BioCryst Pharmaceuticals has terminated a Phase 3 trial of an intravenously administered influenza treatment for which it has received nearly $235 million in federal funding.

It is “unlikely that peramivir development for US registration will continue,” the firm’s chief medical officer added.

Shares in Biocryst plunged more than 40 percent on the news, falling to $1.38 in late-morning trading Thursday.

The RTP-based firm announced the decision after the markets closed Wednesday, saying an independent data monitoring committee had recommended the trial be “terminated for futility.”

Called peramivir, the anti-viral treatment was intended for use in patients admitted to hospitals with serious influenza. The federal government had underwritten much of the development costs.

BioCryst (Nasdaq: BCRX) did report that none of the 320 patients involved in the trial experienced any unexpected adverse effects and the committee had no concerns about peramivir’s safety.

“The goal of this analysis was to reassess the sample size required for the trial, and to make adjustments to the study if necessary. Based on the DMC recommendation, we have suspended enrollment of patients in the trial,” said Dr. William Sheridan, chief medical officer at BioCryst. “We are proceeding with a full analysis of unblinded data from the trial, and a final decision will be made following completion of the analysis and further discussions with our development partners; however, it is unlikely that peramivir development for US registration will continue.”

BioCryst said it has shared the committee’s recommendation with the U.S. Department of Health and Human Services Biomedical Advanced Research and Development Authority as well as other development partners.

The company describes peramivir as “a potent, intravenously administered investigational anti-viral agent that rapidly delivers high plasma concentrations to the sites of infection.”

Peramivir has already been approved for use in Japan and Korea through Biocryst partners Shionogi and Green Cross Corporation.

Just last week, BioCryst said it was its investigational new drug application for a proposed treatment of hepatitis C due to safety concerns.

The decision came after the company discussed its BCX5191 antiviral nucleoside with the Food and Drug Administration.

“The FDA indicated concerns regarding the preclinical toxicity profile of BCX5191 at exposure levels that they believe are likely to be necessary to reduce viral load in patients infected with the hepatitis C virus,” the company said in a statement. “Patient safety remains BioCryst’s highest priority.”

BioCryst (Nasdaq: BCRX) said it will conduct additional studies at lower does. ”BioCryst will then determine whether to continue development of BCX5191, based on the results of these studies,” the company said.