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We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Your question indicates several misunderstandings regarding GLP.  First, the GLPs are applicable only to non-clinical work; clinical assay testing is not within the scope of the GLPs.  Second, GLPs focus on performing work in a manner that can be readily reproduced.  Assay validation is not an aspect of the GLPs. 

Now, to get to the root of your question.  The key aspect is whether you have an appropriate positive control to demonstrate that the assay methodology is valid; an actual human derived NAb positive control is not an absolute requirement.  If the mouse derived positive control, spiked into human matrix, can be shown to neutralize the activity of the therapeutic, it should be an acceptable positive control for the assay.  You should focus, through your assay validation experiments, on demonstrating that the assay is fit for purpose.  Furthermore, the analytical work should be performed in a fully documented manner in order to allow its re-creation. If both of these criteria are met, the assay results should be acceptable to regulators with respect to supporting the clinical immunogenicity conclusions. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Hi Yan,

Although a 'a human matrix sample exhibiting neutralizing ADA activity' would serve as an ideal PC for any clinical assay, the challenge you would run into with using this is sourcing enough of it to use it long term for the duration of your study. Additionally, utilizing a 'serum PC' for a CSF assay may not be appropriate as they may not be indicative of nAb responses in CSF. 

As mentioned in other comments, using an animal derived PC spiked into the same matrix as your study sample serves as an acceptable surrogate PC for studies. (The FDA guidance for Immunogenicity Testing  has a section for Selection of reagents for reference)

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Hi Yan,

Although a 'a human matrix sample exhibiting neutralizing ADA activity' would serve as an ideal PC for any clinical assay, the challenge you would run into with using this is sourcing enough of it to use it long term for the duration of your study. Additionally, utilizing a 'serum PC' for a CSF assay may not be appropriate as they may not be indicative of nAb responses in CSF. 

As mentioned in other comments, using an animal derived PC spiked into the same matrix as your study sample serves as an acceptable surrogate PC for studies. (The FDA guidance for Immunogenicity Testing  has a section for Selection of reagents for reference)

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Hi Yan,

Although a 'a human matrix sample exhibiting neutralizing ADA activity' would serve as an ideal PC for any clinical assay, the challenge you would run into with using this is sourcing enough of it to use it long term for the duration of your study. Additionally, utilizing a 'serum PC' for a CSF assay may not be appropriate as they may not be indicative of nAb responses in CSF. 

As mentioned in other comments, using an animal derived PC spiked into the same matrix as your study sample serves as an acceptable surrogate PC for studies. (The FDA guidance for Immunogenicity Testing  has a section for Selection of reagents for reference)

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!

Hi Yan,

Although a 'a human matrix sample exhibiting neutralizing ADA activity' would serve as an ideal PC for any clinical assay, the challenge you would run into with using this is sourcing enough of it to use it long term for the duration of your study. Additionally, utilizing a 'serum PC' for a CSF assay may not be appropriate as they may not be indicative of nAb responses in CSF. 

As mentioned in other comments, using an animal derived PC spiked into the same matrix as your study sample serves as an acceptable surrogate PC for studies. (The FDA guidance for Immunogenicity Testing  has a section for Selection of reagents for reference)

Thank you, John and all who have responded on this question so far.  

This is a cell-based NAb assay for a AAV mediated gene therapy administered directed into the brain.  We monitor NAb responses in CSF and serum.  I have a follow up question: is it a requirement that the positive QC being a normal human CSF, spiked with a monoclonal or an affinity-purified polyclonal ADA from animals?  Given that ADAs in CSF are likely derived from the blood, a human serum sample exhibiting neutralizing ADA activity could also serve as a suitable positive control for the CSF NAb assay, correct?

You are describing a critical assay reagent that is is mouse-derived. Most positive controls used in immunogenicity assays are produced using animals. It is not possible to obtain a human Ab . As John mentioned, what is needed is a purified animal-derived anti-drug antibody + the assay matrix (e.g. normal human serum). The only GCP-related problem I see now that when you validate the current assay, it will be hard to determine assay sensitivity, drug tolerance, and LPC concentration without using a purified antibody as PC. 

We have a cell-based CSF NAb assay in our clinical study.  A mouse Nab+ serum is used as a positive control because we are not able to find a human NAb+ CSF sample.  As such, is this assay considered to be a non-GLP/ research assay?   Thank you!