The US Food and Drug Administration (FDA) approved the technetium Tc 99m tilmanocept ([Tc 99m], Lymphoseek Injection; Navidea Biopharmaceuticals)—a novel radioactive receptor-targeted tracer for intraoperative lymphatic mapping—for use in patients with breast cancer or melanoma who are undergoing surgery to remove tumor-draining nodes. Tc 99m is an imaging drug that helps locate lymph nodes; it is not a cancer imaging drug.
Lymph nodes filter lymphatic fluid that flows from the body’s tissues. This fluid may contain cancer cells, especially if the fluid drains a part of the body containing a tumor. Surgically removing and examining the lymph nodes that drain a tumor in patients with node-negative breast cancer or melanoma can help determine if a cancer has spread.
“Removal and pathological examination of lymph nodes draining a primary tumor is an important diagnostic evaluation for some patients with breast cancer or melanoma,” said Shaw Chen, MD, Deputy Director of the Office of Drug Evaluation IV in the FDA’s Center for Drug Evaluation and Research. “To use Lymphoseek, doctors inject the drug into the tumor area and later, using a handheld radiation detector, find lymph nodes that have taken up Lymphoseek’s radioactivity.”
Lymphoseek is the first new drug used for lymph node mapping to be approved by the FDA in more than 30 years.
The approval of Tc 99m was based on 2 clinical trials of 332 patients with melanoma or with breast cancer. All patients were injected with Tc 99m and blue dye, another drug used to help locate lymph nodes. Surgeons subsequently removed suspected lymph nodes for pathologic examination. Results showed that Tc 99m and blue dye had localized most lymph nodes, although a notable number of nodes were localized only by Tc 99m.
The most common side effects with Tc 99m reported in clinical trials were pain or irritation at the injection site. (March 13, 2013)
