Synergistic tumor regressive activity observed following treatment of line-10 hepatocellular carcinomas with deproteinized BCG cell walls and mutant Salmonella typhimurium glycolipid

Summary Synergistic tumor-regressive activity was observed when the water-soluble portion of a phenol-water extract from mutant Salmonella typhimurium whole cells was combined with deproteinized cell walls from Mycobacterium bovis strain BCG. As little as 50 g deproteinized cell walls combined with 50 g water-soluble extract from the mutant salmonella produced 89–100% cures of line-10 dermal tumors in treated strain 2 guinea-pigs. However, none of the animals was cured following treatment with 50 g of deproteinized cell walls alone. Only 17% of treated animals were cured following treatment with 50 g of the water-soluble extract from the mutant salmonella. The deproteinized cell walls and water-soluble extract were suspended in oil-in-water emulsions and injected directly into 10 mm tumors. The deproteinized cell walls were prepared by treating BCG cell walls with proteolytic enzymes and denaturing agents (KCl, urea, Triton X-100, and guanidine hydrochloride). Urea or a combination of denaturing agents reduced the protein content of protease-treated cell walls from approximately 2% (w/w) protein to 0.7% protein. The antigenicity of the effectively deproteinized cell walls, as measured by skin testing in presensitized guinea-pigs, was reduced approximately ten-fold compared with untreated cell walls. Injection to mice of 500 g deproteinized cell walls in combination with 500 g water-soluble extract from the mutant salmonella produced transient, clinical signs of toxicity (malaise, conjunctivitis, diarrhea, and rough hair coats) lasting approximately 5 days. However, no deaths were observed. The synergistic antitumor effect of combining deproteinized BCG cell walls with the water-soluble extract from mutant salmonella may be useful for treatment of certain cases of spontaneous neoplastic disease.