scFv and CAR Cell Specificity Testing

Chimeric antigen receptor (CAR) T cell therapy involves engineering the patient’s own immune cells to recognize and attack a specific tumor. It has shown long-term promise in patients with advanced disease. As the therapy works by harnessing the immune system, it is crucial that there is no CAR cell cross reactivity, or off-target binding, that could promote an inappropriate immune response and be very dangerous for the patient. As we have developed a methodology for labelling and analyzing whole CAR cells, our technology is now widely used for cross-reactivity specificity testing of both the finalized engineered CAR cells as well as the precursor antibody / scFv.

Retrogenix Cell Microarray Technology is now a standard IND-enabling safety assessment tool for developers of novel CAR cell therapies. Our CAR cell specificity testing data were included in the BLA submissions for Novartis’ Kymriah in both the US and EU. Since this breakthrough approval in 2017, our screens continue to be widely used in CAR cell therapy INDs / BLAs globally.

Off-Target Profiling Cell Microarray Technology
Discover high quality, exploitable drug targets and mechanisms of action as well as screening for potential off-targets.

Off-Target Screening Off-Target Screening
Understand cross-reactivity to reduce toxicity-based attrition and aid lead selection.

Target Deconvolution Target Deconvolution
Accelerate phenotypic drug discovery through target deconvolution of phenotypic molecules.

Receptor Identification Receptor Identification
Uncover receptors for proteins, viruses, and more complex ligands such as whole cells.


Screen scFv or Whole CAR Cells

Using the Retrogenix Cell Microarray Technology, there are two approaches for CAR cell cross-reactivity screening:

  • Screen the antigen recognition element – the scFv / antibody
  • Screen whole engineered CAR cells

Early specificity testing helps select the right scFv in order to maximize the chances of producing the most promising potential CAR therapy. This can be followed later by screening of the whole engineered T cell (or the final scFv) to provide a more relevant assessment of off-target liability. As there may be a discordance between the off-target profile of the original antibody (or scFv) and the final engineered T cell, it is possible to screen both to ensure that the binding has not been altered in development.

graphic render of molecule binding to the receptors on the cell.

CAR-T Cell Specificity Testing for Safety Assessment of Novel Immunotherapies

Download our poster describing how Retrogenix Cell Microarray Technology has been optimized to screen whole CAR cells for specific interactions and potential cross-reactivity.

Download the Poster

Retrogenix Data in Regulatory Applications

To help with understanding the role of Retrogenix Cell Microarray Technology cross-reactivity screening in regulatory submissions, and to quantify the extent to which it is replacing methods such as IHC-based tissue cross reactivity (TCR) screening, we undertook a survey to find out how recently screened biotherapeutics are progressing. Pharma, biotech, and non-profit sponsors who have undertaken at least one project in the past two years were surveyed – click here to read more.

Contact An Expert


Frequently Asked Questions (FAQs) for CAR Cell Specificity Testing