The US Food and Drug Administration (FDA) has declined to approve Unicycive Therapeutics’ resubmitted new drug application (NDA) for oxylanthanum carbonate (OLC) to treat hyperphosphatemia in chronic kidney disease (CKD) patients on dialysis.

This decision was issued in a Complete Response Letter (CRL) which cited deficiencies at a third-party manufacturing facility producing OLC.

The FDA did not raise concerns related to the clinical efficacy or safety data provided for the therapy, nor did it request new data from Unicycive.

Unicycive noted that the latest CRL is based on the same manufacturing issues identified in a previous CRL issued in June 2025.

As part of the current review process, the FDA has not yet conducted an inspection of the third-party manufacturer.

The NDA was resubmitted after Unicycive believed its manufacturer had made progress towards resolving previously cited deficiencies and demonstrating readiness for FDA inspection.

A Type A meeting between Unicycive and the FDA in September 2025 was held to discuss the status of the manufacturing vendor and to seek feedback on the company’s approach to addressing compliance concerns.

Unicycive reported that at that meeting, the FDA did not raise further issues or concerns regarding the third-party manufacturer’s remediation progress.

The NDA for OLC is supported by three clinical studies: a Phase I trial and a bioequivalence study in healthy subjects, and a tolerability study in patients with chronic kidney disease on dialysis, in addition to multiple preclinical studies and chemistry, manufacturing and controls data.

Unicycive CEO Shalabh Gupta said: “We remain confident in the efficacy and safety of OLC. We are in active and ongoing discussion with the FDA regarding label and packaging, and we are optimistic that there will be a successful inspection of the third-party manufacturing vendor and that we will be able to expeditiously resubmit the NDA.”

Unicycive is seeking approval for OLC via the 505(b)(2) pathway.

The therapy, which is described as an investigational oral phosphate binder, remains under FDA review and is currently protected by a global patent portfolio extending until 2031.