SAN DIEGO, May 11, 2026
aTyr Pharma announced a major regulatory and clinical development update for its lead investigational therapy efzofitimod following a recent FDA Type C meeting focused on the future development pathway for pulmonary sarcoidosis. The company confirmed plans to continue advancing efzofitimod into a new global Phase 3 clinical study targeting patients with chronic symptomatic pulmonary sarcoidosis associated with restrictive lung disease, incorporating direct feedback received from the U.S. Food and Drug Administration. The planned study will utilize forced vital capacity (FVC) as the primary endpoint and the King’s Sarcoidosis Questionnaire-Lung (KSQ-Lung) score as the key secondary endpoint, aligning with the FDA’s position that these measurements most accurately reflect how pulmonary sarcoidosis patients function and feel clinically. aTyr stated that the company intends to submit an Investigational New Drug (IND) application in June 2026 to initiate the next-stage registrational study for efzofitimod, which remains one of the company’s most advanced fibrosis and inflammation-focused biologic programs. The regulatory update follows review of data generated from the previous Phase 3 EFZO-FIT™ study, where patients with more severe restrictive lung disease demonstrated clinically meaningful improvements in lung function compared with placebo.
FDA Feedback Defines New Phase 3 Development Strategy
According to aTyr, discussions with the FDA provided a clearer regulatory framework for advancing efzofitimod toward potential future approval in pulmonary sarcoidosis, a major subtype of interstitial lung disease (ILD). The company stated that the FDA identified FVC as a direct functional measurement capable of demonstrating meaningful clinical benefit in pulmonary sarcoidosis patients, leading aTyr to prioritize it as the primary endpoint for the next study. The KSQ-Lung score will serve as the key secondary endpoint to measure patient-reported symptom improvement and quality-of-life outcomes.
Management emphasized that the decision was also supported by positive subgroup findings observed in EFZO-FIT™, where patients with baseline FVC values of 80% or lower experienced encouraging lung function improvements following efzofitimod treatment. In addition to regulatory endpoint alignment, the company also plans to increase dosing frequency from once every four weeks to once every three weeks in an effort to improve therapeutic exposure while maintaining the favorable safety profile observed across prior studies. aTyr stated that enhanced monitoring and additional risk mitigation strategies will be incorporated into the updated clinical design.
Global Phase 3 Trial Targets Moderate-to-Severe Disease Population
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The upcoming study is expected to be a global, randomized, double-blind, placebo-controlled Phase 3 trial enrolling approximately 372 patients diagnosed with moderate-to-severe pulmonary sarcoidosis and restrictive lung disease. Patients participating in the study are expected to remain on stable background corticosteroid or immunosuppressive therapy throughout the trial duration. The 54-week study will evaluate intravenous administration of 5.0 mg/kg efzofitimod or placebo once every three weeks across two parallel treatment cohorts.
The primary objective will measure change from baseline in lung function using FVC at Week 48, while secondary analyses will evaluate improvements in patient-reported respiratory symptoms and daily functional outcomes using KSQ-Lung scoring. aTyr believes the refined patient selection strategy and updated endpoint structure could strengthen the clinical relevance of the program while potentially improving the probability of regulatory success. Company executives stated that pulmonary sarcoidosis continues to represent a major unmet medical need due to limited treatment options and significant long-term toxicity associated with chronic corticosteroid use.
Efzofitimod Expands aTyr’s Fibrosis and Inflammation Pipeline
Efzofitimod is a first-in-class biologic immunomodulator derived from aTyr’s proprietary tRNA synthetase platform, which is designed to identify novel signaling pathways associated with fibrosis and immune-mediated inflammatory diseases. The therapy selectively targets activated myeloid cells through the neuropilin-2 pathway with the goal of reducing inflammation without broadly suppressing the immune system. Beyond pulmonary sarcoidosis, efzofitimod is also currently being evaluated in the Phase 2 EFZO-CONNECT™ study for systemic sclerosis-associated interstitial lung disease.
aTyr believes the therapy’s differentiated mechanism of action may provide a safer long-term treatment approach for patients suffering from chronic inflammatory lung disorders where current therapeutic options remain limited. The company continues positioning efzofitimod as a potential disease-modifying therapy capable of improving lung function while addressing the underlying inflammatory drivers associated with progressive fibrosis and pulmonary deterioration.
Source: aTyr Pharma press release
