New Imaging Agent Provides Better Cancer Diagnosis with More Effective Staging

The radioactive dye called technetium Tc-99m tilmanocept, effectively identified cancerous lymph nodes and was superior for marking cancers than the conventional standard dye.

The findings from the phase III clinical trial have been published in March 20, 2013, online in the journal Annals of Surgical Oncology. “Tilmanocept is a novel engineered radiopharmaceutical specifically designed for sentinel lymph node detection,” said David R. Vera, PhD, the drug’s developer, who is a professor in the University of California, San Diego (UCSD; USA) School of Medicine’s department of radiology. “The molecule, developed at UC San Diego School of Medicine, offers surgeons a new tool to accurately detect and stage melanoma and breast cancers while in the operating room.”

After a cancer diagnosis, surgeons want to be sure that the disease has not spread to a patient’s lymph nodes, especially the sentinel nodes that may be the first place that a tumor reaches. The lymphatic system is a conglomeration of and ducts and vessels that transmit disease-fighting cells throughout the body, but can also act as a way for cancer cells to access the bloodstream. By surgically removing and examining the sentinel nodes that drain a tumor, clinicians can better determine if a cancer has spread.

“Tilmanocept advances the molecular targeting in breast cancer. It's the first agent that is binding to a lymph node because it is a lymph node that plays an important role in metastasis,” said Anne Wallace, MD. professor of surgery, UC San Diego School of Medicine and principal investigator of the study. “Tilmanocept’s ability to identify more cancer containing nodes will lead to better postoperative care for patients, especially those patients who had more than one positive sentinel node.”

Physicians compared injections of tilmanocept (also known as Lymphoseek), and the conventional blue dye into the tumor area. Next, using a handheld radiation detector, they discovered the lymph nodes that had taken up the drugs radioactivity. The researchers revealed that more than 99% of sentinel lymph nodes containing blue dye also contained tilmanocept. Of these nodes, 18% were positive for cancer. Ninety-four percent of the malignancies were identified by the new radiopharmaceutical whereas the blue dye only detected 76%.

“Tilmanocept is just as accurate as current techniques, simple to use, takes less time to find lymph nodes, and is cleared faster from the body. This could standardize the process of lymph node mapping and make the process easier, particularly for less experienced surgeons,” said Dr. Wallace, chief of plastic surgery at UC San Diego Health System and director of the breast care unit at UC San Diego Moores Cancer Center.

Tilmanocept was originally developed at UC San Diego by Dr. Vera. Dr. Wallace refined the agent through phase 1 clinical trials. The phase III study was supported by Navidea Biopharmaceuticals, Inc. (Dublin, OH, USA).

Lymphoseek’s safety and effectiveness were established in two clinical trials of 332 patients with melanoma or breast cancer. The phase III clinical trial took place at 13 medical centers involving 148 patients who had both breast cancer and melanoma. The most common side effects identified in clinical trials was pain or irritation at the injection site reported by two patients.

Tilmanocept received US Food and Drug Administration (FDA) approval on March 13, 2013.

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