Immunotherapy of Cancer with Nonliving BCG and Fractions Derived from Mycobacteria: Role of Cord Factor (Trehalose-6, 6'-Dimycolate) in Tumor Regression.

Delipidated and deproteinized cell walls from Mycobacterium tuberculosis H37Ra suspended in 1.25% mineral oil emulsion cured established tumors in the skin and metastases in draining lymph nodes of guinea pigs (strain 2) after intratumoral administration in 33% of the cases examined. This was increased to 83% when a mixture of cord factor and the delipidated cell walls was used. A similarly high percentage of cures was obtained after administration of lyophilized, killed BCG alone or with addition of cord factor in 1% mineral oil emulsion. Lyophilized, killed BCG dispersed in a solution of tocopherol acetate in peanut oil or in peanut oil alone showed a limited tumor-regressive activity (36%). However, a mixture of BCG and cord factor suspended in the above media cured 80 and 69% of the treated animals, respectively.