Two Cases Report of Successful Treatment of Refractory Mac Pulmonary Disease in Two Different Elderly Patients Using a Regimen Using a Drug with an Innovative Drug Delivery System, Liposomal Amikacin (ALIS), at Half the Standard Dose

Nontuberculous mycobacteria (NTM) is a general term for mycobacteria other than the Mycobacterium tuberculosis complex and Mycobacterium leprae. There are over 150 species of NTM, which are widely distributed not only in natural environments such as water systems and soil, but also in residential environments such as bathrooms. Inhalation exposure from these environments can lead to pulmonary NTM disease, a respiratory infection. In Japan, 90% of pulmonary NTM disease cases are caused by two species, Mycobacterium avium and M. intracellulare. Because the two species are biochemically similar, they are collectively referred to as Mycobacterium avium complex (MAC). Pulmonary MAC disease is broadly divided into two types: the fibrocavitary type and the nodular/bronchectamic type, each with its own characteristics. The two cases reported here were both elderly women with refractory MAC pulmonary disease, with different phenotypes: a fibrocavitary type and a long-standing, progressive nodular and bronchiectatic type. Treatment was performed with a regimen using liposomal amikacin (ALIS). ALIS is an aminoglycoside antibiotic that works by binding to bacterial liposomes and inhibiting protein synthesis. Using amikacin liposomal technology and a specialized inhaler, ALIS efficiently reaches alveolar macrophages, directly killing MAC bacteria within. However, the unique administration method, which requires inhaler cleaning, makes continued use difficult given the characteristics of patients with refractory MAC pulmonary disease. Even when treatment is possible, frequent side effects, such as hoarseness and dysphonia, while not severe, further contribute to the difficulty of initiating treatment. In both of these cases, treatment was made possible with the cooperation of the patient's family, and no adverse effects were observed. This is the first report in the world to show that the therapeutic effect was confirmed even when the number of treatments was less than half the standard number, and that thanks to the new drug delivery method of inhalation, it can become a new treatment option when existing drugs cannot be used or are ineffective for some reason, and that it may be safe to use even in elderly patients.