Oxylanthanum Carbonate Second CRL Deepens Delay for Patients With Chronic Kidney Disease

Oxylanthanum carbonate (OLC) has failed to be cleared by the FDA for a second time—not because of new questions about its clinical data, but because a third-party manufacturing plant still hasn't been inspected, according to UnicyciveTherapeutics.¹ OLC is a next-generation phosphate binder that leverages nanoparticle technology to ease the pill burden for patients with chronic kidney disease (CKD) on dialysis. The complete response letter (CRL) for OLC extends a regulatory holdup that began a year ago and, absent a resolution, keeps a lower-pill-burden option out of reach for a patient population where most already fall short of phosphorus targets.²

What Prompted the Second CRL for OLC

The FDA's decision centers on the same third-party manufacturing deficiencies flagged in the company's first CRL, issued in June 2025. Unicycive said the agency has not yet completed an inspection of that vendor as part of its review of the resubmitted new drug application (NDA), even though the company had refiled based on its belief that the manufacturer was continuing to resolve the FDA's cited deficiencies and demonstrate inspection readiness.

"We remain confident in the efficacy and safety of OLC," Shalabh Gupta, MD, CEO of Unicycive, said in a statement. He added that the company is in active discussions with the FDA over labeling and packaging and remains optimistic that a successful inspection of the manufacturing vendor will allow it to resubmit the application quickly.

How This CRL Compares With the First One

The findings echo earlier reporting by The American Journal of Managed Care^® (AJMC^®) on Unicycive's first CRL for OLC, issued in June 2025, which similarly cited third-party manufacturing concerns rather than any deficiency in the drug's clinical package.² At the time, Unicycive said it had identified a second manufacturing vendor with experience producing OLC and planned to seek a Type A meeting with the FDA to align on a path to resolution.

Unicycive reported no additional concerns from the agency about the compliance status of the vendor and said it was on track to resubmit the NDA by year-end.³ The resubmission ultimately moved forward on roughly that timeline, but the second CRL indicates the underlying manufacturing-readiness question was not fully resolved by the time of the FDA's review, largely because the agency's inspection of the facility had not yet taken place.

Why Patients Are Still Waiting for Relief

The delay carries real stakes for a population that struggles to control phosphate levels. About 75% of dialysis patients in the US do not meet recommended phosphorus targets despite having access to existing phosphate binders. Uncontrolled hyperphosphatemia is common among the more than 450,000 people in the US who require medication to manage phosphate levels and is associated with higher rates of hospitalization and death among patients with CKD on dialysis.⁴

OLC is designed to ease that burden through nanoparticle technology that Unicycive says allows for fewer, smaller pills than existing binders, addressing a regimen that can otherwise run to a dozen tablets a day. Phase 2 data the company has presented previously found that patients taking OLC reported higher treatment satisfaction and adherence than they had with their prior binder regimens. Until the manufacturing and labeling questions are resolved, that potential remains unrealized for the payers, nephrologists, and dialysis patients weighing treatment options for hyperphosphatemia.

What Comes Next for OLC's Approval Path

Unicycive said it continues to work toward a successful inspection of the third-party facility and intends to resubmit the NDA once that milestone and the labeling discussions are resolved. The company did not provide a specific timeline for either step.

References

1. Unicycive Therapeutics receives Complete Response Letter from FDA regarding resubmitted oxylanthanum carbonate (OLC) New Drug Application (NDA). News release. Unicycive Therapeutics, Inc; June 30, 2026. Accessed July 1, 2026. https://ir.unicycive.com/news/detail/123/unicycive-therapeutics-receives-complete-response-letter
2. Grossi G. Oxylanthanum carbonate fails to secure FDA approval for hyperphosphatemia, CKD. AJMC. June 30, 2025. Accessed July 1, 2026. https://www.ajmc.com/view/oxylanthanum-carbonate-fails-to-secure-fda-approval-for-hyperphosphatemia-ckd
3. Unicycive Therapeutics provides update from FDA Type A meeting and expects to resubmit OLC NDA before year-end. News release. Unicycive Therapeutics, Inc; October 28, 2025. Accessed July 1, 2026. https://www.sec.gov/Archives/edgar/data/0001766140/000121390025102790/ea026272301ex99-1_unicycive.htm
4. Flythe JE. Dialysis—past, present, and future: a Kidney360 Perspectives series. Kidney360. 2023;4(5):567-568. doi:10.34067/KID.0000000000000145