Unicycive Therapeutics (Unicycive Therapeutics (UNCY)) took another hit from the FDA on Monday, and investors are not happy. The stock crashed more than 46% on Tuesday after the agency issued a Complete Response Letter (CRL) for the company's resubmitted New Drug Application (NDA) for oxylanthanum carbonate (OLC), a treatment for hyperphosphatemia in chronic kidney disease patients on dialysis.

The CRL is essentially the FDA saying, "Not yet," and in this case, the holdup is all about manufacturing—specifically, issues at a third-party facility. The FDA didn't ask for more clinical data or raise any red flags about the drug's safety or effectiveness. It's the same song, second verse: the agency's concerns are tied to manufacturing deficiencies at the contract manufacturer, just like in the June 2025 CRL.

Unicycive said it believes the FDA hasn't yet completed an inspection of that third-party facility as part of its review of the resubmitted application. The company had decided to resubmit the NDA after concluding that the manufacturer was making progress on the compliance issues and was ready for an inspection. But apparently, the FDA wasn't satisfied.

The company had a Type A meeting with the FDA in September 2025 to discuss corrective actions related to the manufacturing vendor. According to Unicycive, the agency didn't raise new concerns during that meeting and didn't indicate any dissatisfaction with the manufacturer's progress. So the resubmission seemed like a reasonable move. But the FDA's latest response shows that the manufacturing issues still haven't been resolved to the agency's satisfaction.

Shalabh Gupta, Unicycive's CEO, remains upbeat about the drug itself. "We remain confident in the efficacy and safety of OLC," Gupta said. He added that the company is still engaged with the FDA on labeling and packaging discussions and expects a successful inspection of the third-party facility, allowing for a prompt resubmission.

The NDA for OLC is backed by three clinical studies: a Phase 1 trial in healthy volunteers, a bioequivalence study, and a tolerability study in CKD patients on dialysis. There's also a pile of preclinical data and chemistry, manufacturing, and controls (CMC) information supporting the drug. So the science seems solid—it's the manufacturing that's the bottleneck.

At the time of publication on Tuesday, Unicycive shares were trading at $4.14, down 46.17% from the previous close. That's a brutal drop, but it reflects the market's frustration with a second rejection on the same issue. For now, Unicycive is stuck waiting for the FDA to inspect that facility and give the green light. Investors will be watching closely for any news on that front.