To provide information about chronic dosing of ARIKAYCE to another animal species, a 9-month inhalation toxicology study was conducted in dogs. Foamy alveolar macrophages associated with clearance of the inhaled product were present at dose-related incidence and severity, but they were not associated with inflammation, tissue hyperplasia, or the presence of preneoplastic or neoplastic changes. Dogs were exposed to ARIKAYCE for up to 90 minutes per day, providing inhaled amikacin doses of approximately 5, 10, and 30 mg/kg/day.
Trial 1 (NCT#02344004) was an open-label, randomized (2:1), multi-center trial in patients with refractory Mycobacterium avium complex (MAC) lung disease as confirmed by at least 2 sputum culture results. Patients were considered to have refractory MAC lung disease if they did not achieve negative sputum cultures after a minimum duration of 6 consecutive months of background regimen therapy that was either ongoing or stopped no more than 12 months before the screening visit. Patients were randomized to either ARIKAYCE plus a background regimen or background regimen alone. The surrogate endpoint for assessing efficacy was based on achieving culture conversion (3 consecutive monthly negative sputum cultures) by Month 6. The date of conversion was defined as the date of the first of the 3 negative monthly cultures, which had to be achieved by Month 4 in order to meet the endpoint by Month 6. Patients who achieved culture conversion by Month 6 were continued on study drug (ARIKAYCE plus background regimen or background regimen alone based on their randomization) for a total of 12 months after the first negative sputum culture.
A total of 336 patients were randomized (ARIKAYCE plus background regimen, n=224; background regimen alone, n=112) (ITT population), with a mean age of 64.7 years and there was a higher percentage of females (69.3%) than males (30.7%) in the study. At the time of enrollment, of the 336 subjects in the ITT population, 302 (89.9%) were either on a guideline-based regimen for MAC or off guideline-based therapy for MAC for less than 3 months while 34 (10.1%) were off treatment for 3 to 12 months prior to enrollment. At screening, patients were stratified by smoking status (current smoker or not) and by whether patients were on treatment or off treatment for at least 3 months. Most patients at screening were not current smokers (89.3%) and had underlying bronchiectasis (62.5%). At baseline, 329 patients were on a multidrug background regimen that included a macrolide (93.3%), a rifamycin (86.3%), or ethambutol (81.4%). Overall, 55.6% of subjects were receiving a triple-drug background regimen consisting of a macrolide, a rifamycin and ethambutol.
The proportion of patients achieving culture conversion (3 consecutive monthly negative sputum cultures) by Month 6 was significantly (p<0.0001) greater for ARIKAYCE plus background regimen (65/224, 29.0%) compared to background regimen alone (10/112, 8.9%). Of those receiving ARIKAYCE plus background regimen, 18.3% (41/224) achieved culture conversion by Month 6 and sustained sputum culture conversion (defined as consecutive negative sputum cultures with no positive culture on solid media or no more than 2 consecutive positive cultures on liquid media following culture conversion) for up to 12 months of treatment after the first culture that defined culture conversion, compared to 2.7% (3/112) of patients receiving background regimen alone (p<0.0001). At 3 months after the completion of treatment, 16.1% (36/224) of patients who had received ARIKAYCE plus background regimen maintained durable culture conversion, compared to 0% of patients who had received background regimen alone (p<0.0001).
In Trial 1, 23/224 (10.3%) of patients had MAC isolates that developed MIC of > 64 mcg/mL while receiving treatment with ARIKAYCE. In the background regimen alone arm, 4/112 (3.6%) of patients had MAC isolates that developed amikacin MIC of > 64 mcg/mL.
Additional endpoints to assess the clinical benefit of ARIKAYCE, for example, change from baseline in six-minute walk test distance and the Saint George's Respiratory Questionnaire, did not demonstrate clinical benefit by Month 6.