Clinical Trials a Struggle for Blood Substitutes; Navy Study Blocked Again
BY LAUREN UZDIENSKI, JANUARY 2, 2007
Following up on an earlier blog about orthopedics' demand for a blood substitute, new research developments don't bode well for two synthetic products. Elective orthopedic surgery has one of the highest rates of patient blood loss; an effective blood substitute would provide a safe and unlimited blood supply.
Last week, Northfield Laboratories Inc. released preliminary data on PolyHeme, an oxygen-carrying blood substitute. In a trial on trauma patients, 46 patients died after being given the subsitute, compared with 35 who died under standard treatment. PolyHeme's press release cites two discrepancies in their data that will be corrected before the results are final.
Despite the higher mortality rate, Northfield plans to proceed with their FDA submission. As the Wall Street Journal describes, the study is designed to evaluate not whether PolyHeme is better than donor blood and saline, but whether it is superior, noninferior or inferior to the standard treatment. A status of "noninferior" means that the product isn't statistically better or worse. Given the relatively small size of the study (586 patients), Northfield was able to achieve a "noninferior" performance in the current data, even though, on an absolute basis, more patients died with the PolyHeme.
Northfield's data casts a grim shadow over the U.S. Navy's ongoing effort to initiate its own blood-substitute trial. In December, a committee of FDA advisors recommended the Navy's Hemupure trial remain on hold. Like PolyHeme, Hemopure is an oxygen-carrying blood substitute that has been approved for use in South Africa. In the U.S., Hemopure has been under consideration by the FDA since 2002 for an orthopedic surgery indication, but currently, there is little evidence that the benefits of the blood subsitute outweighs the risks.
