Suggestions teaching away from combining references to arrive at the claimed invention but arising after the time of the invention are irrelevant. “Obviousness, and expectation of success, are evaluated from the perspective of a person having ordinary skill in the art at the time of invention.”
Background / Facts: This patent infringement case concerns a drug for the treatment of hepatitis B. In holding that the claimed compound was invalid for obviousness, the district court focused on the selection of 2′-CDG as a lead compound from the prior art for modification to arrive at the claimed invention, observing, based on the patentee’s expert’s own testimony, that “medicinal chemists during the relevant time frame were actually treating and using 2′-CDG as a lead compound” in the search for new antivirals at the time. Later, however, it was discovered that 2′-CDG was potentially toxic.
Issue(s): Whether a skilled artisan would have been motivated to select 2′-CDG as a lead compound and made the minor modification to arrive at the claimed invention when 2′-CDG itself was later abandoned as an antiviral for health concerns over toxicity.
Holding(s): Yes. “[The patentee] challenges the selection of 2′-CDG as a lead compound because it was [later] discovered to be toxic in the 1990s. However, at the time of [the] invention, the [cited] reference showed that 2′-CDG was generally understood to be safe and nontoxic, and other researchers were already using it as a lead compound. As the district court points out, in ‘October 1990, 2′-CDG was not yet known to have high toxicity,’ and [the patentee’s] expert [] agreed that researchers at the time treated 2′-CDG as a ‘promising compound.’ … Therefore, we see no error in the selection of 2′-CDG as the lead compound here.”