Metastatic and sentinel lymph node mapping using intravenously delivered Panitumumab-IRDye800CW.

Rationale: Sentinel lymph node biopsy (SLNB) is a well-established minimally invasive staging procedure that maps the spread of tumour metastases from their primary site to the regional lymphatics. Currently, the procedure requires the local peri-tumoural injection of radiolabelled and/or optical agents, and is therefore operator dependent, disruptive to surgical workflow and restricted largely to a small subset of malignancies that can be readily accessed externally for local tracer injection. The present study set out to determine whether intravenous (IV) infusion of a tumor-targeted tracer could identify sentinel and metastatic lymph nodes (LNs) in order to overcome these limitations. Methods: We examined 27 patients with oral squamous cell carcinoma (OSCC), 18 of whom were clinically node negative (cN0). Patients were infused intravenously with 50mg of Panitumumab-IRDye800CW prior to surgical resection of their primary tumour with neck dissection and/or SLNB. Lymphadenectomy specimens underwent fluorescence molecular imaging to evaluate tracer distribution to LNs. Results: A total of 960 LNs were analysed, of which 34 (3.5%) contained metastatic disease. Panitumumab-IRDye800CW preferentially localized to metastatic and sentinel LNs as evidenced by a higher fluorescent signal relative to other lymph nodes. The median MFI of metastatic LNs was significantly higher than the median MFI of benign LNs (0.06 versus 0.02, p < 0.05). Furthermore, selecting the highest five fluorescence intensity LNs from individual specimens resulted in 100% sensitivity, 85.8% specificity and 100% negative predictive value (NPV) for the detection of occult metastases and 100% accuracy for clinically staging the neck. In the cN+ cohort, assessment of the highest 5 fluorescence LNs per patient had 87.5% sensitivity, 93.2% specificity and 99.1% NPV for the detection of metastatic nodes. Conclusion: When intravenously infused, a tumour-targeted tracer localized to sentinel and metastatic lymph nodes. Further validation of an IV tumor-targeted tracer delivery approach for SLNB could dramatically change the practice of SLNB, allowing its application to other malignancies where the primary tumour is not accessible for local tracer injection.

Safety and Stability of Antibody-Dye Conjugate in Optical Molecular Imaging.

PURPOSE: The development of molecularly targeted tracers is likely to improve the accuracy of diagnostic, screening, and therapeutic tools. Despite the many therapeutic antibodies that are FDA-approved with known toxicity, only a limited number of antibody-dye conjugates have been introduced to the clinic. Thorough evaluation of the safety, stability, and pharmacokinetics of antibody conjugates in the clinical setting compared with their parental components could accelerate the clinical approval of antibodies as agents for molecular imaging. Here we investigate the safety and stability of a near-infrared fluorescent dye (IRDye800CW) conjugated panitumumab, an approved therapeutic antibody, and report on the product stability, pharmacokinetics, adverse events, and QTc interval changes in patients. PROCEDURES: Panitumumab-IRDye800CW was made under good manufacturing practice (GMP) conditions in a single batch on March 26, 2014, and then evaluated over 4.5 years at 0, 3, and 6 months, and then at 6-month intervals thereafter. We conducted early phase trials in head and neck, lung, pancreas, and brain cancers with panitumumab-IRDye800CW. Eighty-one patients scheduled to undergo standard-of-care surgery were infused with doses between 0.06 to 2.83 mg/kg of antibody. Patient ECGs, blood samples, and adverse events were collected over 30-day post-infusion for analysis. RESULTS: Eighty-one patients underwent infusion of the study drug at a range of doses. Six patients (7.4 %) experienced an adverse event that was considered potentially related to the drug. The most common event was a prolonged QTc interval which occurred in three patients (3.7 %). Panitumumab-IRDye800CW had two OOS results at 42 and 54 months while meeting all other stability testing criteria. CONCLUSIONS: Panitumumab-IRDye800CW was safe and stable to administer over a 54-month window with a low rate of adverse events (7.4 %) which is consistent with the rate associated with panitumumab alone. This data supports re-purposing therapeutic antibodies as diagnostic imaging agents with limited preclinical toxicology studies.