Development of potency assays for infectious diseases comes with a unique set of challenges. Fc engineered monoclonal antibodies require development of multiple bioassays that reflect the complex mechanism of action (MOA), such as virus neutralization and clearance via effector function. Potency assays need to be in place for early clinical development and validated at a later stage. This presentation will discuss the development of bioassays to support late-stage programs including the challenges faced and lessons learned.

A potency assay used for several years showed not to be sensitive to low-affinity insulin analogs as well as impacted by the Drug Product matrix. A story regarding implementation of two new potency assays as well as the learnings will be described.

The respiratory syncytial virus (RSV) prevention landscape has rapidly expanded, with 33 candidates currently in clinical development. We have demonstrated RSV neutralization on dried blood as an alternative for serum.  Functional antibodies in dried blood is a patient-centered solution that may replace serology testing in vaccine trials in LMICs and potentially be used as a tool to monitor protection against RSV globally.

Bioactivity characterisation and bioassays, in addition to reference standards, are essential for regulatory approval throughout the lifecycle of Biotherapeutics. However, harmonisation and traceability of bioactivity data depend on the availability of public reference standards to “translate” manufacturer’s proprietary units into “international units” to understand bioactivity, both longitudinally and across products, whilst using different assay platforms. We are developing a panel of reference reagents to benchmark assays which are used to characterise Fc-interactions. 

This presentation will discuss strategic bioassay development for different phases of a product’s lifecycle with emphasis on the bioassay considerations for undefined and/or complex MOAs at early stage development. The presentation will highlight CMC solutions for designing phase appropriate bioassays with regulatory considerations in mind.

Cancer cells can evade immune surveillance through various mechanisms, including immunosuppression pathways. These pathways stand out as notable targets for new therapies, as blocking these immunosuppression pathways can allow the body’s own immune system to destroy cancer cells. Monoclonal antibodies can be a means of blocking one such pathways. This presentation will discuss the development of bioassays to understand the mechanism of action such immunotherapies and the evolution of bioanalytical strategy from early phase to supporting late phase development.

Biological activity is a critical authenticity and quality attribute of novel biotherapeutics. Since data that we generate attribute to the quality of our products it is critical to create precise, accurate, robust quantitative methods that at the same time reflect clinical mode of action. The development of such tests for novel bispecifics is always a big challenge. Here we describe reporter test systems development and analytical characterization of bispecific antibodies.

In the statistical analysis of bioassays, the replicates at each dose level are often treated as independent when, in fact, they are related. This is especially relevant in the case of pseudo-replicates. One method to address this relationship is to average replicates before model fitting. We will examine the impact of averaging replicates on various aspects of the statistical analysis of bioassays, including parallelism assessment and relative potency estimation.

The concept of the analytical lifecycle has opened up new opportunities for bridging technologies, standards, and critical reagents in bioassay. Science and risk-based thinking combine to develop a program which replaces or complements traditional study-based approaches with effective use of continuous performance verification. This talk will examine and compare bridging approaches as a strategic component of the bioassay control strategy.

An underlying assumption to calculate relative potency is similarity between reference and test curves. This talk focuses on different similarity metrics, and how they impact the estimate of relative potency. The talk will focus on two different models, parallel line assay and the 4-pl assay. Discussion will also include the impact of a constrained model when similarity is not met.

The center of a specification for product potency represents the target value of 100%. Because assays used to measure relative potency yield lognormal data, statistical analyses must be performed on log transformed values. The center of the lot release specification becomes 0 for log base 10 transformation of relative potency 1.0 (100%). To conclude that a lot is satisfactory, statistical equivalence to 0 should be demonstrated. This requires that the reported value and its confidence interval (e.g., 90%) to fall within established equivalence bounds. Drifts in product potency, assay performance, and statistical error tolerance must be considered in setting bounds.