Lawrence Young - Overview

GENE AND IMMUNOTHERAPY FOR THE TREATMENT OF CANCER
L.S.YOUNG, P.F. SEARLE, V. MAUTNER, D.H.ADAMS, N. JAMES, A. B. RICKINSON, P.MOSS
Our research programme in this area is broadly divided into two main areas: (i) adenovirus-mediated gene delivery and (ii) immunotherapy.

(i) Adenovirus-mediated gene therapy. Our virus delivery of prodrug therapy (VDEPT) programme focuses on the E.coli nitroreductase (ntr)/CB1954 system which, in collaboration our commercial partners Cobra Therapeutics, has successfully undergone pre-clinical validation and is currently being examined in a phase I clinical trial. This trial is a dose escalation study using direct intratumoral injection of a recombinant ntr-expressing adenovirus (RAd-ntr) into intrahepatic metastases of colorectal carcinoma. This VDEPT approach, which uses the promiscuous CMV promoter to drive ntr expression in the RAd vector, is now being extended to the treatment of locally recurrent prostatic carcinoma. Clinical support for these trials is provided by local lead physicians in colorectal and prostate cancer and involves collaboration with Professor David Kerr, recently moved to Oxford. Current work is focussed on: (1) the development of improved nitroreductase activity by targeted mutagenesis of the nitroreductase gene, (2) the generation and evaluation of novel tissue-specific promoters, (3) the tumour targeting of adenoviral vectors by mutagenesis of viral fibre, (4) the development of replication-defective recombinant adenoviral vectors (RAds) carrying immunomodulatory genes (CD80, CD86, CD40L, CD95L, 4-1BB and GM-CSF) and (5) exploiting the potential synergy between replication competent adenoviruses (RCA) and either VDEPT (using either the ntr/CB1954 or CD/5-FC systems) or immune stimulation.

(ii) Immunotherapy. Research in this area ranges from fundamental studies on cytotoxic T lymphocyte (CTL) responses to viruses (EBV, HPV, CMV) to clinical trials of novel cell and vaccine-based modalities. A phase I trial of autologous dendritic cells (DCs) pulsed with hepatoma lysate for patients with primary hepatocellular carcinoma (HCC) is currently underway and has demonstrated that reliable DC harvests and expansion can be achieved in patients with late stage disease. This study is continuing with the aim of developing more robust immunological endpoints and using defined tumour antigens rather than tumour cell lysates. We have co-developed an efficient non-viral delivery system with Cobra Therapeutics, and are about to perform a phase II study in patients with metastatic melanoma using autologous DCs transfected with two tumour antigens (melan A, gp100). Adoptive T cell therapy is focussed on the treatment of: (1) EBV-positive tumours such as Hodgkin’s disease (HD) and post-transplant lymphoproliferative disease (PTLD) using CTLs specific for EBV latent antigens and (2) haemopoietic malignancy following stem cell transplantation using minor histocompatibility antigen (mHAg) specific CTLs. Vaccination approaches using either recombinant viruses to deliver antigens (e.g. EBV latent proteins encoded by modified vaccinia virus Ankara) or peptides (e.g. ras oncogene derived epitopes) are currently being investigated. Related studies are employing various techniques including SEREX to identify novel tumour-associated antigens in HCC, HD and haemopoietic malignancy.

THE ROLE OF EPSTEIN-BARR VIRUS IN THE PATHOGENESIS OF NASOPHARYNGEAL CARCINOMA AND HODGKIN’S DISEASE
L.S.YOUNG, C.W. DAWSON, A.G. ELIOPOULOS, P.G. MURRAY
EBV is a ubiquitous human herpesvirus which is found as a predominantly asymptomatic infection in all human communities. The virus is the causative agent of infectious mononucleosis (IM), a self-limiting lymphoproliferative disease resulting from delayed primary EBV infection, and is also associated with a number of malignant tumours originating from both lymphoid and epithelial tissue. Of particular interest is the association of EBV infection with the development of nasopharyngeal carcinoma (NPC), an epithelial malignancy common in the South-East Asia, and Hodgkin’s disease (HD), a B cell-derived tumour which is not geographically restricted. In these tumours EBV adopts a highly restricted pattern of virus latent gene expression producing one nuclear protein, EBNA1, and two membrane proteins, LMP1 and LMP2. We are studying the cell signalling pathways affected by these EBV genes and how these contribute to malignant conversion. This work involves transfection of individual EBV latent genes into cell lines and the subsequent analysis of various signalling pathways and phenotypic consequences. The main focus of our work in these areas is: (i) LMP1 – examination of the cell signalling pathways engaged by LMP1 with particular emphasis on the NF-kB, MAP kinase and phosphoinositide 3-kinase (PI3-kinase) pathways and their effects on cell growth and survival, (ii) LMP2 – the effect of LMP2 on cell adhesion and motility and the role of the src kinase and PI3-kinase pathways in these effects, and (iii) EBNA1 – the cellular requirements for stable EBNA1 expression and how these relate to the maintenance of EBV infection. A major interest is the relevance of the effects observed in in vitro systems to the role of EBV in the pathogenesis of NPC and HD and thus we are examining the status of the various signal transduction pathways and their phenotypic consequences in primary tumours. In vitro systems to examine the interaction of EBV with epithelial cells and with HD cells are being developed. Related work is aimed at developing novel therapeutic approaches based on an understanding of the molecular mechanisms used by EBV latent proteins (e.g. blockade of the NF-kB and PI3-kinase pathways) as well as gene therapy strategies using dominant negative versions of these proteins. The association of EBV with around 50% of HD cases is allowing an analysis of the differences between EBV-positive and negative disease.

The long-term aim of this project is to understand:

(i) How does viral infection contribute to the malignant transformation of an epithelial or B cell?

(ii) What insights can be gained into the oncogenic process by studying the cellular pathways targeted by EBV latent genes?

(iii) What cellular and viral factors influence the outcome of EBV infection in human epithelial cells or B cells?

(iv) How can a knowledge of these effects be exploited for the therapy of EBV-associated tumours?