Potential Assays for Monoclonal Antibodies and Other Therapeutic Proteins

The purpose of this guidance document is to provide recommendations in the development of monoclonal antibodies (mAbs) and other therapeutic proteins that directly target viral proteins or host cell proteins that mediate pathogenic mechanisms of infection. A critical quality control measure for these products is the development and implementation of potency assays to ensure that each batch is consistently manufactured with the potency required for clinical efficacy and that this potency is maintained throughout the shelf life of the product.

The guide provides detailed recommendations for pharmaceutical manufacturers with the goal of ensuring that they provide adequate information to assess efficacy at each stage of a product's life cycle. To ensure the clinical efficacy of mAbs and therapeutic proteins until the end of the product's shelf life, a company must develop one or more methods to monitor the efficacy of the biological product. Potency assays for mAbs and therapeutic proteins should be designed to measure the binding to viral receptors on host cells, inhibition of viral entry, and/or triggering of Fc-mediated effector function. Efficacy assays should also be designed to reflect the biological activity of the mAb or therapeutic protein in vivo. Measurements of potency using these methods should be used to demonstrate that only product batches that meet established specifications or acceptance criteria are administered during all phases of clinical testing and after approval.

All potency methods used for release and stability testing must comply with the applicable biologics regulations and current good manufacturing practice regulations. In evaluating the adequacy of a potency assay for a particular mAb or other therapeutic protein for the treatment or prevention of a viral infection, the FDA considers, among other factors, the following:

• Product characteristics
• Manufacturing processes
• Stage of development at which the assay is to be used
• Risk-based quality assessment
• All information submitted by the manufacturer

The following examples of methods and additional guidance for testing efficacy are considered in the FDA guidance:

• Binding Assays (e.g. ELISA, SPR)
• Viral Neutralization Assays (e.g. pseudo typed virus assay, virus-like particle-based assay)
• Fc-Effector Function Assay

The guidance should be viewed as a recommendation from the FDA, making the implementation described voluntary.

To learn more about the methods described in the article, as well as more on the subject, please access the main FDA article entitled "Potency Assay Considerations for Monoclonal Antibodies and Other Therapeutic Proteins Targeting Viral Pathogens".