A class action lawsuit was filed against aTyr Pharma (ATYR) on October 9, 2025. The plaintiffs (shareholders) alleged that they bought ATYR stock at artificially inflated prices between January 16, 2025, and September 12, 2025 (Class Period) and are now seeking compensation for their financial losses. Investors who bought ATYR stock during that period can click here to learn about joining the lawsuit.
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aTyr Pharma is a clinical-stage biotechnology company that develops innovative medicines by leveraging the biology of tRNA synthetases, a family of ancient and essential proteins.
Efzofitimod is a drug designed to treat interstitial lung disease (ILD), which involves inflammation and scarring of the lungs. It is a biologic immunomodulator derived from tRNA synthetase, targeting activated immune cells to reduce inflammation and prevent lung scarring without suppressing the immune system.
The company’s claims about the efficacy and expectations from Efzofitimod’s clinical trials are at the heart of the current complaint.
aTyr’s Misleading Claims
According to the lawsuit, aTyr and one of its senior officers (the Defendants) repeatedly made false and misleading public statements throughout the Class Period. In particular, they are accused of omitting truthful information about the efficacy of Efzofitimod, specifically its ability to facilitate complete tapering of patients’ steroid use, from SEC filings and related material.
During the Class Period, at the 43rd Annual J.P. Morgan Healthcare Conference, aTyr’s CEO stated that Efzofitimod’s global Phase III trial was fully enrolled and ready for data collection. He explained that the trial was well-designed and statistically strong, with 88 patients in each study group and a total of 268 patients enrolled, testing two effective doses identified from Phase II.
The CEO also added that in their previous trial, the drug was able to reduce patients’ steroid doses to about 5 milligrams. In the current trial, aTyr was aiming to lower the dose even further, possibly to zero. He highlighted that many patients who had completed the trial were already showing improvement and no longer needed to return to steroid use.
Finally, on the March 13, 2025, earnings call, the CEO explained that the company had finalized how they would measure steroid reduction for the primary goal of the study. He noted that they planned to calculate the average daily steroid dose between weeks 12 and 48, which is the period specified in the study protocol after tapering steroids.
However, subsequent events (detailed below) revealed that aTyr misled investors about the true expectations from Efzofitimod’s clinical trials.
Plaintiffs’ Arguments
The plaintiffs maintain that the defendants deceived investors by lying and withholding critical information about the company’s business and prospects during the Class Period. Importantly, the defendants allegedly misled investors into believing that Efzofitimod was effective in reducing steroid dependency among patients.
The information became clear on September 15, 2025, when aTyr held an investor call to announce that the EFZO-FIT study did not meet its primary endpoint. Specifically, the company announced that the study did not meet the primary endpoint in change from baseline in mean daily OSC dose at week 48.
Furthermore, aTyr announced that its next step was to engage with the U.S. Food and Drug Administration (FDA) to determine a path forward, given the disappointing topline results. Following the news, ATYR stock plunged by 83.2% the same day.
To conclude, the defendants misled investors into believing that Efzofitimod was an effective drug designed to treat interstitial lung disease (ILD). Due to these issues, ATYR stock has lost 79.4% year-to-date.
