Modification of a patient’s own T cells to carry a chimeric antigen receptor (CAR) recognising a cancer cell surface antigen can promote a specific anti-tumour response and potentially confer long-term immunity to cancer. Minimising the risk of triggering an inappropriate immune response through unanticipated off-target binding of the engineered CAR T cells is essential in ensuring patient safety.
Screening using human cell microarrays – also known as plasma membrane protein arrays (PMPA) – has been successful in identifying key receptors for orphan ligands and for phenotypic molecules as well as detecting potential off-target receptor interactions that may impact on the safety profile of lead biotherapeutic compounds.
Here we describe a PMPA approach for specificity screening of whole engineered CAR T cells as a supportive tool in safety assessment of novel cancer immunotherapies.
Materials and methods
T cells, isolated from healthy donors and engineered to carry an anti-CD19 CAR, were provided to Retrogenix by bluebird bio, along with donor-matched untransduced T cell controls. All T cells were labelled with a far-red fluorescent cell dye in order to detect interactions with plasma membrane binding partners using Retrogenix’s PMPA technology as described here.
Optimisation of the ratio of T cells to the underlying HEK293s, as well as careful control of washing stringencies, was required to develop the technology in order to reliably and reproducibly identify specific binding events.