Intravesical treatment of bladder cancer with recombinant human interferon-beta. Intravesical GKT-beta Chemotherapy Research Group.

In order to examine its clinical efficacy, recombinant human interferon-beta (rIFN-beta) was instilled intravesically into 51 patients with superficial bladder cancer. Ten patients, who received intermittent intravesical instillation at a dose of (3-36) x 10(6) U rIFN-beta on days 1-3 every week, showed no response. Thirty-two patients received intravesical instillation at a dose of (3-36) x 10(6) U every day for 10-20 days. Eight patients showed partial response, indicating an efficacy rate of 25%. Nine patients received divided doses of 18 x 10(6) U twice a day every day for 10-20 days. Six patients showed partial response, indicating an efficacy rate of 67%. This value was significantly higher than that obtained by administering divided doses. The response to intravesical instillation therapy with rIFN-beta varies with treatment protocol. Frequent and longer exposure to rIFN-beta may induce better regression of superficial bladder cancer. Six incidences of side-effects were found in five cases (9.8%): pollakiuria in one, pain on micturition in two, fever in two, and eruption in one case. All of these side-effects were slight and reversible after drug withdrawal. Laboratory tests showed only a few changes with low severity. Thus, rIFN-beta is potentially a new drug for instillation therapy of superficial bladder cancer, in view of the absence of adverse effects.