Examples of Types of PTM Modification Validations
PTM Method Modification Validations
This document is meant to provide an overview of PTM method modification data requirements based upon past method modifications submitted to the program. Each method modification is assessed when submitted and the appropriate level determined based upon the technology and function of the test method; therefore, data requirements for a method may necessitate other data requirements not listed in this document to substantiate the method modifications. In an effort to maintain consistency in data requirements for PTM method modifications the AOACRI has gathered details of all PTM method modifications from 2015‐2018 to assess the data requirements imposed for each modification to provide a summary of data requirements for modification categories. PTM method modifications are reviewed by the AOACRI office and by the AOAC subject matter expert, to determine if data are required to substantiate the method modifications. If data are required, the AOAC Expert will detail the data requirements and assign a modification level. Level 1 modifications are editorial changes to the package inserts, labels, method name changes and method developer name changes. Data are not required to substantiate these modifications; however, an updated license agreement is required for method name and method developer name changes. If package insert revisions are substantial within the method procedure the revised insert is reviewed by an AOAC subject matter expert to assess whether an evaluation of the method workflow is needed. Internal data may be requested to determine that not modification validation data are needed. Level 2 modifications either impact the method claim or improve the method function. Claim changes include addition of claimed matrices, addition of a reference method and/or expanded inclusivity. Kit changes include a wide variety of modifications. Internal data are often reviewed before specific modification data requirements are determined There are three PTM modification levels: Level 1 ‐ Editorial changes Level 2 ‐ Minor method modifications. Level 3 ‐ Major method modifications.
Table 1. Level 2 Method Modification Examples and Data Requirements Method Modification Data Requirement
Matrix extensions up to four matrices, depending on the number of matrices included in the original validation claim. For example: Original claim 4 – level 2 modification would be acceptable for only one matrix. More than five claimed matrices require an independent lab study. Original claim 6 – level 2 modification for the addition of 4 more matrices is acceptable without an independent study. Changes to non‐critical reagents (lyophilization, Taq,), does not include reagents that may affect specificity/sensitivity such as new antibodies or primer/probe sequences. Enhancement of method workflow (non‐ critical steps) Non‐reagent changes, such as changes to the cartridge or increase in number of wells Changes in matrix sample sizes
Matrix comparison study for all matrices.
Matrix comparison study for all matrices and samples sizes with the reference method samples size.
Inclusivity/exclusivity and matrix comparison data for a subset of claimed matrices. In some instances lot‐to‐lot, stability and robustness required.
Testing of 3 matrices inoculated post enrichment; inclusivity/exclusivity; lot‐to‐lot studies.
Dilution to extinction experiment. Matrix study 1‐3 matrices tested depending upon the overall matrix claim for the method (matrices chosen by AOAC). Inclusivity/exclusivity and matrix comparison data for a subset of claimed matrices (matrices chosen by AOAC). Where possible, the testing of frozen lysates from previous validation on new instrument. Inclusivity/exclusivity and matrix comparison data for a subset of claimed matrices.
New instrument, thermal cycler, PCR platform or other
Addition of DNA preparation methods
Addition or update reference method
Matrix comparison study for a subset of matrices.
Expansion of the inclusivity claim within the same target analyte species; for example, in the case of expansion of Listeria species claim. Expansion of stability claim for reagents/
Inclusivity and exclusivity testing (blind‐randomized).
whole kit
Stability study of frozen and refrigerated product; growth curve analysis, shelf‐life data and lot‐to‐lot; real‐time stability data; testing on several instruments. Depending upon the change and the technology, specific details will need to be reviewed by the AOAC volunteer expert. Lot‐to‐lot comparison testing of 1 lots from previous manufacturing facility and 3 lots from the new manufacturing facility. One target strain at 10XLOD tested using 10 replicate samples with fractional recovery results. Comparison of QA/QC data has been used when old lots are no longer available.
Software changes
Manufacturing location changes
Changes in raw agar ingredients
Inclusivity/exclusivity
Table 1 details a summary of level 2 method modifications and the data requirements to substantiate the changes. For most level 2 modifications a matrix comparison study is required, some inclusivity/exclusivity testing and possible robustness testing. For manufacturing location changes a lot‐to‐lot comparison testing scheme is used with lots from the previous manufacturing site to those lots from the current site. However, in instances where there are no available kits produced at the previous manufacturing site AOACRI has accepted QA/QC comparison data from kits produced at the new manufacturing site compared to QA/QC data from the previous manufacturing site. Level 3 modifications are major changes to the test method, components and/or workflow. Internal and independent study data are required to substantiate the method modification changes.
Table 2. Level 3 Method Modification Examples and Data Requirements Method Modification Data Requirement
Inclusivity/exclusivity, matrix comparison for subset of claimed matrices, robustness testing and an independent laboratory study.
Changes in enrichment media, extraction buffer, temperature and/or times. Matrix extensions where the number of matrices being added is exceeds the independent laboratory testing threshold of 1 matrix independently tested for every 5 claimed matrices in the original validation claim.
Matrix comparisons for all matrices being added and an independent laboratory study for 1 matrix for every 5 matrices in the total claim.
For example: Original claim 3 matrices – 6 matrices will be added bringing the total number of matrices to 9, triggering an independent laboratory study of two matrices (one matrix previously tested and one new matrix tested at the independent laboratory). Original claim 1 matrix – 5 matrices will be added bringing the total number of matrices to 6, triggering an independent laboratory study of two matrices (one matrix previously tested and one new matrix tested at the independent laboratory). Reagent formulation of the amplification reagent master mix Addition or removal of a test step (for example‐LFD step, second PCR step, confirmation step or molecular verification step)
Inclusivity/Exclusivity, matrix comparison for subset of claimed matrices and an independent laboratory study.
Inclusivity/Exclusivity, matrix comparison for subset of claimed matrices, and independent laboratory study.
Table 2 details a summary of level 3 method modifications and the data requirements to support the changes. Major modifications require substantial evaluation to ensure the modified method still meets the method performance claims. Examples of major method changes are changes to the enrichment protocol, addition of more than five matrices, change to a major kit component, reformulation of master mix reagents and addition or removal of a test step.
Reference Methods and Modifications
Method modifications will utilize the most current reference method available regardless of the reference method version used in the original validation study.
Publication of Method Modifications
Currently, Journal of AOAC INTERNATIONAL (JAOAC) publication of method modification study reports is not required. Publication of a method modification study report is at the discretion of the method developer.
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