Ongoing anti-cancer gene therapy clinical trials have highlighted the need for more efficient and safer vectors. Thus, we will develop novel targeted viral vectors for applications to cancer gene therapy. The targeting strategies will be implemented in retroviral, lentiviral, and gutless high capacity adenoviral vectors. Targeting viral vector particles to predetermined cell types will be obtained through genetic engineering of retroviral envelopes or adenoviral capsid proteins, by using single chain antibody fragments or tumour cell receptor ligands.
Transcriptional targeting of transgenes expression to tumour cells will be obtained using tumour cell type specific promoter. All vectors will express a reporter/suicide gene, and they will be tested using in vivo models of liver and brain tumours. The characteristics, efficiency, and toxicity of the novel vectors will be compared to standard vectors in current use. This proposal brings together European leaders with expertise covering from the development of novel viral vectors to the implementation of clinical trials of gene therapy.
Our general objective is the development of new generations of targeted viral vectors for the treatment of liver and brain cancer by directing viral entry and by restricting transgene expression.
Our specific objectives are to obtain: i) targeted retroviral and lentiviral vectors, by engineering retroviral envelope proteins to redirect retroviral entry to tumour cells expressing specific receptors, and by the use of cell type specific promoters; ii) gutless adenoviral vectors, by genetic modifications of the fibre and hexon proteins of the adenoviral capsids, as well as through the use of combined cell type specific and inducible promoters.
The characteristics, efficiency, and toxicity of targeted vectors will first be assessed in vitro on relevant cell lines and primary cell cultures, then in vivo using animal models of brain and liver cancer. A common suicide/reporter gene will first be used for all vectors, and then additional therapeutic genes will be tested.
We thus aim to obtain well characterized, safe, and efficient gene therapy vectors, as well as pre-clinical data supporting the further testing of such vectors in clinical trials.
Description of the work
The work has been divided into three phases.
During Phase-I, we will construct the novel targeted retro-, lenti- and adenoviral vectors. Individual partners will either provide transgenes, or regulatory transcriptional cassettes, which will be assembled into individual novel targeted recombinants. Once new generation targeted viral vectors are generated, they will be sent to the appropriate partners for the in vitro testing of the efficiency of the novel vectors in various cell lines. The programme has been carefully planned to optimise all new information and knowledge to be generated. To this end, all new vectors will express the same identical therapeutic transgene, which will allow comparisons to be made across all novel viral vectors produced. The in vitro testing will allow selection of the most efficient vectors which will then be chosen to be further studied.
During Phase-II production of the most efficient vectors will be scaled up, and distributed to all appropriate partners for the in vivo testing and comparison in available models. The workprogram has been divided in 6 workpackages each corresponding to a targeted vector (retro-, lenti- or adeno-viral) tested in a specific tumour model (liver or brain). There will be joint meetings of the partners for comparisons of results obtained within and across the laboratories and the workpackages. This second round of selection will lead to our choice of the most powerful vectors for each tumour models.
This leads to Phase-III of this research programme in which the most powerful targeted vectors will be chosen to be developed further, by inserting novel powerful therapeutic genes into them. Such new viruses will be prepared and distributed to partners for in vivo testing in the frame of the different workpackages.
The power of our research programme is that the experimental design has been carefully planed, and, in conjunction with the close collaboration fostered among all seven partners, will allow the rapid identification of the most powerful and efficient vectors. Once this is achieved during Phase-II, Phase-III of this research programme will be able to rapidly engineer and test other powerful therapeutic genes into such vectors. We expect this programme to lead to the implementation of clinical trials for cancer utilising the novel vectors developed within 4 years.
Milestone 1: validation of targeted tumour cell type specific retroviral vectors.
Milestone 2: validation of targeted tumour cell type specific lentiviral vectors.
Milestone 3: validation of targeted tumour cell type specific and inducible adenoviral vectors.
Milestone 4: demonstration of efficiency and safety of targeted vectors expressing a reporter/suicide gene in models of liver and brain cancer.
Milestone 5: demonstration of efficiency and safety of targeted vectors in models of liver and brain cancer with therapeutic genes.
Funding SchemeCSC - Cost-sharing contracts