The company has filed a pre-grant opposition application with the controller of patents challenging the validity of patent application concerning crystalline modification of 'Imatinib Mesylate', the company informed the Bombay Stock Exchange, on Monday.
Natco claimed that 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.
The amendment was carried out to curb a widely prevailing practice called the "ever greening" strategies, which involved a manufacturer obtaining patent beyond the basic molecule.
"The basic ground of opposition is that the application for patent would squarely fall within the concept of "ever greening" as the polymorph claimed is the same as that of the 1993 molecule, thus, resulting in no merit for the grant of a patent," Natco said.
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.
Novartis had earlier obtained exclusive marketing rights for 'Imatinib Mesylate', a drug useful in the treatment of certain forms of chronic myeloid leukemia, in November 2003.
Natco had challenged the grant of EMRs for this drug to Novartis, and the case is presently before the Supreme Court of India.
"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 in humans and that the beta form intended to be claimed by Novartis has no patentable substance whatsoever," Natco said.
The drug controller general of India has granted several licences for various crystal forms of Imatinib to other manufacturers including Cipla and Sun Pharmaceutical Industries.
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