Keryx Biopharmaceuticals recently reported positive top-line data for a pivotal 24-week Phase 3 clinical trial on its iron-based ferric citrate, an oral compound in clinical development to treat iron-deficiency anemia (IDA) in adult patients with a stage 3-5 non-dialysis dependent chronic kidney disease (NDD CKD). The trial met its primary endpoint as well as all secondary endpoints.

Ferric citrate (Auryxia), was approved by the U.S. Food and Drug Administration in 2014 to control serum phosphorus levels in patients with CKD who are dependent on dialysis. The compound binds with dietary phosphate in the GI tract and precipitates as ferric phosphate. The unbound portion of ferric citrate increases serum iron parameters, including ferritin and transferrin saturation.

Iron deficiency is frequently encountered in anemic NDD CKD patients. Estimates indicate that in the U.S., about 1.6 million people have stage 3-5 NDD CKD and iron deficiency anemia. An FDA approval of Auryxia to treat stage 3-5 NDD CKD patients with iron-deficiency anemia would signify major progress in treatment options for these patients, as ferric citrate would be the only FDA-approved tablet iron medication for these patients.

In the Phase 3 clinical trial, 234 patients who had failed to respond appropriately to the currently available oral iron drugs were randomized to receive treatment with Auryxia or a placebo. The trial met its primary endpoint with 52 percent (61 of 117) of patients treated with Auryxia, achieving an increase in hemoglobin of or greater than 1g/dL in the 16 weeks of the trial efficacy period, in comparison to 19 percent (22 of 115) of patients who received the placebo.

In the placebo group, two patients discontinued the trial and were not included in the efficacy analysis.

The trial also met all secondary efficacy endpoints, with statistically significant differences. During the 24-week full trial period, ferric citrate was well tolerated and adverse events were consistent with its known safety profile. Diarrhea was the most commonly reported adverse event.

“These Phase 3 results demonstrate that ferric citrate can effectively raise hemoglobin levels in stage 3-5 non-dialysis dependent chronic kidney disease patients, with effects observed as early as two weeks post-treatment initiation,” John Neylan, M.D., chief medical officer of Boston-based Keryx Biopharmaceuticals, said in a press release. “Based on these results, we plan to submit a [supplemental New Drug Application] to the FDA in the third quarter, seeking to expand the label for ferric citrate to include the treatment of iron deficiency anemia in people with stage 3-5 NDD CKD. We believe that the ability to treat iron deficiency anemia, managing hemoglobin and iron levels, could have an important effect on the way kidney specialists treat these patients.”

The company plans to submit detailed Phase 3 results for presentation at a kidney disease medical meeting later this year.