CARGO: advancing chimeric antigen receptor T cell therapy using nanobodydisplaying lentiviral vectors

CAR-T cell therapy is a form of adoptive cell transfer in which a patient’s T cells are isolated and genetically engineered in the lab using lentiviral vectors (LVs) to express so-called chimeric antigen receptors (CARs) recognizing cancer cell-associated surface antigens. These CAR-T cells are expanded in vitro after which they are reinfused into the patient where they recognize and kill cancer cells. While CAR-T cell therapy reached unprecedented results in hematological malignancies, this success has not yet been mirrored in solid tumors, while responsible for ~ 90% of cancer-related deaths. One of the reasons is the difficulty in finding the right target antigen. In this regard, B7-H3 and HER2 are considered antigens of interest, owing to their high expression on malignant tissue and low expression on healthy tissue. As antigen binding domain in CARs, nanobodies are considered a promising alternative to the commonly applied single chain variable fragment (scFv), as they avoid the occurrence of tonic signaling, the need for linker sequence optimization or humanization steps. Besides the
promising results with CAR-T cell therapy obtained so far, the costs associated with it are very high, reaching up to 330,000 euros per infused product. This high cost arises from the patient-specific nature of the CAR-T cell therapy production process and the relatively long vein-to-vein time that is needed to genetically modify and expand the patient’s cells ex vivo. When the treatment of solid tumors is intended, an increasing eligible patient population is expected, and patient-specific therapies are difficult to envision. In that context, in situ CAR-T cell engineering would reduce manufacturing time and cost by circumventing all ex vivo steps of T cell engineeringand increase availability by providing an off-the-shelf product.
The main objectives of my PhD, initiated in November 2020, are the development of a nanobody-based (nano)CAR-T cell therapy for treatment of solid tumors by targeting B7-H3 or HER2, and the development of T cell-targeted LVs for in situ CAR-T cell engineering.