Germany’s Schering AG has licensed worldwide rights to a new formulation of the widely used cancer agent paclitaxel, developed by Sonus Pharmaceuticals and designed to be easier to administer than current formulations of the drug, in a deal valued at up to $168 million dollars.

Schering has also taken a 15 per cent equity stake in Sonus, which last month started a Phase III clinical trial of Tocosol paclitaxel in 800 women with metastatic breast cancer, and has already completed a battery of Phase II tests in a range of solid tumours. The two partners now hope to file for approval of the new product for breast cancer in the USA and Europe by the end of 2007.

Sonus’ Tocosol formulation of paclitaxel takes the form of a vitamin E-based emulsion that does not require preparation prior to dosing and can be infused into a patient in just 15 minutes. In contrast, Bristol-Myers Squibb’s original Taxol formulation of the drug requires an infusion time of either three or 24 hours, depending on the regimen employed.

In addition, the new formulation has been shown to deliver 70% more active paclitaxel than can be achieved with Taxol, which potentially could translate into greater efficacy rates.

Schering said the licensing deal would give it a near-term oncology product, with ‘solid competitive advantages that could differentiate it from other taxane products’, that will complement its own in-house oncology pipeline efforts.