Automated cGMP optical labeling of FDA-approved antibodies for human use

Monoclonal antibodies are commonly used as targeted therapies for autoimmune, infectious and oncologic diseases. Here, we describe a simple protocol to optically label monoclonal antibodies for use as molecular imaging agents for clinical investigation. In preclinical settings, optical imaging has complemented the strengths of nuclear imaging while offering higher resolution and a safer method for antibody-ligand engagement. However, translation of optically labeled monoclonal antibodies to the clinic has been slow because antibodies require a manual process in current good manufacturing practices (cGMP)-compliant facilities; the cost barriers to establish the investigational new drug application by using the traditional contract research organization pathway (>US$1 million) exceed the resources of academic institutions and early-phase pharmaceutical companies. To address these challenges, we repurposed an existing radiolabeling cGMP method for optical labeling that uses an automated, self-contained synthesis module. This method depends on commercially available, single-use, cassette-based production, which simplifies the workflow and does not require a clean room facility. This automated production method reduces both the cost and time required to produce a clinical dose of near-IR fluorescently labeled monoclonal antibody-IRDye800CW, decreasing the development costs for pilot and initial batches by almost 90%, as well as the production time by 40% to 4 h plus quality control (~10 h total). Our cGMP manufacturing method can optically label any compatible monoclonal antibodies at any dedicated radiochemistry facility. We provide the detailed protocol for production of panitumumab-IRDye800CW and nivolumab-IRDye800CW under cGMP regulations, achieving excellent yield, optimal degree of labeling and high purity.