Tilmanocept as a novel tracer for lymphatic mapping and sentinel lymph node biopsy in melanoma and oral cancer

Abstract

Background: Sentinel lymph node biopsy (SLNB) has been pivotal for pathological assessment of nodal status in cutaneous melanoma (CM) and oral cavity squamous cell carcinoma (OCSCC) thus crucial for staging. An ideal agent for lymphatic mapping should have a standardized preparation, appropriate accumulation in first-echelon nodes and no side effects. Tilmanocept, a CD206-receptor targeted novel radiotracer fulfils these properties. This study investigated Tilmanocept for lymphoscintigraphy and intraoperative identification of sentinel lymph nodes (SLN) in CM and OCSCC. Methods: This prospective cross sectional study examined patients who presented to Crown Princess Mary Cancer Centre, Westmead Hospital, Sydney. Patients had biopsy proven tumours with clinically and radiologically negative regional lymph nodes. Tilmanocept guided lymphoscintigraphy was followed by intraoperative SLNs identification via handheld gamma probe. Primary endpoints were detection and retrieval rate of SLNs while secondary endpoints included pathological status of SLNs. Results: Thirty-five patients were included (26 with CM and 9 with OCSCC) with the most common primary tumour site for CM on the extremities (33.3%). Lymphoscintigraphy with Tilmanocept identified at least 1 SLN (sensitivity 100%) in all patients. SLNs were retrieved in all of patients intraoperatively (100% retrieval rate) with positive nodes found in 20% of patients. Tilmanocept also demonstrated 100% tissue specificity, with lymph nodal tissue confirmed histologically, with no false positives. Conclusion: Tilmanocept is a reliable radiotracer for assessing the nodal status in patients with CM and OCSCC. Our group is the first to evaluate the use of Tilmanocept in the Australian setting, adding to the limited studies worldwide.

Comparative aspects of targeted sentinel lymph node mapping in veterinary and human medicine: opportunities for future research

“…The mechanism of action of 99m Tc-tilmanocept for SLN mapping revolves around its small molecular size (16.7 kDa) and diameter (7.1 nm) which allows for rapid transportation through afferent lymphatics ( 55 , 58 ). The mannose receptor (Cluster of Differentiation 206, CD206) is expressed on the surface of macrophages and reticuloendothelial cells, which are highly concentrated in lymph nodes ( 51 , 57 , 59 ). CD206 recognizes and binds to macromolecules with carbohydrate side chains that terminate with a mannose glycoside on 99m Tc-tilmanocept ( 51 ).…”

Diagnostic biopsy of cutaneous melanoma, sentinel lymph node biopsy and indications for lymphadenectomy

“…Tilmanocept, a CD206 receptor-targeted novel radiotracer, has recently been introduced for lymphoscintigraphy to assess nodal mapping[ 28 ].…”