Astellas Pharma launched a $3.5bn (£2.3bn) hostile bid for OSI Pharmaceuticals to gain access to the blockbuster Tarceva cancer drug, in the latest move by a Japanese drugmaker to make inroads in the US. OSI shares surged 51.8 per cent to $56.20, well above Astellas' $52-per-share offer as analysts expected a higher price or even a rival bid from rivals such as Swiss drugmaker Roche, OSI's partner on Tarceva. OSI said it previously rejected the offer from Japan's No. 2 drugmaker as too low and advised shareholders not to act at this time. Astellas' offer represents a 40 per cent premium to the biotech company's Friday closing price.