) --Congratulations,

Keryx Pharmaceuticals

(KERX) - Get Report

. The

long-term data on its phosphate binder Zerenex

released Monday morning look very strong, sending Keryx shares higher by 43% in early trading.

Zerenex met the study's primary goal of reducing serum phosphate levels in kidney dialysis patients, which

wasn't a surprise to anyone

. More importantly, however, Zerenex demonstrated significant benefits related to increased iron stores and reducing the use of IV iron and erythropoietin-stimulating agents (ESAs) like


(AMGN) - Get Report


It's these latter iron benefits that help Zerenex stand apart from other phosphate binders such as


(SNY) - Get Report

Renagel/Renvela, the market leader with nine-month 2012 sales of $640 million worldwide. (Sanofi reports year-end sales next month.) Based on today's study results, Zerenex should have an easy time being approved in early 2014. That's the same time period at which less expensive, generic versions of Renvela -- in addition to generic versions of IV irons -- will also become available to kidney dialysis clinics.

Keryx has long maintained that Zerenex can grab significant market share in kidney dialysis clinics even competing against low-priced, generic phosphate binders. During a conference call Monday, Keryx CEO Ron Bentsur said U.S. dialysis clinics could save $750 million annually from reduced use of IV iron and ESAs if they switched to Zerenex.

"Generic Renvela doesn't have the capacity to compete with the magnitude of these cost savings," said Bentsur.

AMAG Pharmaceuticals

(AMAG) - Get Report

CEO Brian Pereira once made similarly bold pronouncements about how his clinically superior IV iron therapy Feraheme was going to be grab significant kidney dialysis market share from its competitors. That never happened, which forced AMAG to all but abandon the kidney dialysis market.

Perhaps Keryx will buck the trend and convince dialysis providers like


(DVA) - Get Report



that they can save money by using a more expensive phosphate binder when cheaper alternatives are available. Monday's Zerenex data seem to bolster Keryx's argument.

I'm not sure skeptics will be entirely convinced

until Keryx lands a Big Pharma partner willing to shell out big bucks to license Zerenex, or the drug launches strong.

That's a fight for another day. Monday, Keryx deserves credit for delivering a clear win with the Zerenex clinical data, and in the process, helping erase the sting and stigma left from last year's perifosine colon cancer blowup.

Keryx shares are up 43% to $4.89 in early trading.

-- Reported by Adam Feuerstein in Boston.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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