To better understand the in vivo bone-inductive properties of recombinant human (rh) BMP-2, we examined the ability of the protein to alter the phenotype of a bone marrow stromal cell line. W-20-17. rhBMP-2 increased alkaline phosphatase activity in W-20-17 cells in a dose-responsive manner in the absence of an effect on proliferation. The induction of alkaline phosphatase activity was not apparent until 12 h after rhBMP-2 treatment had begun and was effectively eliminated by cotreatment with cycloheximide, suggesting a requirement for protein synthesis. Continued treatment of W-20-17 cells with rhBMP-2 for 8 days resulted in a significant increase, compared to control cultures, in the production of cellular cAMP in response to a PTH challenge. In addition, 4-day treatment with rhBMP-2 induced osteocalcin levels in W-20-17 cells. These results indicate that rhBMP-2 induces the expression of several markers associated with the osteoblast phenotype in W-20-17 cells and raises the possibility that BMP-2 may be involved in the differentiation of osteoblasts from progenitor cells resident in bone marrow.

Purpose: Endosialin/CD248/tumor endothelial marker 1is expressed in stromal cells, endothelial cells, and pericytes in various tumors; however, few studies have focused on expression in malignant cells. Experimental Design: We studied expression of endosialin in clinical specimens, cell culture, and animal models and designed an anti-endosialin therapeutic prototype. Results: Fifty human tumor cell lines and 6 normal cell types in culture were assayed by reverse transcription-PCR and/or flow cytometry for endosialin. Cell surface protein was found on 7 sarcoma lines, 1neuroblastoma, and 4 normal cell types in culture. A fully human anti-endosialin antibody bound to human A-673 Ewing's sarcoma cells and SK-N-AS neuroblastoma cells but not HT-1080 cells. Exposure of cells to an anti-human IgG conjugated to saporin resulted in growth inhibition only of endosialin-expressing cells. Endosialin expression was assessed by immunohistochemistry in 250 clinical specimens of human cancer including 20 cancer subtypes. Endosialin is frequently found in human cancers. Endosialin expression is mainly a perivascular feature in carcinomas, with some expression in stromal cells. In sarcomas, endosialin is expressed by malignant cells, perivascular cells, and stromal cells. Development and characterization of experimental models for studying endosialin biology in sarcomas and evaluating anti-endosialin therapies is presented. Conclusions: Findings suggest that an anti-endosialin immunotoxin might be a promising therapeutic approach for endosialin-positive neoplasia, especially synovial sarcoma, fibrosarcoma, malignant fibrous histiocytoma, liposarcoma, and osteosarcoma. Thus, a diagnostic/therapeutic targeted therapeutic approach to treatment of endosialin-expressing tumors may be possible.

We conclude that there are significant histopathologic consequences, focused in the kidney, resulting from the daily administration of high doses of human recombinant TGF-beta2, and we propose that selective vascular constriction with consequent tissue hypoxia is a contributing factor.

Purpose: Placental growth factor (PlGF) is an angiogenic protein. Upregulation of PlGF has been observed in the clinic following antiangiogenic regimens targeting the VEGF pathway. PlGF has been proposed as a therapeutic target for oncology. sFLT01 is a novel fusion protein that neutralizes mouse and human PlGF (mPlGF, hPlGF) and mouse and human VEGF-A (mVEGF-A, hVEGF-A). It was tested in syngeneic and xenograft tumor models to evaluate the effects of simultaneously neutralizing PlGF and VEGF-A and to investigate changes observed in the clinic in preclinical models. Experimental Design: Production of PlGF and VEGF-A by B16F10 and A673 cancer cells in vitro was assessed. Mice with subcutaneous B16F10 melanoma or A673 sarcoma tumors were treated with sFLT01. Tumor volumes and microvessel density (MVD) were measured to assess efficacy. Serum levels of hVEGF-A, hPlGF, and mPlGF at early and late time points were determined by ELISA. Results: Exposure of cancer cell lines to sFLT01 caused a decrease in VEGF secretion. sFLT01 inhibited tumor growth, prolonged survival, and decreased MVD. Analysis of serum collected from treated mice showed that sFLT01 administration caused a marked increase in circulating mPlGF but not hPlGF or hVEGF. sFLT01 treatment also increased circulating mPlGF levels in non–tumor-bearing mice. Conclusion: With the tumor cell lines and mouse models we used, antiangiogenic therapies that target both PlGF and VEGF may elicit a host response rather than, or in addition to, a malignant cell response that contribute to therapeutic resistance and tumor escape as suggested by others. Clin Cancer Res; 17(5); 976–88. ©2011 AACR.

Using a novel purification scheme, we have characterized BMP as a 30kD fraction. After reduction, which destroys biological activity, this fraction was shown to be comprised of individual polypeptides with molecular weights of 30kD, 18kD and 16kD. Molecular cloning of these polypeptides resulted in the identification of 4 previously undescribed genes (BMP-1, BMP-2A, BMP-2B, and BMP-3) each of which is capable of directing de novo cartilage formation in vivo. While BMP-1 appears to be unrelated to other known growth factors, the derived amino acid sequence of BMP-2A, 2B, and 3 indicate that they are new members of the TGFb gene family. BMP-1, 2A and 2B are expressed in rat embryos during morphogenesis and can be localized by in situ hybridization to developing limb buds. BMP-3 localizes to neural ectoderm and later on in development to newly forming periosteum. Comparisons to other members of the TGFb family suggest that these newly identified BMPs are involved in pattern formation during early skeletal development.

Abstract. Even with current standard-of-care therapies, the prognosis for patients with malignant gliomas is very poor and several new treatment modalities for glioblastomas are currently under investigation. Given the role of TGF-ß in gliomas, anti-TGF-ß strategies against gliomas are currently being investigated. Biodistribution of intravenously injected AF680-labeled 1D11, a pan-neutralizing TGF-ß antibody, was monitored in mice bearing either subcutaneous or orthotopic gliomas using in vivo imaging and fluorescence microscopy. AF680-labeled 1D11 entered both the subcutaneous and intracranial tumors and the antibody was detected within the tumor tissue for several days whereas only low fluorescence was found in organs. The effects of 1D11 on subcutaneous versus orthotopic U87MG and GL261 gliomas in immunocompetent C57BL/6J versus immunodeficient CD1-Foxn1nu mice were observed by direct tumor size measurement, H&E staining and immunohistochemistry. Treatment of immunocompetent mice bearing subcutaneous GL261 tumors with 1D11 resulted in complete remission. In immune deficient mice, the growth of subcutaneous GL261 tumors was increased following treatment with 1D11. Intracranially implanted gliomas in C57Bl/6J mice showed no size reduction after 1D11 treatment but there was reduced invasion of the glioma cells into the adjacent normal brain. Together these data demonstrate that TGF-ß plays different roles in combating the tumor depending on subcutaneous versus orthotopic implantation site.

Topoisomerase I (TopoI), an established anticancer target, is an enzyme producing a single-strand DNA break during transcription. Several noncamptothecin TopoI inhibitors have been identified. One of these, ARC-111, was compared with two clinically used camptothecins, topotecan and irinotecan/SN-38. In mouse and human bone marrow colony formation [colony-forming units granulocytemacrophage (CFU-GM)] assays, the IC 90 values were 519 and 331 nmol/L for topotecan and SN-38 mouse CFU-GM and were 19 and 26 nmol/L for human CFU-GM, giving mouse to human differentials of 28-and 13-fold. ARC-111 produced IC 90 values of 28 nmol/L in mouse and 6.2 nmol/L in human CFU-GM, thus only a 4.5-fold differential between species. Human bone marrow CFU-GM was more sensitive to topotecan than were several human cancer cell lines, but ARC-111 cytotoxicity was similar for human bone marrow CFU-GM and the seven human tumor cell lines tested. In HCT-116 xenografts, tumor growth delays (TGD) were 17 days for irinotecan and 20 days for ARC-111. In HT-29 xenografts, the TGD was 9 days for both irinotecan and ARC-111. Both ARC-111 and docetaxel had a TGD of 21 days in NCI-H460

Purpose: Genz-644282 [8,9-dimethoxy-5-(2-N-methylaminoethyl)-2,3-methylenedioxy-5H-dibenzo [c, h][1,6]naphthyridin-6-one] has emerged as a promising candidate for antitumor agents. This report describes the bone marrow colony-forming unit, granulocyte macrophage (CFU-GM) and tumor cell CFU activity of topoisomerase I (Top1) inhibitors, such as Genz-644282, topotecan, irinotecan/SN-38, and ARC-111, and examines their activity in several human tumor xenograft models.Experimental Design: Colony-forming assays were conducted with mouse and human bone marrow and eight human tumor cell lines. In addition, 29 human tumor cell lines representing a range of histology and potential resistance mechanisms were assayed for sensitivity to Genz-644282 in a 72-hour exposure assay. The efficacy of Genz-644282 was compared with standard anticancer drugs (i.e., irinotecan, docetaxel, and dacarbazine) in human tumor xenografts of colon cancer, renal cell carcinoma, non-small cell lung cancer, and melanoma.Results: Human bone marrow CFU-GM was more sensitive to the Top1 inhibitors than was mouse bone marrow CFU-GM. The ratio of mouse to human IC 90 values was more than 10 for the camptothecins and less than 10 for Genz-644282, which had more potency as a cytotoxic agent toward human tumor cells in culture than the camptothecins in the colony-forming and 72-hour proliferation assays. Genz-644282 has superior or equal antitumor activity in the human tumor xenografts than the standard drug comparators.Conclusions: On the basis of preclinical activity and safety, Genz-644282 was selected for development and is currently undergoing phase 1 clinical trial.