A Randomized, Placebo-Controlled, Dose-Escalation, Phase 1 Study of the Safety and Pharmacokinetics of Amphotericin B Inhalation Powder in Healthy Subjects.

Nektar is developing Amphotericin B Inhalation Powder (ABIP; NKTR-024) to prevent invasive pulmonary fungal infections in immunocompromised patients. NKTR-024 is a proprietary dry-powder amphotericin B (AmB) formulation that is delivered to the patient’s respiratory tract with a proprietary breath-actuated inhalation device (T-326). This study assessed 1) the safety and tolerability and 2) the pharmacokinetics (PK) of AmB in epithelial lining fluid (ELF) and plasma after a loading dose (LD) and 4 weekly maintenance doses (MD) of NKTR-024 in healthy subjects. Thirty-six (36) subjects enrolled in a single center in the US into 2 cohorts 2:1 to receive either NKTR-024 (n=12) or a matching (powder load) placebo inhalation powder (n=6), respectively. Subjects in Cohort 1 (Coh1) received a 25-mg LD and 4 weekly 5-mg MD (25/5) and subjects in Cohort 2 (Coh2) received a 50-mg LD and 4 weekly 10-mg MD (50/10) of NKTR-024 or placebo, respectively. PK assessments used blood [plasma] and bronchoalveolar lavage (BAL) [ELF] samples. Concomitant medications, adverse events (AEs) and other safety parameters were monitored for 17 wk (screening period of up to 28 d, a 4-wk treatment period, and a 9-wk post-treatment period). All 36 subjects received 1 LD and 4 MDs. Subjects were mostly male (n=24, 66.7%) and Caucasian (n=27, 75%). Mean age=28.1 yr, median height=175.3 cm and median weight=77.4 kg. PK data have been previously presented and will not serve as the focus of this abstract. Maximal plasma AmB concentrations occurred at ∼8–12 hr postdose following a ∼1 hr postdose lag. Plasma AmB concentrations ( 20% temporally related to bronchoscopy. Repeated administration of NKTR-024 resulted in high pulmonary and low systemic AmB exposure. Plasma AmB concentrations were well below those associated with renal toxicity; this observation supports an important potential benefit of the NKTR-024 investigational product. Constitutional symptoms and electrolyte abnormalities traditionally seen with systemic administration of AmB were essentially spared.