aTyr Pharma’s Stock Halted After Phase 3 Trial Misses Primary Endpoint

Lead aTyr Pharma (NASDAQ: ATYR) halted trading in its shares premarket on September 15 after announcing that its Phase 3 EFZO-FIT trial of efzofitimod in pulmonary sarcoidosis failed to meet its primary endpoint of steroid reduction.

Nut Graf The late-stage study’s inability to show a statistically significant decrease in daily corticosteroid use underscores challenges in advancing efzofitimod toward approval, raising questions about the drug’s commercial viability in a market with limited treatment options.

Market Reaction and Trading Status

• Trading in ATYR shares was suspended premarket following the trial announcement.
• The stock closed at $6.03 on September 12 and had been trading above $6 in recent sessions.

Trial Results and Key Data

• The randomized, double-blind study enrolled 268 patients receiving monthly 5.0 mg/kg doses of efzofitimod or placebo.
• Mean daily oral corticosteroid dose at week 48 was 2.79 mg for the treatment group versus 3.52 mg for placebo (p = 0.3313).
• Secondary analyses showed nominal improvements in quality-of-life scores (King’s Sarcoidosis Questionnaire-Lung, p = 0.0479) and complete steroid withdrawal rates (52.6% vs. 40.2%, p = 0.0919), but these were not formally hierarchical after the primary endpoint miss.

Conference Call and Next Steps

• Management will host a conference call and webcast on September 15 at 8:30 a.m. ET to discuss the results.
• aTyr plans to engage with the U.S. Food and Drug Administration to determine the regulatory path forward for efzofitimod in pulmonary sarcoidosis.

Implications for aTyr Pharma Missing the primary endpoint in its flagship Phase 3 trial may necessitate additional clinical studies or a re-evaluation of trial design, potentially delaying any submission for approval. The company’s cash runway, bolstered by an August at-the-market offering of $30.7 million, will be critical as it reassesses development plans.