CADEMA's LYMPH-SCAN NDA FOR IMAGING LYMPHATIC DRAINAGE

CADEMA's LYMPH-SCAN NDA FOR IMAGING LYMPHATIC DRAINAGE in patients with breast cancer or malignant melanoma should be revised to focus only on the radiodiagnostic's lymphatic imaging indication and to remove any reference to the imaging technique's efficacy in disease detection, FDA's Radiopharmaceutical Drugs Advisory Cmte. recommended at a May 10 meeting. "I think approvability is what we would like to see," the cmte. chairman Barry Siegel, MD, Washington University, commented, "but I think that as a cmte. we are all troubled with the data as currently presented." Siegal noted that the NDA for Lymph-Scan (Technetium Tc 99m antimony trisul fide) is still in the early stages of agency review and could be revised with the assistance of the cmte. and FDA. "We are sensing that the medical officer who reviewed the NDA is troubled with it. We are also sensing. ..that this potentially is a very useful radiopharmaceutical to study certain kinds of things," the cmte. chairman said. "We are trying to figure out where we can get the groups to meet in the middle so that there might be a way to satisfy the statutory and regulatory requirements to allow this drug to be approved." The medical officer responsible for reviewing the Lymph-Scan NDA, Elias Chacalos, MD, told the cmte. that in his opinion "the clinical studies submitted by the firm are inadequate and too deficient to support" the lymphatic drainage imaging indication as claimed and the implication in Cadema's suggested labeling that the sulpher colloid will detect cancerous involvement in the lymph node. William Kaplan, MD, Harvard University, reported that the antimony sulfide colloid imaging technique has been successfully used in over 1,000 breast cancer and melanoma patients at Harvard's Dana Farber Cancer Institute for seven years. Injecting the antimony, which is non-toxic and chemically inert, Kaplan explained, allows "a gamut of inaccessible lymph channels" to be visualized. He said the procedure could be repeated often, if necessary, since "the side effects are zero and the radiation dose is extremely low." Kaplan stated that the major advantage of the test is that it is physiologic, and allows deficits in lymph node functioning to be seen "just as you can look at a liver scan and see a deficit in [functional] capacity." In treating malignant melanoma, Kaplan said a procedure like the Lymph-Scan "can define preoperatively the potential for metastic sites so the patients do not have to undergo these wide horrendous excisions only to [have tumors] recur regionally." The test, Kaplan stated, "doesn't say that there is definitely tumor in those nodes. But what it says is that before you do a wide excision and a procurative procedure that is disfiguring, the obligation is on the physician to prove that there is not dissemination at the time. . . This test allows us to do that." Kaplan maintained that the imaging technique is particularly valuable in determining the course of radiation treatment in breast cancer patients. "We can approach this now'on a patient by patient basis and limit the amount of radiation that we need to use to do the job," Kaplan explained. Middletown, N.Y.-based Cadema is a four-year-old company with current sales in excess of $1 mil. The company manufactures a patented aerosol device used for ventilation studies to differentiate between pulmonary embolism and obstructive lung disease, and holds the license for a red blood cell kit for cardiac imaging, and an instant imaging liver kit employing a biodegradable colloid. The company is also working on therapeutic drugs for metastatic bone disease and rheumatoid arthritis. Maurice Bordoni is Cadema's president. The company acquired Lymph-Scan from Roche in 1982, and submitted an NDA for the agent in December 1983.