Nonspecific immunotherapy of malignant tumors.

At present, nonspecific immunotherapy of malignant tumors seems to be the most promising among immunotherapeutic modalities. Potent nonspecific immunostimulants, Bacillus Calmette-Guerin (BCG) and Corynebacterium parvum, exhibit an antitumor activity in experimental animals, which is commonly manifested by reduced tumor growth and sometimes by complete regression of tumors. Antitumor effectiveness of these bacteria is largely related to tumor immunogenicity and host immunocompetence. Recently, BCG has frequently been used for clinical immunotherapy and has provided therapeutic benefit in many instances, particularly when combined with chemotherapy, radiotherapy or surgery. Clinical experience with C. parvum is so far limited.