RCC trials are designed to evaluate the safety, immunogenicity and effectiveness of TroVax as a single agent and in combination with standard therapy of interleukin-2 (IL-2) or interferon-a (IFN)
Oxford BioMedica says that Robert Amato has presented further encouraging data from three Phase II trials of TroVax, the company's lead cancer immunotherapy product, in renal cell carcinoma and prostate cancer at the 18th EORTC-NCI-AACR Symposium on "Molecular Targets and Cancer Therapeutics", November 2006 in Prague, Czech Republic.
Amato, of the Genitourinary Oncology Centre, the Methodist Hospital in Houston, USA, is the principal investigator for two ongoing Phase II trials of TroVax in renal cell carcinoma (RCC) and a Phase II trial of TroVax in prostate cancer.
The RCC trials are designed to evaluate the safety, immunogenicity and effectiveness of TroVax as a single agent and in combination with standard therapy of interleukin-2 (IL-2) or interferon-a (IFN).
The regimen comprises seven intramuscular injections of TroVax over 41 weeks.
To date, the two trials have enrolled 33 patients with progressive metastatic RCC and 18 patients are currently receiving therapy.
All patients were heavily pre-treated before entering the trials.
Amato presented data showing that TroVax was well tolerated and has shown promising anti-tumour activity in this patient group.
One patient had a complete response (tumour eradication) and two patients developed a partial response (tumour shrinkage).
A further 15 patients showed disease stabilisation for periods exceeding three months, including one patient that has been stable for more than 46 weeks.
Overall survival in the two studies is too early to assess and has yet to reach a median.
The immunological analysis is ongoing but a preliminary assessment has shown that TroVax induced 5T4-specific antibody responses in more than 90% of evaluable patients.
Importantly, in patients with clear cell RCC, there was a statistically significant correlation (p=0.028) between the immune response to 5T4 and clinical benefit based on changes in patients' tumour burden.
This is particularly encouraging since it supports the rationale that the 5T4-specific immune response induced by TroVax has therapeutic benefit.
Clear cell RCC is the most common subtype of renal cancer and is the patient group for the Phase III TRIST study.
The Phase II trial in prostate cancer is similarly designed to evaluate the safety and immunogenicity of TroVax as a single agent and in combination with standard therapy of GM-CSF.
The regimen comprises ten intramuscular injections of TroVax over 45 weeks.
The trial has enrolled 27 patients with hormone-refractory prostate cancer and eight patients continue to receive therapy.
TroVax was well tolerated and all patients developed a strong 5T4-specific antibody response whether or not they received GM-CSF.
Analysis of cytotoxic T-cell immune responses stimulated by TroVax in the renal and prostate cancer trials is ongoing.
Mike McDonald, Oxford BioMedica's chief medical officer, commented on the new data: "We are very encouraged by the data emerging form these Phase II trials.
"The data provide further evidence that TroVax can be administered safely and that it induces consistent antibody responses to the target tumour antigen 5T4.
"The correlation between immune and clinical responses supports our Phase III development strategy of TroVax in renal cancer".
