Aridis, FDA Agree to Simplify AR-501 Trial Design Based on Positive Safety Data

The U.S. Food and Drug Administration (FDA) has agreed to simplify Aridis Pharmaceuticals‘ planned Phase 2 trial of AR-501, an investigational inhaled treatment for chronic lung infections in patients with cystic fibrosis (CF).

The decision was based on positive safety data from a Phase 1 trial in healthy adults.

“The change to an adaptive style clinical trial design is an important milestone for the AR-501 program as it streamlines the regulatory pathway, expedites program timeline, and maximizes overall resources,” Vu Truong, PhD, CEO of Aridis, the candidate therapy’s developer, said in a press release.

Volunteers in that Phase 1 trial (NCT03669614) received either a single ascending dose (SAD) or a multiple ascending dose (MAD) regimen. Both were found to be safe and well-tolerated.

Based on the trial’s results, the FDA has agreed to remove the SAD regimen from the Phase 2 trial and only conduct a MAD regimen.

The FDA also agreed to allow the company to expand its originally planned Phase 2a study design into a combined Phase 2a/2b study.

The combined design will help the study progress more fluidly from one phase to the next, using the same clinical trial protocol. Data from the Phase 2a portion will be used to inform decisions regarding the doses to be given and the number of participants to recruit to achieve meaningful efficacy data in Phase 2b.

“We look forward to initiating the Phase 2a trial in the coming months and anticipate completing the study towards the end of 2021,” Truong said.

AR-501 is an inhaled formulation of gallium citrate. It is intended to be self-administered on a weekly basis with the help of a hand-held nebulizer that delivers the medication directly to the lungs.

Gallium is an antimicrobial small molecule that closely resembles iron. It binds to iron receptors on bacterial cells and disrupts many of their iron-dependent processes, some of which microbes rely upon for infection and antibiotic resistance.

AR-501 has demonstrated effectiveness against a wide range of bacteria in pre-clinical studies, including antibiotic-resistant strains. Further, it can improve the efficacy of multiple antibiotics and few bacteria have demonstrated resistance to it.

The potential therapy has been granted orphan drug designations in the U.S. and the EU, and has received fast track and qualified infectious diseases product designations from the FDA for the treatment of lung infections in CF patients. Fast track is a process designed to speed the development of treatments that fill an unmet medical need for a serious condition, so as to get new medicines to patients more quickly.