Inhaled liposomal amikacin is an investigational liposomal formulation of the antibiotic amikacin. It is being assessed as a treatment for lung infections caused by nontuberculous mycobacteria (NTM), including in patients with cystic fibrosis (CF). Amikacin is currently approved for intravenous or intramuscular use to treat serious bacterial infections.
How inhaled liposomal amikacin works
Liposomes are microscopic spheres that contain water. In liposome drug delivery systems, water-soluble substances, such as amikacin, are contained inside those spheres. The goal of inhaled liposomal amikacin is to deliver the treatment directly to the site of the lung infection.
NTM invade macrophages and multiply, resulting in lung infections. When amikacin non-liposomal is inhaled, it does not achieve the same level of intracellular delivery as does liposomal amikacin.
Moreover, because the bacteria produce negatively charged materials to protect themselves, and antibiotics such as amikacin are positively charged, the two essentially cancel one another. The antibiotic cannot reach the spaces where the bacteria are multiplying.
Insmed, the company developing the treatment, reports that the liposomal packaging of amikacin, which goes by the trade name Arikayce, allows it to be delivered to the macrophages at what is believed to be high concentrations. In other words, the particle nature of the liposomes could be the key to its effectiveness.
A Phase 2 trial (NCT01315236) for treating NTM with Arikayce was undertaken in patients with nontuberculous mycobacterial lung infections. Results reported in 2014 show the treatment did not reach its primary endpoint, or goal, of a change in mycobacterial density on a seven-point scale from baseline, or the study’s start. But a key secondary goal, that of culture conversion to negative, did reach statistical significance, with 11 of 44 patients given Arikayce (590 mg once daily) plus standard care demonstrating negative cultures by day 84, compared to three of 45 patients on placebo plus standard care.
An open-label Phase 3 clinical trial (NCT02344004) in people with NTM lung infections is now underway worldwide (with multiple sites in the U.S., U.K., Europe, Canada and parts of Asia), and enrolling participants. Its primary goal is culture conversion brought about by treatment with liposomal amikacin for inhalation (LAI) plus standard care. As an open-label study, it has no placebo arm.
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