Aridis Pharmaceuticals, Inc. announced positive feedback from the FDA on the Company's proposed single confirmatory Phase 3 study of investigational monoclonal antibody candidate AR-301, which is being developed as an adjunctive therapy in combination with standard of care (SOC) antibiotics for the treatment of pneumonia caused by Gram-positive bacteria Staphylococcus aureus (S. aureus) in mechanically ventilated hospitalized patients. Key agreements with FDA: FDA agreed on the design of the single confirmatory Phase 3 superiority study required to support the submission of a Biologics License Application (BLA). FDA agreed to the proposed expansion of the confirmatory Phase 3 study in S. aureus ventilator associated pneumonia (VAP) patients to include ventilated hospital acquired pneumonia (HAP) and ventilated community acquired pneumonia (CAP) patients.

The clinical efficacy endpoint will be the same endpoint of Clinical Cure of pneumonia on Day 21 used in the previous Phase 3 superiority trial AR-301-002. However, the primary efficacy endpoint will be in older adults =65 years of age - given that the absolute efficacy in the AR-301-002 Phase 3 study was higher in older adults than the overall population, i.e., +34% improvement on Day 21 (p= 0.057) and by +38% on Day 28 (p= 0.025) in older adults versus +11% improvement (p=0.24) in the overall population. The confirmatory AR-301-003 Phase 3 superiority study will be powered for efficacy in both the primary efficacy endpoint in adults =65 years of age, and for the key secondary efficacy endpoint in all study subjects (>=65 and subjects (>=65 and the primary efficacy endpoint.