Quantitative comparison of BCG strains and preparations in immunotherapy of a rat sarcoma.

Ten preparations of BCG, six clinical vaccines, and four experimental preparations were compared for suppression of tumor growth by regional application. The preparations differed widely in their proportions of viable bacterial units and in bacterial unit:dry weight ratios. As assessed by their ability to suppress tumor development following direct admixtures with cell inocula of a rat sarcoma, one of the six clinical vaccines (Connaught) was significantly superior to Glaxo on any parameter (dry weight, No. of total units, or No. of viable units), immuno BCG Pasteur F was superior to Glaxo on two parameters (dry weight and No. of viable units), and Pasteur scarification was superior to Glaxo only on a viable unit basis. The Tice and Rijks Institute vaccines were not significantly different from Glaxo on any basis. Experimental vaccines from the Trudeau Mycobacterial Collection, stored as frozen liquid suspensions, showed a less marked variation in physical properties; here too, the Pasteur strain was superior to two other Trudeau preparations examined (Tice and Phipps). Viable organisms were not essential for tumor suppression, gamma-radiation-sterilized vaccine being equally effective. Tests with pulmonary tumor deposits, treated by iv BCG, and tests with pleural deposits, treated by intrapleural BCG, indicated that agents identified as superior in the subcutaneous screening system were also superior in the treatment of thoracic deposits.