Functional Equivalence Alone is Insufficient for Prima Facie Obviousness

Equivalence is a common tool used by Examiners to demonstrate the obviousness of a claimed component that is known to be interchangeable with a component in the prior art. However, Ex parte Breder illustrates that the interchangeability alone is insufficient for obviousness – the context of the equivalence is key. Appeal No. 2021-002289 (PTAB Oct. 5, 2021) (non-precedential).

In Breder, the claims were directed to a method of antagonizing 5-HT7 and 5-HT1B receptor activity in a patient suffering from ADHD by administering viloxazine. The primary reference relied on by the Examiner taught a method of treating ADHD with a norepinephrine reuptake inhibitor reboxetine. The primary reference emphasized the high selectivity of reboxetine for norepinephrine processing and its efficacy for treating ADHD, but said nothing whatsoever about viloxazine.

Attempting to present a prima facie case of obviousness for the treatment of ADHD with viloxazine, the Examiner found a secondary reference that disclosed reboxetine and viloxazine as norepinephrine reuptake inhibitors and alleged that a skilled artisan “would have been motivated to substitute the norepinephrine reuptake inhibitor, viloxazine, … with the norepinephrine reuptake inhibitor, reboxetine, in the method of treating ADHD.” Despite this apparent equivalence, the Board did not agree.

From the Board’s perspective, any functional equivalence between viloxazine and reboxetine as norepinephrine reuptake inhibitors was outweighed by the secondary reference had nothing to do with ADHD. In fact, the secondary reference was directed to a topical composition for the transdermal delivery of active agents for ailments such as muscle pain and muscle cramps, which could optionally include norepinephrine reuptake inhibitors. According to the Board, the “sole nexus between the teaching of [the prior art]” is “that reboxetine and viloxazine are norepinephrine reuptake inhibitors,” and this was not enough.

Simply put, the Board did not agree that an optional ingredient in a topical composition for treating muscle pain provided sufficient motivation for a skilled artisan to replace the reboxetine with viloxazine in a complexly different method for treating ADHD, with a reasonable expectation of success. The primary reference’s emphasis on the high selectivity and efficacy of reboxetine bolstered this conclusion.

Takeaway: Context is key. Functional equivalence can be essential for a prima facie case when the primary reference lacks a claimed component but includes a component known to be interchangeable with it. But as shown by Breder, this functional equivalence will not carry the day when the references being combined have nothing in common. Therefore, it is important to thoroughly assess the purpose and end use of each of the references being combined when an Examiner relies on a theory of functional equivalence for the obviousness of a claimed component.

Judges: R. Lebovitz, J. New, D. Cotta