Immunotherapy of murine transitional cell carcinoma

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Transitional cell carcinoma (TCC) is a significant challenge in urologic oncology.
• Nonspecific immunotherapies are explored for their potential in cancer treatment.
• Murine bladder tumor (MBT2) models provide a platform for evaluating novel therapeutic strategies.

Purpose of the Study:

• To evaluate the efficacy of various nonspecific immunotherapeutic agents against transplantable murine bladder tumor (MBT2).
• To determine the optimal dosage and strains of Bacillus Calmette-Guerin (BCG) for treating transitional cell carcinoma.
• To assess the development of long-term immunity following immunotherapy.

Main Methods:

• Six controlled experiments were conducted in C3H/He mice using an intradermal MBT2 inoculation.
• Immunotherapeutic agents included live BCG (Tice, Pasteur, Glaxo strains), Re mutant glycolipid (ReG), BCG cell wall skeletons (CWS), CWS plus B4, and Keyhole-Limpet Hemocyanin (KLH).
• Immunotherapy was administered intralesionally one day post-transplantation; tumors were excised, and animals were rechallenged, treated, and monitored for tumor incidence, growth rate, and survival.

Main Results:

• ReG, CWS, and CWS plus B4 showed no significant antitumor effect.
• Keyhole-Limpet Hemocyanin (KLH) demonstrated a measurable antitumor effect.
• Tice and Pasteur strains of live BCG, at doses of 5 X 10(5) to 1 X 10(7) colony forming units, induced statistically significant antitumor responses (p < 0.01), including prolonged survival and decreased tumor growth rate.
• Doses exceeding 1 X 10(7) colony forming units of BCG reduced the antitumor response.
• Glaxo strain BCG was ineffective at its maximal dose (10(6) colony forming units).
• Intermediate doses of live Tice or Pasteur BCG resulted in effective long-term immunity.

Conclusions:

• Live BCG, specifically the Tice and Pasteur strains, are the most effective agents identified for treating transitional cell carcinoma in this murine model.
• Optimal dosing is crucial, with intermediate doses of live BCG promoting significant antitumor activity and long-term immunity.
• While other immunotherapeutic agents have been investigated, live BCG strains offer a promising and effective approach for TCC treatment.