Patent Law

Pfizer v. Teva (Fed. Cir. 2008)

A family of three Pfizer patents cover aspects of the bestselling drug Celebrex. Seeing some possible chinks in the patents, Teva field an Abbreviated New Drug Application (ANDA) with the FDA with a Paragraph IV certification challenging the patents as invalid and unenforceable.

Continuation-in-Part After Restriction: 35 USC 121 blocks the use of a parent application “as a reference … against a divisional application” if the divisional was the result of a restriction requirement. 

One of the Pfizer patents (the ‘068) is a continuation-in-part (CIP) filed after a restriction requirement. On appeal, the CAFC confirmed that Section 121 does not apply to CIPs: “a divisional application contains an identical disclosure to its parent application, but a CIP introduces new matter. . . . [T]he protection afforded by section 121 . . . is limited to divisional applications.”

Thus, the parent application of a CIP will potentially be used for an obviousness-type double patenting rejection. Here, the CAFC held that the CIP claims were indeed obvious when compared to the parent application.

Best Mode: A patent is invalid when the applicant fails to satisfy the best mode requirement of Section 112. The requirement can be broken down into two elements:

1. Whether the applicant subjectively “possessed” a best mode for practicing the invention at the time the application was filed; and, if so,
2. Whether the disclosure would objectively enable a PHOSITA to practise the best mode.

Like other invalidity issues, best mode is determined on a claim-by-claim basis.  There was no real question here that the COX-specific claims did satisfy the best mode requirement. The appellate panel refused to speculate further on the moot issue of how the best mode requirement is met for claims covering a larger class of compounds.