Oxford Biomedica Provides FDA Response, Update On TroVax

Oxford BioMedica has received final comments following the FDA’s review of the phase-III TRIST study of TroVax in renal cancer, and the proposed clinical development outline. FDA acknowledged all of the points raised by Oxford BioMedica, and has provided a clear path for further development of TroVax in multiple cancer settings. TroVax is a therapeutic cancer vaccine that targets the 5T4 tumour antigen.

The phase-III TRIST study is evaluating TroVax plus standard of care against placebo plus standard of care. The trial enrolled 733 patients with advanced or metastatic renal cancer that were classified as having a good or intermediate prognosis. Patients were randomised to one of the three standards of care, interleukin-2, interferon-alpha or sunitinib. As previously reported, vaccinations were discontinued on 11 July 2008, based on the recommendation of the study’s independent Data Safety Monitoring Board (DSMB). It concluded that the study would not meet its predefined primary endpoint of an improvement in overall survival.

The data evaluated by DSMB were discussed with FDA. It was agreed at a meeting that plans to initiate further phase-III trials in colorectal cancer would be paused, pending FDA’s review of additional data from the TRIST study.

Based on the clinical trial, FDA said that confounding factors may have contributed to the increased number of deaths in the TroVax arm at the August cut-off date. Furthermore, FDA accepted that there was no evidence of specific adverse events that could attribute the imbalance of deaths to TroVax.

FDA noted that the analysis of patients receiving TroVax or placebo in combination with interleukin-2 was encouraging. Furthermore, FDA agreed that, scientifically, it is reasonable to postulate that patients with a better haematological profile might respond more favourably to treatment with a cancer vaccine such as TroVax.