Window Trial of Fluorescently Labeled Panitumumab (Panitumumab-IRDye800) in Head and Neck Cancer

The primary objective of this study is to understand biologic dosing of panitumumab which would contribute to the field by establishing new methodology for dose selection with the aim of reducing toxicity in cancer patients. For the individual patient in this trial, panitumumab itself is unlikely to demonstrate anti-tumor efficacy. However, previous studies have shown some benefit when using panitumumab-IRDye800 (pan800) as an imaging agent intraoperatively. The investigators hope to improve patient outcomes by gathering clinical data to support pan800 as a tool for reducing positive surgical margins and to identify malignant lymph nodes during surgical resection.

The drug being used in this study, panitumumab, is approved by the US FDA for treatment of certain types of advanced colorectal cancer at a dosage of 6 mg/kg given every 14 days. Many of the reported adverse events are associated with repeat administration of panitumumab, rather than 1-2 doses being administered in this study. However, the investigators do anticipate some adverse events at therapeutic dosing (anticipated grade 1-2). The most common side effects patients have experienced when receiving panitumumab primarily include skin reactions (including acne like rash, dry or itchy skin, cracking of skin around the participants nail beds, skin infections, and dry eyes), fatigue, nausea, and diarrhea.

Currently, there is no standardized method to identify the optimal biologic dose (OBD) for oncology therapies. Traditionally, dosing has been based on toxicity levels, specifically the maximally tolerated dose (MTD), rather than actual therapeutic effectiveness. In early-stage oncology trials, MTD often guides dose selection, with plasma drug concentrations serving as a rough measure for dose optimization. However, this plasma provides limited insight into how much of the drug actually reaches the tumor or binds to the intended target.

This study proposes a novel approach to finding OBD by measuring tumor drug concentration in head and neck cancer patients using an optically labeled antibody therapy. The investigators hypothesize that if a drug reaches a maximum concentration at a lower dose that previously thought, there may be no utility in increasing systemic dosing and risk unnecessary toxicity as well as financial burden.

Our group has previously published data using a fluorescent labeled therapeutic antibody (panitumumab-IRDye800) to show heterogenous distribution of antibody within a patient tumor in head and neck cancer. These studies used a single standard dose of panitumumab-IRDye800 which was shown to localize to malignant tumor tissue with minimal adverse events. In this proposed clinical trial, investigators will leverage this previously used fluorescent drug to investigate tumor concentration at multiple dose points up to and including the current FDA approved therapeutic dose to investigate our primary objective. Investigators will similarly use intraoperative fluorescence to assess the ability of the labeled antibody to distinguish malignant vs benign tissue at a range of doses. This intraoperative use has the potential to help optimize surgical margins and identification of malignant lymph nodes in addition to our primary objective of dose selection.

The main aim of this study is to investigate tumor concentration of fluorescently-labeled panitumumab at multiple doses up to the current FDA-approved therapeutic dose of panitumumab. This will allow us to identify if tumor saturation with this agent occurs below the currently approved dose. For other molecularly-targeted agents, there is evidence that lower doses can provide similar therapeutic benefit to approved doses. For panitumumab, over 30% of patients receiving this agent receive dose reductions due to adverse effects, resulting in a significant proportion of patients receiving a dose that is below the approved level. However, it is unclear if patients receiving this reduced dose achieve tumor saturation and similar therapeutic benefit. In this study, researchers will investigate if tumor saturation plateaus at a lower dose - an objective in line with dose optimization guidelines from the FDA. Our group has previously published data using fluorescently-labeled panitumumab to show heterogenous distribution of antibody within a patient tumor in head and neck cancer. Data from our previous and current work have allowed us to elucidate the relationship between fluorescence and intratumoral antibody concentration. An additional aim of this study is to provide further data on the efficacy of fluorescently-labelled panitumumab in identifying cancer relative to surrounding normal tissue. Improved tumor localization of the fluorescent agent could facilitate improved margin resections in the operating room.