apoptosis. This was accompanied by a significant increase in cleaved caspase-3, -8, and -9 as detected by flow cytometry, and in cleaved caspase-7 detected by RPPA and western blot. Exposure to TAK-243 reduced the cellular content of ubiquitin-protein conjugates, and did not enhance expression levels of a fusion protein degraded by the proteasome in a ubiquitin-independent manner, indicating the lack of direct proteasome inhibition. GEP analysis and RPPA detected enhanced expression of p53-pathway related proteins, including MDM2, TP53, and p21 in TAK-243 treated MM1.S cells. Several mRNAs and proteins in the ER stress pathway, including ATF6, ATF4, IRE1a and XBP1 were also elevated, as were many non-coding RNAs and DNA-damage related genes. Combination experiments in MM cell lines demonstrated synergy between TAK-243 and lenalidomide, pomalidomide, panobinostat, melphalan and doxorubicin. Finally, TAK-243 demonstrated in vivo antitumor activity against MM1.S and MOLP-8 xenograft models when dosed at 12.5 mg/kg IV twice-weekly for 2 weeks (tumor growth inhibition of 60% and 73%, respectively). Elevation of BiP, ATF4, XBP1s and cleaved-caspase 3 was detected within the first 24 hrs after dosing in the sensitive MM1.S xenografts. In contrast, RPMI 8226 cells, which showed a 2000 nM IC50 in cell culture, were also resistant to TAK-243 in vivo, with no tumor growth inhibition detected. Conclusions: TAK-243 is a UAE inhibitor that is active against myeloma cells in vitro and in xenograft models in vivo, overcomes conventional and novel drug resistance, and its action is associated with stimulation of the TP53 and ER stress pathways. Thus, it may deserve further evaluation as an anti-myeloma agent. Disclosures Berger: Takeda Pharmaceuticals: Employment. Hyer:Takeda Pharmaceuticals: Employment. Chattopadhyay:Takeda Pharmaceuticals: Employment. Syed:Takeda Pharmaceuticals: Employment. Shi:Takeda Pharmaceuticals: Employment. Yu:Takeda Pharmaceuticals International Co, Cambridge, MA: Employment. Shinde:Takeda Pharmaceuticals: Employment. Kreshock:Takeda Pharmaceuticals: Employment. Tirrell:Takeda Pharmaceuticals: Employment. Menon:Takeda Pharmaceuticals: Employment. Orlowski:Takeda Pharmaceuticals: Research Funding.

scholarly journals CD47 Monoclonal Antibody SRF231 Is a Potent Inducer of Macrophage-Mediated Tumor Cell Phagocytosis and Reduces Tumor Burden in Murine Models of Hematologic Malignancies

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1843-1843 ◽  
Author(s):  
Pamela M Holland ◽  
Emmanuel Normant ◽  
Ammar Adam ◽  
Caroline M Armet ◽  
Rachel W O'Connor ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cell ◽  
Tumor Growth ◽  
Tumor Cell ◽  
Growth Inhibition ◽  
Single Agent ◽  
B Cell Lymphoma ◽  
Hematologic Malignancies ◽  
Tumor Growth Inhibition ◽  
Phagocytic Uptake

Abstract The transmembrane protein CD47 is an immunoglobulin superfamily member involved in multiple cellular processes, including cell migration, adhesion and T cell function. The interaction between CD47 and signal regulatory protein alpha (SIRPα), an inhibitory protein expressed on macrophages, prevents phagocytosis of CD47-expressing cells. CD47 was originally identified as a tumor antigen on human ovarian cancer and was subsequently shown to be expressed on multiple human tumor types, including both hematologic and solid tumors. In many hematologic cancers, high CD47 expression is associated with poor clinical outcomes. CD47 is also expressed at low levels on virtually all non-malignant cells, and loss of expression or changes in membrane distribution may serve as markers of aged or damaged cells, particularly on red blood cells (RBC). High expression of CD47 on tumors blocks phagocytic uptake, subsequent antigen cross-presentation and T cell activation, which collectively contribute to tumor immune evasion. Agents that block the CD47-SIRPα interaction can restore phagocytic uptake of CD47+ target cells and lower the threshold for macrophage activation, which can enhance the efficacy of therapeutic antibodies with ADCC-enabling activity. We developed and characterized a CD47 blocking antibody and evaluated its activity in multiple hematologic models. SRF231 is a fully human monoclonal antibody that binds with high affinity to human CD47 and blocks the CD47-SIRP▢ interaction. SRF231 promotes macrophage-mediated phagocytic clearance of several hematologic primary tumor samples and cell lines in vitro. For example, SRF231 increases phagocytosis of Raji tumor cell line targets with an EC50 of ~300 ng/ml. Enhanced phagocytosis is preferential for tumor cells over normal leukocytes and RBC. Tumor cell phagocytosis can be enhanced in the presence of opsonizing antibodies (e.g., anti-CD20 Ab) when co-administered with SRF231. In vivo efficacy of SRF231 was assessed in several preclinical murine xenograft models of hematologic malignancies. Notably, SRF231 administration led to profound tumor growth inhibition in models of multiple myeloma, diffuse large B cell lymphoma and Burkitt's lymphoma as a single agent and in combination with opsonizing antibodies. In the Raji xenograft model, single agent therapy leads to 112% tumor growth inhibition. This anti-tumor activity is at least partially dependent on macrophages, as depletion of macrophages via clodronate administration leads to reduced tumor growth inhibition. Tumor-associated macrophage (TAM) numbers and polarization status are also modulated by SRF231 treatment. In summary, the CD47 mAb SRF231 induces robust tumor cell phagocytosis and tumor clearance both alone and in combination with opsonizing antibodies in pre-clinical models of myeloma and lymphoma. These properties warrant further development of SRF231 in hematologic malignancies. SRF231 is currently in IND-enabling studies and is expected to enter clinical trials in 2017. Disclosures No relevant conflicts of interest to declare.

A Phase I Study of XL019, a Selective JAK2 Inhibitor, in Patients with Primary Myelofibrosis and Post-Polycythemia Vera/Essential Thrombocythemia Myelofibrosis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 553-553 ◽  
Author(s):  
Srdan Verstovsek ◽  
Animesh D. Pardanani ◽  
Neil P. Shah ◽  
Lubomir Sokol ◽  
Martha Wadleigh ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Tumor Growth ◽  
Tumor Cell ◽  
Phase I ◽  
Growth Inhibition ◽  
Cell Lines ◽  
Essential Thrombocythemia ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Tumor Growth Inhibition

Abstract Since the identification of the JAK family of intracellular tyrosine kinases and their downstream signaling partners, the STATs (Signal Transducers and Activators of Transcription), evidence has accumulated that activation of JAK signaling pathways can contribute to proliferation and survival of cancer cells. A direct link to oncogenesis was made when an activated form of JAK2 (JAK2 V617F) was identified in the majority of patients with myeloproliferative disorders (MPDs) including approximately half of patients with myelofibrosis (MF). Introduction of this JAK2 mutation into the bone marrow of mice induced erythrocytosis [Wernig et al. (2006) Blood107:4274] supporting JAK2 as a relevant target for treatment of myeloproliferative disorders. We have identified a novel small molecule inhibitor of JAK2, XL019, which may prove to have utility in treating MPDs. XL019 is a potent and reversible inhibitor of the JAK2 enzyme, with a Ki of 2 nM, and shows excellent selectivity (minimum of 50-fold selectivity against >120 protein kinases tested including other JAK family members). XL019 downregulates STAT signaling in cell lines expressing both wild type and activated forms of JAK2. IC50s for inhibition of STAT5 phosphorylation by XL019 ranged from 623 nM (HEL92.1.7) to 3398 nM (KG-1) in tumor cell lines. XL019 showed increased potency in primary human erythroid cells in vitro, where the IC50 for inhibition of EPO-stimulated phospho-STAT5 was 64 nM. XL019 inhibits proliferation in cell lines harboring activated or overexpressed JAK2, including certain lines derived from patients with Hodgkin’s Lymphoma (L-1236, 928 nM IC50), AML (MV4-11, 992 nM IC50), essential thrombocythemia (SET-2, 386 nM IC50), and erythroleukemia (HEL92.1.7, 6777 nM IC50). Preclinical single-dose pharmacodynamic studies demonstrate a potent effect of XL019 on JAK-STAT signaling in HEL92.1.7, CFPAC-1 and DU 145 xenograft tumors. Twice daily dosing (bid) led to substantial tumor growth inhibition in the DU145 and HEL models (maximum tumor growth inhibition of 86% and 60%, respectively), accompanied by increases in tumor cell apoptosis (4 – 4.4 fold increase) and decreases in tumor microvasculature (44% reduction in DU 145 xenograft tumors). Based on these encouraging data, XL019 is being evaluated in subjects with primary or post PV/ET MF in a Phase I dose escalation study, which has completed enrollment of the first cohort. The primary objectives of this study are to determine the safety and tolerability of XL019 when administered orally once daily for 21 days in 28 day cycles. Secondary objectives include determination of the pharmacokinetics and pharmacodynamics of XL019, and to evaluate response using the International Working Group for MF consensus response criteria. We have developed a flow-based mechanistic assay for JAK2 activity, which measures GM-CSF-stimulated phospho-STAT5 in peripheral granulocytes in whole blood samples. Additional pharmacodynamic assessments for this study include JAK2 V617F allele burden, erythropoietin-independent colony formation, cytokine levels, and changes in bone marrow histology. Our initial findings regarding the pharmacokinetics, pharmacodynamics, tolerability and efficacy of XL019 in MF patients will be presented.

Novel Approach to the Potential Treatment of Patients with B-Cell Lymphomas Harboring the MYD88 L265P Mutation: Combination Treatment with TLR Antagonist and Rituximab

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 508-508 ◽  
Author(s):  
Daqing Wang ◽  
Wayne Jiang ◽  
Tim Sullivan ◽  
Lakshmi Bhagat
Keyword(s):  
Tumor Growth ◽  
Growth Inhibition ◽  
B Cell ◽  
B Cell Lymphoma ◽  
Tumor Growth Inhibition ◽  
B Cell Lymphomas ◽  
Oncogenic Mutation ◽  
Myd88 L265p Mutation ◽  
Model Tumor ◽  
Myd88 L265p

Abstract Introduction. Patients with B-cell lymphomas harboring the oncogenic MYD88 L265P mutation have poor response to standard of care regimens such as R-CHOP (Fernandez-Rodriguez et al, Leukemia, 2014, Jun 6). These patients also have not responded well to new therapies under development, including BTK inhibitors (Wilson et al, Blood 2012; 120). The MYD88 L265P oncogenic mutation has been shown to over-activate TLR7- and TLR9-mediated signaling pathways, including NF-κB, IRAK1/4 and STAT3, which in turn promote cell survival and proliferation (Lim et al., AACR 2013, Abstract #2332). Our approach to a potential treatment of B-cell lymphomas harboring the MYD88 L265P mutation is to block TLR7- and TLR9-mediated signaling through use of a TLR antagonist. IMO-8400 is an antagonist of TLR7, TLR8, and TLR9 that inhibits cell signaling and induces apoptosis specifically in B-cell lymphoma cell lines harboring the MYD88 L265P mutation (Bhagat et al, AACR 2014, Abstract #2570). IMO-8400 is currently in clinical development for the treatment of relapsed/refractory patients with Waldenström’s macroglobulinemia (WM) and diffuse large B-cell lymphoma (DLBCL). Methods. The current preclinical studies were designed to evaluate the combination of IMO-8400 with rituximab, which is a key component of R-CHOP. The studies were conducted in xenograft models of the activated B-cell like (ABC) DLBCL cell line OCI-Ly10 and the WM cell line MWCL-1, both positive for the MYD88 L265P mutation. For the ABC-DLBCL model, OCI-Ly10 cells were implanted s.c in NOD-SCID mice on day 0 and treatment was initiated on day 9 when mean tumor volume reached ~200 mm3. For the WM model, MWCL-1 cells were implanted s.c. in NOD-SCID mice on day 0 and treatment was initiated on day 6 when mean tumor volume reached ~250 mm3. In both models, the tumor-bearing mice were treated with PBS (control group), IMO-8400 (25 mg/kg, i.p.), rituximab (10 mg/kg, i.p.) or a combination of the two agents. IMO-8400 was administered twice per week for 3 weeks and continued further as maintenance treatment once per week. Rituximab was administered twice per week for three weeks in the ABC-DLBCL model whereas it was given only on days 3, 6, and 9 in the WM model. Results. Treatment of tumor-bearing animals with IMO-8400 or rituximab alone and in combination was well tolerated in both the models. In the ABC-DLBCL model, tumor growth inhibition compared to PBS control was 91.3% in the combination therapy group vs. 40.8% with IMO-8400 alone (p<0.001) and 51.6% with rituximab alone (p=0.003). Inhibition of tumor growth was associated with decreases in levels of several tumor-secreted circulating human cytokines including IL-10 (p<0.05 vs control) in all the three treatment regimens. In the WM model, tumor growth inhibition was 87% in combination group vs. 47% with IMO-8400 (p<0.001) and 72% with rituximab (p<0.001). Further, tumor growth inhibition in the WM model was associated with reduction in serum IgM levels (p<0.03 vs control) in the single-agent as well as the combination treatment groups. Importantly, combination therapy resulted in complete tumor regression in more than 80% of mice in both ABC-DLBCL and WM models. Histological analysis of the residual tumors showed disappearance of malignant lymphocytes with replacement by fibrotic stroma. Conclusions. Our data show that IMO-8400 in combination with rituximab was well tolerated in mouse xenograft models and exerted potent anti-tumor activity against B-cell lymphomas with the MYD88 L265P oncogenic mutation. These observations provide a strong rationale to evaluate IMO-8400 in combination with first-line rituximab-based therapies for the treatment of patients with B-cell lymphomas harboring the MYD88 L265P mutation. Disclosures Wang: Idera Pharmaceuticals: Employment. Jiang:Idera Pharmaceuticals: Employment. Sullivan:Idera Pharmaceuticals: Employment. Bhagat:Idera Pharmaceuticals: Employment.

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