Patent enforceability US Case [CRCT Vs Barr]

Temodar [temozolomide] is marketed by Merck/Schering and is used for treatment of brain cancer [glioblastoma multiforme and refractory anaplastic astrocytoma]. Barr Pharma had filed ANDA seeking approval to market generic version of temozolomide. As the product patent has not expired and listed in Orange book, Barr has filed ANDA with PIV certification on product patent.

Product patent details

Patent No: US 5,260,291; Assignee: Cancer Research technology UK Ltd

Title: Tetrazine derivatives

US Expiry date: Aug 11, 2013

Patent claims original priority of first application filing date: 23/08/1982 and patent term extended around 3 years

Merck Schering is exclusive licensee of this patent ['291]

Upon filing ANDA with PIV certification on product patent, CRT has sued Barr (Teva) and consequently ANDA approval stayed for 30 months. In complaint, CRT argued that Barr's ANDA will infringe claims '291 patent. In answers, Barr has raised enforceability of '291 patent.

Defendant argument on Patent unenforceability

1) Doctrine of prosecution laches: This patent application's prosecution involves 11 patent application and 10 abandonment is unreasonable delay and no substantive prosecution for decades.

2) Inequitable conduct: Applicant was in possession of Human clinical trial data during the patent application prosecution and withheld from PTO

Court agrees on both arguments of defender by analyzing various facts and evidences submitted during trial.

Merck will appeal this decision

Links

[Teva Press release] [Merck press release] [District court decision]