In vivo CAR-T-cell HIV therapy using in vitro reconstituted virus-like particles

PROJECT SUMMARY/ABSTRACT “Killer” (“cytotoxic”) T cells are the cells of the immune system that have the job of killing cancerous and virus-infected cells. But they do so only if they have receptors capable of recognizing antigens – expressed on the surface of target cells – that are specific to the cancer or

virus involved. And often it is the absence or shortage of these antigen-specific receptors that is responsible for a patient not surviving the growth and metastasis of a cancer or the spread of a viral infection. Accordingly, immunotherapies have been developed that involve: extracting T cells from a patient; transforming them so that they express the desired receptors; “expanding”

(“growing up”) the cells; and, finally, putting them back into the patient so that they can lower the load of cancerous or virus-infected tissue. Aside from the cost and danger of extraction and infusion of immune cells, this ex vivo procedure – the current state-of-the-art of immunotherapy – introduces serious risk of oncogenesis because the T-cell transformation involves the (poorly-

controlled) integration of receptor genes into the T-cell chromosomes. What we are proposing is a totally different approach that avoids the risks of both the extraction/infusion and of the chromosomal transformation. More explicitly, our aim is to transform T cells in vivo, by delivering the receptor genes directly to the T cells in the blood and

lymph system of the patient; further, the genes are in mRNA form so that their expression is transient, involving no change in chromosomal DNA; finally, the mRNA is protected and targeted by being self-assembled in vitro with purified viral capsid protein, so that its shell is functionalized with an antibody against proteins uniquely expressed in T cells.

Our methodology involves the complementary expertises of the two PIs. Dr.Gelbart’s lab has worked for the past 15-years on the in vitro packaging of mRNA into virus-like particles (VLPs) using the capsid protein of a plant virus that is capable of self-assembling around arbitrary- sequence RNA, and on the functionalization of these particles with targeting antibodies and other

protein ligands. Dr. Yang’s lab has worked for the past 25-years on the basic biology of HIV infections and specifically on the ex vivo transformation of T cells with T-cell receptors (TCRs) and/or chimeric antigen receptors (CARs) that are specific against HIV or cancer antigens and on quantifying the cell-killing activity of these transformed T cells. Together we will be developing

an In vivo T-cell therapy along the lines outlined above and demonstrating its efficacy in a mouse model of HIV.