Efficacy of mycobacterium phlei cell wall-nucleic acid complex (MCNA) in BCG-unresponsive patients.

Abstract

342 Background: Previously, we reported the results of a single-armed, multi-institutional study on the efficacy of MCNA in patients who failed intravesical BCG treatment. Since that publication, a new standardized definition for BCG-unresponsiveness has been established. We re-analyzed the oncologic outcomes following intravesical MCNA in patients classified as BCG-unresponsive according to the new definition. Methods: Patients with recurring high grade NMIBC after intravesical BCG were enrolled. For this analysis, we focused on the patients satisfying the minimum criterion for adequate BCG treatment (5/6 induction and 2/3 maintenance). Treatment course included 6 weekly intravesical instillations of 8mg MCNA followed by 3 weekly instillations at months 3, 6, 12, 18, and 24. Followup assessments included cystoscopy, urine cytology and biopsy. Patients absent of high grade disease confirmed by central review of biopsy were deemed disease-free. Results: Of the 129 patients enrolled, 94 (68 CIS with/without papillary tumors, 26 papillary only tumors) fit the criteria for the new BCG-unresponsive definition. In the group with papillary tumors, DFS measured at months 6, 12, and 24 were 61.2%(38.2-77.8%), 61.2(38.2-77.8%), and 50.1%(27.5-69%). In the CIS-containing group, the corresponding DFS were 44.8%(32.3-56.4%), 26.5%(16.3-37.9%), and 16.6%(8.6-26.9%), respectively. Conclusions: Intravesical MCNA therapy has the potential to offer 26.5% of patients with CIS and 61.2% of patients with papillary tumors a chance to safely preserve their bladder for at least 1 year. The efficacy in BCG-unresponsive patients was higher than that reported with all-comers, suggesting that adequate priming with BCG might be required for further immune-based response.