- breakthrough
- exploratory
- method development narrative
- optimization
- pre-validation
- regulated bioanalysis
- R&D
Vertical lines indicate iterations of and changes to the assay procedure. The magenta line corresponds to the method BT.
BT: Breakthrough; EP: Exploratory phase; MV: Method validations; OP: Optimization phase; PV: Pre-validation phase.
First draft submitted: 13 November 2016; Accepted for publication: 30 November 2016; Published online: 13 January 2017
Regulated bioanalysis (RB) often contradicts intrinsic R&D values. RB is intended to comply with regulations and as such follows a fixed study plan and experimental procedure, whereas methods in development evolve dynamically. Method development (MD) performed with a RB mindset may focus more on abiding to RB procedures and workflow rather than grasp the science at play. Except for exploratory method validations (MV) for biomarkers [1] and such, it is typically not possible to ‘fix’ a failing validated method without revalidation, which further emphasizes the importance of adequate MD before moving on to MV.
If it is true that R&D can be difficult to predict in terms of outcomes, timelines and budget, bearing in mind a robust method for productive sample analyses is the objective, the bioanalytical MD cycle can be schematized as a narrative informally followed to achieve that very objective.
A tentative to circumscribe bioanalytical MD is set forth (Figure 1) that outlines three MD phases: the exploratory phase (EP), the optimization phase (OP) and the pre-validation phase (PV). In addition, the turning point in MD is described as the breakthrough (BT).
The EP is ground-breaking and uncertain by nature. The EP could also be called a feasibility phase because usually it is where the method will make or break. At onset, the EP seeks signal responses over noise to shape a standard curve. The EP then lets the experimenter test and qualifies the method parameters for assay functionality, inner workings and pitfalls. One can alternatively view the EP as a sequence of hypotheses testing or troubleshooting experiments. It is also a self-educational crash course on the method. The EP can take the form of a method transfer. Nevertheless, the EP method is evolutive by nature and multiple iterations of the procedure are implemented with each assay leading to a functional assay.