Purpose: Advanced melanoma is a highly drug-refractory neoplasm representing a significant unmet medical need. We sought to identify melanoma-associated cell surface molecules and to develop as well as preclinically test immunotherapeutic reagents designed to exploit such targets. Experimental Design and Results: By transcript profiling, we identified glycoprotein NMB (GPNMB) as a gene that is expressed by most metastatic melanoma samples examined. GPNMB is predicted to be a transmembrane protein, thus making it a potential immunotherapeutic target in the treatment of this disease. A fully human monoclonal antibody, designated CR011, was generated to the extracellular domain of GPNMB and characterized for growth-inhibitory activity against melanoma. The CR011monoclonal antibody showed surface staining of most melanoma cell lines by flow cytometry and reacted with a majority of metastatic melanoma specimens by immunohistochemistry. CR011alone did not inhibit the growth of melanoma cells. However, when linked to the cytotoxic agent monomethylauristatin E (MMAE) to generate the CR011-vcMMAE antibody-drug conjugate, this reagent now potently and specifically inhibited the growth of GPNMB-positive melanoma cells in vitro. Ectopic overexpression and small interfering RNA transfection studies showed that GPNMB expression is both necessary and sufficient for sensitivity to low concentrations of CR011-vcMMAE. In a melanoma xenograft model, CR011-vcMMAE induced significant dose-proportional antitumor effects, including complete regressions, at doses as low as 1.25 mg/kg. Conclusion: These preclinical results support the continued evaluation of CR011-vcMMAE for the treatment of melanoma.
Short-term anti-tumor effects and long-term effects (complete regression) were observed with CR011-vcMMAE, but not with the reference agents. These results suggest that CR011-vcMMAE may provide therapeutic benefit in malignant melanoma.
Summary. Alveolar macrophages (AM) lavaged from lungs of normal F344 rats were rendered tumoricidal following their direct interaction with squalene-treated Nocardia rubra cell wall skeleton (N-CWS) present in the culture medium. Maximum tumoricidal activity was obtained by incubating A M with 1 #g N-CWS
N-(5-Fluorobenzothiazol-2-yl)-2-guanidinothiazole-4-carboxam ide (1) is a member of a series of amides found to substantially increase lifespan in mice bearing established micrometastatic 3LL Lewis lung carcinoma. Amide 1 is effective after either oral or intraperitoneal dosing in acute, subacute, or chronic regimens. 1 is well tolerated in this model with an excellent therapeutic index relative to the cytotoxic anticancer drug adriamycin.
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