Antitu mor Activity of Killed Corynebacterium parvum Suspensions in a Murine

SUMMARY-We studied the antitumor activity of killed Coryne-bacterium parvum on the CaD2 mammary adenocarcinoma in DBA/2 mice. Intratumor treatment had little or no effect on subcutaneous tumor growth. Admixture of tumor cells with C. parvum before inoculation completely suppressed tumor growth. No tumor transplantation immunity was detected in mice inoculated with admixtures of C. parvum and tumor cells, but tumors were enhanced under certain circumstances. Growth of a tumor inoculated sc or iv was consistently retarded after iv or ip C. parvum therapy, but tumors rarely regressed. Tumor transplantation immunity was detected in mice treated iv with C. parvum before surgical excision of established tumors. Certain adverse effects of iv or ip administration of C. parvum were also discussed.-J Natl Cancer Inst 56: 1171-1175, 1976. Growth retardation and regression of several animal neoplasms have been observed after either local (sc or intratumor) or systemic (iv or ip) administration of killed Corynebacterium parvum (1-7). Furthermore, tumor transplantation immunity was augmented after C. parvum therapy in some tumor systems (8) 9). We are developing animal tumor models to evaluate the effec-tiveness of immune stimulants in the eradication of residual host neoplastic cell burden. We report here our observations of the antitumor effects of C. parvum against the CaD2 mammary adenocarcinoma in DBA/2 mice. We examined the effects of intratumor, iv, and ip administration of C. paroum, and the prior admixture of tumor cells with C. parvum on growth of the CaD2 tumor and on host resistance to secondary challenge with this tumor