The Delhi Patent Office has rejected the patent application of the California-based Gilead Science Inc for its anti-influenza drug, Tamiflu (oseltamivir phosphate), in favour of a pre-grant opposition filed by the Mumbai-based Cipla Ltd. The refusal of patent gives a green signal for Cipla to go ahead with their marketing operations of oseltamivir phosphate, it is learnt.

The deputy controller of patents and designs, Delhi Patent Office, refused the application stating that the Gilead failed to furnish any supportive evidence for its claims on lengthy biological half lives, elevated potency, substantial oral bioavailability (more than 15 per cent) and clinically acceptable or absent toxicity compared to known compounds, by means of comparative data.

The patent office opined that the description of the innovation provided by the company is ambiguous amounting to insufficiency and alleged that invention falls under section 3 (d) of the Patent Act 1970. The decision comes as a breather to the Indian companies including Cipla and Ranbaxy.

The refusal of patent for Tamiflu even at the preliminary stage of filing clearly shows that the Indian generic companies can go ahead and market their oseltamivir phosphate product, said Varun Chhonkar, CEO with the Mumbai-based intellectual property consultancy firm, IP Feathers. Currently, oseltamivir phosphate is the only known drug that combats a bird flu infection in humans.

"There is few option for Gilead or Roche to go for an appeal on the rejection, as the decision has gone against the patent right at the initial stage of filing. The decision denies novelty to the particular basic drug compound and any Indian generic company can manufacture oseltamivir phosphate based on this," he averred.

Roche Holding AG, which holds the manufacturing and marketing rights of Tamiflu worldwide, has sublicensed the Hyderabad-based Hetero Drugs to produce the drug thereby reducing the generic threat from the latter. The generic version developed by Hetero in 2003 was expected to be 30 to 35 per cent cheaper than Tamiflu, according to a claim made by the company in 2005. At present the country has stocked around nine lakh doses of Tamiflu, as per reports.

"After having considered all the circumstance of this case, representation for opposition, reply of the applicants, expert evidence in support of the applicants, written submissions and arguments in the hearing made by both parties and also my discussion and findings as mentioned above, I am of the opinion that the alleged invention as clamed is not only obvious to person skilled in the art and lacking in inventive step but also insufficient and ambiguous as described in the specification," states the official.

Gilead has filed their patent application No 396/Del/1996 on 26th February 1996 as WTO application under section 5(2) of the Patents Act 1970 for the grant of product patent for their invention entitled carbocyclic compounds claiming the priorities of three US applications No 08/395,245, 08/476,946 and 08/580,567 filed on February 27, 1995, June 6, 1995 and December 29, 1995 respectively. However, the request for examination was filed with the Indian Patent Office on June 17, 2005, after the Patents Act 1970 was amended. Tamiflu is marketed by Roche in India right from 2005.