Predicting the Immune Response Following Intravesical BCG; is it Possible?

Objective: To demonstrate and quantify the immune response changes over time in patients with Non-muscleinvasive Bladder Cancer (NMIBC) treated with bacillus Calmette-Guerin (BCG).Methods: The study enrolled 52 patients. Group A included 32 patients with high risk and intermediate risk NMIBC treated with TURBT and intravesical BCG. Group B included 20 patients underwent cystoscopy for other indications. Monitoring immune changes was done by quantifying the percentage of T lymphocytes in urine samples taken before BCG therapy, immediately after BCG therapy and 3 months later. Patients in Group A were followed for 1 year and the clinical outcome was correlated to the level of the immune response.Results: In the initial urine samples taken before BCG therapy the mean flowcytometeric percentages of the T lymphocytes were comparable in both groups. Six weeks after BCG therapy, Group A revealed a significantly elevated mean flowcytometeric measurement 53.3% which dropped after 3 months to 22.4% but still significantly more than that of Group B (which did not show a significant rise after 6 weeks and after 3 months). Out of the 32 patients in Group A, 25 patients (78%) revealed significantly elevated flowcytometeric measurements after BCG therapy in comparison to the mean percentage of the control group (strong responders), while 7 patients (22%) revealed minimally elevated measurements (weak responders). Three cases from the strong responders group (12%) had tumor recurrence during follow up period compared to 3 cases (43%) from the weak responders.Conclusion: Flowcytometery is a feasible method for monitoring the BCG immune response by measuring the percentage of T lymphocytes in urine.