(M1230-01-02) Bridging Strategy Methods for an Accelerated Late-Stage mAb

Purpose: As Biologics products move into later stages of development, new or updated methods are often required to monitor product critical quality attributes (CQAs). Method changes may be required for multiple reasons including new knowledge about the process and/or product, process changes, new specifications, internalization of methods from an externally acquired program, or the availability of technology at validation sites. At times, the transferred analytical methods may not be consistent with the internal analytical lifecycle requirements and phase-appropriate needs and thus do not meet the internal Analytical Target Profiles (ATP), such as Accuracy, Resolution, Specificity, and Stability-indicating needs. Because of these differences, the release and stability specifications may not translate appropriately between updated and original methods. Therefore, bridging studies are performed to understand the differences in the analytical methods and corresponding impact on reportable results.

Methods: Size Exclusion Chromatography (SEC) and Capillary Electrophoresis Sodium Dodecyl Sulfate (CE-SDS) are two common analytical methods used to measure aggregation and fragmentation, respectively, of large molecules. Here, we discuss the bridging strategy for the transition from the original SEC and CE-SDS (under reduced and non-reduced conditions) analytical methods to updated methods for a traditional mAb.  For this case study, the results from each method were subjected to statistical analysis and their profiles were compared visually to further understand differences.

Results: Results for SEC and CE-SDS for the legacy and new methods showed that the new methods improve resolution and quantitation of aggregates (in SEC) and fragmentation (in CE-SDS) to meet the target ATP. However, these improvements resulted in statistical offsets which required re-evaluation of specifications and a strategy for framing legacy versus new stability for shelf-life indicating attributes including the observation of “new” impurities due to the optimized methods.

Conclusion: This case study will discuss the benefits of introducing new methods (i.e., improved robustness, efficient analytical lifecycle management, setting of patient centric specifications, etc.) while highlighting a strategy to address statistical offset of the results and better resolution to quantify new impurities in later stages of development.

Figure 1: SEC Assay: In Legacy method HMW1 merges to the monomer peak or resolves in the monomer shoulder (run to run variation). New method consistently resolves HMW1 from the monomer peak.


Figure 2 and 3: SEC Bridging: There is an offset of 0.7 for %HMWS and -0.7 for %Monomer.


Figure 4:: CE-SDS Assay: (A) Legacy method tends to underestimate the impurities by not quantifying the impurity peaks which either co-resolve with the 10 kDa standard or which are below QL of the main peak. (B) New method consistently quantitates all impurity peaks.