Roche and Pharmasset to develop new generation HCV therapies

Swiss-based Roche and US company Pharmasset have formed a partnership to develop nucleoside polymerase inhibitors for the treatment of chronic hepatitis C virus (HCV) infections.

Pharmasset will receive an upfront fee, r&d support, and milestone payments that could total US$168m for PSI-6130, the lead nucleoside compound of the partnership. In addition, Pharmasset will receive royalties on product sales and retain certain co-promotion rights in the US.

Under the terms of the agreement, Roche will gain worldwide rights, excluding Latin America and Korea, to Pharmasset's PSI-6130 and its prodrugs. Pharmasset will be responsible for preclinical work, investi-gational new drug (IND) filings, and phase I proof of concept studies, with Roche managing other preclinical studies and clinical development. Roche will also receive options to related nucleoside polymerase inhibitors, which, if exercised, could result in Pharmasset receiving in excess of $300m in total milestones under the agreement.

Pharmasset will continue to develop and retain worldwide rights to ongoing and future hepatitis C programmes unrelated to the PSI-6130 series of nucleoside polymerase inhibitors. In addition, the Roche Venture Fund has made a $4m investment in Pharmasset and has received warrants to purchase an additional $6m in shares within the next two years.

'We believe that nucleosides are likely to be an important class of drugs in HCV treatment,' said Jonathan K.C. Knowles, Roche president of global research. 'PSI-6130 fits perfectly within our virology portfolio. When used in combination with Pegasys and Copegus, this therapy may offer significant benefit to patients who have previously been resistant to treatment, especially those with a difficult to treat virus.'