The number of serious side effects in surgical patients receiving



experimental blood substitute, Hemopure, was significantly higher than comparable patients who received red blood cells, new data show.

The first detailed airing of Hemopure's safety profile was presented this morning at the annual meeting of the American Society of Anesthesiology, being held in Orlando, Fla. The results appear to contradict prior statements made by Biopure executives that Hemopure is just as safe as blood.

The Food and Drug Administration is currently reviewing Hemopure as a possible substitute for red blood cell transfusions in patients undergoing orthopedic surgery. A decision on the product's approval is expected in the middle of next year.

Biopure concluded a 688-patient pivotal clinical study of Hemopure in August 2000. The company has insisted that results of this trial showed the product to be safe and effective, but has never fully released data from the study to back up its claims.

Wednesday, safety data finally released from that study showed 118 serious adverse events in 350 patients receiving Hemopure. By comparison, there were 83 serious adverse events in 338 patients given red blood cells.

Eighty-eight patients, or 25%, given Hemopure during the study experienced at least one serious adverse event. That compares to the reporting of at least one serious adverse event in 59 patients, or 17.5%, receiving red blood cells. The difference between the two patient groups was statistically significant, according to the study.

Breaking down these adverse events, 22 patients in the Hemopure arm of the study fell victim to cardiac problems, compared to eight patients in the red blood cell arm.

There were six incidents of kidney problems, including four cases of acute renal failure, in the Hemopure arm. In the red blood cell arm, there were four incidents of kidney problems, including two cases of acute renal failure. has reported previously on cases of

acute renal failure in Hemopure patients.

There were 10 deaths in the Hemopure group, compared to six deaths in the red blood cell group. The difference here was not statistically significant.

The big question left unanswered, of course, is what caused the higher number of safety problems in patients given Hemopure. Biopure spokesman Brad Miles says Hemopure is not the likely cause. Many of the Hemopure patients in the study were old -- some in their 80s and 90s -- and had pre-existing diseases that caused complications after surgery.

"If you take these patients out of the study, I think the results will look quite different," he says, adding, "Doctors who we've spoken to -- doctors who give transfusions every day -- are not concerned about these serious side effects because they resolve themselves."

But according to the study's demographic profile, there were nearly as many patients over 80 in the red blood cell arm as there were in the Hemopure arm. In fact, the median age of the red blood cell group was one year older. And the baseline medical characteristics of these two patient groups, prior to their surgeries, were almost identical.

The study does conclude that Hemopure is "safe for administration as treatment for acute signs/symptoms of anemia in adult patients undergoing elective orthopedic surgery." But at the same time, it offers some caution: "While safe, certain precautions and close monitoring of patients is warranted, especially of patients with underlying evidence of cardiovascular, renal and/or pulmonary disease"

In August 2001, Biopure issued a press released claiming that

safety trials for Hemopure met their primary endpoint, which was to prove that "patients treated with Hemopure have outcomes no worse than patients treated with allogenic red blood cells per statistical methodology previously agreed to by the FDA."

Commenting on the results at that time, then-Biopure CEO Carl Rausch said, "These results are a win for the company because they meet the study endpoints previously agreed to by the FDA and are supportive of our plan to file a marketing application this year."

At the time, the company didn't release any actual data to back up its claim. Now that safety data have been made public, how does Biopure explain the discrepancy between its past statements and the actual results?

Miles says that statements about Hemopure's safety made in August 2001 were based on a separate analysis performed by an independent committee of experts, and not on the data presented Wednesday. This so-called SEEC analysis, Miles says, is actually more important to the FDA than the analysis released today. Yet Miles acknowledges that information from the SEEC analysis has never been released publicly.

Biopure shares closed Wednesday down a penny to $5.01.