Immunotherapy of Cancer: Regression of Intradermal Tumors and Prevention of Growth of Lymph Node Metastases After Intralesional Injection of Living Mycobacterium bovis

Abstract

Intradermal (ID) inoculation of cells of a syngeneic transplantable ascites guinea pig hepatocarcinoma led to a progressively growing 10 tumor. Tumor cells metastasized to the regional lymph node by 6–7 days after tumor implantation. Excision or irradiation of the tumor prevented tumor growth locally but did not prevent metastases from growing and killing the host. Specific immunization did not impair growth of established 10 tumors or growth of tumor in the draining lymph node. Inoculation of living bacillus Calmette-Guerin (BCG) organisms into established 10 tumors caused local tumor regression and prevented growth of tumor cells present in the regional lymph node. Intratumor (IT) injection of BCG led to complete tumor regression in 63% of guinea pigs with tumor nodules weighing 95 mg and in 16% of guinea pigs with tumor nodules weighing 425 mg. Guinea pigs treated by IT injection of BCG developed systemic tumor immunity; some animals rejected distant artificial metastases.