Shaw Chen, MD, PhD
The FDA approved the radioactive diagnostic imaging agent technetium Tc 99m tilmanocept (Lymphoseek Injection) to identify lymph nodes for potential removal in patients with breast cancer or melanoma. It is the first lymph node mapping drug to be approved by the FDA in more than 30 years.
The newly approved diagnostic tool is a first-in-class mannose receptor (CD206)-binding radiopharmaceutical agent that is used for external lymph node imaging (lymphoscintigraphy) and intraoperative lymphatic mapping. Surgical oncologists can use these methods to identify lymph nodes that drain a tumor. By removing such nodes, doctors can check for lymphatic fluid that contains cancer cells as a means of determining whether a patient’s disease 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, PhD, deputy director of the Office of Drug Evaluation IV in the FDA’s Center for Drug Evaluation and Research, in a statement. “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.”
Two other agents have been approved by the FDA for lymph node mapping, but the Lymphoseek Injection is the first to receive approval from the government agency in decades. Sulfur colloid was approved in 1974, and isosulfan blue, also known as vital blue dye (VBD), was approved 1981.
Lymphoseek was approved based on the results of previously reported phase III trials. In the results of a study that were presented at the 2011 Annual Meeting of the American Society of Clinical Oncology, Lymphoseek was compared to VBD for intraoperative lymphatic mapping in 153 breast cancer and melanoma patients across eight centers. When compared with VBD, Lymphoseek identified more lymph nodes (373 vs 227), had a higher sensitivity (100% vs 72%), and had a lower false negative rate (0% vs 28%) than its predecessor.1
The new drug is relatively well tolerated, with the most commonly reported adverse event being pain or irritation at the injection site.
“Over the past 20 years, surgical staging of the regional nodes with intraoperative lymphatic mapping and sentinel node biopsy has emerged as the worldwide standard of care for patients with clinically node-negative intermediate and thick melanomas, and for selected patients with higher-risk thin primaries as well,” said Vernon K. Sondak, MD, chair of the Department of Cutaneous Oncology at Moffitt Cancer Center in Tampa, Florida, and principal investigator for melanoma in the Lymphoseek phase III clinical trials, in a statement. “New technologies offer the promise of improving intraoperative lymphatic mapping, allowing procedures to be done more quickly and potentially lessening the risk of misclassifying patients as node-negative when in fact their tumor has already spread to the regional nodes.”
The drug is marketed by Dublin, Ohio-based Navidea Biopharmaceuticals, Inc. In addition to breast cancer and melanoma, Lymphoseek is being investigated for use in head and neck cancer, and a phase III clinical trial is currently enrolling patients (NCT00911326).
1. Cope FO, Sondak VK, Wallace AM, et al. A phase III study of receptor-targeted 99mTc-tilmanocept versus blue dye in the evaluation of SLNs in breast cancer and melanoma. J Clin Oncol. 2011;30(suppl 29; abstr LBA8526).