The graphic shows the difference between the wild form of the protein (left) and the stable form SuperFolder CD19 developed by the research team. The red building blocks symbolize the stabilizing mutations.

A team of researchers at BOKU Vienna succeeded in producing a stable variant of the protein CD19. This SuperFolder CD19 opens up new possibilities in cancer therapy. It makes it possible to monitor the activity of CAR-T cells, a new type of immunotherapy whose success is currently triggering a boom in cancer research, but which can also lead to side effects.

The protein CD19 is one of the most relevant target molecules in the immunotherapy of leukaemia and lymphoma. So-called CAR-T cells recognise the CD19 structure on the surface of tumour cells and can thus destroy them. Until now, however, the CD19 protein has been extremely unstable and very difficult to produce because it often folds incorrectly or clumps together. "With the SuperFolder CD19, we now expressed a variant of the protein that is much more stable and much easier to produce than the wild type," explains Michael Traxlmayr from the Institute of Biochemistry at University of Natural Resources and Life Sciences, Vienna. This means that the activity of the CAR-T cells in the blood can be monitored and the treatment can be adjusted at an early stage.

Great expectations for personalized CAR-T cell therapy

In CAR-T cell immunotherapy, the body's own immune cells, the so-called T cells, are genetically reprogrammed and then administered to the patient. This enables the patient's own immune system to attack the cancer cells. The modified T-cells, the CAR-T-cells, therefore act in the body like a living medication. "They can multiply in the organism, which on the one hand is a great advance," Traxlmayr explains, "but on the other hand can lead to side effects." Therefore, CAR-T cells in the body must be monitored accordingly - their proliferation, multiplication and what functions they perform. A detection agent is needed for this. The protein CD19, which binds to the CAR-T immune cells, is ideally suited for this purpose.

Search among millions of mutants

In the course of their research, the team randomly introduced mutations into the CD19 protein. In this way, they created a library of several million CD19 mutants and then tested these variants for stability. The SuperFolder CD19 showed a particularly high quality. In addition to monitoring CAR-T cells, it also helps to analyse different CAR-T cell subtypes and their efficiency. "For science as well as medicine, it is extremely relevant to be able to examine whether and which CAR-T cell subtypes are active or inactive in the blood sample of patients," says Traxlmayr.

Traxlmayr's team has already patented the SuperFolder CD19 variant and is currently looking for exploitation partners who are interested in a licence.

The study was published in the journal ACS Synthetic Biology:
https://doi.org/10.1021/acssynbio.1c00010

Contact
DI Dr. Michael Traxlmayr
University of Natural Resources and Applied Life Sciences, Vienna
Institute of Biochemistry
E-mail: michael.traxlmayr@boku.ac.at
Phone: +43 1 47654-77274

Lisa-Ariadne Schmidt, MSc.
University of Natural Resources and Applied Life Sciences, Vienna
E-mail: lisa.schmidt@boku.ac.at
Tel.: +43 1 47654-33034