AR-501 (Panaecin)

Inhaled Gallium Citrate for Chronic Lung Infection in CF

AR-501 (Gallium Citrate): Novel anti-infective for the growing problem of antibiotic resistance

AR-501 is a novel small molecule anti-infective that diversifies our mAb immunotherapy-focused product portfolio. AR-501 is an inhalable form of gallium citrate, which acts as an iron analog to starve bacteria of iron. Gallium is believed to inhibit multiple iron-dependent synthetic and metabolic pathways required for pathogenicity.

As with our monoclonal antibody programs, the mechanism of action of AR-501 is different from all antibiotics, and is effective against antibiotic resistant bacteria.

AR-501 has broad anti-bacterial activity against Gram-negative and Gram-positive bacteria in vitro, including antibiotic-resistant strains. AR-501’s inhibitory activity reaches bacteria growing in mature biofilms and prevents biofilm formation in viro. In mouse models of bacterial lung infections, a single inhalation exposure of aerosolized AR-501 protected the animal from morbidity and mortality. AR-501 was also protective when used in combination with antibiotics.


AR-501 is being developed as an inhaled treatment for the treatment of life-threatening bacterial lung infections in patients with cystic fibrosis (CF).

Intravenously administered gallium was found to be safe and efficacious in a recent Phase 2 clinical trial involving cystic fibrosis patients (the study was conducted by Univ. of Washington). However, intravenous formulation of gallium involves a 5-day continuous infusion, which is a demanding treatment regimen for the patients. AR-501’s inhaled dosage form can be self-administered within minutes, designed to be given once weekly, and allows for direct delivery of gallium to the lungs where the infections reside.

It is currently being evaluated in a Phase 1/2a clinical study in healthy adult volunteers and cystic fibrosis adult patients.