Obviousness of Chemical Compounds: The "Lead Compound" Concept – Addendum

As the July issue of IP Today was going to press, the Court of Appeals for the Federal Circuit handed down its decision and opinion in Takeda Chem. Indus., Ltd. v. Alphapharm Pty., Ltd., No. 06-1325 (June 28, 2007).  My paper in the July issue discussed the district court’s decision and opinion in this case as it relates to whether the law of obviousness of chemical compounds requires that the prior art motivate a person of ordinary skill to select a "lead compound" for modification before that compound can be used to render a later- claimed compound prima facie obvious, and whether such a requirement was consistent with the Supreme Court’s opinion in KSR v. Teleflex.  As discussed in the paper, there is no per se "lead compound" requirement stemming from earlier Federal Circuit precedent and such a requirement would run afoul of KSR.  This addendum addresses the Federal Circuit’s treatment of that concept in its recent decision in Takeda v. Alphapharm.

The Federal Circuit’s holding in Takeda v. Alphapharm is neither ground-breaking nor surprising.  In fact, it is rather reasonable and straightforward.  The Court held that

in cases involving new chemical compounds, it remains necessary to identify some reason that would have led a chemist to modify a known compound in a particular manner to establish prima facie obviousness of a new claimed compound.

Id., Slip op., at 10.

Alphapharm argued that one of ordinary skill would begin with "compound b" because it was the "lead compound," or as Judge Lourie put it, "the most promising to modify in order to improve upon its antidiabetic activity and obtain a compound with better activity."  Id., Slip op., at 10-11.   Because Alphapharm chose to establish prima facie obviousness based on this "lead compound" theory, the court specifically stated that it was "deciding the appeal as it has been argued."  Id., Slip op., at fn. 3.   The court found that the prior art did not identify "compound b" as a lead compound.  In fact, the prior art singled out "compound b" for causing considerable side effects and Alphapharm’s 30(b)(6) witness admitted that because of its side effects it would "’presumably not’ be a suitable candidate."  Id., Slip op., at 13.

Takeda represents the Federal Circuit’s first post- KSR­ decision in the chemical compound area.  The Takeda decision makes clear that in order to establish prima facie obviousness of a new compound one must identify "some reason that would lead a chemist to modify a known compound."  It need not be established in all cases that the known compound was a "lead compound;" such an inflexible standard would be inconsistent with KSR.

The author is a director in the Biotechnology/Chemistry practice group of the Washington, D.C. intellectual property law firm of Sterne, Kessler, Goldstein, & Fox P.L.L.C. This article(presentation) reflects the present thoughts of the author, and should not be attributed to Sterne, Kessler, Goldstein & Fox or any of its former, current, or future clients.  The content is for purposes of discussion and should not be considered legal advice.  He can be reached at vcapuano@skgf.com.