By Steve Usdin
Contributing Editor

SILVER SPRING, Md - The second time was lucky for Immunomedics Inc., which on Friday received the endorsement of an FDA advisory committee for its CEA-Scan colorectal imaging agent.

The Medical Imaging Drugs Advisory Committee unanimously voted to recommend approval of CEA-Scan as an imaging agent for recurring colorectal cancer. MIDAC members specified that the product, a monoclonal antibody fab' fragment labeled with technetium-99m, only should be used in conjunction with CT scans or other diagnostic procedures that may be developed in the future. Its primary utility is in staging colorectal cancer patients to determine whether they can be treated surgically.

Resection, the surgical removal of tumors, is the only effective therapy for colorectal cancer, but it is effective only in the subset of patients who have relatively few lesions in the liver and few if any lesions outside the liver.

False negatives from CT

Although resection provides a dramatic benefit in appropriate patients - the response rate is 100 percent, 60 percent of patients have long-term absence of liver disease, and 5-year and 3-year survival rates are 33 percent and 25 percent, respectively - the conventional CT technique for determining resectability is not powerful, said Kevin Hughes, a surgical oncologist at Lahey Hitchcock Clinic.