Multi-Perspective Tolerance Evaluation of Bacillus Calmette-Guerin with Interferon in the Treatment of Non-Muscle Invasive Bladder Cancer

Background: Bacillus Calmette-Guerin (BCG) toxicities have been reported but with relative agranularity regarding severity and temporal changes during therapy. In its most severe form, BCG intolerance remains poorly understood and exploring ways to optimize toleration of the most effective treatment (BCG) is prudent. Objective: To report the results of both patient- and physician-centered metrics of BCG toxicity as part of the National Phase II BCG/Interferon (IFN) study, as well as the efficacy of low-dose BCG/IFN for previously deemed BCG intolerant patients. Methods: Patients were treated with 6 weekly treatments of BCG (various dosing based on prior BCG exposure) with 50 million units of IFN. BCG intolerance was strictly defined. Maintenance BCG was instituted if disease free. Treatment tolerance during induction was measured using physician- and patient-completed evaluations. Linear mixed effects regression was used to evaluate differences. Results: 533 BCG naive, 415 BCG failure, and 37 BCG intolerant patients were enrolled. There was no significant difference in quality of life scores between groups (p = 0.70). A predictable temporal toxicity pattern was identified in all groups with symptom resolution by day 2-3. Despite BCG intolerant patients having significantly worse bladder pain/spasms and cystitis, treatment discontinuation was under 4%. Recurrence-free survival was similar between naive and intolerant patients. Conclusions: BCG toxicity is common and follows a predictable pattern. While at slightly increased risk of toxicity, BCG intolerant patients may be managed successfully with 1/10th dose BCG with IFN.