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Federal Circuit Invalidates Pfizer's Latest-Expiring Patent on Celebrex, for Double Patenting

By Aaron Barkoff

Pfizer et al. v. Teva Pharms. USA, No. 2007-1271 (Fed. Cir. 2008)

Pfizer owns three Orange Book-listed patents protecting its blockbuster arthritis drug Celebrex (celecoxib): U.S. Patent Nos. 5,466,823; 5,563,165; and 5,760,068.  As we previously reported, last year a district court held that Teva's ANDA infringes all three patents, and enjoined Teva from marketing its generic version of Celebrex until 2015, when the '068 patent expires.  (There is also a fourth, later-expiring, patent listed in the Orange Book for Celebrex, No. 5,972,986, but presumably Teva filed a section viii statement on it).

On Friday, the Court of Appeals for the Federal Circuit held that the '068 patent, claiming methods of use, is invalid for double patenting in view of the '165 patent, claiming compositions.  The decision effectively results in a loss of one and a half years of patent protection on Celebrex.

The primary issue in the case appears to be one of first impression: whether 35 U.S.C. § 121 applies not only to divisional patent applications, but also to continuation-in-part ("CIP") applications.  35 U.S.C. § 121 provides, in part, as follows:

A patent issuing on an application with respect to which a requirement for restriction under this section has been made, or on an application filed as a result of such a requirement, shall not be used as a reference either in the Patent and Trademark Office or in the courts against a divisional application or against the original application or any patent issued on either of them, if the divisional application is filed before the issuance of the patent on the other application.

Thus, section 121 provides a "safe harbor" to divisional applications from obviousness-type double patenting rejections.  Teva contended that section 121 applies exclusively to divisional applications, and that because the '068 patent issued on a CIP rather than a divisional application, the '068 patent is not entitled to the protections of the statute.  According to the Federal Circuit's opinion, Pfizer argued "that the terms 'divisional' and 'continuation-in-part' are merely labels used for the administrative convenience, and that accordingly, although the '068 is termed a CIP, it is in effect a divisional for purposes of section 121."

The Federal Circuit sided with Teva.  The court reviewed the text of section 121 (which refers exclusively to divisional applications), the statute's legislative history, and case law, concluding that "the protection afforded by section 121 to applications (or patents issued therefrom) filed as a result of a restriction requirement is limited to divisional applications."  Moreover, because "[t]he claims at issue of the '068 merely recite methods of administering a 'therapeutically-effective amount' of the compositions found in claim 5 of the '165 patent," the court found them not patentably distinct over the claims of the '165 patent, and therefore invalid for obviousness-type double patenting.

Although the Federal Circuit invalidated the '068 patent, the court upheld the validity of the '823 and '165 patents, rejecting Teva's arguments that they are invalid for failure to disclose the best mode and unenforceable for inequitable conduct.  Thus, Celebrex will remain protected until at least May 30, 2014, when pediatric exclusivity attached to the '165 patent expires.

RELATED READING:

• Pfizer press release
• Reuters
• Wall St. Journal

Full post as published by Orange Book Blog: At the Intersection of Patent Law and FDA Law on March 10, 2008 (boomark / email).