That's a good point. I was assuming that when he said it passed titer but not S/N that both criteria were based on assay performance during validation. It is true that the within 2-fold dilutions can encompass a very wide range of S/N, so not necessarily the same.
Towards your question about imprecision, the challenge with immunogenicity assays is the absence of a reference standard to calibrate the signal. So in cases like this change in critical reagent, there isn't a built-in way to tune the signal.
Personally, I don't think we need more precision for a quasi-qualitative method, but perhaps a good topic for an upcoming Immunogenicity Working Group meeting?
But getting back to the original question, since it is a titer based assay, I don't see much issue in updating the QC ranges for the new reagent set UNLESS there are a lot of pre-existing antibodies that seeing titer changes OR if S/N is changed enough relative to negative control that you would impact the assay sensitivity. Perhaps running a sensitivity experiment with the new lots would be a good investigation step to see if the assay is still performing as expected with the new reagents?
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Joleen White Ph.D.
AAPS 2024 Global Health Community Chair
Bioanalytical 101 Course Development
Senior Advisor
BioData Solutions LLC
[email protected]Disclaimer: Opinions expressed are solely my own and do not express the views or opinions of my employer.
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Original Message:
Sent: 06-10-2025 11:36
From: Lauren Stevenson
Subject: Qualification/Bridging New Labeled Reagent for Immunogenicity Assay
@Joleen White, you raise an interesting question, which begs another question - if the assay is suitable for its intended purpose if using titers, why would it not be when using S/N? The assay itself and its precision are the same even if the chosen readout differs. Given the inherent imprecision of titers vs S/N it is not surprising that S/N would more finely detect differences in performance with different lots of reagents.
To the original poster, I would consider how you are using the data and whether the changes you've observed with the new lots will impact your ability to reliably distinguish clinically relevant from irrelevant responses and if you are trying to pool data across studies, how that may be impacted.
As an industry we have long accepted that a titer change <4x (assuming 2-fold dilutions) is not a real change. Are we still happy with that level of imprecision? If so, we should be mindful not to build more stringent criteria for S/N just because we can 'see' the imprecision more clearly. That said, I'll put on my biomarker hat and say in each instance we should consider context of use and ensure the assay meets the needs of the context and then determine allowable performance limits.
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Lauren Stevenson Ph.D.
Chief Scientific Officer
Immunologix Laboratories
Tampa FL
[email protected]
Disclaimer: Opinions expressed are solely my own and do not express the views or opinions of my employer.
Original Message:
Sent: 06-09-2025 12:33
From: Joleen White
Subject: Qualification/Bridging New Labeled Reagent for Immunogenicity Assay
If the titers are maintained and you are using a titer readout for the assay, then I don't think there is a major issue with using the new lots and establishing a new HPC and LPC range. This would be more problematic if you were using the S/N as a readout, so I'd love to hear from people using that readout about crossing in new reagents.
For what it's worth, this is one reason that I started shifting to having reagents made at a company that makes commercial FACS reagents. The cost is similar, but they have much better control of their process since it's what they do every day rather than what they do once in a while.
Also, while I know you posted anonymously, consider joining the critical reagent subteam. The next meeting is this Friday and this is very much the sort of topic they discuss regularly.
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Joleen White Ph.D.
AAPS 2024 Global Health Community Chair
Bioanalytical 101 Course Development
Senior Advisor
BioData Solutions LLC
[email protected]
Disclaimer: Opinions expressed are solely my own and do not express the views or opinions of my employer.
Original Message:
Sent: 06-03-2025 09:26
From: Anonymous Member
Subject: Qualification/Bridging New Labeled Reagent for Immunogenicity Assay
This message was posted by a user wishing to remain anonymous
Hello,
I would like to ask the community member for recommendations about the acceptance criteria when switching to the new Labeled Biotin and sulfo-tag reagent for immunogenicity assay (MSD bridging format).
We generated the new labeled reagents in several tries but the signal/noise ratios of HPC and LPC are outside the mean±3SD range of the historical lot while the titers are maintained. Is it ok to accept the new lot with high PC S/N result, what could be the impact? Thanks!