aTyr Pharma secures FDA alignment on efzofitimod Phase 3 design
aTyr Pharma has announced that it has reached agreement with the US Food and Drug Administration on the protocol for a Phase 3 trial of efzofitimod, its lead biologic candidate, in patients with chronic, symptomatic pulmonary sarcoidosis accompanied by restrictive lung disease. The San Diego-based company expects to begin study-related activities before the end of 2026 and will pursue regulatory submissions in both the US and Europe in parallel.
The announcement represents a material step forward for aTyr's development programme. FDA alignment on a Phase 3 protocol is a significant de-risking event, reducing the likelihood of costly redesigns later and giving the company a clearer path toward a potential new drug application.
Study design and endpoints
The planned trial is a global, randomised, double-blind, placebo-controlled study expected to enrol approximately 372 patients. Participants will receive either 5.0 mg/kg efzofitimod or placebo administered intravenously once every three weeks over 54 weeks, totalling 17 doses. The primary endpoint is change from baseline in forced vital capacity (FVC) at week 48, a standard lung-function measure in interstitial lung disease trials. The key secondary endpoint is change in the King's Sarcoidosis Questionnaire Lung score, a patient-reported outcome tool, at the same timepoint.
The design was informed by a subgroup analysis from aTyr's earlier Phase 3 EFZO-FIT study. That analysis identified a clinically meaningful FVC benefit in patients with restrictive lung disease, defined as FVC percent predicted at or below 80% with a normal FEV1/FVC ratio, treated with the 5.0 mg/kg dose. Results were presented at the World Association of Sarcoidosis and Other Granulomatous Disorders Congress earlier in 2026. By narrowing the target population to this subgroup, aTyr is concentrating on the patients most likely to show a measurable treatment effect, a strategy that can improve signal detection but also reduces the addressable commercial market.
Sanjay Shukla, president and chief executive of aTyr, described the FDA feedback as an important milestone, adding that efzofitimod "has the potential to become an important new treatment option" for patients who have limited choices, particularly those requiring chronic corticosteroid therapy.
Market context and funding position
Pulmonary sarcoidosis sits within the broader interstitial lung disease space, which has seen growing pharmaceutical interest following the approvals of nintedanib and pirfenidone in idiopathic pulmonary fibrosis. Sarcoidosis, however, remains largely managed with corticosteroids and off-label immunosuppressants; no therapy holds a formal approval specifically for the pulmonary form of the disease. That regulatory gap makes efzofitimod's mechanism of particular interest: the drug is derived from aTyr's tRNA synthetase platform and is designed to modulate activated myeloid cells via neuropilin-2, resolving inflammation without broad immune suppression.
A number of other companies are pursuing disease-modifying approaches in granulomatous and fibroinflammatory lung conditions, and the sarcoidosis field has historically suffered from small, heterogeneous trial populations that complicate endpoint selection. aTyr's decision to anchor on FVC in a restrictive subgroup reflects lessons learned from prior trial failures across ILD indications.
The company was explicit in its release that additional capital will be required to execute the Phase 3 programme, whether through equity, debt, grants, or a licensing or collaboration deal. aTyr is simultaneously running the Phase 2 EFZO-CONNECT study of efzofitimod in systemic sclerosis-related ILD, which adds to its financing needs. Investors will watch closely for news of a partnership or a capital raise as the next critical milestone alongside the formal study initiation.