Natco Pharma Ltd has opposed an application made by Novartis India Ltd to the controller of Patents, Government of India, for grant of a patent for an anti-cancer drug (Imatinib Mesylate).

Novartis had obtained EMRs for Imatinib Mesylate (a drug useful in the treatment of certain forms of Chronic Myeloid Leukaemia), in November 2003. The Company had challenged the grant of EMRs for this drug to Novartis, and the case is presently before the Honourable Supreme Court of India.

The Company has now filed a pre-grant opposition application with the Controller of Patents, Government of India, challenging the validity of patent application [No. 1602/MAs/1998) concerning crystalline modification of Imatinib Mesylate. The basic ground of opposition is that the application for patent would squarely fall within the concept of "evergreening" as the polymoph claimed is the same as that of the 1993 molecule, thus, resulting in no merit for the grant of a patent. Among other things, the Company has also claimed "lack of novelty and inventive step" in the said application for grant of a patent.

According to Natco, the invention of the drug in question was made in 1993, and the Indian patent application merely claims a crystal form (Beta) version of the same substance, and hence would not deserve consideration.

In its pre-grant opposition, the Company has also relied on extensive tests, including bio-equivalence to show that the crystal structures of Imatinib have equal efficacy. Thus, the two forms are identical in efficacy for treatment of blood cancer (CML) in humans and that the beta form intended to be claimed by Novartis has no patentable substance whatsoever. Several licences have been granted by the Drug Controller General of India for various crystal forms of Imatinib to other manufacturers including Cipla, Sun Pharmaceutical Industries etc, the Natco release added.

To curb a widely prevailing practice (called the "evergreening" strategies), which essentially involve a manufacturer obtaining patent beyond the basic molecule, the Indian Patents Act was amended in April 2005, excluding, grant of patents to salts, esters, ethers, polymorphs, and similar forms complexes, combinations of known substance unless they differ significantly in properties with regards to efficacy.