A Phase 2 Clinical Trial of Oxylanthanum Carbonate in Patients Receiving Maintenance Hemodialysis with Hyperphosphatemia

Key Points Oxylanthanum carbonate (OLC) was well tolerated with fewer than 10% of patients stopping treatment due to side effects. More than 90% of patients with hyperphosphatemia taking OLC achieved effective phosphate control. Two thirds of patients required three or fewer OLC tablets per day to control serum phosphate. Background In patients with kidney failure receiving maintenance dialysis, hyperphosphatemia is managed by dietary phosphate restriction and the provision of phosphate binders. Oxylanthanum carbonate (OLC) is a phosphate binder in development with high potency and formulated in a small pill swallowed whole. Methods We conducted a phase 2, open-label, single-arm, multicenter trial in adult patients receiving maintenance hemodialysis with hyperphosphatemia. The primary objective was to evaluate the tolerability of OLC at clinically effective doses with a goal serum phosphate (sP) concentration ≤5.5 mg/dl. The trial included washout, titration, and maintenance periods. Eligible patients had sP ≥4.0 and ≤7.0 mg/dl for at least 8 weeks before screening while receiving thrice weekly hemodialysis and a stable phosphate binder regimen. Patients started titration when sP was >5.5 mg/dl and entered maintenance once sP was ≤5.5 mg/dl. The starting dose of OLC during titration was 1500 mg/d (500 mg thrice daily). We assessed tolerability on the basis of the incidence of discontinuations due to treatment-related adverse events (TRAEs). Results Eighty-six patients were treated with OLC during the study. At screening, sP was ≤5.5 mg/dl in 51 (59%) patients. Seventy-eight (91%) patients entered maintenance, and 71 (91%) patients achieved sP ≤5.5 mg/dl on a median OLC dose of 500 mg three times a day. The most common TRAEs were gastrointestinal and included diarrhea (9%) and vomiting (6%); all other TRAEs were reported in <5% of patients. Three (4%) patients discontinued drug due to TRAEs. Minimal to no systemic absorption of lanthanum was observed after administration of OLC 1000 mg thrice daily. Conclusions In this open-label phase 2 trial, OLC was well tolerated and enabled sP control in >90% of patients with a low pill burden (two thirds of patients receiving three or fewer tablets/day). Clinical Trial registry name and registration number: NCT06218290.