OXFORD BIOMEDICA PRESENTS ENCOURAGING FINAL PHASE II RESULTS WITH TROVAX^® IN COLORECTAL CANCER AT THE INTERNATIONAL COLORECTAL CANCER CONGRESS

Confirms safety, immunogenicity and clinical benefit

Oxford BioMedica (LSE: OXB), the leading gene therapy company, today announced that further encouraging data were presented from the Phase II trials of TroVax, its cancer immunotherapy, in metastatic colorectal cancer (CRC) at the Fourth International Colorectal Cancer Congress in Aventura, Florida, USA, on Saturday 15 October 2005.

The presentation included a complete and final analysis of safety and immunology from the two Phase II trials with TroVax in first line treatment of CRC alongside irinotecan-based (IFL) and oxaliplatin-based (FOLFOX) chemotherapy. The presentation also included additional information on tumour responses based on CT scan data. The results confirm the preliminary conclusions that were presented at the American Society of Clinical Oncology (ASCO) meeting on 15 May 2005. The conclusions are that the primary endpoints of safety and immunogenicity were achieved and that the secondary endpoint of clinical benefit has exceeded the Company’s expectation based on tumour responses.

Enrolment in the trials was completed in September 2004 with 36 patients recruited. A key objective of these studies was to confirm that the anti-tumour immune response observed in the Phase I/II trial with TroVax as a single agent was preserved in patients receiving chemotherapy. Analysis, therefore, focused on “per protocol” patients who received all prescribed cycles of chemotherapy and six immunisations of TroVax. As expected, about one third of patients did not complete the chemotherapy regimen and, therefore, dropped out of the trials for reasons unrelated to TroVax. Across both trials, there were 23 “per protocol” patients.

TroVax was safe and well tolerated in all patients with no serious adverse events being associated with TroVax treatment. All 23 patients showed an anti-tumour immune response, elicited by TroVax, against the 5T4 tumour antigen. Compared with the Phase I/II study, these Phase II chemotherapy protocols do not appear to impair the ability of TroVax to stimulate an anti-tumour response and may, in fact, enhance the response at particular time points during the therapy.

The human immune system is made up of multiple interacting elements including the humoral (antibody) and cell-mediated (T cell) arms. In these Phase II trials, Oxford BioMedica performed a comprehensive analysis of both arms of the immune response as detailed below:

• Antibody response: Over 90% of patients mounted anti-5T4 antibody responses, which were of higher magnitude and longer duration than those seen in the Phase I/II trial that evaluated TroVax in the post chemotherapy CRC setting.
• T cell response: 100% of patients showed T cell responses. 70% of these have been confirmed as cytotoxic T cell (CD8) responses, which, in some patients, were at levels comparable to those observed in response to infectious disease pathogens. The frequency and levels of CD8 responses with TroVax are at the top end of the range in the field of cancer immunotherapy. This is of particular significance because the industry as a whole, including several potential partners for the TroVax programme, believes that it is these CD8 cells that are the main effectors of anti-tumour activity.

The secondary endpoint of clinical benefit includes analysis of tumour responses and overall survival. The number of tumour responses in the trials has been encouraging so far (NB: the data are unaudited and subject to third party review). Across both trials, 91% of patients have shown disease control, which comprises complete responses, partial responses and stable disease according to industry standard RECIST criteria. The detailed tumour response figures are as follows:

• TroVax plus IFL trial: Twelve patients completed the chemotherapy and TroVax regimen. Tumour response data are based on CT scans at 26 weeks. There was one complete response, six partial responses and four patients with stable disease.
• TroVax plus FOLFOX trial: Eleven patients completed the chemotherapy and TroVax regimen. Tumour response data are based on CT scans at 14 weeks. There were three complete response, five partial responses and two patients with stable disease. In this trial, an independent statistician identified a statistical relationship (p < 0.02) between the anti-5T4 immune response and tumour responses.

Although the trials were small, in terms of patient numbers, and were not designed with control arms, the levels of clinical benefit are encouraging when compared to published trial data for chemotherapy alone in similar settings. For both trials, the final audited tumour response figures and patient survival will be reported in 2006. The trials have not been running long enough to comment on survival at this time.

The International Colorectal Cancer Congress, which was held in Aventura, Florida, USA, on 14-16 October 2005, is designed as a learning opportunity for medical, surgical, and radiation oncologists as well as gastroenterologists and internal medicine and primary care physicians. The presentation of the Phase II results with TroVax was given by Richard Harrop, Director of Clinical Immunology at Oxford BioMedica, during a session titled “New Agents of Interest” on Saturday, 15 October 2005. The presentation can be accessed on line at www.oxfordbiomedica.co.uk. The title of the presentation is “Vaccination with TroVax in Combination with Chemotherapy: A Productive Partnership”

The Phase II results are also being presented at another conference called Colorectal Cancer: Molecular Pathways and Therapies on 19-23 October in Dana Point, California, USA. This meeting is being organised by the American Association for Cancer Research (AACR). Oxford BioMedica will make a poster presentation on Friday, 21 October 2005. Further information is available at www.aacr.org/page4553.aspx

Commenting on the TroVax Phase II results, Oxford BioMedica’s Chief Medical Officer, Dr Mike McDonald, said: “We are very pleased that the final data from the TroVax Phase II trials have confirmed our preliminary conclusions that the product is both safe and immunogenic. The tumour response rates are similarly encouraging. As more data emerge from our Phase II trials, we are increasingly confident that TroVax will have a role to play in the treatment of a wide range of solid tumours”.

Oxford BioMedica’s Chief Executive, Professor Alan Kingsman said: “One of our main goals within the TroVax programme is to secure a development partner within the next 12 months. The promising results reported recently from our Phase II trials in both colorectal and renal cancer have been key in our ongoing discussions with prospective partners for TroVax”.

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