Merck’s Temodar continues to face generic threat!
First Publication Date: 23rd September 2010
Schering Corp, a subsidiary of Merck & Co, filed a patent infringement suit against Sun Pharma in response to Sun’s Abbreviated New Drug Application (ANDA). Sun Pharma through this ANDA is trying to seek FDA’s approval to commercially manufacture the generic version of the drug even before its patent term expires.
Temodar, active ingredient Temozolomide, is one of world’s best selling brain cancer drug which is being marketed by Schering (now Merck). The patent,US5260291, governing Temodar was granted to Cancer Research Campaign Technology Ltd (CRT) in 1993 and is due to expire in 2013. Schering has an exclusive license to the drug and markets the drug in capsule form in various dosage strengths.
A look at Temodar’s history discloses it has earlier faced threat from a generic copycat by Barr Pharma, a subsidiary of Teva, in 2007. Barr (now Teva) had filed an ANDA under para IV certification, seeking approval for its copycat version of the drug. Through para IV certification, Barr questioned the validity of the patent ‘291. In response to Barr’s ANDA, Schering filed a patent infringement suit.
Barr alleged that the patent governing Temodar was not valid and is unenforceable. Barr applied the doctrine of prosecution latches and the rule of inequitable conduct to prove Schering’s patent was unenforceable.
Inequitable conduct refers to the failure to disclose relevant information or misstatements of fact to patent office by the applicant. While, prosecution latches refers to the unreasonable and unexplained delay by the applicant during prosecution. Both, prosecution latches and inequitable conduct are grounds that may be used to prove a patent unenforceable.
The case was decided in favour of Teva by the US district court holding the patent ‘291 unenforceable. Schering reacted to the district court’s decision by filing an appeal at the federal circuit. Although, Teva’s copycat of Temodar has received tentative approval to market the drug it is still awaiting the decision on Schering’s appeal before launching the drug.
Another reason for Teva to stall product launch is that Teva and Merck have come to an agreement according to which Teva agrees to enter the market only after 2013 in case the district court’s decision is upheld by the federal circuit. During that period, Merck would still have the paediatric exclusivity on the drug which expires in 2014.
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