Your comments on Recommendation for Large Molecule Bioanalysis
Reagents and their Stability
There are three sections to this questioner. After reviewing the L4 Draft Recommendations, please
respond to the questions and provide your thoughts/comments.
Please email your responses to King, Lindsay (GRO) Lindsay.King@pfizer.com.
I. Your expectations for the recommendation document (for the L4
team)
1) Do you prefer the recommendations as a best practices (A), as a general recommendation (B) or as
more a specific recommendation (C)?
 (A)
(B)
Please Comment
(C)
2) Would you like to have a table with an overview of a general understanding of the stability of the
different groups of critical reagents, which could be used to set the first stability period, if there is no
experience with the reagent or similar reagents?
 Yes  No
Please comment
3) Would it add value to the recommendations to include examples for further understanding?
 Yes
 No
If you answered ‘Yes please provide a brief explanation
4) Would you like the recommendation to include issues, that it is important to be aware of?
 Yes
 No
Please comment
Page 1 of 8
II. Current practices at your company
1) Do you have an SOP or other document that describes how you will test if you change lots/batches of
critical reagents and the description of the stability testing you use?
 Yes
 No
Please comment
2) Do you have any minimum requirements for the documentation of the production of critical reagents?
 Yes
 No
Please comment
3) If you test for stability of a reagent by the acceptance of the assay performance, how many QC
concentration levels would you use for testing?
Please comment
4) If you test for stability of a critical reagent by the acceptance of QC's in the assay, would you also include
(QC and or max) response to be able to follow a possible trend in response?
 Yes
 No
Please comment
5) Would you include critical reagents stability in your method validation or would it be keep separately?
 Include
 Separate
6) Would you like the recommendation to include issues that it is important to be aware of?
 Yes
 No
Please comment
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7a) If you have a commercially available critical reagent would you use the expiry date from the supplier?
 Yes
 No
7b) Are you able to extend this?
 Yes
 No
Please comment
8) Have you identified what changes in reagents would lead to a revalidation of the assay and how to do
this?
 Yes
 No
Please comment
9) Do you have any minimum requirements for your CoA for critical reagents?
 Yes
 No
Please comment
10 a) Would you add expiry date or retest date to the CoA for critical reagents?
 Yes
 No
10 b) Is it possible to extend the expiry date of a critical reagent as long as the assay is performing
acceptably?
 Yes
 No
Please comment
11) Do you consider a new dilution from your "mother" stock as a new lot or the same lot?
 Yes
 No
Please comment
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III.L4 Reagents and their Stability Recommendations
(This questionnaire is to be reviewed in conjunction with the L4 slide desk which contains addition
information and explanation)
1) Defining Critical Reagents
The L4 team recommends the following: Reagent that are analyte specific are most often considered
critical reagents; Ab, peptides, proteins, conjugates, Drug as reagent, ADA reagents including positive and
negative control.
Do you agree with this recommendation?
Yes
No
Would you find the recommendation useful or hard to fulfill in practice?
Yes
No
If you answered ‘No’ to either of the above, please provide a brief explanation
2) Documentation
The L4 team recommends an SOP or similar document that defines reagent requirements including how,
what, where and when. We recognize that documentation may take many forms. Documentation is
required to ensure a consistent and reproducible process.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
3a) Characterization of selected critical reagents
The L4 team recommends sufficient characterization to enable consistency/process control including;
identity, source, purity, concentration (or titer), binding affinity, isotype (Mab/polyclonal), MW, specificity,
incorporation ratio, aggregation level, storage.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
4) Reagent Characterization/Qualification Based on Assay Performance:
4a) The L4 team recommends that specificity (e.g. min. cross-reactivity with structurally related
compounds) is tested/defined as per guidance.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Page 4 of 8
Yes
Yes
No
No
4b) The L4 team recommends that selectivity (non-specific binding and/or interference) is tested as per
guidance.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5a) Changing Critical Reagents (Tier 1)
5a1) The L4 team recommends a comparison to original reagent in assay (re-optimize assay if needed)
based on assay acceptance criteria including maximum signal.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5a2) The L4 team recommends, where possible, testing in parallel with current/original reagent over
multiple runs.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5a3) The L4 team recommends testing in reagent qualification runs and then decide on degree of
validation required
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5b) Changing Critical Reagents (Tier 2)
5b1) The L4 team recommends testing performance in assay when a Single Critical Reagent Changes –
min. 1 reagent qualification run in parallel with current/original lot, include 5 QC levels and max. response
as an acceptance criteria.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Page 5 of 8
Yes
Yes
No
No
5b2) The L4 team recommends testing performance in assay when a Single Critical Reagent Changes and
no overlap with current /original lot – min. 3 independent reagent qualification runs, include 5 QC levels
and max. response as an acceptance criteria. (e.g. second biotinylation of a monoclonal from same lot of
purified Ab as use initially).
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5b3) The L4 team recommends testing performance in assay when a Multiple Critical Reagent Change –
min. 3 independent runs. May require some degree of re-validation for Regulated work. Include 5 QC
levels and max signal as acceptance criteria.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
5b4) The L4 team recommend that a failure of assay to meet performance specifications after ‘minor’
changes, loop back to Tier1 and;
• Review new reagent characterization;
• If acceptable, re-optimize assay
• Redefine Assay performance in multiple runs
• New assay validation may be required
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
Yes
Yes
No
No
5c) The L4 team recommends control charting for monitoring assay performance.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
6) Reagent Stability: within the assigned stability period
6a) The L4 team recommend assigning test/retest rather that expiry dates to define critical reagent
stability initially.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Page 6 of 8
Yes
Yes
No
No
6b) The L4 team recommend critical reagents be stored long term at -20C or colder unless there are
specific known stability issues.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
6c) The L4 team recommend defining how to test regent stability including; who will do what test, where
the data will be stored, what criteria will be used, where to document this work.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
6d) The L4 team recommend reagents stability specific runs be documented in a separate folder from the
validation. (Option to link to method(s)). Define these stability test runs using the assay as stability runs to
differentiate from other runs.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
6e) The L4 team recommends acceptance criteria include back calculated concentrations of 5 QC levels.
Recommend including max. signal monitoring through the use of control charts from all acceptable runs
with the assay (validation and sample analysis) until enough data is obtained to include max signal as
acceptance criteria.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
6f) The L4 team recommend defining a process for addressing stability related failures to allow a
scientifically defendable rational for either repeating the stability test or concluding that the reagent is no
longer stable.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Page 7 of 8
Yes
Yes
No
No
7) Stability Test/Retest Expiry Date Extension. Beyond the assigned stability period
7a) The L4 team recommend defining extension of reagent expiry a priori (test/retest date) and then
define how and against what criteria.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
7b) The L4 team recommends that extension be based on data (there are a number of potential ways d to
obtain this).
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
No
No
8) Reagent life cycle management
The L4 team recommends that regardless of the approach used to address reagent stability and test/retest
date, assay performance must be monitored for both in house and commercial reagents.
Do you agree with this recommendation?
Would you find the recommendation useful or hard to fulfill in practice?
If you answered ‘No’ to either of the above, please provide a brief explanation
Yes
Yes
Please email your responses to King, Lindsay (GRO) Lindsay.King@pfizer.com.
Page 8 of 8
No
No