By Frances Bishopp

Immunomedics Inc. reports its diagnostic imaging product, LeukoScan, a rapid method of locating sites of infection in the body, has received final clearance from the European Commission for sale and marketing in the 15 nations of the European Union.

The approved indication for LeukoScan is the detection and diagnosis of osteomyelitis, or bone infection, in long bones, particularly in diabetic patients with foot ulcers, for which osteomyelitis can be a frequent complication. Osteomyelitis afflicts approximately 800,000 Americans each year.

LeukoScan is a monoclonal antibody fragment directly labeled with technetium-99m (a widely available, inexpensive radioisotope with high quality imaging capability). Following a simple, five-minute labeling procedure, a small amount of the antibody is administered to the patient. The antibody seeks out and binds to granulocytes (white blood cells) associated with a potentially wide range of infectious diseases and carries the radioisotope to the infection site. The patient can be imaged, in certain circumstances, within an hour of administration, using a standard nuclear medicine gamma camera.

One of LeukoScan's major safety benefits is there is no residual radiation after a certain amount of time for the doctor or patient to worry about. It is excreted through the urinary system and has a half-life of only six hours.

LeukoScan approval was based on data from clinical trials in approximately 500 patients from 31 clinical centers in both the U.S. and Europe, Paul Herron, director of finance at Immunomedics, told BioWorld Today. Tests of LeukoScan in detecting osteomyelitis showed it accurately diagnosed bone infection (sensitivity) 88 percent of the time and it accurately ruled out infection (negative predictive value) 85 percent of the time.

"There are other agents on the market," Herron said, "that are used to label white blood cells. The patient's blood is first extracted and separated into the white and red cells. The white cells are then labeled with the isotope and reinjected. That is a long, cumbersome procedure that involves the lab and there is always the danger that the patient will get the wrong blood reinjected," Herron explained. "It is not something that has been considered efficient or easy. LeukoScan offers a very nice alternative to that."

On Dec. 19, 1996, Immunomedics, of Morris Plains, N.J., filed a biologics license application to the FDA seeking approval for LeukoScan for detection of osteomyelitis in long bones and in patients with diabetic foot ulcers, and also for use in patients with right lower quadrant disease, particularly acute atypical appendicitis.

"This application contains the same indication for which we just got approved in Europe," Herron said, "plus the additional indication for acute atypical appendicitis. This data was not ready when we filed in Europe back in August of 1995."

The patient data that supported the application in the U.S. is the same data that was used in the European application, Herron said.

"The next step [after European approval]," Herron said, "is for Immunomedics to identify a partner for the distribution of the product, which is an effort that is ongoing at this time."

"It is possible that we could handle some limited sales ourselves," Herron said, "but strategically it would be very difficult."

Immunomedics' first product, CEA-Scan, for the detection of colorectal cancer, has been approved in both the U.S. and Europe. It is being marketed by Mallinckrodt Group Inc., of Saint Louis, Mo., and its European affiliate, Mallinckrodt Medical B.V.

Immunomedics, a biopharmaceutical company founded in 1982, has approximately $20 million and a burn rate of approximately $1.3 million a month. Besides diagnostic imaging, the company focuses on the development, manufacture and commercialization of therapeutic products for the detection and treatment of cancer and infectious disease. Immunomedics' stock ( NASDAQ: IMMU) closed Friday at $6, up $.063. *