How an evidence-led decision takes shape.

Improving protein stability in a biological fluid

Challenge: A protein's performance varied with storage and buffer conditions, making results inconsistent and its use in assay development uncertain.

Approach: A Design of Experiments study tested buffer components and storage conditions together. It showed that interactions between the protein and specific buffer components drove the variability.

Outcome: A reformulated buffer improved stability and consistency, giving development a reliable starting point.

Holding assay performance through scale-up

Challenge: An assay that performed well at prototype scale became more variable on larger equipment, putting transfer timelines at risk.

Approach: A side-by-side comparison of the two methods covered equipment settings, critical materials, process parameters and acceptance criteria, and showed where the larger equipment did not reproduce prototype conditions.

Outcome: Critical parameters were redefined and the methods aligned, reducing variation and giving a sound basis for manufacturing transfer.

Reducing recurring QC failures

Challenge: Repeated QC failures caused investigations, material loss and disruption. Some acceptance criteria were also stricter than the product required.

Approach: A root-cause investigation covered reagents, raw materials, process conditions, test methods and operator factors. Controls were then reviewed against product requirements and process capability.

Outcome: Process changes and evidence-based control limits reduced QC failures, with controls still matched to quality requirements.

Making feasibility data reliable enough to decide

Challenge: A sandwich immunoassay gave acceptable signal, but variability across runs and reagent lots made feasibility conclusions unreliable.

Approach: Variability was mapped across plates, operators and reagent lots, alongside a review of conjugation, blocking and controls. The conjugation approach and controls that masked matrix effects were the main drivers.

Outcome: Variability fell within acceptable limits, supporting a confident decision to proceed to development.

Tracing calibration drift to protein loss and instability

Challenge: Calibration in an immunoassay drifted over time, undermining confidence in results across runs.

Approach: Two causes were found. At low concentration, the calibrator protein was adsorbing to its storage vessel, and the protein was also losing stability even at low temperature. Stock concentrations were checked against the international standard and the storage buffer was reassessed.

Outcome: Adding a carrier protein reduced adsorption and a revised storage buffer improved stability, giving more consistent calibration over time.

When buffer results don't hold in real samples

Challenge: Proof-of-concept results in buffer and mock samples looked good, but performance changed with real samples. A few outliers pushed CVs outside acceptable limits.

Approach: Outlier samples were investigated for interactions within the sample matrix, and performance was compared across buffer, mock and real samples to separate assay issues from matrix interference.

Outcome: The sources of interference were identified and addressed, so the data reflected how the assay performs in real samples.

Keeping low-concentration reagents stable through storage and shipping

Challenge: Conjugates and reagents at low protein concentration lost activity over time and during shipping stress tests.

Approach: Storage buffers were reformulated with added stabilisers and surfactants such as Tween, and tested under storage and simulated shipping conditions.

Outcome: Reagent stability improved through storage and shipping, supporting reliable performance across shelf life.

Replacing a critical material when a supplier withdrew

Challenge: A supplier stopped selling a critical material, putting continued production at risk.

Approach: Alternative sources were identified, evaluated and qualified against the assay's performance requirements.

Outcome: Supply was secured without loss of performance, and qualifying a secondary supplier became part of the risk strategy for critical materials.