A randomized controlled study of intravesical alpha-2b-interferon in carcinoma in situ of the bladder.

We treated 87 patients with carcinoma in situ of the bladder in a prospective randomized trial of 2 dose levels of intravesically administered alpha-2b-interferon. Patients received either low dose (10 million units) or high dose (100 million units) recombinant alpha-2b-interferon weekly for 12 weeks and then monthly for a maximum of 1 year. Of the 47 high and 38 low dose patients 20 (43%) and 2 (5%), respectively, achieved a complete response. Additionally, partial responses (cytology results positive with no histological evidence of carcinoma in situ) were noted in 23% of the high dose group. Notably, 6 of 9 patients who had failed prior intravesical bacillus Calmette-Guerin therapy responded to alpha-2b-interferon treatment. Preliminary assessment has shown that among the complete responders 18 of 20 (90%) in the high dose group have maintained responses for at least 6 months after the completion of treatment (10 for more than 12 months). Seven patients in each treatment group have undergone radical cystectomy. All 14 patients had progressive disease except 1 who chose cystectomy although she was still responding to treatment. The median intervals from initial treatment to cystectomy were 18 and 32 weeks in the low and high dose groups, respectively. Local irritation or toxicity did not occur and other adverse effects were rare except for mild to moderate flu-like symptoms (8% in the low dose and 17% in the high dose groups). No patient discontinued therapy due to treatment-related adverse effects. Intravesical alpha-2b-interferon demonstrated a high level of activity in the treatment of carcinoma in situ of the bladder with the 100 million unit dose producing a significantly greater response rate (43% complete response, p less than 0.0001) than the low dose (5% complete response). Safety and tolerance were excellent with no local irritative toxicity.