BCG treatment of human tumour xenografts in athymic nude mice.

Xenografts of 3 human malignant cell lines in congenitally athymic nude mice have been examined for susceptibility to BCG. Growth of all 3 tumours, a bladder carcinoma, a melanoma and a colon carcinoma, was suppressed when cells were injected in admixture with BCG. Distant injection of BCG was ineffective. Mice with progressive growths had no detectable anti-human antibody, and rejection of cells and BCG failed to confer protection against subsequent tumour challenge. These studies indicate that human malignant cells are susceptible to local BCG-activated host responses, and that athymic mouse xenografts may be a useful model for assessing the response of human tumours to such agents.