**3. Qualification of characterization methods**

118 Analytical Chemistry

and Kelner 2008).

validation manufacturing lots.

new, under development, or subject to process or method changes, this activity is often called qualification, while more formal confirmation of method suitability for commercial applications is called validation (Ritter, Advant et al. 2004; Apostol and Kelner 2008; Apostol

The strategy for method validation involves a continuum of activities that begins at the start of process and product development and carries through to the marketing application and beyond. Typically, analytical method development begins after the biological target has been identified and verified, the protein therapeutic has been defined (primary sequence), and the sponsor has made the decision to develop a manufacturing process that will enable human clinical trials. The initial demonstration that the method is suitable for its intended purpose for use as a release and stability method is generally carried out in the form of method qualification, an activity that generally takes place prior to the release of the material for first-in-human (Phase 1) clinical trials. At the later stage of product development, typically prior to the start of pivotal phase III clinical trials, method developers perform qualification studies which will enable method validation. Finally, method validation generally takes place prior to the release and stability testing of the

It should be noted that although method qualification, which evaluates the performance characteristics of the method against meaningful target expectations, is a critical development activity that establishes the suitability of the method for release of early to mid-phase clinical materials, this activity is not, to the best of our knowledge, clearly defined in regulatory guidance, which tends to focus on method validation. It is therefore difficult to define the scope of method qualification, though regulatory expectations and industry practices have evolved to define method qualification as a means to assure acceptable method performance during process and product development, prior to the

The necessity of method validation has been reinforced by a variety of national and international regulations (USP 1994; USP 1999; CDER 2001; ICH 2005) which are subject to user interpretation. For example, current GMP regulations, [21 CFR 211.194 (a)] require that methods used in testing of the samples meet proper standards of accuracy and repeatability. Validation provides assurance that this regulation is met. USP <1225> defines validation of analytical procedures as the process by which it is established by laboratory studies that the performance characteristics of the procedure meet the requirements of the intended analytical application. ICH guideline Q2R1 defines validation of analytical procedures as the demonstration that the method is suitable for its intended purpose. ICH guidance specifies that validation of analytical procedures needs to be included as part of the registration package submitted within the EU, Japan and USA. While the biotechnology industry, in a manner analogous to the pharmaceutical industry, is heavily regulated, the majority of the regulations are targeted at commercial products, leaving a significant gap in available regulatory guidance for earlier stages of product development. While numerous articles have been published to provide the scientific principles and exemplify the types of

formal validation exercise that occurs before the testing of the validation lots.

Characterization methods typically involve highly specialized technologies which are labor intensive and difficult to perform on a routine basis, which includes, for example, AUC, CD, FTIR, DSC, SEC-LS , and NMR. These methods are often used to supplement lot release methods to provide orthogonal detection/separation modes and/or to verify structural integrity (e.g. primary, secondary, tertiary structure). This is in contrast to Quality Control methods, which typically employ proven technologies to enable in-process controls, lot disposition and GMP stability assessment in the GMP laboratory setting, requiring stringent assessment of performance characteristics that follow ICH guidelines. Therefore, it is important to define an appropriate level of qualification for these complex and non-routine characterization methods. Industry practice has evolved multiple means of defining a qualification path for characterization methods, including:


Recently Jiang et al. provided an excellent review of the qualification of the biophysical methods including AUC, CD, FTIR, DSC, SEC-LS, MFI and LO based methods. The authors describe how qualification of these methods enables better knowledge of the methods and objective interpretation of the results. The general considerations described there can be applied to other biophysical methods as appropriate as well (Jiang, Li et al. 2012). In most cases qualification of biophysical methods is focused on the determination of precision and demonstration that the methods are suitable for their intended applications. Successful qualification enables the understanding of the method capability and the consistent determination of product attributes.
