B69-19 Evaluating the Role of Clofazimine in Pulmonary NTM Disease: A Retrospective Analysis of Clinical Outcomes and Adverse Effects in the US Bronchiectasis and NTM Research Registry

Abstract Introduction Nontuberculous mycobacterial (NTM) pulmonary infections are difficult to treat due to the need for prolonged antibiotic regimens with multiple potential adverse effects. Clofazimine, an oral antimycobacterial agent, has been increasingly used as part of multidrug regimens in cases of refractory disease, drug resistance or intolerance. This study aims to evaluate the use of clofazimine as a component of NTM pulmonary disease treatment. Methods We conducted a cross-sectional, retrospective analysis of baseline data from patients with physician-reported NTM diagnoses enrolled in the US Bronchiectasis and NTM Research Registry (BRR). Patients not receiving NTM treatment during the baseline period were excluded, with baseline defined as the 2-year period prior to enrollment. Patients were grouped by treatment regimen: clofazimine-containing vs. non-clofazimine-containing. Patient clinical characteristics, culture results and susceptibility, treatment regimens, and treatment outcomes were summarized. Group differences were assessed using Wilcoxon-Mann-Whitney U tests for continuous variables and Chi-square or Fisher’s exact tests for categorical variables. Results 2,179 patients with NTM pulmonary disease receiving treatment were identified. 309 patients (14.2%) received a clofazimine-containing regimen, while 1,870 patients (85.8%) were treated with a non-clofazimine-containing regimen.Compared to patients on non-clofazimine regimens, those receiving clofazimine had lower median FEV1% predicted (67% [IQR 54–83] vs. 75% [IQR 60–90], p < 0.001), greater lobar involvement (median 4 lobes [IQR 2–6] vs. 3 lobes [IQR 2–6], p < 0.001), lower BMI and more reported symptoms. Clofazimine use was more prevalent among patients with drug-resistant NTM (Table 1). Adverse events and drug intolerance were reported in 48.8% of patients receiving clofazimine, a proportion similar to that observed with macrolides, ethambutol, and rifampin. Patients on clofazimine-containing regimens were more likely to remain culture-positive beyond 6 months of therapy (31.3% vs. 16.7%, p < 0.001) and less likely to achieve culture negativity for at least 12 months while on treatment (13.1% vs. 25.8%, p < 0.001). However, there was no significant difference in NTM disease recurrence between the two groups. Conclusion Although patients receiving clofazimine-containing regimens for NTM pulmonary infection were less likely to achieve culture conversion at 6 months and maintain culture negativity for 12 months on therapy, these findings are likely attributable to greater disease severity and higher prevalence of drug-resistant infections. The uneven sample sizes may limit the robustness of these conclusions. Reassuringly, recurrence rates did not differ between groups, and clofazimine demonstrated a comparable tolerability profile to that of other commonly used agents for NTM pulmonary infections. This abstract is funded by: None