Continuation of Patent battle Between Cipla...

Erlotinib is a derivative of gefitinib which is a pre-1995 invention, published before 1995 (in AU, GB & other countries). Gefitinib’s product patent, claiming markush structure in which n number of derivatives disclosed including gefitinib, does not disclose the ethynyl group attach to the phenyl ring in dependent claims. So invalidity for the Erlotinib’s patent may be cumbersome task for Cipla to prove the existence of product before 1995.