CYTOGEN’s ONCOSCINT CR/OV APPROVED FOR IMAGING OF COLORECTAL/OVARIAN CANCERS; CYTOGEN AND COMARKETER KNOLL LAUNCHING MAJOR MEDICAL EDUCATION EFFORT

Cytogen's OncoScint CR/OV became the first monoclonal antibody-based imaging agent approved by FDA when Cytogen's PLAs were cleared on Dec. 29 for the imaging of "known" colorectal and ovarian cancers. OncoScint (satumomab pendetide) is indicated for "determining the extent and location of extrahepatic malignant disease in patients with known colorectal and ovarian cancer," the approval letter states. The cancers must be either recurrent or previously diagnosed by other methods, such as computed tomography. The approved indication conforms to January 1992 recommendation by FDA's Biological Response Modifiers Advisory Committee that OncoScint not be used as a first-line imaging agent to diagnose new cancers. The PLAs for OncoScint (89-600, 89-601, 90-0278) were approved two to three years their filing by Cytogen: the colorectal cancer indication was filed in September 1989 and the ovarian indication was submitted in March 1990, receiving an orphan designation. FDA approved the recurrent ovarian cancer treatment Taxol, which could be used following tumor reappearance, on the same day (see preceding stories). Cytogen estimates that 677,000 patients are currently being monitored for reoccurrence of colorectal cancer and 38,000 for ovarian cancer. Approximately 156,000 new cases of colorectal cancer and 21,000 new ovarian cancers are diagnosed each year. OncoScint CR/OV will be comarketed by Cytogen and Knoll Pharmaceuticals. The firms have had 20 and 45 sales reps, respectively, at the ready since June, when Cytogen initially expected approval, to detail the product to the 1,500 to 2,000 hospitals that are expected to account for 75% of sales. In addition, Knoll has 350 detail people available to target secondary hospitals and physicians outside the nuclear medicine field. Cytogen and Knoll are mounting a major medical education program for nuclear medicine physicians beginning in late January, around the same time that the firms will begin shipping product. The companies will conduct 70 workshops nationwide over an eight- week period and have hired a technical staff to assist physicians in the use of the product and in interpretation of results. Cytogen has learned through its European experience with OncoScint that medical education is of paramount importance for the product's success. In its third quarter report, the company noted its dissatisfaction with the 1992 sales of OncoScint of $351,000 through September. "EuroCetus, our partner responsible for marketing OncoScint in Europe, has defined the issue as a lack of familiarity by European nuclear medicine practitioners with this new diagnostic tool and a need for more comprehensive medical education." The OncoScint CR/OV monoclonal antibody kit will be sold directly to hospitals or radiopharmacies at a cost of about $400. The monoclonal antibody is to be linked to the radioisotope Indiclor (indium-111 chloride) manufactured by Amersham that will be sold separately at a price of $400-$450. Cytogen expects that hospitals will order the already "linked" imaging agent from radiopharmacies such as Amersham's Medi-Physics, Syncor or Mallinckrodt at an added cost of $50-$100. The MAb is produced under a shared manufacturing arrangement with Celltech, which produces bulk satumomab in England. In clinical studies, the MAb-imaging agent showed a 70% sensitivity in detecting tumors. When OncoScint imaging by gamma camera is used in addition to CT scans, the sensitivity rises to about 90%. In a Dec. 30 "Talk Paper," FDA noted that "diagnostic testing with the new imaging product does not replace CT scans and other standard tests but can be used with them." The major safety issue identified by the advisory committee involved OncoScint's human anti-mouse monoclonal antibody response in 40% of the patients in the Phase III trials. Cytogen has conducted repeat administration studies to see whether the HAMA response has an effect on the accuracy of multiple uses of the imaging agent. The company said it has filed the data with FDA.