Antibiotics, Antineoplastic/pharmacology; Antibodies, Monoclonal/pharmacology; Apoptosis/drug effects; Doxorubicin/pharmacology; Endothelium, Vascular/drug effects; Leiomyosarcoma/therapy; Neovascularization, Pathologic/therapy; Receptor Protein-Tyrosine Kinases/immunology; Receptors, Growth Factor/immunology; Rhabdomyosarcoma/therapy; Soft Tissue Neoplasms/therapy; Animals; Combined Modality Therapy; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Synergism; Endothelium, Vascular/pathology; Female; Humans; Leiomyosarcoma/blood supply; Leiomyosarcoma/drug therapy; Leiomyosarcoma/pathology; Mice; Mice, SCID; Neovascularization, Pathologic/drug therapy; Neovascularization, Pathologic/pathology; Receptors, Vascular Endothelial Growth Factor; Rhabdomyosarcoma/blood supply; Rhabdomyosarcoma/drug therapy; Rhabdomyosarcoma/pathology; Soft Tissue Neoplasms/blood supply; Soft Tissue Neoplasms/drug therapy; Soft Tissue Neoplasms/pathology; Xenograft Model Antitumor Assays