British biotech firm Oxford BioMedica has halted mid-stage trials of its lead product TroVax in the US.

The company said it was stopping the US portion of trials in order to assess the activity of TroVax (MVA-5T4) in patients with progressive hormone refractory prostate cancer. The market didn’t react well, with BioMedica’s share price tumbling 9% yesterday on the news.

The drug, which works as an immunotherapy against cancer, will continue Phase II development programme in other indications outside the US, and will now be solely led by academic collaborators in the UK.

The firm started its open-label, Phase II study in patients with metastatic HRPC in September 2010. But since then, the prostate cancer treatment landscape in the US has changed, with new products available and other clinical trials targeting the same indication, the company said.

These products include its rival Denderon’s prostate cancer vaccine Provenge, and Johnson & Johnson’s pill Zytiga, which have both received FDA approval in the past two years. This means that competition for its drug – which is still some years off any potential regulatory approval – has increased substantially, and the company will want to make sure it has the goods to compete.

BioMedica also said that competition for suitable patients with HRPC ‘has been high’ and recruitment into the study has been much slower than originally anticipated, with just 26 patients recruited to date.

This has not been the first time its drug has come across problems – in 2009, TroVax failed to meet its primary endpoint in Phase III trials, with the Data Safety Monitoring Board stating that overall survival improvement would not be increased. It was originally indicated for colorectal, prostate and renal cancers.

Given this failure, the company decided to go back to mid-stage trials, and focus on the prostate cancer licence, but this week’s news will be another blow to the firm.

UK trial focus

Whilst the company believes that early data from this study are encouraging, the board has made a strategic decision to close the US trial in order to focus on investigator-led Phase II studies, currently in the UK.

In July 2012, Oxford BioMedica’s partners at Cardiff University in Wales initiated a Phase II trial to assess the safety and immunological activity of TroVax in patients with inoperable metastatic colorectal cancer – this will now be the focus of research for the firm.

The company expects two further investigator-led Phase II studies in mesothelioma and ovarian cancer to be initiated in the UK by academic collaborators by the end of the year.

But it will first need to find the funds to do this, and BioMedica said that securing a development or financial partner for TroVax’s future late-stage development “remains a key strategic priority for the company,” adding that discussions with interested parties are on-going.

John Dawson, chief executive of Oxford BioMedica, said: “Whilst changes to the treatment landscape in the US have challenged recruitment into our prostate cancer trial, early data support the use of our biomarker which is an important step in the on-going clinical development of TroVax.