Omadacycline pharmacokinetics/pharmacodynamics in the hollow fiber model and clinical validation of efficacy to treat pulmonary Mycobacterium abscessus disease

Background: Guideline-based therapy (GBT) for pulmonary Mycobacterium abscessus (Mab) disease achieves sustained sputum culture conversion (SSCC) rates of 30%; this is reflected by poor efficacy of GBT in the hollow fiber system model of Mab (HFS-Mab), which killed ∼1.22 log₁₀ CFU/mL. This study was performed to determine which clinical dose of omadacycline, a tetracycline antibiotic, should be used in combination therapy to treat pulmonary Mab disease for relapse-free cure. Methods: First, omadacycline intrapulmonary concentration-time profiles of seven daily doses were mimicked in the HFS-Mab model and exposures associated with optimal efficacy were identified. Second, 10,000 subject Monte-Carlo simulations were performed to determine whether oral omadacycline 300 mg/day achieved these optimal exposures. Third, a retrospective clinical study on omadacycline vs. primarily tigecycline-based salvage therapy was conducted to assess rates of SSCC and toxicity. Fourth, a single patient was recruited to validate the findings. Results: Omadacycline efficacy in the HFS-Mab was 2.09 log₁₀ CFU/mL at exposures achieved in >99% of patients on 300 mg/day omadacycline. In the retrospective study of omadacycline 300 mg/day-based combinations vs. comparators, SSCC was achieved in 8/10 vs. 1/9 (P=0.006), symptom improvement in 8/8 vs. 5/9 (P=0.033), toxicity in 0 vs. 9/9 (P<0.001), and therapy discontinuation due to toxicity in 0 vs. 3/9 (P<0.001) cases, respectively. In one prospectively recruited patient, omadacycline 300 mg/day salvage therapy achieved SSCC and symptom-resolution in 3 months. Conclusion: Based on the preclinical and clinical data, omadacycline 300 mg/day in combination regimens could be appropriate for testing in Phase III trials in patients with Mab pulmonary disease.