SAN FRANCISCO – Ron Bentsur, CEO of Keryx Biopharmaceuticals Inc., disappointed some attendees on the final morning of the J.P. Morgan Healthcare Conference when he acknowledged the company is still waiting for Phase III data on Zerenex (ferric citrate) in end-stage renal disease (ESRD) patients with hyperphosphatemia.

The data were scheduled to report by the end of the fourth quarter.

The reason was plausible, however. Bentsur said the company's East Coast-based contract research organization (CRO) was "near the epicenter" of Hurricane Sandy and lost a full work week. Data lockdown then fell prey to holiday schedules and the year-end departure of a coordinator. Although the delay is frustrating, the company must wait for every site to report because findings are "only as good as that last piece of information," he said.

Overall, Bentsur expressed confidence in the CRO and maintained the study was being handled properly. "We can't coerce the process," he said. "We have to let them do their thing."

Still, the wait has played on the nerves of the company and its investors. Keryx is solely reliant on Zerenex after its oral Akt inhibitor perifosine, partnered with Canadian biotech Aeterna Zentaris Inc., failed to improve overall survival in a Phase III colorectal cancer trial last year. (See BioWorld Today, April 3, 2012.)

Zerenex won kudos in late 2010 after hitting primary and key secondary endpoints in a short-term Phase III trial in hyperphosphatemia in dialysis patients. Analysts – and the company – hope to see similarly positive data from the long-term study, being conducted under a special protocol assessment, in ESRD patients. (See BioWorld Today, Dec. 1 , 2010.)

Bentsur concurred in a breakout session that, "obviously, we'd like to hit the primary and all of the secondary endpoints. That would be the ideal conclusion."

While the company "isn't worried" about the key phosphate or ferritin efficacy data, Bentsur suggested the study could have "background noise" where cheaper agents were substituted for EPO due to bundled payments, reducing EPO usage by 25 percent across the board over the course of the study.

"When you conduct a study and in the background you have that kind of noise, obviously that's a challenge," Bentsur said.

Keryx is confident about safety and tolerability, since more than a half-dozen data safety monitoring committee meetings have been conducted around the study, according to Bentsur.

Not surprisingly, the company's shares (NASDAQ:KERX) have languished in the dearth of news flow. Though the stock has rebounded from its 52-week low of $1.28 after the perifosine blow-up, it continues to hang below $3 waiting for the Zerenex data report. On Thursday, shares fell 3 cents, closing at $2.92.

That said, Bentsur offered some potential upside on the compound. Earlier in the week, partner Japan Tobacco Inc., of Tokyo, filed a new drug application with the Japanese Ministry of Health, Labor and Welfare for marketing approval of ferric citrate for hyperphosphatemia in patients with chronic kidney disease (CKD). The application triggers a $7 million milestone payment under Keryx's license agreement with Japan Tobacco and subsidiary Torii Pharmaceutical Co. Ltd. That deal includes another $65 million in remaining potential milestone payments.

The company also learned that, as part of the recently signed American Taxpayer Relief Act, the bundling of Medicare payments scheduled to ensnare Zerenex in 2014 was postponed until 2016, potentially giving the company an additional two years of higher reimbursement.

Another plus: As advanced medical care reaches emerging markets, the global dialysis population is expected to nearly double, to some 3.8 million individuals, by 2020, Bentsur pointed out.

But the key potential differentiator for Zerenex is a potential benefit on the incidence of anemia in the dialysis population, he said. ESRD patients lose blood with every dialysis procedure – typically three times a week. Because the kidneys don't function, red blood cell production is inherently impaired, and patients require anemia drugs.

"What we're saying is that, intuitively, an iron-based phosphate binder such as Zerenex could potentially, over time, increase the iron stores in these patients," Bentsur explained.

Should Zerenex demonstrate such an effect, the company could explore its potential to become the first phosphate binder to seek approval in pre-dialysis, chronic kidney disease patients.

Assuming a positive trial outcome and FDA approval, Zerenex still must contend with existing phosphate binders, such as Shire plc's Fosrenol (lanthanum carbonate), Fresenius Medical Care's PhosLo (calcium acetate) and Sanofi SA's market-leading Renagel (sevalamer hydrochloride) and Renvela (sevelamer carbonate). Bentsur characterized the Keryx compound as a safer alternative to Fosrenol and PhosLo with a lower pill burden than Renagel/Renvela.

"All three products in hyperphosphatemia have significant shortcomings," Bentsur said.