ABSTRACT
3F8 is a murine IgG3 monoclonal antibody specific for the antigen disialoganglioside GD2. Immunofluorescence staining showed strong binding of 3F8 to 15 of 17 human osteosarcomas, including primary and metastatic tumors. The targeting potentials of the native monoclonal antibody (3F8) and the F(ab')2 fragment (p-3F8) were tested in BALB/c athymic nude mice xenografted with human osteosarcomas. After radiolabeling with iodine using the chloramine T method, both 3F8 and p-3F8 retained immunoreactivities. The irrelevant IgG3 antibody TIB114 and its F(ab')2 fragment were used as negative controls. A Ewing's sarcoma xenograft, which was low in GD2 antigen, was also studied for comparison. Mice were sacrificed 1 day and 4 days after i.v. antibody injection. 3F8 and p-3F8 showed preferential accumulation in osteosarcoma over normal tissues with tumor:nontumor ratios of 2.7-58:1 and 1.4-82:1, respectively, on Day 1. These ratios improved to 10-163:1 and 6.0-75:1 on Day 4. The intact antibody 3F8 showed selective tumor uptake with a much higher percentage of injected dose per g than the fragment p-3F8 and exhibited a longer tissue half-life than p-3F8. These data indicate that anti-GD2 monoclonal antibodies may be useful for imaging and targeted therapy of human osteogenic sarcoma. The F(ab')2 fragment has the advantage of achieving favorable tumor:nontumor ratios sooner after antibody injection while the intact antibody shows better retention by tumor tissues.
Subject(s)
Antibodies, Monoclonal/analysis , Bone Neoplasms/immunology , Gangliosides/immunology , Osteosarcoma/immunology , Animals , Autoradiography , Fluorescent Antibody Technique , Half-Life , Humans , Iodine Radioisotopes/metabolism , Mice , Mice, Inbred BALB C , Mice, Nude , Sarcoma, Ewing/immunology , Tissue DistributionABSTRACT
The murine IgG3 monoclonal antibody (MoAb) 3F8, specific for the ganglioside GD2, activates human complement, is active in antibody-dependent cell-mediated cytotoxicity (ADCC), and can target specifically to human neuroblastoma in patients with metastatic disease. In a phase I study, 3F8 was administered intravenously (IV) to 17 patients with metastatic GD2 positive neuroblastoma or malignant melanoma at doses of 5, 20, 50, and 100 mg/m2. Serum 3F8 levels achieved were proportional to the dose of 3F8 infused. However, serum antimouse antibody levels did not increase with the amount of 3F8 administered. Toxicities included pain, hypertension, urticaria, and complement depletion. All acute side effects were controllable with symptomatic therapy. No long-term side effects were detected in patients observed for more than 14 months. None of the 17 patients received any antitumor therapy postantibody treatment. Antitumor responses occurred in seven of 17 patients. These ranged from complete clinical remissions to mixed responses. The murine monoclonal antibody (MoAb) 3F8 has clinical utility for the diagnosis and therapy of neuroblastoma and melanoma.