Preclinical study of CD19 detection methods post tafasitamab treatment
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Dynamic Imaging of Chimeric Antigen Receptor T Cells with [18F]Tetrafluoroborate Positron Emission Tomography/Computed Tomography
Published on: February 17, 2022
Kristina Ilieva1, Markus Eberl1, Jan Jaehrling2
1Department of Translational Research, Translational Sciences, MorphoSys AG, Planegg, Germany.
Introduction:
Several CD19 targeted antibody-based therapeutics are currently available for patients with diffuse large B-cell lymphoma (DLBCL), including the Fc-modified antibody immunotherapy tafasitamab. This therapeutic landscape warrants the evaluation of potential sequencing approaches. Prior to a subsequent CD19-targeted therapy, CD19 expression on tafasitamab-treated patient biopsy samples may be assessed. However, no standardized methods for its detection are currently available. In this context, selecting a tafasitamab-competing CD19 detection antibody for immunohistochemistry (IHC) or flow cytometry (FC) may lead to misinterpreting epitope masking by tafasitamab as antigen loss or downregulation.
Methods:
We analyzed a comprehensive panel of commercially available CD19 detection antibody clones for IHC and FC using competition assays on tafasitamab pre-treated cell lines. To remove bound tafasitamab from the cell surface, an acidic dissociation protocol was used. Antibody affinities for CD19 were measured using Surface Plasmon Resonance (SPR) or Bio-Layer Interferometry (BLI).
Results:
While CD19 was successfully detected on tafasitamab pre-treated samples using all 7 tested IHC antibody clones, all 8 tested FC antibody clones were confirmed to compete with tafasitamab. An acidic dissociation was demonstrated essential to circumvent CD19 masking by tafasitamab and avoid false negative FC results.
Discussion:
The current study highlights the importance of selecting appropriate CD19 detection tools and techniques for correct interpretation of CD19 expression. The findings presented herein can serve as a guideline to investigators and may help navigate treatment strategies in the clinical setting.
Insights
Selecting the right CD19 detection antibody is crucial for diffuse large B-cell lymphoma (DLBCL) treatment. Acidic dissociation is essential for accurate flow cytometry results after tafasitamab therapy.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Several CD19-targeted antibody therapies, including tafasitamab, are available for diffuse large B-cell lymphoma (DLBCL).
- Assessing CD19 expression after tafasitamab treatment is important for subsequent therapy sequencing.
- Standardized methods for CD19 detection in this context are lacking, risking misinterpretation due to epitope masking.
Purpose of the Study:
- To evaluate commercially available CD19 detection antibodies for immunohistochemistry (IHC) and flow cytometry (FC).
- To assess the impact of tafasitamab pre-treatment on CD19 detection.
- To identify optimal methods for accurate CD19 expression analysis in DLBCL patients treated with tafasitamab.
Main Methods:
- Analyzed commercial CD19 antibody clones using competition assays on tafasitamab-treated cell lines.
- Employed an acidic dissociation protocol to remove bound tafasitamab from cell surfaces.
- Measured antibody affinities using Surface Plasmon Resonance (SPR) and Bio-Layer Interferometry (BLI).
Main Results:
- All 7 tested IHC antibody clones detected CD19 on tafasitamab-treated samples.
- All 8 tested FC antibody clones competed with tafasitamab.
- Acidic dissociation was critical to overcome CD19 masking by tafasitamab and prevent false-negative FC results.
Conclusions:
- The choice of CD19 detection antibody and technique significantly impacts interpretation accuracy.
- Standardized methods are needed for reliable CD19 assessment in DLBCL patients undergoing tafasitamab therapy.
- These findings provide guidance for selecting appropriate tools and interpreting CD19 expression in clinical settings.
