Oxylanthanum Carbonate Fails to Secure FDA Approval for Hyperphosphatemia, CKD

Oxylanthanum carbonate may improve treatment adherence.

Image Credit: Nirusmee - stock.adobe.com

Oxylanthanum carbonate (OLC) received a Complete Response Letter (CRL) from the FDA for the treatment of hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis, according to an announcement from Unicycive Therapeutics.¹ OLC is a next-generation lanthanum-based phosphate binder that utilizes proprietary nanoparticle technology.

“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,” Shalabh Gupta, MD, chief executive officer of Unicycive, said in the statement.

Hyperphosphatemia, or high phosphate levels in the blood, impacts nearly all patients with end-stage renal disease and is linked to higher mortality among those on dialysis.² Untreated, it can lead to serious complications like cardiovascular disease. Despite available phosphate binders, about 75% of dialysis patients in the US do not meet recommended phosphorus levels.

If approved in the future, OLC has the potential to advance treatment by reducing the pill burden that currently impacts adherence among this patient population, who often face a regimen that can involve up to 12 pills daily, according to Unicycive. In addition to reduced pill count per dose, OLC is designed to be easily swallowed rather than chewed.

On June 10, Unicycive Therapeutics announced that the FDA had identified manufacturing deficiencies at a third-party subcontractor involved in producing OLC and that the agency had paused any label discussions related to the drug.³ At the time, Unicycive stated it was working with its partners to address the concerns; according to today's statement,¹ this citation was unrelated to OLC and no other technical concerns related to the submitted CMC documentation or testing of OLC itself were noted by the FDA in the application review.

“With a second manufacturing vendor identified that has produced OLC drug product, we remain optimistic about our ability to bring this promising new treatment option to patients with CKD on dialysis who are managing hyperphosphatemia, and we plan to provide an update as soon as we have additional clarity on next steps from the FDA," Gupta continued.

Reduced Treatment Burden; Improved Adherence

Patient-reported outcomes from the phase 2 UNI-OLC-201 study presented at the 2025 National Kidney Foundation Spring Clinical Meetings suggest that OLC may significantly improve treatment satisfaction, reduce pill burden, and enhance adherence among patients with CKD on dialysis.⁴ The open-label, single-arm, multicenter trial enrolled 86 dialysis patients with elevated serum phosphate levels to assess the impact of OLC on adherence and patient experience compared with their existing phosphate binder regimens.

At baseline, patients reported a median daily intake of six phosphate binder tablets, with only 58% indicating adherence to their prescribed treatment. After a washout period and a 10-week regimen of OLC, which included dose titration followed by a maintenance phase, patients reported taking a median of just three OLC tablets per day. Notably, 70% of patients were adherent to OLC treatment, reflecting a meaningful improvement over pre-trial adherence rates.

The results further showed that 79% of participants preferred OLC over their previous phosphate binder, and nearly all (98%) described OLC as easy to take, a stark contrast to the 38% who found their prior medication easy to use. Patient satisfaction with treatment also increased considerably, with 89% reporting satisfaction with OLC compared to 49% who were satisfied with their earlier phosphate binder.

The NDA for OLC was submitted under the FDA’s 505(b)(2) pathway, leveraging data from 3 clinical studies and multiple preclinical evaluations.² The product is protected by a broad global patent portfolio, with exclusivity extending through at least 2031 and possibly until 2035 with patent term extensions.

Unicycive received a waiver for the PDUFA application fees, saving the company approximately $4 million as it prepares for potential commercialization of OLC in the second half of 2025. The global market for hyperphosphatemia treatments is estimated to exceed $2.5 billion, with the US market accounting for over $1 billion of that total.

References

1. Unicycive Therapeutics announces receipt of Complete Response Letter for oxylanthanum carbonate for the treatment of hyperphosphatemia in patients with chronic kidney disease on dialysis. News release. Unicycive Therapeutics. June 30, 2025. Accessed June 30, 2025. https://www.globenewswire.com/news-release/2025/06/30/3107365/0/en/Unicycive-Therapeutics-Announces-Receipt-of-Complete-Response-Letter-for-Oxylanthanum-Carbonate-for-the-Treatment-of-Hyperphosphatemia-in-Patients-with-Chronic-Kidney-Disease-on-Di.html

2. Unicycive Therapeutics announces U.S. FDA acceptance of the New Drug Application (NDA) for oxylanthanum carbonate (OLC) for the treatment of hyperphosphatemia in patients with chronic kidney disease on dialysis. News release. Unicycive Therapeutics. November 11, 2024. Accessed June 24, 2025. https://www.globenewswire.com/en/news-release/2024/11/11/2978178/0/en/Unicycive-Therapeutics-Announces-U-S-FDA-Acceptance-of-the-New-Drug-Application-NDA-for-Oxylanthanum-Carbonate-OLC-for-the-Treatment-of-Hyperphosphatemia-in-Patients-with-Chronic-K.html

3. Unicycive provides update on New Drug Application for oxylanthanum carbonate to treat hyperphosphatemia in patients with chronic kidney disease on dialysis. News release. Unicycive Therapeutics. June 10, 2025. Accessed June 24, 2025. https://www.globenewswire.com/news-release/2025/06/10/3096422/0/en/Unicycive-Provides-Update-on-New-Drug-Application-for-Oxylanthanum-Carbonate-to-Treat-Hyperphosphatemia-in-Patients-with-Chronic-Kidney-Disease-on-Dialysis.html

4. Brooks A. Oxylanthanum carbonate may offer desirable alternative to current phosphate binders. HCPLive. April 10, 2025. Accessed June 24, 2025. https://www.hcplive.com/view/oxylanthanum-carbonate-may-offer-desirable-alternative-current-phosphate-binders