Natco has filed a Paragraph IV Certification asserting that various Revlimid patents are invalid, unenforceable and/or not infringed. Lenalidomide is a derivative of thalidomide and is used in the treatment of multiple myeloma.

Revlimid, had global sales of US$1.7 billion last year, and made up the majority of Celgene's total revenue of US$2.7 billion in 2009. Despite the challenge, any copycat version of the drug likely will not hit the market for years as a legal battle should ensue.

Revlimid was approved in late 2005, therefore generic challenges were to be expected, as Paragraph IV Certifications may be filed as early as four years after FDA approval of the brand product.

Celgene has stated that it intends to vigorously enforce its extensive intellectual property rights for Revlimid and plans to file a complaint alleging infringement within the required 45-day response period. This would delay generic entry, as approval to market the generic drug will be automatically postponed for 30 months, unless, before that time, the patent expires or is judged to be invalid or not infringed.

Revlimid is currently protected by 12 patents, including one that expires in 2019 and another—covering the crystal polymorph form of the drug—that only expires in 2026 and others are pending. In order for Natco to avoid liability, all patent claims in the suit must be deemed invalid, not infringed, unenforceable, or expired.

Natco, however, has much to gain, as it believes it may be the first applicant to file an ANDA for the 25 mg generic version of Revlimid and, should its ANDA be approved, may be entitled to 180 days of generic market exclusivity for that strength.

References

Natco News and Events. NATCO confirms filing of ANDA for Generic Revlimid. 31 August 2010.

Celgene Press Releases. Celgene Officially Notified of ANDA Filing for REVLIMID. 3 September 2010.

FDA Drugs. Paragraph IV Drug Product Applications: Generic Drug Patent Challenge Notifications [Monograph on Internet] [updated 05 May 2009; cited 2010 September 9].