Shares of Sarepta Therapeutics (SRPT) - Get Report  plunged Tuesday after the Food and Drug Administration rejected the biotech company's proposed treatment for Duchenne muscular dystrophy.

The stock price of Sarepta took a beating Tuesday, sinking 17.63% to $99.10.

In its rejection of golodirsen, the Cambridge, Mass.-based biotech's second treatment for DMD, the FDA cited concerns over infection risk "related to intravenous infusion ports" as well as "renal toxicity," the company said in a statement.

The proposed drug, targeted at rare genetic, muscle-wasting disorder found mainly in boys that leaves 90% of those affected in wheelchairs by age 15, was expected by analysts to generate more than $400 million in sales, according to Reuters.

Sarepta executives said the FDA's rejection letter came as a surprise. While acknowledging the toxicity concerns, these stemmed from animal-based trials with doses that were 10 times that of those used in the clinical trial, Sarepta said.

In the clinical trial, no issues with renal toxicity were detected, the company said.

Sarepta executives said their next step will be to sit down with FDA officials to go over the agency's concerns and "find an expeditious pathway forward for the approval of golodirsen," said Doug Ingram, Sarepta's president and chief executive officer, in a statement.

"We are very surprised to have received the complete response letter this afternoon," Ingram said. "Over the entire course of its review, the Agency did not raise any issues suggesting the non-approvability of golodirsen, including the issues that formed the basis of the complete response letter."

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