Astex Pharmaceuticals has pulled the plug on its investigational lung cancer drug amuvatinib after a mid-stage trial just missed its primary endpoint.

The US firm has announced that clinical development of amuvatinib (also known as MP-470) has been discontinued on the basis of results from a Phase II trial designed to show that the drug had a response rate of not less than 10% in platinum refractory small cell lung cancer (SCLC) patients. However the data revealed two partial responses in the 21 evaluable patients, ie a 9.5% response rate.

Astex noted that no new safety issues were identified and biological markers studies are ongoing. Nevertheless, Astex chief executive James Manuso said "we have decided to end the clinical development of amuvatinib despite the favourable safety and preliminary clinical activity we observed in the first stage of this Phase II trial and in the earlier Phase Ib trial in combination platinum-etoposide based chemotherapy".

He added that "we will consider the possibility of licensing the compound to any partners who would be interested in its further development." Chief medical officer Mohammad Azab noted that there is no effective treatment for SCLC patients with truly platinum-refractory disease similar to the patients enrolled in this study.

He concluded that "while some clinical activity was observed", the drug, multi-targeted tyrosine kinase inhibitor, has been pulled. This is "consistent with our corporate strategy to move into advanced clinical stages only those agents that meet our pre-specified primary endpoints".

The news went down badly with investors and Astex shares fell 8.1% to $3.05.