Combining 5-azacitidine with the E-selectin antagonist uproleselan is an effective strategy to augment responses in myelodysplasia and acute myeloid leukaemia

The interaction of acute myeloid leukaemic (AML) blasts with the bone marrow (BM) microenvironment is a major determinant governing disease progression and resistance to treatment. The constitutive expression of E-selectin in the vascular compartment of BM, a key endothelial cell factor, directly mediates chemoresistance via E-selectin ligand/receptors. Despite the success of hypomethylating agent (HMA)-containing regimens to induce remissions in older AML patients, the development of primary or secondary resistance is common. We report that following treatment with 5-azacitidine, promoter regions regulating the biosynthesis of the E-selectin ligands, sialyl Lewis X, become further hypomethylated. The resultant upregulation of these gene products, in particular α(1,3)-fucosyltransferase VII (FUT7) and α(2,3)-sialyltransferase IV (ST3GAL4), likely causes functional E-selectin binding. When combined with the E-selectin antagonist uproleselan, the adhesion to E-selectin is reversed and the survival of mice transplanted with AML cells is prolonged. Finally, we present clinical evidence showing that BM myeloid cells from higher risk MDS and AML patients have the potential to bind E-selectin, and these cells are more abundant in 5-azacitidine-non-responsive patients. The collective data provide a strong rationale to evaluate 5-azacitidine in combination with the E-selectin antagonist, uproleselan, in this patient population.

Abstract LB164: A novel glycomimetic compound (GMI-1757) with dual functional antagonism to E-selectin and galectin-3 attenuates fibrosis, facilitates mononuclear cell infiltration and optimizes anti-PD-L1 therapeutic activity in a pancreatic adenocarcinoma model

The inability to generate robust anti-tumor responses with therapeutics affecting T cell function has been ascribed to multiple parameters such as the tumor fibrotic compartment and the degree/makeup of host infiltrative cells. These parameters are affected through pathways involving the interaction of galectin-3 and E-selectin with cognate ligands. In the current investigations we assessed the impact of a dual E-selectin and galectin-3 glycomimetic antagonist, GMI-1757, in combination with anti-PD-L1 on tumor progression using an orthotopic pancreatic carcinoma model. Eight days following the orthotopic injection of 5x105 luciferase-enabled Pan02 carcinoma cells into the pancreas of female C57BL/6 mice, mice began daily IP treatment for 11 days with control diluent (C) or 50 mg/kg GMI-1757. Beginning on study day 15 C- or GMI-1757-treated mice were given 10 mg/kg anti-PD-L1 or an isotype control antibody (LTF-2). Sixteen mice were allocated into each of 4 groups: group 1 = C + LTF-2; group 2 = GMI-1757 + LTF-2; group 3 = C + anti-PD-L1; and group 4 GMI-1757 + PD-L1. Bioluminescence imaging (BLI) intensities were determined over the course of the study (Day 0 to 26) to assess anti-tumor activity, and tissue was excised at study conclusion to assess fibrosis and immune infiltration. Tumor growth progressed in mice treated with LTF-2 in combination with C or GMI-1757 (final %T/C of 100 and 60.7, respectively), and appeared arrested in mice treated with C and anti-PD-L1 antibody (%T/C = 18.3). In contrast, treatment of tumor-bearing mice with GMI-1757 in combination with anti-PD-L1 antibody resulted in tumor regressions in 5/8 mice with a final %T/C = 0.60. Using a histopathologic scoring system, the extent of fibrosis within the primary pancreatic tumors was dependent on treatment with GMI-1757. Tumor fibrosis was moderate to marked in groups 1 and 3, and minimal to mild in groups 2 and 4. These results were confirmed by morphometric analysis of Masson's Trichrome stained sections where the percent tumor fibrosis area was approximately 29 and 19% in groups 1 and 3, respectively, and 10 and 5% in groups 2 and 4, respectively. Notably, tumor infiltrating immune cells were enhanced with GMI-1757 treatment as compared to C (moderate to marked vs. minimal). The immune phenotypes comprising the increased mononuclear cell infiltration into orthotopic Pan02 tumors continues to be investigated. In summary, we report on the use of a dual E-selectin and galectin-3 antagonist to attenuate fibrosis and enhance mononuclear cell infiltration in an orthotopic model of pancreatic carcinoma. The shifts in fibrotic response and cellular infiltration obtained with GMI-1757 treatment in this model creates a more robust antitumor effect when combined with anti-PD-L1 treatment compared to anti-PD-L1 treatment alone. The impact of GMI-1757 to combine with immune modulators where fibrosis and restricted host cell infiltration negatively impact tumor response continues to be investigated.

Citation Format: William E. Fogler, Theodore A. Smith, Ji-Won Lee, Silvia Locatelli-Hoops, David Stewart, John Peterson, John L. Magnani. A novel glycomimetic compound (GMI-1757) with dual functional antagonism to E-selectin and galectin-3 attenuates fibrosis, facilitates mononuclear cell infiltration and optimizes anti-PD-L1 therapeutic activity in a pancreatic adenocarcinoma model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB164.

Abstract CT144: Development of GMI-1359, a novel agent targeting tumor-microenvironment cross-talk in bone metastatic cancer

Pre-clinical and clinical data suggest that the bone marrow (BM) environment provides breast cancer (BC) cells a protective haven against chemotherapeutic insult, endocrine therapies, and immune recognition. Novel agents that intercept cross-talk between BC cells and the host could therefore improve the depth of response to therapies and potentially increase overall survival in metastatic BC. We have previously shown that bone metastatic BC cells reside in perivascular niches expressing high levels of SDF-1α (CXCL12) and E-selectin, two molecules for which emerging data have demonstrated a significant role in metastatic BC progression. Our prior pre-clinical studies have shown that E-selectin inhibition specifically prevents circulating BC cells from homing to the BM, whereas CXCR4 blockade mobilizes micrometastases from the marrow into circulation, where they may be sensitized to chemotherapeutic cell kill. Given the normal role of these molecules in host immune responses, E-selectin/CXCR4 blockade has additional potential to impact the tumor immune microenvironment.

GMI-1359 is a small molecule, glycomimetic compound with dual inhibitory activity against E-selectin and CXCR4. We hypothesize that GMI-1359 can block E-selectin and CXCR4 binding to E-selectin ligands and SDF-1, disrupting the protective effects of the bone microenvironment on tumor cells. A single-center, phase 1b, open-label, single and multiple ascending dose study (NCT04197999) is therefore evaluating GMI-1359 in patients with HR+ metastatic breast cancer with bony metastases who are stable or minimally progressive on endocrine therapy, with or without a CDK4/6 inhibitor. To date, 2 patients have been enrolled and received single monthly doses of 3.5, 5.0 and 7.0 mg/kg followed by 3 daily doses of 7 mg/kg. Both patients have completed treatment with no dose limiting toxicities observed. Coincident with GMI-1359 administration at all dose levels, we observed mobilization of CD34+ cells coupled with a reduction in elevated serum sE-selectin levels, demonstrating the dual functionality of the compound. Initial peripheral blood immunophenotype data on one patient revealed a redistribution of myeloid derived suppressor cells and a shift in macrophage polarization from M2 to M1. Notably, we observed similar immune alterations in ongoing preclinical studies in the E0771 syngeneic BC mouse model. We found that orthotopically-engrafted mice treated with single agent 1359 had a significant increase in the ratio of CD8/Tregulatory cells isolated from the primary tumor and BM. We also observed a decrease in primary tumor M-MDSCs and lung metastasis-associated macrophages.

In summary, our preliminary clinical data suggest that GMI-1359 is well-tolerated and elicits on-target effects expected from disruption of the host microenvironment. Ongoing clinical and preclinical work will define the efficacy of this strategy to enhance responses to chemo and immune therapies.

Citation Format: P. Kelly Marcom, Trevor T. Price, Andrew S. Murray, William E. Fogler, John L. Magnani, Helen Thackray, Eric Feldman, Dorothy Sipkins. Development of GMI-1359, a novel agent targeting tumor-microenvironment cross-talk in bone metastatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT144.

Abstract 6038: Combined targeting of E-selectin/CXCR4 and FLT3 by GMI-1359 and sorafenib effectively reduces leukemia cell burden and protects normal hematopoiesis in a patient-derived AML xenograft model

Acute myelogenous leukemia (AML) is characterized by an accumulation of abnormal white blood cells. Internal tandem duplications in the Fms-like tyrosine kinase 3 (FLT3-ITD) account for 30% of adult AML cases and confer poor prognosis (Kottaridis et al., 2003; Thiede et al., 2002). FLT3 inhibitors like sorafenib efficiently eliminate leukemia blast in the peripheral blood (PB), but frequently not in the bone marrow (BM) (Zhang et al., 2008). This suggests a protective effect of the BM on leukemic stem cells, which is mediated by E-selectin and CXCL12 expression in endothelial cells (ECs) and mesenchymal stem cells (MSCs) in the BM vascular and endosteal niches (Horacek et al., 2013; Peled and Tavor, 2013). Our previous study demonstrated that targeting E-selectin/CXCR4 with the dual E-selectin/CXCR4 antagonist GMI-1359 markedly reduced leukemia cell adhesion to ECs and MSCs and eliminated the BM-mediated protection of leukemic cells during FLT3-targeted therapy in vitro, and effectively reduced leukemia cell in the BM in vivo (Zhang et al., 2016). Further, GMI-1359 combined with cytarabine/daunorubicin provided a profound survival benefit in FLT3-mutated leukemia cell MV4-11-bearing mice (Zhang et al., 2015). In the preset study, we compared expression levels of E-selectin ligands and CXCR4 in FLT3 inhibitor-sensitive Ba/F3-FLT3-ITD cells and their inhibitor-resistant counterparts Ba/F3-FLT3-ITD+D835Y and Ba/F3-FLT3-ITD+F691L. The resistant cells expressed 1.7 to ~5.6-fold higher E-selectin ligand and 10-fold higher CXCR4 levels. In addition, BM-mimetic hypoxia culture profoundly upregulated P-selectin glycoprotein ligand-1 (PSGL-1) and CXCR4 levels on leukemia cells. PSGL-1 is also a high-efficiency ligand for E-selectin. We then evaluated anti-leukemia effects of co-targeting E-selectin/CXCR4 and FLT3 with GMI-1359 and sorafenib in a patient-derived AML xenograft model (harboring FLT3-ITD and WT1 mutations). Leukemia cell engraftment was evaluated using FACS and immunohistochemistry by hCD45 staining. We observed that GMI-1359 efficiently mobilized leukemic cells into PB and in combination with sorafenib enhanced the anti-leukemia activity and significantly reduced leukemia cell infiltration by 92%, 82%, 69% and 45% in liver, lung, spleen and BM, respectively, as compared with vehicle-treated mice (p < 0.05). The GMI-1359/sorafenib combination improved mouse survival (median survival were 109, 87, 126 and 138.5 days for the vehicle, GMI-1359, sorafenib and combination groups, respectively). Importantly, we observed that the combination protected normal hematopoiesis by increasing the number of BM megakaryocytes, myelocytes, and erythrocytes. The underlying mechanism(s) for this effect is under investigation. Our findings suggest that co-targeting E-selectin/CXCR4/FLT3 exerts remarkable protection of normal hematopoiesis in addition to more efficiently reducing leukemia cells.

Citation Format: Weiguo Zhang, Kyung Hee Chang, Mahesh Basyal, Yannan Jia, Lauren Ostermann, William E. Fogler, John L. Magnani, Michael Andreeff. Combined targeting of E-selectin/CXCR4 and FLT3 by GMI-1359 and sorafenib effectively reduces leukemia cell burden and protects normal hematopoiesis in a patient-derived AML xenograft model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6038.

Abstract 5867: Transcriptome profiling of ST3GAL4 and FUT7 in multiple tumor types and prognostic value in adult acute myeloid leukemia

E-selectin is a cell adhesion glycoprotein expressed on endothelial cells and participates in the development of environmental-mediated drug resistance and poor clinical outcome in cancer. The E-selectin antagonist, uproleselan, interrupts leukemic cell homing to the vascular niche and increases susceptibility to cytotoxic therapies. Recent clinical data demonstrate a correlation between leukemic cell surface E-selectin ligands and response to uproleselan, linking E-selectin ligand expression to response. Multiple genes involved in the glycan synthesis of E-selectin ligands are highly expressed in pediatric AML. Expression levels of two of these genes, ST3GAL4 and FUT7 are associated with poor outcome and are associated with cell surface E-selectin ligand expression. In the current studies we extend transcriptome profiling of E-selectin ligand forming glycosylation genes with an emphasis on ST3GAL4 and FUT7 in different cancers. Initially, we investigated expression levels of ST3GAL4 and FUT7 in 10,258 samples covering 33 cancer types from the TCGA PanCanAtlas. ST3GAL4 and FUT7 were consistently expressed in the majority of cancers evaluated. The cancer types that expressed ST3GAL4 most highly were melanoma (uveal and skin), kidney chromophobe, adrenocortical carcinoma and bladder urothelial carcinoma, while for FUT7, it was AML, diffuse large B-cell lymphoma, thymoma, testicular germ cell tumors and head and neck squamous cell carcinoma. Of particular interest was the identification of adult AML for the highest expression of FUT7 and high expression of ST3GAL4 (mean log2 gene expression = 8.1 and 9.4, respectively). Augmented expression of FUT7 and ST3GAL4 were also observed in an analysis of 39 AML cell lines among the 1,457 cell lines comprising the Cancer Cell Line Encyclopedia RNAseq data set. The prognostic significance of FUT7 and ST3GAL4 in adult AML was further assessed using the TCGA-LAML RNAseq dataset for differential expression and associations with overall survival (OS). The data set included 151 RNAseq profiles of bone marrow samples from adult patients with AML, and within this data set the status of the FMS-like tyrosine kinase 3 (FLT3) proto-oncogene was considered. Mutational alterations of FLT3 are associated with higher risk of relapse and shorter OS compared with wild-type FLT3. ST3GAL4 and FUT7 were both identified as being upregulated (fold-change = 1.73 and 1.40, respectively) in the mutated FLT3 subset (n=46) as compared to wild type FLT-3 (p=0.000033 and 0.046, respectively). Notably in the mutated FLT-3 subset expression of FUT7 was significantly associated with a poor prognosis and decreased OS (HR = 4.56, p= 0.015). Collectively, these studies extend the prognostic importance of the E-selectin ligand glycosylation genes, ST3GAL4 and FUT7, to adult AML where these genes may be useful as predictive biomarkers. In addition, these studies suggest potential additional tumor types beyond AML where treatment protocols with uproleselan may have therapeutic benefits.

Citation Format: William E. Fogler, Vince Deng, David Stewart, Michael Jarman, Simone Daminelli, Adrian Carr, John L. Magnani. Transcriptome profiling of ST3GAL4 and FUT7 in multiple tumor types and prognostic value in adult acute myeloid leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5867.

Abstract 486: Enhanced survival of lethally-irradiated mice with HSC reconstitution in combination with the E-selectin antagonist, GMI-1271 (uproleselan)

The involvement of the adhesion molecule E-selectin and its interactions with E-selectin ligands as pertains to hematopoietic stem cells (HSC) and transplantation has been investigated (Winkler et al. 2012; Winkler et al. 2014). These preclinical studies focused on the role of E-selectin and the use of uproleselan, an E-selectin antagonist, during HSC mobilization in harvesting procedures of donors to accelerate recovery in transplant recipients. However, the impact of E-selectin and uproleselan administration on transplant recipients was less clear. In the current investigations we assessed the survival outcome of bone marrow depleted mice when reconstituted with HSC in combination with uproleselan. Lethally-irradiated, bone marrow depleted C57BL/6 mice were reconstituted with bone-marrow harvested from a congenic strain. Twenty-four hours post irradiation (6Gy x2), cohorts of mice (n=10/group) were injected i.v. with 1 × 106 cells (study day 0) from congenic donors using three i.p. dosing regimens with 40 mg/kg uproleselan. These regimens were: (a) bid on study days 0 and1; (b) bid on study days 1 and 2; and (c) bid on study day 1 only. Control groups in this study included irradiated mice alone (expected survival = 0%), non-irradiated mice alone (expected survival = 100%), and irradiated, reconstituted mice (no uproleselan). The survival of mice was determined over the course of the study (Day 0 to 30). Additional parameters of evaluation included sinusoidal obstructive syndrome such as hepatic veno-occlusive disease known to be E-selectin dependent and a complication of HSC transplantation. Treatment with uproleselan as part of the transplant regimen significantly increased the median survival time (MST) of mice compared with the control group – the MST of mice treated with uproleselan and HSC was >30 days with 80-90% of mice alive at study completion. In contrast, the MST of irradiated mice (no transplant) was 11.5 days with no survivors at study conclusion. The MST of mice irradiated and transplanted with congenic HSC was 9 days with 40% survival on day 30. The impact of uproleselan on survival represented a >233.3% increase in life span. Flow cytometric analysis in all surviving mice on day 30 showed that the mean percentage of CD45.1+ cells from donor congenic mice was approximately 90% (blood and bone marrow) indicating that all surviving mice were successfully reconstituted. In summary, we report on a novel therapeutic use of inhibitors of E-selectin, such as uproleselan, which results in the increased survival of mice when combined with HSC transplantation for reconstitution of depleted and compromised bone marrow. The impact on increased host survival could extend to the use of peripheral blood and stem cell transplantations as a therapeutic option in various malignancies where curative intent is intended.

Citation Format: William E. Fogler, Dylan Daniel, Sheri Barnes, Alden Wong, David Draper, John L. Magnani. Enhanced survival of lethally-irradiated mice with HSC reconstitution in combination with the E-selectin antagonist, GMI-1271 (uproleselan) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 486.

Abstract 5211: Dual E-selectin and CXCR4 inhibition reduces tumor growth and metastatic progression in an orthotopic model of osteosarcoma

Osteosarcoma is the most common bone cancer in children and young adults and has a strong propensity to develop lung metastases. E-selectin is known to be involved in the focal adhesion of tumor cells to cytokine exposed endothelial cells and we postulated may play a central role in osteosarcoma progression. Previously we identified that SDF-1, the main ligand for CXCR4, was upregulated in the pre-metastatic niche (Kaplan et al Nature 2005). Many tumor cells express CXCR4 and may use this signaling pathway to direct disseminated tumor cells to pre- and early metastatic sites in the lung. Based on these findings we examined human osteosarcoma cell lines and primary patient derived xenografts (PDXs) for the expression of CXCR4 and E-selectin ligands by flow cytometry. We found robust expression of these ligands in the majority of both the human osteosarcoma cell lines and PDXs examined. We therefore, investigated the impact of targeting these two axes on metastatic progression of orthotopic osteosarcoma using a small molecule, glycomimetic compound with dual inhibitory activity against E-selectin and CXCR4, GMI-1359. Five days post paratibial injection the HOS cell line, female NMRI-nu mice (n=12/group) were treated with saline; GMI-1359 alone (40 mg/kg IP BID x 25 days); doxorubicin (DOX) alone (5 mg/kg IV days 5, 15 and 25), or the combination of GMI-1359 and DOX. All treatments were well tolerated. The % tumor volume in treatment/control on day 27 of mice treated with GMI-1359, DOX or the combination was 35.5, 36.7 and 32.5, respectively. At study conclusion the incidence of lung metastases was approximately 60% and 50% in mice treated with saline or DOX and 15% in mice treated with GMI-1369 alone or in combination with DOX. Moreover, the extent of ectopic bone formation and/or osteolytic lesions was lower in mice treated with GMI-1359 compared to saline and DOX. These results indicate that the E-selectin and CXCR4 axes are important for the progression of osteosarcoma, and further, that inhibition of these two pro-tumor growth components by GMI-1359 has a therapeutic advantage over chemotherapy alone. Furthermore, studies in the adjuvant setting can provide proof of concept of utility of targeting CXCR4 and E- selectin ligands in the metastatic niche as a therapeutic strategy to limit metastatic progression in high risk patients.

Citation Format: Wei Ju, Choh L. Yeung, Arnulfo Mendoza, Meera Murgai, Sabina Kaczanowska, Jennifer Zhu, Shil Patel, David A. Stewart, William E. Fogler, John L. Magnani, Rosandra N. Kaplan. Dual E-selectin and CXCR4 inhibition reduces tumor growth and metastatic progression in an orthotopic model of osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5211.

Abstract 1757: Mobilization of tumor-primed, marrow-infiltrating lymphocytes into peripheral blood with inhibitors of E-selectin or E-selectin and CXCR4

Marrow-infiltrating lymphocytes (MILs) primed to tumor antigens have been described in patients with hematologic malignancies and in metastatic disease arising from carcinomas. The presence of tumor-reactive MILs in these patients has suggested the possibility of their utilization in T-cell immunotherapeutic approaches. Inherent in this approach are considerations that mediate MIL interactions with the microenvironment and how these may be governed for adoptive or active immunotherapy. Both E-selectin and CXCR4 are known to regulate the homing and retention of T cells to the bone marrow. GMI-1271 and GMI-1359 are potent, small-molecule glycomimetic antagonists of E-selectin and E-selectin/CXCR4, respectively. GMI-1359 is a potent small-molecule glycomimetic dual antagonist targeting E-selectin and CXCR4. In the present studies tumor-specific MILs were established in BALB/c mice that had been induced to reject the syngeneic CT26 colon carcinoma via treatment with anti-CTLA-4 T cell checkpoint antibody, and the subsequent effects of antagonizing E-selectin and/or CXCR4 with GMI-1271 or GMI-1359 on the mobilization and distribution of these bone marrow-derived tumor-specific CD8+ T cells were determined. CT26-immune mice were treated for three days with saline, GMI-1271 (40 mg/kg), or GMI-1359 (40 mg/kg) and 12 hours following the last injection, the phenotype and functional activity of CD8+ T cells were determined in bone marrow and peripheral blood. Additional controls included CT26-immune mice treated with G-CSF (0.125 mg/kg) and tumor-naïve mice treated with saline. Treatment of mice with GMI-1271 and to a greater extent with GMI-1359 led to an approximate 3-4 fold increase in CD8+CD62L+CD44- naïve and CD8+CD62L+CD44+ central memory T cells in peripheral blood. This was not observed following treatment of tumor-immune mice with G-CSF. Treatment of mice with GMI-1271 or GMI-1359 did not affect distribution of CD8+CD62L-CD44+ effector memory T cells in peripheral blood. The increase in percentages of CD8+ naïve and central memory T cells in peripheral blood following treatment with GMI-1271 or GMI-1357 functionally correlated with increased production of IFN-γ ex vivo in response to irradiated CT26 tumor cells or the immunodominant CT26 peptide, AH-1. Collectively these results demonstrate the mobilization or redistribution of marrow-infiltrating tumor-specific CD8+ T cells into peripheral blood as a consequence of E-selectin and/or E-selectin and CXCR4 antagonism. Once in the periphery, these MILs could (1) be collected for adoptive immunotherapy approaches or (2) serve as a systemic augmentation of T cells for combination with immune stimulants as a foundation to boost active immunotherapy.

Citation Format: William E. Fogler, Theodore A. Smith, Rachel K. King, John L. Magnani. Mobilization of tumor-primed, marrow-infiltrating lymphocytes into peripheral blood with inhibitors of E-selectin or E-selectin and CXCR4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1757.

Abstract 2867: Glycomimetic antagonist of E-selectin, GMI-1271, enhances therapeutic activity of the hypomethylating agent 5-azacitidine in the KG1 model of AML

Binding of AML blasts to E-selectin activates cellular survival pathways leading to chemoresistance. GMI-1271 is a novel E-selectin antagonist that when used in combination with chemotherapy results in improved survival in mouse syngeneic and xenogeneic AML tumor models. GMI-1271 in combination with two chemotherapy regimens is in early clinical trials for the treatment of AML. Azacitidine (5-AC) is a DNA-methyltransferase inhibiting cytosine nucleoside analog that at low doses induces DNA hypomethylation and transcriptional activation, while at higher doses is directly cytotoxic to neoplastic cells including AML blasts. 5-AC is approved in Europe for the treatment of limited populations with AML. We evaluated GMI-1271 in combination with 5-AC in the KG1 AML tumor model to assess the potential for therapeutic benefit of the combination.

NSG mice (10/group) received i.v. injections of KG1 cells, and were treated with saline, GMI-1271 alone, 5-AC alone, or the combination of GMI-1271 and 5-AC. The median survival time (MST) of mice treated with 5-AC was 88 days and statistically different (P<0.002) to groups treated with saline (MST=69.5 days) or GMI-1271 alone (MST=69 days). All mice treated with saline or GMI-1271 alone succumbed to progressive tumor growth. At study conclusion (Day 104 post tumor injection) 20% of mice treated with 5-AC remained alive. Importantly, the therapeutic activity of 5-AC was significantly enhanced when combined with GMI-1271 (MST>104 days, P=0.0140 compared to 5-AC alone) with 70% of mice surviving to study conclusion. These results indicate that E-selectin/AML blast interaction in the KG1 model protects from the anti-tumor activity of 5-AC and that GMI-1271 attenuates this protection.

To investigate the nature of the observed in vivo activity of GMI-1271 and 5-AC, KG1 cells were cultured for 96 h in a noncytotoxic concentration (100 nM) of 5-AC and the reactivity of the cells to HECA-452 (an antibody that recognizes an E-selectin carbohydrate ligand) and binding to E-selectin were determined by flow cytometry. Treatment with 5-AC resulted in a 28% increase in reactivity of cells to HECA-452 and a 32% increase in binding to E-selectin. Further in vitro assays of static adhesion revealed an increase in the adhesion of 5-AC-treated KG1 cells to E-selectin. Notably, the enhanced adhesion of KG-1 cells to E-selectin was reversed using GMI-1271. Collectively, these results demonstrate that 5-AC can lead to increased expression of E-selectin ligands on AML cells and that the therapeutic potential of 5-AC could be improved by combination with GMI-1271.

Citation Format: Theodore A. Smith, William E. Fogler, Ji-Won Lee, John L. Magnani. Glycomimetic antagonist of E-selectin, GMI-1271, enhances therapeutic activity of the hypomethylating agent 5-azacitidine in the KG1 model of AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2867.

P- and E-selectin receptor antagonism prevents human leukocyte adhesion to activated porcine endothelial monolayers and attenuates porcine endothelial damage

BACKGROUND

Alongside the need to develop more effective and less toxic immunosuppression, the shortage of human organs available for organ transplantation is one of the major hurdles facing the field. Research into xenotransplantation, as an alternative source of organs, has unveiled formidable challenges. Porcine lungs perfused with human blood rapidly sequester the majority of circulating neutrophils and platelets, which leads to inflammation and organ failure within hours, and is not significantly attenuated by genetic modifications to the pig targeted to diminish antibody binding and complement and coagulation cascade activation.

METHODS

Here, we model the interaction of freshly isolated human leukocytes with xenotransplanted vasculature under physiologic flow conditions using microfluidic channels coated with porcine endothelial cells. Both isolated human neutrophils and whole human blood were perfused over transgenic pig aortic endothelial cells that had been activated with rhTNF-α or rhIL-4 using the BioFlux system. Novel compounds GMI-1271 and rPSGL1.Fc were tested as E- and P- selectin antagonists, respectively. Cellular adhesion and rolling events were tracked using FIJI (imageJ).

RESULTS

Porcine endothelium activated with either rhTNF-α or rhIL-4 expressed high amounts of selectins, to which isolated human neutrophils readily rolled and tethered. Both E-and P-selectin antagonism significantly reduced the number of neutrophils rolling and rolling distance in a dose-dependent manner, with near total inhibition at higher doses (P < .001). Similarly, with whole human blood, selectin blocking compounds exhibited dose-dependent inhibition of prevalent leukocyte adhesion and severe endothelial injury (Untreated: 394 ± 97 PMNs/hpf, 57 ± 6% loss EC; GMI1271+rPSGL1.Fc: 23 ± 9 PMNs/hpf, 8 ± 6% loss EC P < .01).

CONCLUSIONS

Selectin blockade may be useful as part of an integrated strategy to prevent neutrophil-mediated organ xenograft injury, especially during the early time points following reperfusion.

Abstract 5005: Inhibition of E-selectin or E-selectin together with CXCR4 resensitizes multiple myeloma to treatment

INTRODUCTION: Multiple myeloma (MM) is a plasma cell malignancy localized in the bone marrow. Selectins and CXCR4 play a pivotal role in homing, adhesion, and proliferation of MM. Herein, we tested the role of E-selectin in the pathophysiology of MM by using a specific E-selectin antagonist (GMI-1271) and a dual E-selectin/CXCR4 antagonist (GMI-1359) on the proliferation and cell trafficking of MM in vitro and in vivo.

PROCEDURES: Endothelial cells (HUVECs), stromal cells (HS5), MM patient-derived stromal cells (MSP1), and MM cell lines (MM1s, H929, U266 and RPMI8226) were tested for expression of E-selectin, CLA (E-selectin ligand) and CXCR4 by flow cytometry. The effect of GMI-1271 and GMI-1359 was studied on MM cell adhesion to stroma; chemotaxis to stromal media or SDF1; and MM cell survival by MTT assay, where MM cells were treated with lenalidomide or carfilzomib; in the presence, or absence of GMI-1271 or -1359. In a xenograft mouse model, the sensitivity of MM was tested in mice treated with vehicle, lenalidomide, GMI-1271, or a combination of GMI-1271 and lenalidomide (n=10 mice/group); and tumor growth was monitored weekly using bioluminescence imaging.

SUMMARY: Expression of E-selectin was high in HUVECs, MSP1 and HS5; CLA was high only in RPMI8226; and CXCR4 was high in all MM cells. MM1s cell adhesion to stroma was decreased by GMI-1271 and even more profoundly decreased by GMI-1359 in a dose-dependent manner. Chemotaxis of MM1s cells towards conditioned media or SDF1 was modestly affected by GMI-1271, but greatly reduced by GMI-1359. MM cell proliferation was significantly inhibited by GMI-1359, only when MM cells were co-cultured with stroma, but not alone. Stroma-induced drug resistance of MM cells to carfilzomib and lenalidomide was reduced in the presence of the GMI compounds, while the effect of GMI-1359 was stronger than GMI-1271. In vivo, GMI-1271 and lenalidomide as single agents delayed tumor growth compared to vehicle by 40% and 35%, respectively; however, a combination treatment delayed tumor growth more profoundly than vehicle by 64% (p=0.04).

CONCLUSIONS: GMI-1271 and GMI-1359 disrupt the interaction between MM cells and bone marrow microenvironment as determined by reduction of adhesion, chemotaxis and microenvironment-induced drug resistance in vitro. However, the dual inhibition of E-selectin and CXCR4 produced more profound effects compared to E-selectin alone. Moreover, GMI-1271 sensitized MM cells to lenalidomide by alleviating chemoresistance and delayed tumor growth in vivo.

Citation Format: Barbara Muz, Henna Y. Bazai, Anita Sekula, William E. Fogler, Ted Smith, John L. Magnani, Abdel Kareem Azab. Inhibition of E-selectin or E-selectin together with CXCR4 resensitizes multiple myeloma to treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5005. doi:10.1158/1538-7445.AM2017-5005

Abstract 902: A small molecule glycomimetic antagonist of E-selectin and CXCR4 (GMI-1359) delays pancreatic tumor metastasis and significantly alters the pancreatic tumor microenvironment

The cellular and molecular composition of the pancreatic tumor microenvironment includes a complex matrix that encases tumor cells and presents a conundrum in respect to therapy. The dense desmoplasia that accompanies tumor growth reduces blood flow to tumors and creates an environment that compromises delivery of therapeutics. As well, elimination of certain stromal elements enhances the aggressiveness and metastatic potential of pancreatic cancer cells. Recent studies attempt to target stroma in an effort to enhance delivery and efficacy of therapeutic agents and to block metastasis. In this context we have investigated the activity of GMI-1359, a potent dual antagonist that targets both E-selectin and CXCR4. Adhesion protein E-selectin is crucial for regulating vascular and lymphatic endothelial cell (EC) interactions with tumor cells during transmigration. The CXCL12-CXCR4 chemokine axis contributes to the formation of the tumor microenvironment including fibroblast and immune cell recruitment, lymph- and angiogenesis, tumor cell proliferation/survival, and tumor stem cell mobilization. Our in vitro results demonstrate that pancreatic fibroblasts secrete significant amounts of CXCL12 which promotes tumor cell and lymphatic and vascular EC directional migration; this migration toward CXCL12-secreting fibroblasts was completely blocked by GMI-1359. Additionally, CXCL12-stimulated ECs facilitated increased transendothelial migration (TEM) by pancreatic tumor cells. Dual antagonist GMI-1359 inhibited this CXCL12-dependent increase in pancreatic tumor cell TEM and was more effective than an independent small molecule E-selectin only inhibitor. Using an in vivo orthotopic model of pancreatic cancer in athymic mice, we evaluated the ability of GMI-1359 (with and without co-administration Gemcitabine (Gem)) to suppress tumor progression, modulate tumor microenvironment composition, and prolong survival. Our work demonstrated GMI-1359 slightly inhibited tumor growth when used alone or in combination with Gem but did not prolong survival in this immune compromised model. However, GMI-1359 inhibited tumor metastasis to the spleen, liver, and lungs. Interestingly, GMI-1359 significantly modulated the cellular composition of the tumor microenvironment. Immunohistochemical analysis revealed mice treated with GMI-1359 (with or without Gem administration) had drastically reduced desmoplasia and reduced lymphatic and blood vessel densities compared to mice treated with vehicle control or Gem alone. The E-selectin only inhibitor had no effect on tumor microenvironment composition. Further studies of GMI-1359, particularly in immune competent models, are warranted to understand its potential for disrupting the pancreatic tumor microenvironment, inhibiting dissemination, and enhancing anti-tumor immune responses.

Citation Format: Maria M. Steele, William E. Fogler, John L. Magnani, Michael A. Hollingsworth. A small molecule glycomimetic antagonist of E-selectin and CXCR4 (GMI-1359) delays pancreatic tumor metastasis and significantly alters the pancreatic tumor microenvironment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 902.

Abstract 3284: Targeting E-selectin/CXCR4 with GMI-1359 effectively mobilizes bone marrow leukemia cells and enhances FLT3 inhibitor-induced anti-leukemia efficacy in a murine acute myeloid leukemia model

FLT3 internal tandem duplication (ITD) mutations are the most common alterations in acute myeloid leukemia (AML) and are associated with poor disease prognosis. Targeted therapy using FLT3-ITD inhibitors showed limited effect in reducing leukemia blasts in bone marrow (BM) than that in peripheral blood. The BM microenvironment is enriched with cytokines and adhesion molecules, such as CXCR4 and E-selectin, which are believed to provide AML cells protection against chemotherapeutic agents. Therefore, blocking CXCR4 and E-selectin concomitantly with FLT3 inhibition could theoretically eliminate the protection in FLT3-mutant AML patients. We recently reported that targeting CXCR4/E-selectin with the dual inhibitor GMI-1359 showed significant prolongation of survival of mice engrafted with FLT3-ITD mutant MV4-11 leukemia cells. In the present study, we further investigated anti-leukemia effects of dual CXCR4/E-selectin inhibition. Results indicate efficient mobilization of leukemia cells into the circulation by GMI-1359 in a MOLM14-engrafted murine model 2h after drug treatment, which was 3.3-fold (± 0.3) higher compared with the CXCR4 antagonist plerixafor, and 7.4-fold (± 2.7) higher compared with controls. In addition, GMI-1359 also mobilized normal murine leukocytes from the BM, suggesting that GMI-1359 may block interactions of leukemia cells with various BM components. Combination therapy of GMI-1359 and sorafenib significantly reduced leukemia burden (1.9e7 vs. 2.3e9, 1.0e9 and 8.5e7 photons/sec in the combination group versus control, GMI-1359 and sorafenib groups, respectively, at day 20 as determined by Xenogen IVIS bioluminescence Imaging; p &lt; 0.001). Moreover, the combination treatment profoundly reduced leukemia burden in the BM of leukemic mice after a 15-day treatment (1.7e7 vs. 1.6e9, 6.3e8 and 7.0e7 photons/sec, p &lt; 0.01; and 1.76% vs. 70.96%, 72.8% and 33.8%.leukemia cell engraftment measured as GFP positive leukemic cells in BM by flow cytometry, in the combination group vs. vehicle, GMI-1359 and Sorafenib groups, respectively, p &lt; 0.01). Of note, the combination therapy profoundly extended the median survival of the leukemia-bearing mice from 27 days in the control group to 46.5 days in the combination treatment groups (p &lt; 0.001). Mechanistically, we demonstrated that direct blockade of the interaction of E-selectin-CXCR4/SDF-1α with GMI-1359 was critical for leukemic cell mobilization via the disruption of adhesion to stromal cells. Furthermore, the presence of GMI-1359 enhanced sorafenib-induced apoptosis in FLT3-ITD mutated leukemic cells co-cultured with stromal cells. This effect occurred even under hypoxia, which is characteristic for the leukemic BM microenvironment. These findings provide the pre-clinical basis for the evaluation of GMI-1359 in patients with FLT3-mutant AML.

Citation Format: Weiguo Zhang, Hong Mu, Qi Zhang, Nalini B. Patel, William E. Fogler, John L. Magnani, Michael Andreeff. Targeting E-selectin/CXCR4 with GMI-1359 effectively mobilizes bone marrow leukemia cells and enhances FLT3 inhibitor-induced anti-leukemia efficacy in a murine acute myeloid leukemia model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3284.

Abstract 3212: Metastatic breast cancer cell communication within a pro-dormancy bone marrow niche

Distant metastases are the major cause of death from breast cancer. In estrogen receptor positive (ER+) breast cancer (BC) in particular, metastatic relapse can occur years after initial treatment, suggesting that disseminated tumor cells have a prolonged dormant phase before becoming proliferative. A major site of early disease dissemination and metastatic relapse of ER+ BC is the bone, although the critical signals that allow circulating breast cancer cells (BCCs) to identify bone marrow (BM) vasculature, enter the tissue, and tether to the BM microenvironment (BMM) are little understood. Investigating these interactions of BCCs with the BMM, however, could enable us to target the key biologic determinants allowing safe harbor for metastases within bone. To address the features of breast tumors associated with late recurrence, but not confounded by variations in systemic treatment, we compiled breast tumor gene expression data from 4,767 patients and established a discovery cohort consisting of 743 lymph node-negative patients who did not receive systemic neoadjuvant or adjuvant therapy. Using this data set, we found that expression of E-selectin ligands and CXCR4 were significantly elevated in ER+ tumors that had late recurrences. Based on these observations, we used intravital fluorescence microscopy to study the precise functions of E-selectin ligands and CXCR4 (SDF-1 receptor) in tumor metastasis in in vivo xenograft models and found that these play distinct roles in ER+ BCC migration in the BMM. Using highly specific E-selectin (GMI-1271) and CXCR4 (AMD3100) inhibitors, we determined that E-selectin interactions were critical for BCC entry into bone, while CXCR4/SDF-1 interactions anchored BCCs to the BMM. CXCR4 inhibition led to significant mobilization of BC micrometastases from the BMM into the peripheral circulation. Moreover, we found that dormant and proliferating BCCs occupy distinct regions of the BMM, with dormant BCCs predominantly found in SDF-1 and E-selectin rich regions and thus highly susceptible to AMD3100 mobilization. These findings shed light on how dormant and proliferating BCCs interact with the BMM and suggest new interventions to break the foothold of dormant BC micrometastases in bone.

Citation Format: Trevor T. Price, Clara H. Lee, Qing Cheng, H. Kim Lyerly, William E. Fogler, John L. Magnani, Dorothy A. Sipkins. Metastatic breast cancer cell communication within a pro-dormancy bone marrow niche. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3212. doi:10.1158/1538-7445.AM2015-3212

Abstract 428: Dual E-selectin and CXCR4 inhibition reduces tumor growth and increases the sensitivity to docetaxel in experimental bone metastases of prostate cancer

Prostate cancers preferentially metastasize to the skeleton where the bone microenvironment can stimulate excessive tumor cell growth and spread, and promote the emergence of clinically-resistant disease. An improved understanding of the complex relationship between prostate carcinoma (PCa) cells and the bone microenvironment has created a powerful opportunity to develop novel therapies. PCa cells preferentially roll and adhere on bone marrow vascular endothelial cells, where constitutive E-selectin expression and abundant stromal cell-derived factor-1α (SDF-1α) are expressed and interact with E-selectin ligands and CXCR4 present on PCa cells. These molecular interactions initiate a cascade of activation events that lead to the development of treatment resistant metastases. This suggests that agents able to antagonize these molecular interactions may be used as pharmacological treatments of bone metastatic disease.

In the current studies we investigate if a dual E-selectin/CXCR4 inhibitor (GMI-1359) could impact the intraosseous growth of the metastatic, androgen-independent PC3M cell line and affect chemosensitivity to docetaxel. PCa cells, including PC3M, selected for increased visceral and bone metastatic potential express high levels of E-selectin ligands and CXCR4 as compared to nonmetastatic PCa cell lines. We evaluated the ability of GMI-1359 administered alone or in combination with docetaxel to inhibit the growth and metastasis of intratibially implanted luciferase-transfected PC-3M cells. Approximately two weeks post tumor cell implantation, mice were treated by intraperitoneal injection for 2 weeks with either saline twice daily; 40 mg/kg GMI-1359 twice daily, 5 mg/kg docetaxel once weekly or a combination of GMI-1359 and docetaxel. Thirty-five days after initiation of treatment, the percentage of tibiae positive by X-ray and the size of osteolytic lesions was impacted by treatment with GMI-1359 alone or in combination with docetaxel. Docetaxel alone had only a modest impact on intraosseous lesions. Lytic units were reduced by 38%, 78% and 88% in mice treated with docetaxel alone, GMI-1359 alone, or GMI-1359 in combination with docetaxel, respectively. The significantly reduced intraosseous growth of PC3M cells correlated with decreased serum levels of both mTRAP and type I collagen fragments.

Our data provides a clear biologic rationale for the use of a dual E-selectin/CXCR4 inhibitor as an adjuvant to taxane-based chemotherapy in men with high-risk prostate cancer to prevent bone metastases. Given its complementary mechanism of action to traditional chemotherapy, GMI-1359 warrants further development not only in prostate carcinoma, but also in other malignancies where tumor cells are likely to spread to bone.

Citation Format: Giovanni L. Gravina, Andrea Mancini, Alessandro Colapietro, Simona D. Monache, Adriano Angelucci, Alessia Calgani, William E. Fogler, John L. Magnani, Claudio Festuccia. Dual E-selectin and CXCR4 inhibition reduces tumor growth and increases the sensitivity to docetaxel in experimental bone metastases of prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 428. doi:10.1158/1538-7445.AM2015-428

Abstract 425: A small molecule glycomimetic antagonist of E-selectin and CXCR4 (GMI-1359) prevents pancreatic tumor metastasis and improves chemotherapy

The tumor microenvironment's cellular and molecular composition includes a complex matrix that encases tumor cells and presents a conundrum in respect to pancreatic tumor therapy. On one hand, the dense desmoplastic reaction that accompanies growth of well differentiated pancreatic tumors reduces blood flow to tumors and creates an environment in which it is difficult to deliver therapies. On the other hand, elimination of certain stromal elements enhances the aggressiveness and metastatic potential of pancreatic cancer cells. Several current studies are attempting to target stroma in an effort to enhance delivery and efficacy of therapeutic agents and to block metastasis. We have investigated the activity of GMI-1359, a potent dual antagonist that targets both E-selectin and CXCR4. Adhesion protein E-selectin plays an important role in the tumor microenvironment by regulating cell contacts, including tumor cell binding to vascular and lymphatic endothelial cells during extravasation. Chemokine receptor CXCR4's role in the chemoattraction of tumor cells toward endothelial cells (ECs) contributes to tumor microenvironment remodeling by influencing lymphangiogenesis/angiogenesis, tumor cell survival/proliferation, and tumor stem cell mobilization. Our in vitro studies show that pancreatic ductal adenocarcinoma (PDAC) cells do not attract growth of lymphatic nor vascular ECs toward themselves. However, tumor associated fibroblasts, a major component of the PDAC tumor microenvironment, significantly increase EC directional migration. GMI-1359 completely blocked lymphatic and vascular EC migration toward fibroblast cells and disrupted these cell-cell interactions. In addition, GMI-1359 inhibited the capacity of invasive PDAC cell lines S2.013 and Colo357 to bind and migrate across EC barriers. The dual antagonist was more effective than an independent small molecule E-selectin inhibitor. We evaluated the capacity of GMI-1359 to inhibit growth and metastasis of orthotopically implanted S2.013 cells with and without administration of Gemcitabine. Two weeks post implantation, mice were treated by intraperitoneal injection for 4 weeks with either PBS once daily; 40 mg/kg GMI-1359 once daily; 100 mg/kg Gemcitabine every 4 days; or a combination of GMI-1359 and Gemcitabine. GMI-1359 treatment slightly, but not significantly, decreased primary tumor size as compared to the vehicle control. However, GMI-1359 in combination with Gemcitabine significantly reduced metastasis of this tumor to liver and diaphragm as compared to mice that received only Gemcitabine. Further studies of GMI-1359 are warranted to understand its potential for disrupting cellular contacts and blocking pancreatic tumor dissemination through the vascular and lymphatic systems, and for enhancing the efficacy of chemotherapeutic approaches to pancreatic cancer.

Citation Format: Maria M. Steele, William E. Fogler, John L. Magnani, Michael A. Hollingsworth. A small molecule glycomimetic antagonist of E-selectin and CXCR4 (GMI-1359) prevents pancreatic tumor metastasis and improves chemotherapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 425. doi:10.1158/1538-7445.AM2015-425

ENMD-2076 is an orally active kinase inhibitor with antiangiogenic and antiproliferative mechanisms of action

ENMD-2076 is a novel orally active, small molecule kinase inhibitor with a mechanism of action involving several pathways key to tumor growth and survival: angiogenesis, proliferation, and the cell cycle. ENMD-2076 has selective activity against the mitotic kinase Aurora A, as well as kinases involved in angiogenesis (VEGFRs, FGFRs). ENMD-2076 inhibited the growth in vitro of a wide range of human solid tumor and hematopoietic cancer cell lines with IC(50) values ranging from 0.025 to 0.7 μmol/L. ENMD-2076 was also shown to induce regression or complete inhibition of tumor growth in vivo at well-tolerated doses in tumor xenograft models derived from breast, colon, melanoma, leukemia, and multiple myeloma cell lines. Pharmacodynamic experiments in vivo showed that in addition to inhibiting Aurora A, single doses of ENMD-2076 had sustained inhibitory effects on the activation of Flt3 as well as the angiogenic tyrosine kinases, VEGFR2/KDR and FGFR1 and 2. ENMD-2076 was shown to prevent the formation of new blood vessels and regress formed vessels in vivo at doses equivalent to those that gave substantial activity in tumor xenograft models. These results indicate that ENMD-2076 is a well-tolerated, orally active multitarget kinase inhibitor with a unique antiangiogenic/antiproliferative profile and provides strong preclinical support for use as a therapeutic for human cancers. Several phase 1 studies involving ENMD-2076 have been recently completed, and the compound is currently being evaluated in a phase 2 clinical trial in patients with platinum-resistant ovarian cancer.

Disease modifying and antiangiogenic activity of 2-methoxyestradiol in a murine model of rheumatoid arthritis

Background

A critical component of disease progression in rheumatoid arthritis (RA) involves neovascularization associated with pannus formation. 2-methoxyestradiol (2ME2) is a naturally occurring molecule with no known physiologic function, although at pharmacologic concentrations it has antiproliferative and antiangiogenic activities. We investigated the impact of orally administered 2ME2 on the initiation and development of proliferative synovitis using the anti-collagen monoclonal antibodies (CAIA) model.

Methods

Severe polyarticular arthritis was induced in Balb/c female mice by administration of 2 mg of a monoclonal antibody cocktail intravenously into the tail vein of mice. Twenty-four hours following monoclonal antibody administration, mice were injected with 25 μg of LPS (E. coli strain 0111:B4) via the intraperitoneal route. Treatment with 2ME2 (100, 75, 50, 25, 10, 1 mg/kg, p.o., daily), or vehicle control began 24 hrs following LPS challenge and continued to day 21. Hind limbs were harvested, sectioned and evaluated for DMARD activity and general histopathology by histomorphometric analysis and immunohistochemistry (vWF staining). In a separate study, different dosing regimens of 2ME2 (100 mg/kg; q.d. vs q.w. vs q.w. × 2) were evaluated. The effect of treatment with 2ME2 on gene expression of inflammatory cytokines and angiogenic growth factors in the joint space was evaluated 5 and 14 days after the induction of arthritis.

Results

Mice treated with 2ME2 beginning 24 hours post anti-collagen monoclonal antibody injection, showed a dose-dependent inhibition in mean arthritic scores. At study termination (day 21), blinded histomorphometric assessments of sectioned hind limbs demonstrated decreases in synovial inflammation, articular cartilage degradation, pannus formation, osteoclast activity and bone resorption. At the maximal efficacious dosing regimen (100 mg/kg/day), administration of 2ME2 resulted in total inhibition of the study parameters and prevented neovascularization into the joint. Examination of gene expression on dissected hind limbs from mice treated for 5 or 14 days with 2ME2 showed inhibition of inflammatory cytokine message for IL-1β, TNF-α, IL-6 and IL-17, as well as the angiogenic cytokines, VEGF and FGF-2.

Conclusion

These data demonstrate that in the CAIA mouse model of RA, 2ME2 has disease modifying activity that is at least partially attributable to the inhibition of neovascular development. Further, the data suggests new mechanistic points of intervention for 2ME2 in RA, specifically inhibition of inflammatory mediators and osteoclast activity.

Significant antitumor activity in vivo following treatment with the microtubule agent ENMD-1198

Clinical studies using the microtubule-targeting agent 2-methoxyestradiol (2ME2; Panzem) in cancer patients show that treatment is associated with clinical benefit, including prolonged stable disease, complete and partial responses, and an excellent safety profile. Studies have shown that 2ME2 is metabolized by conjugation at positions 3 and 17 and oxidation at position 17. To define structure-activity relationships for these positions of 2ME2 and to generate metabolically stable analogues with improved anti-tubulin properties, a series of analogues was generated and three lead analogues were selected, ENMD-1198, ENMD-1200, and ENMD-1237. These molecules showed improved metabolic stability with >65% remaining after 2-h incubation with hepatocytes. Pharmacokinetic studies showed that oral administration of the compounds resulted in increased plasma levels compared with 2ME2. All three analogues bind the colchicine binding site of tubulin, induce G(2)-M cell cycle arrest and apoptosis, and reduce hypoxia-inducible factor-1alpha levels. ENMD-1198 and ENMD-1200 showed improved in vitro antiproliferative activities. Significant reductions in tumor volumes compared with vehicle-treated mice were observed in an orthotopic breast carcinoma (MDA-MB-231) xenograft model following daily oral treatment with all compounds (ANOVA, P < 0.05). Significantly improved median survival time was observed with ENMD-1198 and ENMD-1237 (200 mg/kg/d) in a Lewis lung carcinoma metastatic model (P < 0.05). In both tumor models, the high-dose group of ENMD-1198 showed antitumor activity equivalent to that of cyclophosphamide. ENMD-1198 was selected as the lead molecule in this analogue series and is currently in a phase I clinical trial in patients with refractory solid tumors.

ENMD-1198, a novel tubulin-binding agent reduces HIF-1alpha and STAT3 activity in human hepatocellular carcinoma(HCC) cells, and inhibits growth and vascularization in vivo

Background

Hepatocellular carcinoma (HCC) represents a highly vascularized tumor entity and the process of angiogenesis is essential for the growth of HCC. Importantly, the pro-angiogenic transcription factors HIF-1α and STAT3 have been implicated in HCC progression, thus representing interesting targets for molecular targeted therapy. We hypothesized that therapeutic inhibition of HIF-1α could be achieved by using a novel tubulin-binding agent (ENMD-1198). ENMD-1198 is an analog of 2-methoxyestradiol (2ME2) with antiproliferative and antiangiogenic activity.

Methods

The human HCC cell lines HUH-7 and HepG2 were used for experiments. Effects of ENMD-1198 on constitutive and inducible (hypoxia, growth factors) activation of signaling cascades, including HIF-1α and STAT3, were investigated by Western blotting. Changes in VEGF expression were determined by real-time PCR. Effects of ENMD-1198 on cancer cell migration and invasion were evaluated in in vitro-assays. The growth-inhibitory effects of ENMD-1198 (200 mg/kg/day) were determined in a subcutaneous tumor model (HUH-7).

Results

ENMD-1198 inhibited the phosphorylation of MAPK/Erk, PI-3K/Akt and FAK. Moreover, activation of HIF-1α and STAT3 was dramatically reduced by ENMD-1198, which resulted in lower VEGF mRNA expression (P < 0.05). In addition, tumor cell migratory and invasive properties were significantly inhibited (P < 0.05, for both). In vivo, treatment with ENMD-1198 led to a significant reduction in tumor growth, tumor vascularization, and numbers of proliferating tumor cells (P < 0.05 for all).

Conclusion

The novel microtubule destabilizing agent ENMD-1198 is suitable for inhibiting HIF-1α and STAT3 in human HCC cells and leads to reduced tumor growth and vascularization in vivo. Hence, inhibition of HIF-1α and STAT3 could prove valuable for therapy of hepatocellular carcinoma.

Phase II study of recombinant human endostatin in patients with advanced neuroendocrine tumors

PURPOSE

Endostatin is a 20-kd proteolytic fragment of collagen XVIII that, in preclinical studies, has been shown to have antiangiogenic and antitumor activity. Both preclinical and human phase I studies of recombinant human endostatin (rhEndostatin) suggested activity in neuroendocrine tumors, which are known to be hypervascular. We therefore performed a multicenter phase II study of rhEndostatin in patients with carcinoid or pancreatic neuroendocrine tumors.

PATIENTS AND METHODS

Forty-two patients with advanced pancreatic endocrine tumors or carcinoid tumors were treated with rhEndostatin administered as a bid subcutaneous injection at a starting dose of 60 mg/m2/d. Steady-state trough levels were obtained after 6 weeks of therapy; patients who did not achieve a target therapeutic level of 300 ng/mL underwent dose escalation to 90 mg/m2/d. Patients were observed for evidence of toxicity, response, and survival.

RESULTS

rhEndostatin was associated with minimal toxicity. However, among 40 patients assessable for radiologic response, none experienced partial response to therapy, as defined by WHO criteria. The median steady-state trough level achieved after dose escalation was 331 ng/mL, within the postulated therapeutic range.

CONCLUSION

Treatment with rhEndostatin did not result in significant tumor regression in patients with advanced neuroendocrine tumors.

Rapid, in vivo, evaluation of antiangiogenic and antineoplastic gene products by nonviral transfection of tumor cells

Using a nonviral, electroporation-based gene transfection approach, we demonstrate the efficient and consistent transfection of two poorly immunogenic tumor cell lines: B16F10 melanoma and renal carcinoma (RENCA). Three genes, IL-12, angiostatin (AS), and an endostatin:angiostatin fusion protein (ES:AS) were subcloned into a DNA plasmid containing EBNA1-OriP, which was then transfected into B16F10 and RENCA cells. Significant levels of protein were secreted into the culture supernatants of transfected cells in vitro. Transfected tumor cells were injected subcutaneously into mice. All the three transgenes were capable of significantly delaying and reducing the formation of primary B16F10 and RENCA tumors, as well as B16F10 lung metastases. By day 11 post-injection, all control mice that received either mock-transfected or empty vector DNA-transfected B16F10 tumor cells had developed large primary tumors. In contrast, mice that received IL-12-transfected B16F10 cells did not develop appreciable tumors until day 17, and these were significantly smaller than controls. Similar results were observed for the RENCA model, in which only one of the IL-12 mice had developed tumors out to day 31. Expression of AS or ES:AS also significantly delayed and reduced primary tumors. Overall, ES:AS was more effective than AS alone. Furthermore, 25% of the AS mice and 33% of the ES:AS mice remained tumor-free at day 17, by which point all control mice had significant tumors. Mouse survival rates also correlated with the extent of tumor burden. Importantly, no lung metastases were detected in the lungs of mice that had received either AS or ES:AS-transfected B16F10 tumor cells and significantly fewer metastases were found in the IL-12 group. The consistency of our transfection results highlight the feasibility of directly electroporating tumor cells as a means to screen, identify, and validate in vivo potentially novel antiangiogenic and/or antineoplastic genes.

Anti-angiogenic vaccines as a treatment modality for cancer

Targeting angiogenesis to inhibit tumor development is now considered a valid approach to disease modulation. Recently, a number of laboratories have focused their research on the development of cancer vaccines that target modulators of angiogenesis. In this review we describe a number of novel vaccines that target mediators of angiogenesis and inhibit tumor progression in preclinical models.

Generation of a Specific Immunological Response to FGF‐2 Does Not Affect Wound Healing or Reproduction

Angiogenesis, the process of new capillary formation from pre-existing vessels, has been established as an important mechanism involved in pathologic processes, such as cancer, as well as in normal physiology (Ribatti, D.; Vacca, A.; Roncali, L.; Dammacco, F. Angiogenesis under normal and pathological conditions. Haematologica 1991, 76 (4), 311-320). Basic fibroblast growth factor (FGF-2) is a critical mediator of angiogenesis that is important for normal reproduction and wound healing. FGF-2 mediates its pro-angiogenic effects by binding to heparin sulfate proteoglycan in addition to a tyrosine kinase receptor (Baird, A.; Schubert, D.; Ling, N.; Guillemin, R. Receptor and heparin-binding domain of basic fibroblast growth factor. Proc. Natl. Acad. Sci. U. S. A. 1998, 5 (7), 2324-2328; Richard, C.; Roghani, M.; Moscatelli, D. Fibroblast growth factor (FGF)-2 mediates cell attachment through interactions with two FGF receptor-1 isoforms and extracellular matrix or cell-associated heparin sulfate proteoglycans. Biochem. Biophys. Res. Commun. 2000, 276 (2), 399-405; Casu, B.; Guerrini, M.; Naggi, A.; Perez, M.; Torri, G.; Ribatti, D.; Carminati, P.; Giannini, G.; Penco, S.; Pisano, C.; Belleri, M.; Rusnati, M.; Presta, M. Short heparin sequences spaced by glycol-split urinate residues are antagonists of fibroblast growth factor 2 and angiogenesis inhibitors. Biochemistry 2002, 41 (33), 10519-10528; Murphy, P.V.; Pitt, N.; O'Brien, A.; Enright, P.M.; Dunne, A.; Wilson, S.J.; Duane, R.M.; O'Boyle, K.M. Identification of novel inhibitors of fibroblast growth factor (FGF-2) binding to heparin and endothelial cell survival from a structurally diverse carbohybrid library. Bioorg. Med. Chem. Lett. 2002, 12 (22), 3287-3290). We developed a liposomal-based peptide vaccine, L(HBD) that targets the heparin binding domain of the FGF-2 molecule. This vaccine, when inoculated into mice, inhibits angiogenesis in response to FGF-2 in a hepatic sponge model as well as tumor progression in two models of pulmonary metastatic disease. In the present studies, we further characterize the immunological and physiological responses to this vaccine. Vaccinated animals generated a specific anti-FGF-2 antibody (titer of 1:5000) that was able to inhibit FGF-2 binding to heparin sulfate in a dose dependent fashion. Cell mediated immunity was evidenced by a delayed type hypersensitivity response following challenge with the heparin binding domain peptide. Despite an immune response toward FGF-2, vaccination with L(HBD) did not result in alterations in mean time to wound healing when compared to unvaccinated animals or those treated with a liposome control. In reproductive studies, vaccinated females were not impaired in their ability to: 1) become pregnant, 2) support the growth and development of their embryos, and 3) deliver viable offspring. Furthermore, when assessed histologically, these offspring did not demonstrate any alterations in organogenesis when compared to pups born to untreated or liposome control treated females. Thus, while vaccination against FGF-2 induces a specific FGF-2 antibody response, and inhibits angiogenesis and tumor development in a pathological setting, it does not adversely alter normal physiological events dependent on FGF-2.

Zinc ligand-disrupted recombinant human Endostatin: potent inhibition of tumor growth, safety and pharmacokinetic profile

Endostatin, a potent endogenous inhibitor of angiogenesis, inhibits the growth of primary tumors without induction of acquired drug resistance in mice. We report that a soluble recombinant human (rh) Endostatin produced with characteristics of the native Endostatin, effectively inhibited the growth of primary tumors and pulmonary metastases in a dose-dependent manner. We also show that deletion of two of the four zinc ligands of rhEndostatin did not affect this potent tumor inhibiton. The growth of established Lewis lung primary tumors implanted into mice was inhibited (80-90%) upon systemic treatment with 50 mg/kg/12 h of rhEndostatin. Using the B16-BL6 murine experimental pulmonary metastases model, rhEndostatin administered at 1.5 mg/kg/day or 4.5 mg/kg/day beginning 3- or 11-days post tumor cell injection, respectively, resulted in an approximate 80% inhibition of tumor growth. At effective anti-tumor doses of 1.5 and 50 mg/kg, pharmacokinetic modeling in mice showed (a) the protein was 100% bioavailable, (b) the AUC ranged from 16 to 700 ng ml/h and (c) the Cmax ranged from 161 to 4582 ng/ml. At the highest dose tested (300 mg/kg), delivered as a single bolus, no drug-related toxicity was observed in a Cynomolgus monkey infused with rhEndostatin. No toxicity was observed even at AUC and Cmax values that were 1.3- to 56-fold higher than those observed in mice with tumors that were potently inhibited. Our production system yields a well characterized, soluble and potent rhEndostatin at quantities sufficient for human use. The preclinical studies described herein are an important first step toward the assessment of Endostatin in the clinic.

Synergistic activity of recombinant human endostatin in combination with adriamycin: analysis of in vitro activity on endothelial cells and in vivo tumor progression in an orthotopic murine mammary carcinoma model

PURPOSE

Current combination treatment strategies in malignancy are designed to evaluate the use of cytotoxic drugs and antiangiogenic agents. Endostatin, a fragment of collagen XVIII, specifically inhibits proliferation, migration, and differentiation of endothelial cells in vitro as well as angiogenesis and tumor progression in in vivo models. In this study, we determine the antitumor effect of rhEndostatin administered alone or in combination with Adriamycin against established orthotopic murine mammary carcinoma.

EXPERIMENTAL DESIGN

Mice bearing orthotopically established DA-3 mammary adenocarcinoma tumors received varying doses of rhEndostatin alone and in combination with Adriamycin to assess tumor growth inhibition. Additional studies of this in vivo combination included a determination of Adriamycin-induced cardiotoxicity and in vitro effects on human umbilical vein endothelial cell proliferation and cord formation.

RESULTS

For single-agent activity, optimal tumor growth inhibition was observed after s.c. administration of 50 mg/kg/day rhEndostatin or 5 mg/kg Adriamycin injected i.v. every 4 days. Combination of Adriamycin with optimal or suboptimal doses of rhEndostatin resulted in synergistic inhibition of DA-3 tumor growth. Importantly, unlike other antiangiogenic agents, rhEndostatin did not exacerbate the cardiotoxicity of Adriamycin. The synergistic interaction between rhEndostatin and Adriamycin was also observed in vitro for inhibition of human umbilical vein endothelial cell proliferation and inhibition of cord formation.

CONCLUSIONS

These data suggest that the synergy observed with rhEndostatin in combination with Adriamycin is exerted at the level of the endothelial cell and can result in enhanced tumor growth inhibition. The potential benefit of Adriamycin used in combination with rhEndostatin is being considered for clinical evaluation.

Recombinant human angiostatin by twice-daily subcutaneous injection in advanced cancer: a pharmacokinetic and long-term safety study

PURPOSE

A clinical study was performed to evaluate the pharmacokinetics (PK) and toxicity of three dose levels of the angiogenesis inhibitor recombinant human (rh) angiostatin when administered twice daily by s.c. injection.

EXPERIMENTAL DESIGN

Eligible patients had cancer not amenable to standard treatments. Three groups of 8 patients received 7.5, 15, or 30 mg/m(2)/day divided in two s.c. injections for 28 consecutive days followed by a 7-day washout period. PK assessment was done at days 1 and 28. Thereafter, in absence of toxicity or a 100% increase in tumor size, treatment was continued without interruption.

RESULTS

Median age was 53 years (range, 43-75), male:female ratio 10:14, Eastern Cooperative Oncology Group performance 0-1. At the range of doses evaluated, serum PK of all 24 of the patients showed linear relation between dose and area under the curve (0- infinity) and C(max) (reached after 2 h). Thirteen of 24 patients developed erythema at injection sites (11 patients, CTC grade 1; 2 patients, CTC grade 2) without pain or itching, spontaneously resolving within 2-3 weeks of treatment. Two patients went off study after developing hemorrhage in brain metastases, and 2 patients developed deep venous thrombosis. No other relevant treatment-related toxicities were seen, even during prolonged treatment. A panel of coagulation parameters was not influenced by rhAngiostatin treatment. Long-term (>6 months) stable disease (<25% growth of measurable uni- or bidimensional tumor size) was observed in 6 of 24 patients. Five patients received rhAngiostatin treatment for >1 year (overall median time on treatment 99 days).

CONCLUSIONS

Long-term twice-daily s.c. treatment with rhAngiostatin is well tolerated and feasible at the selected doses, and merits additional evaluation. Systemic exposure to rhAngiostatin is within the range of drug exposure that has biological activity in preclinical models.

Phase I clinical trial of recombinant human endostatin administered as a short intravenous infusion repeated daily

PURPOSE

To perform a phase I trial of recombinant human endostatin (rhEndostatin; EntreMed, Rockville, MD) given as a daily 20-minute intravenous (IV) injection in adult patients with refractory solid tumors.

PATIENTS AND METHODS

The daily dose was increased from 15 to 240 mg/m(2) by a factor of 100% in cohorts of three patients. In the absence of dose-limiting toxicity, uninterrupted treatment was continued until the tumor burden increased by more than 50% from baseline. Correlative studies included dynamic contrast-enhanced magnetic resonance imaging of tumor blood flow, urinary vascular endothelial growth factor and basic fibroblast growth factor levels, rhEndostatin serum pharmacokinetics, and monitoring of circulating antibodies to rhEndostatin.

RESULTS

There were no notable treatment related toxicities among 15 patients receiving a total of 50 monthly cycles of rhEndostatin. One patient with a pancreatic neuroendocrine tumor had a minor response and two patients showed disease stabilization. Linearity in the pharmacokinetics of rhEndostatin was indicated by dose-proportionate increases in the area under the curve for the first dose and the peak serum concentration at steady state. Daily systemic exposure to rhEndostatin in patients receiving 240 mg/m(2)/d was approximately 50% lower than that provided by the therapeutically optimal dose in preclinical studies.

CONCLUSION

rhEndostatin administered as a 20-minute daily IV injection at doses up to 240 mg/m(2) showed no significant toxicities. Evidence of clinical benefit was observed in three patients. Due to high variability between the peak and trough serum concentrations associated with the repeated short IV infusion schedule, daily serum drug levels only briefly exceeded concentrations necessary for in vitro antiangiogenic effects.

Assessment of antiangiogenic effect using 99mTc-EC-endostatin

PURPOSE

Tumor vascular density may provide a prognostic indicator of metastatic potential or survival. The purpose of this study was to develop 99mTc-ethylenedicysteine-endostatin (99mTc-EC-endostatin) for the evaluation of anti-angiogenesis therapy.

METHOD

99mTc-EC-endostatin was prepared by conjugating ethylenedicysteine (EC) to endostatin, followed by adding pertechnetate and tin chloride. Radiochemical purity was > 95%. In vitro cell viability, affinity and TUNEL assays were performed. Tissue distribution and planar imaging of radiolabeled endostatin were determined in tumor-bearing rats. To assess anti-angiogenic treatment response, rats were treated with endostatin, paclitaxel and saline, followed by imaging with 99mTc-EC-endostatin. Tumor response to endostatin therapy in tumor-bearing animal models was assessed by correlating tumor uptake dose with microvessel density, VEGF, bFGF and IL-8 expression during endostatin therapy.

RESULTS

In vitro cell viability and TUNEL assays indicated no marked difference between EC-endostatin and endostatin. Cellular uptake assay suggests that endostatin binds to endostatin receptor. Biodistribution of 99mTc-EC-endostatin in tumor-bearing rats showed increased tumor-to-tissue count density ratios as a function of time. Tumor uptake (%ID/g) of 99mTc-EC-endostatin was 0.2-0.5. Planar images confirmed that the tumors could be visualized clearly with 99mTc-EC-endostatin. The optimal time for imaging using radiolabeled endostatin was 2 hrs. 99mTc-EC-endostatin could assess treatment response. There was a correlation between tumor uptake and cellular targets expression.

CONCLUSION

The results indicate that it is feasible to use 99mTc-EC-endostatin to assess efficiency of anti-angiogenesis therapy.

Continuous administration of endostatin by intraperitoneally implanted osmotic pump improves the efficacy and potency of therapy in a mouse xenograft tumor model

In the first Phase I clinical trials of endostatin as an antiangiogenic therapy for cancer, the protein was administered as an i.v. bolus for approximately 20-30 min each day. This protocol was based on experimental studies in which animals were treated by s.c. bolus once a day. However, it was not clear in the previous studies whether this schedule could be maximized further. Therefore, we developed experimental models involving continuous administration of endostatin to determine the potency and efficacy of this approach. Endostatin was administered to tumor-bearing mice either s.c. or i.p. in single bolus doses. The efficacy of these regimens was compared with endostatin administered continuously via an i.p. implanted mini-osmotic pump. Our results show that endostatin remains stable and active in mini-osmotic pumps for at least 7 days. We show that endostatin injected i.p. is rapidly cleared within 2 h, whereas endostatin administered continuously via mini-osmotic pump maintains systemic concentrations of 200-300 ng/ml for the duration of administration. Furthermore, continuous i.p. administration of endostatin results in more effective tumor suppression at significantly reduced doses (5-fold), compared with bolus administration. Additional experiments using a human pancreatic cancer model in severe combined immunodeficient mice showed that there was a significant decrease in the microvessel density between the treatment groups and the control group. These data show that continuous administration of human endostatin results in sustained systemic concentrations of the protein leading to: (a) increased efficacy manifested as increased tumor regression; and (b) an 8-10-fold decrease in the dose required to achieve the same antitumor effect as the single daily bolus administration of endostatin. On the basis of this approach, an additional clinical trial has been designed and initiated and is under way in two countries.

Administration of a liposomal FGF-2 peptide vaccine leads to abrogation of FGF-2-mediated angiogenesis and tumor development

Basic fibroblast growth factor (FGF-2) is an important stimulator of angiogenesis that has been implicated in neoplastic progression. Attempts to neutralize or modulate FGF-2 have met with some success in controlling neovascularity and tumor growth. In the present study, two peptides: one corresponding to the heparin binding domain and the other to the receptor binding domain of FGF-2, exerted dose-dependent inhibition of FGF-2-stimulated human umbilical vein endothelial cell proliferation (IC(50)=70 and 20 microg/ml, respectively). The identification of these functional regions suggested that targeting these domains might be an approach for the modulation of FGF-2 function. To investigate this possibility, we vaccinated mice with either the heparin binding domain peptide or the receptor binding domain peptide of FGF-2 in a liposome/adjuvant format, and analyzed the effect of vaccination on FGF-2-driven angiogenesis, tumor development and immune status. Mice vaccinated with the heparin binding domain peptide generated a specific antibody response to FGF-2, blocked neovascularization in a gelfoam sponge model of angiogenesis, and inhibited experimental metastasis by >90% in two tumor models: the B16BL6 melanoma and the Lewis lung carcinoma. These effects were not observed in mice treated with the receptor binding domain peptide conjugated to liposomes or liposomes lacking conjugated peptide. These data suggest that a heparin binding domain peptide of FGF-2, when presented to a host in a liposomal adjuvant formulation, can ultimately lead to inhibition of angiogenesis and tumor growth.

Serum endostatin levels are elevated and correlate with serum vascular endothelial growth factor levels in patients with stage IV clear cell renal cancer

Clear cell renal carcinoma (CCRC) is a highly angiogenic tumor known to secrete vascular endothelial cell growth factor (VEGF). Endostatin is an endogenous antiangiogenic agent with antitumor activity in mice. The purpose of this study was to evaluate serum levels of endostatin in normal subjects and in patients with CCRC and to examine the relationship of these levels to circulating VEGF levels. Fifteen patients (mean age, 48 years) on a clinical protocol for stage IV CCRC at the National Cancer Institute were included in the study. Archived prenephrectomy serum samples were analyzed for endostatin and VEGF concentrations. Endostatin and VEGF levels were compared with those of an age-matched group of volunteer blood donors (n = 18) using a competitive enzyme immunoassay. Data were analyzed using the Mann-Whitney U test and the Spearman rank correlation. Median serum endostatin levels were 24.6 ng/ml (range, 15.1-54.0 ng/ml) in CCRC patients versus 14.1 ng/ml (range, 1.0-19.3 ng/ml) in healthy controls (P < 0.0001). Median VEGF levels were 3.4 ng/ml (range, 0.1-11.2 ng/ml) and 2.5 ng/ml (range, 0.1-4.2 ng/ml), respectively (P = 0.065). A highly significant correlation was observed between endostatin and VEGF levels among the CCRC patients (r = 0.81, P = 0.0003) but not among controls (r = -0.22, P = 0.37). Endostatin levels are detectable in serum from healthy subjects as well as from CCRC patients. Levels are significantly elevated and correlate with VEGF levels in CCRC patients. Elucidating the nature of this correlation may lend insight into the regulation of tumor angiogenesis in patients with renal cancer.

The tumor-suppressing activity of angiostatin protein resides within kringles 1 to 3

Angiostatin protein, which comprises the first four kringle domains of plasminogen, is an endogenous inhibitor of angiogenesis that inhibits the growth of experimental primary and metastatic tumors. Truncation of Angiostatin K1-4 to K1-3 retained the activity of Angiostatin. We recombinantly expressed full-length human Angiostatin protein corresponding to the first four kringle domains of human plasminogen and a truncated form of the Angiostatin protein, kringles 1-3. Purified recombinant Angiostatin K1-3 and K1-4 proteins inhibited the formation of experimental B16-BL6 lung metastases by greater than 80% when administered at 30 nmol/kg/day. We demonstrate for the first time that Angiostatin protein, consisting of the first three kringle domains of human plasminogen, has in vivo biological activity in this assay indistinguishable from that of the full-length Angiostatin K1-4 protein and that the fourth kringle of plasminogen, when linked in sequence to K1-3, plays no direct role in the antitumor activity of Angiostatin.

Intradermal delivery of IL-12 naked DNA induces systemic NK cell activation and Th1 response in vivo that is independent of endogenous IL-12 production

In this study four murine IL-12 naked DNA expression plasmids (pIL-12), containing both the p35 and p40 subunits, were shown to induce systemic biological effects in vivo after intradermal injection. Three of the four IL-12 expression vectors augmented NK activity and induced expression of the IFN-gamma and IFN-gamma-inducible Mig genes. Both IL-12 p70 heterodimer and IFN-gamma proteins were documented in the serum within 24 h after intradermal injection of the pIL-12o- plasmid, which also induced the highest level of NK activity in the spleen and liver among the IL-12 constructs. Interestingly, both p40 mRNA expression at the injection site and serum protein levels followed a biphasic pattern of expression, with peaks on days 1 and 5. Subsequent studies revealed that the ability of intradermally injected pIL-12o- to augment NK lytic activity was prevented by administration of a neutralizing anti-IL-12 mAb. Finally, injection of the pIL-12o- into BALB/c IL-12 p40-/- mice also resulted in a biphasic pattern of IL-12 p70 appearance in the serum, and induced IFN-gamma protein and activated NK lytic activity in liver and spleen. These results demonstrate that injection of delivered naked DNA encoding the IL-12 gene mediates the biphasic systemic production of IL-12-inducible genes and augments the cytotoxic function of NK cells in lymphoid and parenchymal organs as a direct result of transgene expression. The results also suggest that these naked DNA plasmids may be useful adjuvants for vaccines against infectious and neoplastic diseases.

Intradermal Delivery of IL-12 Naked DNA Induces Systemic NK Cell Activation and Th1 Response In Vivo That Is Independent of Endogenous IL-12 Production

In this study four murine IL-12 naked DNA expression plasmids (pIL-12), containing both the p35 and p40 subunits, were shown to induce systemic biological effects in vivo after intradermal injection. Three of the four IL-12 expression vectors augmented NK activity and induced expression of the IFN-γ and IFN-γ-inducible Mig genes. Both IL-12 p70 heterodimer and IFN-γ proteins were documented in the serum within 24 h after intradermal injection of the pIL-12o− plasmid, which also induced the highest level of NK activity in the spleen and liver among the IL-12 constructs. Interestingly, both p40 mRNA expression at the injection site and serum protein levels followed a biphasic pattern of expression, with peaks on days 1 and 5. Subsequent studies revealed that the ability of intradermally injected pIL-12o− to augment NK lytic activity was prevented by administration of a neutralizing anti-IL-12 mAb. Finally, injection of the pIL-12o− into BALB/c IL-12 p40−/− mice also resulted in a biphasic pattern of IL-12 p70 appearance in the serum, and induced IFN-γ protein and activated NK lytic activity in liver and spleen. These results demonstrate that injection of delivered naked DNA encoding the IL-12 gene mediates the biphasic systemic production of IL-12-inducible genes and augments the cytotoxic function of NK cells in lymphoid and parenchymal organs as a direct result of transgene expression. The results also suggest that these naked DNA plasmids may be useful adjuvants for vaccines against infectious and neoplastic diseases.

Recruitment of hepatic NK cells by IL-12 is dependent on IFN-gamma and VCAM-1 and is rapidly down-regulated by a mechanism involving T cells and expression of Fas

NK cells have been shown to be important antitumor or antiviral effector cells in the liver. In the present study we have examined the factors that regulate the initial recruitment and subsequent fate of hepatic NK and T cells in mice treated with IL-12 or IL-2. Daily administration of IL-12 caused a rapid initial increase in NK cells followed by a subsequent decrease that coincided with an accumulation of T cells. The recruitment of hepatic NK cells by IL-12, but not the subsequent T cell infiltrate, was abrogated in IFN-gamma(-/-) mice. In contrast, daily administration of IL-2 caused a sustained increase in liver-associated NK cells that was not diminished in IFN-gamma(-/-) mice. The IL-12-induced recruitment in both hepatic NK and T cells was abrogated by in vivo treatment with anti-VCAM-1 mAbs, while treatment with anti-ICAM-1 Abs decreased only the recruitment of T cells in the IL-12-treated mice. The rapid loss of newly recruited hepatic NK cells in IL-12-treated mice did not occur in SCID mice or in B.MRL-Fas(lpr) (Fas-) and B6Smn.C3H-Fasl(gld) (FasL-) mutant mice, suggesting that T cells can actively eliminate hepatic NK cells through a Fas-dependent mechanism. These findings also imply that during the endogenous innate immune response to infectious agents or tumors or in the host response induced by cytokine therapies, the biologic effects of NK cells may be limited by T cell-mediated effects.

Recruitment of Hepatic NK Cells by IL-12 Is Dependent on IFN-γ and VCAM-1 and Is Rapidly Down-Regulated by a Mechanism Involving T Cells and Expression of Fas

NK cells have been shown to be important antitumor or antiviral effector cells in the liver. In the present study we have examined the factors that regulate the initial recruitment and subsequent fate of hepatic NK and T cells in mice treated with IL-12 or IL-2. Daily administration of IL-12 caused a rapid initial increase in NK cells followed by a subsequent decrease that coincided with an accumulation of T cells. The recruitment of hepatic NK cells by IL-12, but not the subsequent T cell infiltrate, was abrogated in IFN-γ−/− mice. In contrast, daily administration of IL-2 caused a sustained increase in liver-associated NK cells that was not diminished in IFN-γ−/− mice. The IL-12-induced recruitment in both hepatic NK and T cells was abrogated by in vivo treatment with anti-VCAM-1 mAbs, while treatment with anti-ICAM-1 Abs decreased only the recruitment of T cells in the IL-12-treated mice. The rapid loss of newly recruited hepatic NK cells in IL-12-treated mice did not occur in SCID mice or in B.MRL-Faslpr (Fas−) and B6Smn.C3H-Faslgld (FasL−) mutant mice, suggesting that T cells can actively eliminate hepatic NK cells through a Fas-dependent mechanism. These findings also imply that during the endogenous innate immune response to infectious agents or tumors or in the host response induced by cytokine therapies, the biologic effects of NK cells may be limited by T cell-mediated effects.

Differential tyrosine phosphorylation of inhibitory versus activating Ly-49 receptor proteins and their recruitment of SHP-1 phosphatase

Killer cell inhibitory receptors represent a family of p58/70-Ig-like proteins expressed on the surface of human NK cells. Engagement of class I MHC by killer cell inhibitory receptors turns off the lytic machinery of NK cells. This receptor/ligand interaction results in phosphorylation of intracellular tyrosine residues of p58/70 proteins. Murine NK cells express surface receptors of an unrelated family of type II lectin-like proteins, Ly-49, that have similar functions. Ly-49A, -C, and -G2 represent murine inhibitory receptors. However, Ly-49D functions as an activation receptor on the surface of NK cells. This dichotomy of function between Ly-49 family members suggested different signaling events upon receptor/ligand interaction. Here we demonstrate that: 1) in transfected Cos7 and murine NK cells, Ly-49A, -C, and -G2 are phosphorylated following pervanadate stimulation, whereas Ly-49D is not; 2) mAb-induced receptor ligation mediates tyrosine phosphorylation of Ly-49A and -G2, but not Ly-49D; 3) SHP-1 coprecipitates with Ly-49A and -G2 following receptor phosphorylation; and 4) tyrosine phosphorylation of Ly-49 inhibitory receptors depends on tyrosine residues restricted to the immunoreceptor tyrosine-based inhibitory motif. Our data further support the involvement of immunoreceptor tyrosine-based inhibitory motifs as crucial sequences regulating receptor-mediated inhibitory functions in NK cells.

Differential tyrosine phosphorylation of inhibitory versus activating Ly-49 receptor proteins and their recruitment of SHP-1 phosphatase

Killer cell inhibitory receptors represent a family of p58/70-Ig-like proteins expressed on the surface of human NK cells. Engagement of class I MHC by killer cell inhibitory receptors turns off the lytic machinery of NK cells. This receptor/ligand interaction results in phosphorylation of intracellular tyrosine residues of p58/70 proteins. Murine NK cells express surface receptors of an unrelated family of type II lectin-like proteins, Ly-49, that have similar functions. Ly-49A, -C, and -G2 represent murine inhibitory receptors. However, Ly-49D functions as an activation receptor on the surface of NK cells. This dichotomy of function between Ly-49 family members suggested different signaling events upon receptor/ligand interaction. Here we demonstrate that: 1) in transfected Cos7 and murine NK cells, Ly-49A, -C, and -G2 are phosphorylated following pervanadate stimulation, whereas Ly-49D is not; 2) mAb-induced receptor ligation mediates tyrosine phosphorylation of Ly-49A and -G2, but not Ly-49D; 3) SHP-1 coprecipitates with Ly-49A and -G2 following receptor phosphorylation; and 4) tyrosine phosphorylation of Ly-49 inhibitory receptors depends on tyrosine residues restricted to the immunoreceptor tyrosine-based inhibitory motif. Our data further support the involvement of immunoreceptor tyrosine-based inhibitory motifs as crucial sequences regulating receptor-mediated inhibitory functions in NK cells.

IL-7 activates alpha4beta1 integrin in murine thymocytes

IL-7, a cytokine produced by thymic epithelium, was shown to induce adhesion of murine thymocytes to gelatin-coated membranes. A major binding component of gelatin was identified as fibronectin. IL-7-induced adhesion was observed for all of the major thymocyte subsets, including double-negative, double-positive, and single-positive cells, and specific IL-7R were verified on each subset. Fibronectin binding was mediated via alpha4beta1 integrin (VLA-4), which is expressed at high levels on thymocytes. VLA-4 surface expression was not increased following IL-7 treatment, but was shown to undergo rapid tyrosine phosphorylation on the beta1 subunit. This tyrosine phosphorylation was blocked by genistein, which also blocked IL-7-induced adhesion. IL-7 was detected on the extracellular matrix of the thymus, suggesting that it could promote matrix association through an integrin pathway.

IL-7 activates alpha4beta1 integrin in murine thymocytes

IL-7, a cytokine produced by thymic epithelium, was shown to induce adhesion of murine thymocytes to gelatin-coated membranes. A major binding component of gelatin was identified as fibronectin. IL-7-induced adhesion was observed for all of the major thymocyte subsets, including double-negative, double-positive, and single-positive cells, and specific IL-7R were verified on each subset. Fibronectin binding was mediated via alpha4beta1 integrin (VLA-4), which is expressed at high levels on thymocytes. VLA-4 surface expression was not increased following IL-7 treatment, but was shown to undergo rapid tyrosine phosphorylation on the beta1 subunit. This tyrosine phosphorylation was blocked by genistein, which also blocked IL-7-induced adhesion. IL-7 was detected on the extracellular matrix of the thymus, suggesting that it could promote matrix association through an integrin pathway.

Regulation of local host-mediated anti-tumor mechanisms by cytokines: direct and indirect effects on leukocyte recruitment and angiogenesis

The regulation of tumor growth by cytokine-induced alterations in host effector cell recruitment and activation is intimately associated with leukocyte adhesion and angiogenic modulation. In the present study, we have developed a novel tumor model to investigate this complex series of events in response to cytokine administration. Gelatin sponges containing recombinant human basic fibroblast growth factor (rhFGFb) and B16F10 melanoma cells were implanted onto the serosal surface of the left lateral hepatic lobe in syngeneic C57BL/6 mice. The tumor model was characterized by progressive tumor growth initially localized within the sponge and the subsequent development of peritoneal carcinomatosis. Microscopic examination of the sponge matrix revealed well developed tumor-associated vascular structures and areas of endothelial cell activation as evidenced by leukocyte margination. Treatment of mice 3 days after sponge implantation with a therapeutic regimen consisting of pulse recombinant human interleukin-2 (rhIL-2) combined with recombinant murine interleukin-12 (rmIL-12) resulted in a marked hepatic mononuclear infiltrate and inhibition of tumor growth. In contrast to the control group, sponges from mice treated with rhIL-2/rmIL-12 demonstrated an overall lack of cellularity and vascular structure. The regimen of rhIL-2 in combination with rmIL-12 was equally effective against gelatin sponge implants of rhFGFb/B16F10 melanoma in SCID mice treated with anti-asialo-GM1 in the absence of a mononuclear infiltration, suggesting that T, B, and/or NK cells were not the principal mediators of the anti-tumor response in this tumor model. The absence of vascularity within the sponge after treatment suggests that a potential mechanism of rhIL-2/rmIL-12 anti-tumor activity is the inhibition of neovascular growth associated with the establishment of tumor lesions. This potential mechanism could be dissociated from the known activities of these two cytokines to induce the recruitment and activation of host effector cells. Moreover, this model provides a unique opportunity to study the cellular and molecular mechanism(s) underlying both tumor angiogenesis and leukocyte recruitment to metastatic lesions.

NK cell infiltration into lung, liver, and subcutaneous B16 melanoma is mediated by VCAM-1/VLA-4 interaction

The mechanisms that regulate the adhesion and migration of NK cells to and across endothelium have been studied under nonflow conditions; however, the involvement of these processes in vivo is poorly understood. The present studies investigated the potential vascular adhesion ligand interactions that determine the in vivo recruitment of NK cells to pulmonary and hepatic parenchyma, and s.c. tumor after treatment of mice with biologic response modifiers. Seventy-two hours after a single injection of the cytokine-inducing agent poly-L-lysine stabilized in carboxylmethyl cellulose (poly-ICLC), pulmonary NK cell lytic activity and N-alpha-carbobenzoxy-L-lysine thiobenzyl ester (BLT)-esterase were augmented 29- and 14-fold, respectively, and the number of lung-associated NK cells was increased from 2.3 x 10(5) to 7.4 x 10(5). Similar fold increases in NK cell number and activity were observed in the liver and s.c. B16 melanoma after poly-ICLC injection or in the lungs and liver of mice treated with IL-2. Concomitant treatment of mice with alpha-VCAM-1 or alpha-VLA-4 mAb, but not alpha-ICAM-1 or alpha-LFA-1, abrogated the poly-ICLC and IL-2-induced increase in organ-associated NK activity and percentage of tumor-associated NK cells, resulted in a 61 to 76% decrease in pulmonary and hepatic NK cell number, and was independent of T and/or B cells. The decrease in NK cell number in organ parenchyma and tumor lesions was correlated to an increase in the number of NK cells in peripheral blood, but not bone marrow. These results demonstrate that VCAM-1/VLA-4 interaction is critically involved in the infiltration of newly recruited NK cells in to lung, liver, and progressively growing tumor after mobilization from the bone marrow.

NK cell infiltration into lung, liver, and subcutaneous B16 melanoma is mediated by VCAM-1/VLA-4 interaction

The mechanisms that regulate the adhesion and migration of NK cells to and across endothelium have been studied under nonflow conditions; however, the involvement of these processes in vivo is poorly understood. The present studies investigated the potential vascular adhesion ligand interactions that determine the in vivo recruitment of NK cells to pulmonary and hepatic parenchyma, and s.c. tumor after treatment of mice with biologic response modifiers. Seventy-two hours after a single injection of the cytokine-inducing agent poly-L-lysine stabilized in carboxylmethyl cellulose (poly-ICLC), pulmonary NK cell lytic activity and N-alpha-carbobenzoxy-L-lysine thiobenzyl ester (BLT)-esterase were augmented 29- and 14-fold, respectively, and the number of lung-associated NK cells was increased from 2.3 x 10(5) to 7.4 x 10(5). Similar fold increases in NK cell number and activity were observed in the liver and s.c. B16 melanoma after poly-ICLC injection or in the lungs and liver of mice treated with IL-2. Concomitant treatment of mice with alpha-VCAM-1 or alpha-VLA-4 mAb, but not alpha-ICAM-1 or alpha-LFA-1, abrogated the poly-ICLC and IL-2-induced increase in organ-associated NK activity and percentage of tumor-associated NK cells, resulted in a 61 to 76% decrease in pulmonary and hepatic NK cell number, and was independent of T and/or B cells. The decrease in NK cell number in organ parenchyma and tumor lesions was correlated to an increase in the number of NK cells in peripheral blood, but not bone marrow. These results demonstrate that VCAM-1/VLA-4 interaction is critically involved in the infiltration of newly recruited NK cells in to lung, liver, and progressively growing tumor after mobilization from the bone marrow.