Therapy in an intracerebral murine glioma model, using Bacillus Calmette-Guérin, neuraminidase-treated tumor cells, and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea.

The s.c.-propagated murine glioma, GL-26, was established in tissue culture. The tissue culture line, with a doubling time of 36 hr, was used as the common source for all tumor cells. Suspensions of the tumor cells were transplanted intracerebrally in mice to produce an anaplastic ependymoblastoma. In vitro 51-Cr cytotoxicity assays did not detect any cellular immunity against GL-26 tumor cells in animals bearing either s.c. or i.c. tumors, indicating that the tumor itself is not highly immunogenic. Howeveer,significant cellular cytotoxicity was elicited in non-tumor-bearing animals by immunization with Vibrio cholerae neuramini-animals by immunization with Vibrio cholerae neuraminidase and mitomycin C-treated tumor cells plus complete Freund's adjuvant. In vivo therapy studies revealed significant increases in survival of animals preimmunized with V. cholerae neuraminidase- and mitomycin C-treated cells plus complete Freund's adjuvant. 1(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea, when given i.p. on Day 3 or 12 after tumor challenge, also resulted in significant increases in survival. Furthermore, the effects of 1-(2-chloroethyl)- 3-cyclohexyl-1-nitrosourea and preimmunization were additive, with significanchloroethyl)-3-cyclohexyl-1-nitrosourea. In contrast to results reported for several extracranial tumor systems, immunotherapy, using either V.cholerae neuraminidase- and mitomycin-treated tumor cells, Bacillus Calmette-Guerin, or both, beginning 3 0r 4 days after tumor challenge, did not produce any significant increases in survival.