In our blog discussing the use of cellular assays for neutralizing antibody (NAb) detection, we touched on the value that bioassays offer through their ability to closely mimic the effects that a biotherapeutic drug product will have on the body without the use of animals in the study. This is what makes cell-based potency assays the choice for measuring and validating the therapeutic activity of a drug product within prescribed ranges of safety, purity, and strength (potency), which is a requirement for regulatory submission and both clinical and commercial lot release.

Potency testing measures drug product attributes related to quality and manufacturing controls, assessing, as FDA describes, “the specific ability or capacity of the product, as indicated by appropriate laboratory tests or by adequately controlled clinical data obtained through the administration of the product in the manner intended, to effect a given result.” These measurements assure the potency and stability indicated of products used during all clinical investigation phases are consistent, and that only product lots that meet defined specifications or acceptance criteria are administered throughout the clinical study and following market approval.

As you can imagine, manufacturers are prohibited from releasing any lot until potency and related tests of conformance, comparability, and stability are completed to applicable standards. While cell-based assays for potency testing can be more difficult to develop than nonbiological methods such as ligand-binding assays, regulatory authorities still prefer and recommend that manufacturers make every attempt to first develop a cell-based potency assay to measure process consistency and drug potency. This is because cell-based assays are reflective of mechanism of action and can evaluate a product’s active ingredient(s) within a living biological system. This provides a better understanding of the actual physiological response a patient may have. The earlier the method is established for product testing, the more data can be collected and leveraged in later phases of product development prior to commercial launch.

Upholding Good Manufacturing Practice (GMP) Standards
While the appropriate measurements of potency are determined on a case-by-case basis based on individual product attributes, all potency assays used for lot release or stability testing must comply with current GMP regulations. This process includes assay validation to identify and quantify potential sources of error related to all relevant assay parameters such as accuracy, precision, specificity, linearity, range, system suitability, and robustness.

Unfortunately, the complexity of biotherapeutic drug products – from the inherent variability of cell lines to multiple active ingredients and potential effector function of cells – make it difficult to establish potency assays that can uphold GMP requirements through various phases of product development. For that reason, FDA recommends an incremental approach to potency assay implementation and encourages development of a method in early phases of the product life cycle for dosing and clinical protocol design purposes.

The Value of Progressive Potency Testing
Potency assays for product lots used in early clinical studies are more likely to have a wider acceptance range than those used in later phase trials. To save time and ensure the assay’s ultimate ability to gather meaningful data about product efficacy, this range should be adjusted throughout development stages as clinical and manufacturing experience is gained and historical data are collected.

Continuously refining and ‘dialing in’ quantitative potency measurements as the clinical study progresses helps to streamline later phase product development by obtaining sufficient proof of the appropriateness of its usage for GMP lot release, confirming suitability of product specification range, and demonstrating adequate control strategies in manufacturing processes. This approach ensures that product lots are quantitatively measured, biologically active, and consistently manufactured within well-defined limits.

Potency Assay Design Considerations
When designing a cell-based potency assay to GMP standards, the objective is to collect data that will allow you to evaluate the assay’s suitability for its intended use. This includes but is not limited to:

  • Incorporating a sufficient number of replicates to allow for statistical analysis and meaningful result reporting;
  • Using sample randomization to reduce biases; and
  • Including appropriate controls to accept or reject data collected

Assay design should also address factors that can influence assay variability and ensure accurate result reporting that is as close to the real value as possible. Although you should strive to limit variability wherever possible, some sources of variation are unavoidable and should therefore be properly accounted for, balanced, and measured. Ensuring lot-controlled laboratory supplies, pre-qualified critical reagents and reference standards, calibrated and regularly maintained instrumentation, and appropriately trained staff that adhere to defined standard operating procedures (SOPs) are all ways to reduce variability and create a well-designed assay.

Potency Testing Requires Cell-Based Assay Expertise
When working to develop robust potency assays for lot release testing, many manufacturers find it difficult to maintain the level of expertise and/or resources required in-house to meet and establish current GMP regulation standards. It takes a partner with deep cell-based assay knowledge and a wealth of hands-on experience to effectively navigate both the scientific and regulatory complexities of such potency testing. Because considerable data are needed to develop a suitable measurement of product potency, the assay will likely need to be optimized over time as more information is obtained. This also makes it critical to team with a bioanalytical lab that is open and collaborative in their approach, so you can ensure that assay parameters are being continually reviewed and refined.

BioAgilytix’s experts have extensive expertise in developing and supporting cell-based potency assays using various platform methods under GMP guidelines. Combining scientific expertise and statistician support, we are capable of utilizing both biological and statistical tools in stages from assay development to sample analysis to ensure data collected and trended meet current industry standard and health authority expectations. We deliver these services through a proactive, transparent project management model, working scientist-to-scientist to overcome complexities by applying extensive past cell-based method experience, new GMP laboratory suite, and expert GMP knowledge to optimize your method to comply with all regulatory guidelines. GMP potency assays developed, qualified, or validated at BioAgilytix include:

  • Proliferation (Celltiter Glo, resazurin, MTS, ANP)
  • Cytokine Secretion (MSD, Luminex, ELISA)
  • Growth Factor Stimulated Phosphorylation (MSD)
  • Complement Dependent Cytotoxicity (CDC, MTS)
  • Erythrocyte Lysis (Absorbance)
  • Oligonucleotide/protein competitive binding (Absorbance)
  • cAMP upregulation
  • Reporter and engineered proximity assays

Interested in how we can help you with your complex cell-based potency assay? Speak to one of our scientists today. Also be sure to stay tuned for the next blog in our series which will discuss how BioAgilytix is utilizing cell-based assays to bring new insights at the discovery phase of development.