Lymph node-targeting tracer pinpoints more metastatic breast cancer

The newly approved imaging agent, Lymphoseek, sought out 94 percent of found breast cancer metastases to the sentinel lymph nodes, according to a study published in the March edition of the Annals of Surgical Oncology.

Anne M. Wallace, MD, chief of plastic surgery, from the University of California, San Diego School of Medicine, and colleagues, described a phase 3 trial focused on the comparative evaluation of [99mTc]Tilmanocept for sentinel lymph node mapping in breast cancer patients.

On the heels of the FDA granting approval for Lymphoseek earlier in March for use in intraoperative lymph-node mapping, this study published phase III findings for the lymph-node mapping agent, Tc-99m tilmanocept, comparing it to conventional vital blue dye (VBD) to assess potential metastatic breast cancer in tumor-draining and nearby sentinel lymph nodes. Lymphoseek was found to detect 111 more lymph nodes than VBD alone.

“The indication that [Tc-99m tilmanocept] may be able to better identify multinode pathology-positive patients may be important to the future of breast cancer treatment,” wrote the authors. “Specifically, extended field radiation therapy will be offered to these patients if not full node dissection.”

For this study, 148 patients with breast cancer were evaluated for metastases to sentinel lymph nodes using both Lymphoseek and VBD. A total of 320 nodes were identified by Lymphoseek imaging. VBD detected 207 out of 320. Lymphoseek detected 99 percent of the 209 nodes independently detected by VBD.

Of the 18 percent or 33 nodes that tested positive for malignancy with further histology, 31 had been detected with Lymphoseek, whereas VBD caught 25. Imaging with Lymphoseek works to pinpoint potentially problematic sentinel lymph nodes by targeting expression of CD206 receptors, so far an accurate homing device for sentinel lymph nodes.

“If blue dye alone were used, the addition of tilmanocept could potentially change the diagnosed number of positive nodes in 1.35 percent of our nation’s 190,000 or so breast cancer patients, which is roughly 2,000 patients per year,” noted the authors.