FDA puts Biopure study on hold

Biopure Corp. said yesterday that the Food and Drug Administration, citing safety issues, has put on hold a clinical trial of its artificial blood, a setback for the Cambridge biotechnology company and its development partner, the US Navy.

Biopure said the FDA ''remains concerned" about risks posed by the company's experimental Hemopure product, made from cow's hemoglobin. The agency also wants more safety data incorporated into the written material that will be used to notify the public that patients in trauma situations could be given the artificial blood without their consent, the company said.

Douglas Sayles, a Biopure spokesman, said the FDA's comments clarify the challenges facing Hemopure.

''The good news about this letter is that all the issues are on the table" and can be addressed, Sayles said, though he declined to say when the company would respond. A spokeswoman for the Naval Medical Research Center in Silver Spring, Md., said officials wouldn't comment on the clinical trial while it remains under discussion with the FDA.

The federal agency's concerns mark the latest chapter in Biopure's 21-year quest to market Hemopure.

Last year the company replaced its chief executive and decided to focus on selling Hemopure as a specialized product for heart attack patients.

But the Navy still considers Hemopure a potential trauma tool. It has invested millions of dollars in the technology in hopes of creating a universal blood substitute that doesn't have to be refrigerated.

In June Biopure disclosed to investors that the Navy was proposing to the FDA to test Hemopure on civilian ambulance patients with severe bleeding. A similar trial now being conducted by Northfield Laboratories, a Biopure competitor, has become disputed. Some critics say that neither the Illinois company nor regulators have made public enough details about the underlying science to justify giving patients the substance without their consent.

Nancy King, a professor of social medicine at the University of North Carolina, said yesterday that the FDA appears to be questioning some of Biopure's statements about Hemopure's benefits. ''Reading between the lines, the FDA is saying that they may believe that the way the Navy and Biopure are describing the trial may be overstating the potential benefits and underplaying the potential risks," she said.

A spokeswoman for the FDA, Lenore Gelb, said the agency wouldn't discuss the application or the FDA's concerns.

Technically, Hemopure would be used to boost the oxygen-carrying capacity of blood until patients reach an emergency room stocked with human blood. Currently, ambulance crews carry only saline as a blood replacement. According to Biopure, the FDA wants more information showing the product can be safely used despite previous concerns that it might raise patients' blood pressure, which could increase the rate of bleeding.

The FDA also ''remains concerned that patients in the proposed trauma trial would face the same safety risks in the ambulance setting as were seen in other clinical trials," the company said in a press release. In January 2004 the agency asked Biopure for the results of three animal studies before it would approve further trials on humans. Sayles said the FDA did not ask the Navy for the same studies.

An member of the Navy trial advisory board, Lewis J. Kaplan, director of the surgical intensive care unit at Yale-New Haven Hospital, said the FDA's concerns seem routine. The agency wants more explanation, but not necessarily more research, he said.

Ross Kerber can be reached at kerber@globe.com.