Clinical proof of concept
Results from nine completed Phase I/II and II trials in colorectal, renal and prostate cancer in approximately 190 patients have shown that TroVax is safe, well tolerated and can be administered in combination with various other treatments. Approximately 90% of patients treated with TroVax mounted an anti-cancer immune response to the 5T4 antigen. A cross-trial analysis of all evaluable patients showed a statistically significant association between immune responses to 5T4 and overall survival. There were no correlations between the immune response to MVA and patient survival, suggesting that the benefit associated with the 5T4 response is not related to patients’ general health status. Across all nine trials, a doubling in the 5T4-specific antibody response between the first and third vaccinations was associated with a reduction in the relative risk of death of 16% (p < 0.002).
Phase III TRIST study in renal cancer
A Phase III trial in advanced and metastatic renal cell carcinoma, known as TRIST (TroVax Renal Immunotherapy Survival Trial), started in November 2006 and reached full recruitment of 733 patients in March 2008. The study was amended in July 2008, following the recommendation of the Data Safety Monitoring Board (DSMB) that TRIST would not meet the predefined primary efficacy endpoint of survival improvement. The DSMB recommended that patients continue to be monitored without further vaccinations.
|
 |
At a meeting with the FDA in October 2008, Oxford BioMedica agreed a series of amendments to the study. With these amendments, a key aspect of the ongoing study is to explore the potential benefit of TroVax in subsets of patients. Although the TRIST study alone is unlikely to support registration of TroVax in renal cancer, the results may form part of a regulatory submission alongside an additional confirmatory trial.
The FDA requested further analysis of the data in order to provide guidance on the potential development path for TroVax. The response from the FDA is an important step for regulatory clearance to initiate further clinical trials.
Market opportunity
The global cancer market is expected to generate sales in excess of US$60 billion by 2010. The market for therapeutic cancer vaccines, although minimal at present, has the potential to mirror the growth seen in the monoclonal antibody market, and reach sales in excess of US$5 billion by 2012 (source: Research and Markets). Many leading companies recognise this opportunity and are investing in the field. With the potential to benefit patients with some of the most common types of cancer, TroVax could capture a significant share of the market.
|
