A Navy plan to test a blood substitute on civilian trauma victims should remain on hold, federal health advisers recommended Thursday, saying the experiment's risks outweigh its benefits.
The nonbinding vote appears to be the latest blow to the Navy, which has repeatedly sought FDA approval to test the product, derived from cow blood, on roughly 1,100 trauma victims in emergency situations. It proposes doing so without obtaining the customary informed consent of patients.
Dr. Jay Epstein, director of FDA's office of blood research and review, told panelists that trials done without consent must clear a higher hurdle. The trials can't just minimize the harm that might befall participants but should promise them some benefit as well, he said.
The panelists later voted 11-8, with one abstention, to say the experiment's potential benefits don't outweigh its risks. The FDA isn't required to follow the recommendations of its advisory committees, but it usually does.
If it does in this case, it would mark the fourth time since June 2005 that the FDA has blocked Hemopure trials from starting. Each time, it has cited safety concerns about using Hemopure as an experimental substitute for the saline fluids typically given in ambulances.
Hemopure's manufacturer, Biopure Corp., based in Cambridge, Mass., contends that its benefits outweigh its risks, as does the Navy. A Navy official said the blood substitute could save lives on the battlefield in places like Iraq.
In Iraq, 68 percent of the U.S. troops who die of trauma before reaching a hospital suffer severe bleeding as part of their injuries, the Navy's deputy surgeon general, Rear Adm. John Mateczun, told panelists. Blood substitutes could save many of those lives.
"We urgently need an oxygen-carrying capability that does not require refrigeration, is universally compatible and can be readily administered in a field setting," Mateczun said.
The Navy wants to test Hemopure in the civilian world because the battlefield is too uncontrolled an environment. The most likely subjects would be young male trauma victims under the influence of alcohol, according to the Naval Medical Research Center and FDA.
The panel later encouraged the Navy to redesign the experiment proposal to include only situations in which blood transfusions are not available, such as rural areas or combat zones, an FDA spokeswoman said.
In testimony Thursday, one critic said the proposed trial is unethical and that the FDA's previous reasons for blocking the trial remain valid.
"Human subjects would be exposed to an unreasonable and significant risk," said Dr. Sidney Wolfe of the watchdog group Public Citizen. Thursday's meeting originally was to have been held in secret in July, but the FDA postponed it at the last minute after Public Citizen sued.
Researchers say blood substitutes can both counter a dangerous drop in blood pressure in bleeding victims and carry oxygen from the lungs to the body. Saline fluids can do the former but not the latter. While blood can do both, it has its own limitations. Unlike blood, blood substitutes theoretically could be stored for years and then used without concern for infection or blood type.
The development and testing of experimental blood substitutes has been fraught with controversy: Baxter International Inc. stopped research on one such product in 1998 when more than 20 patients given the substitute died.
A second company, Northfield Laboratories Inc., began clinical trials in 2004 of another product, called Polyheme, giving it to trauma patients without their consent on the way to — and later, at — the hospital. Hemopure would be given only en route to the hospital under the Navy proposal.