May 12, 2021by Richard Treanor

The Patent Trial and Appeal Board issued a decision in Ex Parte Shaw in which an Examiner’s choice of lead compounds (i.e., prior art compounds identified by the Examiner which are then modified to produce the claimed compounds) was reviewed.

In Shaw, Appellant’s principal argument was that the Examiner lacked any basis for choosing Examples 33 and 53 of the primary reference as lead compounds because there was nothing in the reference that distinguished them from the other 363 disclosed compounds. Arguing that the reference failed to provide specific, favorable biological activity for Examples 33 and 53, and citing the activity requirements for lead compounds set out in Daiichi Sankyo Co., Ltd. v. Matrix Labs. Ltd., 619 F.3d 1346 (Fed. Cir. 2010) (“proving a reason to select a compound as a lead compound depends on more than just structural similarity, but also knowledge in the art of the functional properties and limitations of the prior art compounds. Potent and promising activity in the prior art trumps mere structural relationships.”) Appellant urged that the Examiner’s selection of Examples 33 and 53 was improperly based on hindsight structural similarity to the claimed compounds, as there was simply no other good reason to choose Examples 33 and 53 as lead compounds.

The Board disagreed, affirmed the Examiner, and cited a passage in the primary reference seemingly generic to all compounds disclosed therein:

The compounds of Examples 1-365 were tested in the … in vitro AMPK activation assay . . . and found to have EC50 values of less than 10 micromolar and greater than 80% maximum AMP activation.

In explaining its opinion, the Board took the position that this indication of activity was sufficient to justify the Examiner’s choice of lead compounds, even in view of the Daiichi court’s instruction, cited with approval by the Board, that:

[T]he analysis still requires the challenger to demonstrate by clear and convincing evidence that one of ordinary skill in the art would have had a reason to select a proposed lead compound or compounds over other compounds in the prior art.

While the primary reference in Shaw did not do this, likely underlying the Board’s decision were several factors hinted at in the decision – the fact that the lead compound analysis was Appellant’s only real argument, and the fact that Appellant’s claimed compounds were only as efficacious as those of the primary reference.

Takeaway: In Shaw we see the Board willing to bend somewhat on the requirements of the lead compound analysis in a case where Appellant was not able to (or at least, did not) argue the existence of better lead compound candidates in the prior art, and in which no unexpected results were provided. With nothing to tip the scales in Appellant’s favor, the Board seemed willing to set a lower limit on the evidence needed to sustain a lead compound designation.

Judges: F. Prats, R. Guest, D. Katz

by Richard Treanor

Richard (Rick) L. Treanor, Ph.D., is a founding partner of Element IP. Rick has more than three decades of experience in intellectual property in both the U.S. Patent and Trademark Office and private practice. Rick focuses his efforts on the creation, maintenance, and defense of IP rights in proceedings that take place inside the USPTO: patent prosecution, patent appeals, inter partes review, post-grant review, derivation proceedings, covered business method review, re-examination, interference, third party submissions, revival, foreign filing licenses, supplemental examination, etc.