Shares of Aldeyra Therapeutics Inc. (ALDX) are taking a beating, down sharply in premarket trading Thursday. The reason? The company just hit another major roadblock with the U.S. Food and Drug Administration for its experimental dry eye treatment, reproxalap. Since Tuesday, the stock has cratered by about 67%.
FDA Says 'Not So Fast'—Again
The company announced it received a Complete Response Letter (CRL) from the FDA for its New Drug Application for reproxalap. In regulatory speak, a CRL is basically a rejection, and this one pointed to a "lack of substantial evidence from controlled studies" to support approval.
Here's the twist: while the FDA raised concerns over the drug's efficacy and stated that further trials are not recommended, it did suggest the company could explore specific patient populations where reproxalap might work. That's a notable shift in tone from previous rejections.
Aldeyra's CEO emphasized in a statement the urgency of working with the FDA to find a path forward for what the company calls a potential breakthrough treatment. On the financial side, Aldeyra reported having $70 million in cash as of December 31, 2025, which it believes is enough to keep the lights on into 2028.
This Isn't Their First Rodeo
If this story sounds familiar, it's because it is. This marks the third time the FDA has sent a rejection letter for reproxalap.
Back in April 2025, the agency issued a CRL for a resubmitted application, stating it "failed to demonstrate efficacy in adequate and well-controlled studies" and that at least one more solid study was needed to show a positive effect on dry eye symptoms.
Go back even further to November 2023, and the initial NDA got a CRL that also requested at least one additional symptom trial. So, the efficacy question has been a persistent hurdle.












