by Loren Bonner
, DOTmed News Online Editor
On Wednesday, the U.S. Food and Drug Administration approved a new radioactive diagnostic imaging agent used to help doctors with the staging and management of breast and melanoma cancer patients.
According to Frederic H. Fahey, DSc, president of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), the new drug, technetium Tc 99m tilmanocept (Lymphoseek), will give doctors a more accurate way to find the sentinel lymph node, which in turn will help them determine where the patient's cancer has spread.
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During the standard sentinel node biopsy procedure for breast and melanoma cancer patients, which determines if the cancer has spread beyond the primary tumor and into the lymphatic system, doctors use a handheld radioactive detector to find which lymph nodes have been taken up by the agent's radioactivity. They remove them and look for cancer.
"Tc 99m tilmanocept lets you be more confident that you are taking the correct lymph node out," Fahey told DOTmed News.
Previous lymph node mapping agents — including sulfur colloid and isosulfan blue — were based on the size of the particle and would occasionally miss the correct sentinel lymph nodes. Sulfur colloid was approved by the FDA in 1974 and isosulfan blue in 1981.
Over 30 years later, the arrival of a new lymph node mapping agent — Lymphoseek — is a testament to the advancements in molecular imaging that have taken place over the past 10 to 15 years.
"It's a receptor-based agent that targets receptors on the surface of the lymphatic cells," said Fahey. "It has more of targeted approach to how it decides what the sentinel lymph node is."
In other words, whether the agent goes to the correct lymph node is no longer based on the size of the particle; instead it depends on the agent actually seeking out the lymphatic cells and sticking to them, according to Fahey.
For patients, this means the agent can be injected in a more convenient manner because it stays in place for a longer period of time.
"You can inject the agent on the day of the surgery or inject it the day before surgery," said Fahey.
According to a statement from the FDA, data from the clinical trials that established approval of the drug showed a notable number of nodes were localized only by Lymphoseek, compared with blue dye, another drug used to help locate lymph nodes.
The trials consisted of 332 patients in two trials with melanoma or breast cancer. All patients were injected with Lymphoseek and blue dye.
Lymphoseek is marketed by the Dublin, Ohio-based Navidea Biopharmaceuticals Inc., but will be distributed in the U.S. by Cardinal Health Inc., according to a statement from Navidea Biopharmaceuticals.Back to HCB News