The US Food and Drug Administration has issued a Complete Response Letter for Unicycive Therapeutics' resubmitted New Drug Application for oxylanthanum carbonate, an investigational oral phosphate binder for the treatment of hyperphosphatemia in patients with chronic kidney disease receiving dialysis, according to a press release from the company.

According to Unicycive, the Complete Response Letter (CRL) relates to deficiencies previously identified at a third-party manufacturing vendor. The company said the US Food and Drug Administration (FDA) did not identify concerns regarding the clinical efficacy or safety data supporting the application and did not request additional data.

Unicycive stated that the CRL is based on the same third-party manufacturing deficiencies identified in a previous CRL issued in June 2025. The company also said the FDA did not inspect the third-party manufacturing facility during its review of the resubmitted New Drug Application (NDA).

According to the company, the NDA was resubmitted based on the company's belief that the third-party manufacturing vendor had made continued progress in resolving FDA-cited deficiencies and demonstrating inspection readiness. Unicycive said it discussed these milestones with the FDA during a Type A meeting in September 2025 and that the agency did not raise additional issues related to the manufacturer's progress during that meeting.

The company also said labeling discussions with the FDA remain ongoing. According to Unicycive, the most recent communication from the agency was received on June 29 and concerned carton and container labeling.

The NDA is supported by data from a phase 1 study in healthy volunteers, a bioequivalence study in healthy volunteers, a tolerability study in patients with chronic kidney disease receiving dialysis, multiple preclinical studies, and chemistry, manufacturing, and controls data, according to the company.

Oxylanthanum carbonate is an investigational oral phosphate binder that uses proprietary nanoparticle technology to deliver high phosphate-binding potency, according to the company. Unicycive is seeking FDA approval through the 505(b)(2) regulatory pathway.

Source: Unicycive Therapeutics Inc.