Title: Supporting homing and longevity of gamma delta T cells for cancer immunotherapy
Funder: The Academy of Medical Sciences

Abstract: Engineered T-cell therapies successfully treat haematological malignancies but not solid tumours, due to engineered cells failing to home to the tumour and a lack of fitness within the hostile microenvironment. Gamma-delta T cells (gdT) are a relatively overlooked subset of cells, but their presence in a tumour is the strongest positive correlate of good clinical outcome. Osteosarcoma, the commonest bone tumour in adolescents brightly expresses the tumour-associated antigen B7-H3, and compared to normal bone overexpresses a number of key chemokines, making it an amenable model for testing a novel approach. Using in-vitro validation followed by in-vivo live cell tracking by SPECT/CT, we propose the following: 1) Enhancing gdT homing. We will over-express chemokine receptors CXCR4, CCR2 and CXCR6 in gdT, determining the effects on homing to osteosarcoma cells in vitro and taking the lead receptor forward to in-vivo experiments using orthotopically injected osteosarcoma PDX. T-cells will be labelled with a sodium iodide symporter allowing repeated imaging for live-cell tracking over time. 2) Improving intra-tumoral fitness. IL-15 supports gdT cell expansion and survival. We will add an IL-15 secretion module to our construct and determine the effects on gdT cell phenotype and persistence in-vitro. Engineered cells will be injected into mice for live-cell tracking, using homing and persistence as readouts. 3) Enhanced anti-tumour cytotoxicity. We will add an anti-B7H3 antibody-secretion module to the construct, engaging the potent ADCC capacity of gdT cells and also allowing bystander ADCC engagement. Anti-tumour efficacy (measured by bioluminescence) and mouse survival will be used as readouts.

Lay abstract: Cancer immunotherapy using genetically modified immune cells to target tumours has been successful in blood cancers but not in solid cancer. Osteosarcoma, the commonest bone cancer in teenagers, is a particularly challenging target given its location in the bone. Three problems which prevent this kind of immunotherapy working for diseases such as osteosarcoma; getting the engineered immune cells to the tumour, they keeping them fit enough once they get there, and giving then a cancer-specific killing mechanism. First, we will modify T-cells to enhance their ability to seek out the tumour, and pick the construct that gives the best “homing” to test it in a mouse model of osteosarcoma. Using cutting-edge live-cell tracking technology we can see where the T-cells go after they’ve been injected, observing their movement to the tumour. Once we can get T-cells to the tumour, we will enhance their fitness. After testing the effects of adding immune stimulating factors to osteosarcoma/T-cell co-cultures, we will engineer the T-cells to secrete these factors themselves. Using live cell tracking in the mouse model we will observe whether our modifications help the T-cells survive in the tumour microenvironment. Finally, we will enhance T-cell tumour killing, using a technology we recently patented and which works well in other settings. At this point, we will determine the effect of treatment with these T-cells to control the growth of the tumour in the mice, before collecting the cells to analyse not only whether they kill the cancer, but how they do it.

Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS;5.2 CELLULAR AND GENE THERAPIES
Health categories: CANCER AND NEOPLASMS