Clinical Translation of Gene Modified T-cell Therapy for Solid Tumours

Prostate cancer is the second most common cause of cancer related death in men in the United Kingdom (UK) . Despite recent advances there is a pressing need for new therapies for this important patient group. One approach that is showing great promise across a range of cancer types is the use of a patients own immune system to fight their cancer. The aim of this fellowship is to develop a cellular immune therapy for men with advanced prostate cancer.
Synthetic genes known as chimeric antigen receptors (CARs) can be introduced into human immune cells called T-cells using viruses. The T-cells then express the CAR on the surface of the cell. The CAR functions by recognising surface molecules on cancer cells. At the time of recognition the CAR molecule activates the T-cell, telling it to kill the cancer cell. We have a CAR which recognises a protein on prostate cancer cells called prostate specific membrane antigen (PSMA). The PSMA targeting CAR has been tested extensively, and been shown to be highly efficient at activating T-cells to kill prostate cancer tumours in the laboratory. To further improve the CAR therapy we can express two other genes with the CAR in human T-cells. The first is a gene made from two different cell surface receptors for immune signalling molecules called cytokines and the second if a gene for a cell membrane pump found naturally in the thyroid called hNIS. Together these three genes are known as PiN4. T-cells engineered to express PiN4 have been studied, showing that all three genes work as required.
To develop PiN4 for a clinical trial we need to keep the T-cells alive and well once they are re-introduced into the patient. We also need to improve their ability to travel to tumours, and to enable them to survive, expand and kill tumours once they encounter them. With these aims in mind this fellowship will develop methods for delivering the cytokine interleukin-4 (IL-4) into tumours by fusing it to an antibody specific for the tumour. If we are successful at this we predict that the fusion molecule called FAB4DE will improve CAR T-cell survival and ability to kill in the tumour itself, whilst reducing the likelihood that the CAR T-cells will find low levels of PSMA in normal tissue causing unwanted damage.
The second important part of this fellowship is use of the hNIS to enable imaging of the T-cells once they are back in a patient. The hNIS in normal life is used by the body to take iodine into the thyroid for the manufacture of hormones. We can use it to take up molecules called radioisotopes into our T-cells which can then be detected using scanning techniques. This enables us to see where the T-cells which have hNIS on their surface have gone in the body. We have some proof of concept data to show that this can be accomplished, but the process needs to be tested to ensure it is reliable. We also want to investigate the best combination of radioisotope and scanning technique to ensure maximum sensitivity for detecting the PiN4 T-cells in humans. Ultimately this imaging approach will help us determine if our T-cells are going where we want them to go, and doing what we want them to do. It will help us to tailor treatment to individual patients depending on the penetration of the PiN4 cells into their tumours.
Finally the goal of this fellowship is to reach the point of being able to test PiN4 in prostate cancer patients. To this end work will be done to ensure all the safety and efficacy testing is in place to enable us to seek approval from the regulatory authorities in the UK to undertake a first in man clinical trial.
The Fellow is a medical oncologist an clinical scientist with a background in CAR therapy research. Working on this fellowship will enable the Fellow to develop as a clinician scientist and clinical trial investigator for the direct benefit of cancer patients in the UK.

Aim:
The aim of this fellowship is to develop immunotherapy for prostate cancer for the purpose of clinical translation.
Methodology:
A chimeric antigen receptor (CAR) P28z, which selectively recognises the prostate cancer antigen prostate specific membrane antigen (PSMA) co-expressed in one retroviral open reading frame with a chimeric cytokine receptor 4ab and the human sodium iodide symporter (hNIS) (collectively known as PiN4) has been generated. The expansion, survival and homing of PiN4 T-cells requires optimisation. To this end two novel immunocytokines will be compared with interleukin-2 (IL-2) and IL-4 for their ability to support PiN4 cytotoxicity via the 4ab. PiN4 function will be evaluated by production of pro-inflammatory cytokines and destruction of tumour monolayers after co-culture. Cytotoxicity will be quantified by MTT assays.
Homing, and persistence of PiN4 cells in vivo will be studied by SPECT and PET imaging of the adoptively transferred T-cells capitalising on expression of the hNIS.
The optimal combination of PiN4, immunocytokine/cytokine support and treatment schedule will be determined in vivo by studies of tumour xenograft destruction quantified by bioluminescence imaging of established xenografts engineered to express luciferase.
Scientific and medical opportunities of the research:
The scientific opportunities of this work focus on overcoming hurdles to translation of CAR therapy in solid tumours. Specifically to improving T-cell homing and persistence in the tumour micro-environment, whilst reducing the risk of PiN4 T-cells damaging normal tissues in which low levels of PSMA can be found. If successful these techniques can be used to enhance the function and safety of CARs targeting different tumour associated antigens.
Medically the generation of a protocol and regulatory documents for a first in man study is the ultimate goal of this fellowship.

Who will benefit from this research?
As outlined in Academic beneficiaries this research will contribute to the efficient development of CAR therapy through addressing obstacles to translation. Wider beneficiaries may be found in the private sector through the development of immunocytokines. These molecules are potentially amenable to intellectual property (IP) protection and commercial development.
Finally it is hoped that this research will directly impact on prostate cancer patients, and through the development of process, and the development of immunocytokines it will be translatable into treatment protocols for other malignancies.
How will they benefit from this research?
The academic community will benefit through the publication of data which helps in the design of CAR therapies.
The development of IP may lead to a commercially viable drug which in turn could lead to industry investment in further development of CAR therapy in the UK.
For patients the way in which they benefit is the greatest question. Hopefully we will be seeing future studies showing robust statistically significant survival benefits for cancer patients treated with CAR therapy in the next decade. One potential criticism of the study of cell therapy in man to date is the relative lack of randomisation. It is difficult to make a case for new therapy, especially with significant risk of toxicity without concrete evidence of benefit. It is an ambition of this Fellow to address this through well designed research for the benefit of cancer patients.
Finally the research technician employed on this grant will learn skills which they will take forward in their career as a researcher.