Intravesical interleukin-2 in T1 papillary bladder carcinoma: Regression of marker lesion in 8 of 10 patients

Purpose: We evaluate the therapeutic effect of intravesical interleukin-2 (IL-2) on T1 papillary bladder carcinoma after incomplete transurethral resection. Materials and Methods: After incomplete transurethral resection we treated 10 patients in whom the marker lesion was left in place with 3 x 10(6) Chiron units IL-2 in 50 mi. saline plus 0.1% human serum albumin. The solution remained in the bladder for 2 hours and it was instilled on 5 consecutive days. The effect of IL-2 treatment on the marker lesion was evaluated by cystoscopy and repeat biopsy of the marker site 2 months after treatment. In addition, the effect on the recurrence of bladder tumors was studied. Results: At 2 months 8 of the 10 marker lesions (80%) had completely regressed and there were no tumor cells on repeat biopsy. Four patients remained tumor-free after 30 to 54 months. We noted no toxic effects. In 1 patient with a 7-year history of bladder cancer the marker was only partially regressed after 2 months. After removal of the marker this patient remained tumor-free at a followup of 54 months. Conclusions: To our knowledge this report represents the first study of the effect of IL-2 on marker lesions left in place after transurethral resection. The results indicate that IL-2 instillations are feasible, and the combination of transurethral resection and IL-2 instillation may have a powerful antitumor effect. The therapeutic effects may not simply be due to intravesical IL-2, because previous transurethral resection probably caused some influx of infiltrating cells and the marker may have had tumor associated antigens. Consequently these effects may be due to the interaction of tumor associated antigens, infiltrating cells and IL-2.