Immunotargeting of Cervical Cancer Cells with the Adaptor CAR T-Cell Platform RevCAR

The Prostate Stem Cell Antigen (PSCA) is not only overexpressed in prostate cancer (PC) but also in many other tumors, including cervical cancer (CC). The adaptor chimeric antigen receptor (CAR) platform RevCAR can be used for immunotargeting of PSCA-expressing tumor cells. We found that the CC cell line SiHa natively expresses PSCA. The expression was sufficient for redirection of RevCAR T-cells using recently described RevCAR target modules (RevTMs) directed against PSCA. Like almost all PC cell lines, however, SiHa cells also downregulate their PSCA expression in cell culture. To overcome this limitation, we established artificially PSCA-overexpressing SiHa cells. Retargeting of RevCAR T-cells strictly depends on PSCA-directed RevTMs and PSCA-expressing target cells. It leads to (i) upregulation of CD69, Perforin and Granzyme B, (ii) lysis of target cells with EC50 values in the picomolar range, and (iii) cytokine secretion of IFN-γ, TNF-α, GM-CSF and IL-2. Phenotypic analysis shows a prominent increase in memory RevCAR T-cells but only a slight increase in exhausted cells, indicating a low level of tonic signaling of RevCAR T-cells. Together, our data supports an efficient and safe immunotargeting of PSCA-expressing CC cells with the RevCAR technology.