A98-06 Standardized Clofazimine-based Regimens Have Moderate Microbiological Outcomes in Mycobacterium Avium Complex Pulmonary Disease

Abstract Background As the role of rifampicin has become controversial, clofazimine is increasingly used for the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD). We evaluated culture conversion and microbiological cure in MAC-PD patients treated with clofazimine-containing regimens at a Dutch tertiary care center. Methods Single-centre retrospective cohort study of adults with macrolide-susceptible MAC-PD who initiated treatment with clofazimine as part of either a standard ethambutol-macrolide regimen or an intensified multidrug regimen, typically containing intravenous amikacin, between 2021 and 2024. The primary outcome was sputum culture conversion within six months; the secondary outcome was microbiological cure at end of treatment. Results Forty-six patients with MAC-PD treated with clofazimine-containing regimens were included. Nineteen received standard triple therapy, 27 received intensified regimens with more than three agents. A clofazimine loading phase was used in 84.8% of patients, usually 4-6 weeks. Culture conversion within six months was achieved in 25 patients (54.3%), and microbiological cure in 19 (41.3%). Conversion rates were similar between the 3-drug regimen group and intensified regimen group (52.6% vs 55.6%, p = 0.919). In the 3-drug regimen group, conversion occurred in 9 of 14 (64.3%) patients with nodular-bronchiectatic disease and 1 of 5 (20.0%) with fibro-cavitary disease. In the intensified group, 8 of 9 (88.9%) patients with nodular-bronchiectatic disease and 7 of 18 (38.9%) with fibro-cavitary disease converted within six months. In univariate analysis, only nodular-bronchiectatic disease was significantly associated with culture conversion (aOR, 8.32 [95% CI, 1.50-46.00], p = 0.015). Multivariate analysis did not identify predictors for microbiological cure. Conclusion Clofazimine-containing regimens achieved moderate culture conversion and microbiological cure rates in patients with MAC-PD. These findings support its use as an antimycobacterial agent, both as an alternative to rifampicin and as an adjunct in intensified treatment regimens. Further regimen optimisation is needed to improve outcomes. Optimizing clofazimine maintenance dosing could be a first step. Funding source: no external funding was obtained for this study. Table 1: Baseline characteristics of all patients, stratified by treatment Data are presented as number (percentage) or median (interquartile range). ALIS = amikacin liposome inhalation suspension. This abstract is funded by: None