Keryx jumps as kidney drug impresses in PhII, promises wider label

Keryx Biopharmaceuticals' ($KERX) shares leapt nearly 20% Tuesday morning on news that its chronic kidney disease (CKD) drug Zerenex cleared a Phase II trial on nondialysis-dependent patients, possibly setting the stage for a broader indication once the much-scrutinized drug is approved.

Zerenex is designed to treat hyperphosphatemia, a common ailment among CKD patients in which phosphorus levels reach dangerous heights, but Keryx is looking to flesh out its benefits in iron-deficiency anemia with eyes on a bigger market. In a midstage study of 149 anemic, nondialysis-dependent CKD patients, the drug charted statistically significant reductions in phosphorus and increases in iron over 12 weeks, and Keryx believes those data will help persuade the FDA to give Zerenex a labeled indication to treat a broader population.

Keryx's move to widen Zerenex's possible indications comes amid long-running concerns that the drug's launch will be blunted by soon-to-launch generics of Sanofi's ($SNY) Renvela and Shire's ($SHPG) Fosrenol, two phosphate-lowering drugs indicated for dialysis patients. As a result, Keryx is touting its drug's tertiary benefits--like a reduced need for intravenous iron and erythropoiesis-stimulating agents--in an effort to set Zerenex apart from the competition.

The drug is slated for a final FDA decision in June, based on positive Phase III results in dialysis patients with hyperphosphatemia. If Keryx can stretch that approval to include less-dire CKD patients with iron-deficiency anemia, Zerenex would become the first oral iron drug indicated for another roughly 1.5 million currently underserved patients, CEO Ron Bentsur said, adding that the treatment has the potential to lead the $2.4 billion market for phosphate binders.

But despite Wall Street's cheery reaction to the latest data, Keryx has done little to assuage fears that Zerenex's time on top would be short-lived. The drug's active ingredient bears a strong resemblance to Otsuka's long-ago-approved Ferriseltz, stoking worries that it won't get New Chemical Entity status from the FDA and thus would face generic competition sooner than expected.

- read the announcement

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