In mice, significant immunoprotection was achieved using B16 melanoma cells transfected with granulocyte-macrophage colony-stimulating factor (GM-CSF) as vaccines (Dranoff G, Jaffee E, Lazenby A, et al. Vaccination with irradiated tumor cells engineered to secrete murine granulocyte-macrophage colony-stimulating factor stimulates potent, specific, and long-lasting anti-tumor immunity. Proc Natl Acad Sci USA 1993;90:3539-43). The aim of this study is to test the hypothesis that recombinant human GM-CSF (rhGM-CSF) injected with autologous melanoma vaccine may result in tumor rejection in melanoma patients. Twenty stage IV melanoma patients were treated as outpatients with multiple cycles of autologous melanoma vaccine and bacillus Calmette-Guérin (BCG) plus rhGM-CSF injection in the vaccine sites. Two patients (10%) showed a complete response, with one patient showing resolution of subcutaneous, hepatic, and splenic metastases. In the second patient, buccal, subcutaneous, pulmonary, paraaortic, hepatic, splenic, and retroperitoneal metastases regressed completely. Two patients (10%) showed partial response, with regression of a paraaortic metastasis in one patient. In the second patient, there was shrinkage (> 75%) of a large hepatic lesion. One patient has been rendered free of disease after resection of a single pulmonary metastatic nodule. Three patients (15%) had stable disease during treatment but subsequently developed progression of disease. In 12 patients (60%), the disease progressed. Side effects were minimal. In a separate pilot study, 15 stage IV melanoma patients were also treated with autologous melanoma vaccine with BCG but not with rhGM-CSF; none responded. The fact that four patients showed objective responses to active specific immunotherapy with rhGM-CSF demonstrates that melanoma patients bearing a significant tumor burden may respond specifically to their autologous melanoma.