FDA Denies Approval for Oxylanthanum Carbonate in CKD Patients

On June 30, 2025, Unicycive Therapeutics announced that the U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (CRL) regarding the New Drug Application (NDA) for oxylanthanum carbonate (OLC), a treatment aimed at addressing hyperphosphatemia in patients with chronic kidney disease (CKD) undergoing dialysis. This decision, which stemmed from manufacturing deficiencies at a third-party subcontractor, has significant implications for both the company and the patient population it aims to serve.

Hyperphosphatemia, characterized by elevated phosphate levels in the blood, poses severe health risks for patients with end-stage renal disease, including increased mortality and cardiovascular complications. Approximately 75% of dialysis patients in the United States fail to achieve recommended phosphorus levels, highlighting an urgent need for effective treatments. OLC, a next-generation lanthanum-based phosphate binder developed with proprietary nanoparticle technology, was designed to ease the treatment burden by reducing the number of pills patients must take daily.

Dr. Shalabh Gupta, Chief Executive Officer of Unicycive Therapeutics, expressed his commitment to work closely with the FDA to resolve the manufacturing issues promptly. "We plan to immediately seek a Type A meeting with the Agency to gain alignment on the best strategy to ensure rapid resolution of the CRL," Gupta stated. He emphasized that the deficiencies identified were unrelated to the drug's formulation or efficacy, which were noted to be sound during the FDA's review process.

The development of OLC is particularly significant considering the global market for hyperphosphatemia treatments is projected to exceed $2.5 billion, with the U.S. market accounting for over $1 billion. If approved, OLC could substantially improve treatment adherence, as indicated by findings from the phase 2 UNI-OLC-201 study presented at the National Kidney Foundation's Spring Clinical Meetings. This study revealed a reduction in pill burden, with patients reporting a decrease from a median of six tablets to three per day, and an increase in adherence from 58% to 70%.

The NDA for OLC was submitted under the FDA’s 505(b)(2) pathway, which allows applicants to incorporate data from existing studies in lieu of conducting extensive new clinical trials. Unicycive holds a robust patent portfolio, ensuring exclusivity through at least 2031, with possibilities for extensions until 2035.

Despite the setback, Unicycive remains optimistic about OLC's potential. The company identifies a secondary manufacturing vendor ready to produce the drug, and they are committed to providing further updates as they engage with the FDA. The focus remains on bringing this innovative treatment option to patients managing hyperphosphatemia, who typically face a cumbersome pill regimen.

In conclusion, while the FDA's CRL presents a challenge for Unicycive Therapeutics, the ongoing dialogue with regulatory authorities and the promising clinical outcomes associated with OLC suggest a pathway forward. The implications for CKD patients on dialysis are profound, potentially reshaping the therapeutic landscape for hyperphosphatemia management in the future.