Obviousness

The analysis of obviousness for US Patent 11358953 under 35 U.S.C. § 103 is significantly influenced by the U.S. Court of Appeals for the Federal Circuit (CAFC) decision, which has already ruled all claims invalid due to anticipation under 35 U.S.C. § 102.

Anticipation, as found by the CAFC, means that every element of the claimed invention was disclosed in a single prior art reference. This is a higher bar for invalidity than obviousness, which allows for the combination of multiple prior art references. If a patent claim is anticipated, it is inherently considered obvious (or, more accurately, lacking in novelty). Therefore, the CAFC's finding of anticipation effectively subsumes any obviousness argument.

However, to address the request to identify combinations of prior art references that would render the claims obvious under 35 U.S.C. § 103, there is a limitation based on the provided "Prior art" section. The "Prior art" section explicitly identifies only one pivotal piece of prior art: "Pfizer's Public Disclosure of Nirmatrelvir" in April 2021. It notes that "other patent and non-patent citations exist within the US11358953 document" but does not enumerate them for this analysis.

Since an obviousness analysis under 35 U.S.C. § 103 typically requires the combination of two or more prior art references, along with a motivation for a person having ordinary skill in the art (POSA) to combine them, it is not possible to construct such a combination argument based solely on the single, explicitly identified prior art reference provided.

Given that the CAFC found the nirmatrelvir disclosure anticipated all claims (meaning it disclosed every element), a hypothetical obviousness argument, if it were to be made, would likely center on:

• Primary Reference: Pfizer's Public Disclosure of Nirmatrelvir (April 2021). This disclosure covers a compound (nirmatrelvir) containing a one-carbon alkyl group, which was the key feature leading to the invalidation of the '953 patent's claims due to lack of priority.
• Motivation for Combination (Hypothetical): In the absence of other explicit references, a POSA in the field of antiviral peptide chemistry, particularly for 3CLpro inhibitors, would have been motivated to explore various alkyl substitutions, including C1-alkyl groups, in known peptide scaffolds to optimize binding affinity, metabolic stability, or pharmacological properties. This motivation would stem from the common practice in medicinal chemistry of making routine variations to known compounds to find improved analogs. The general knowledge of peptide modifications for antiviral agents, as discussed in the patent's background (e.g., the need for more effective therapies for coronavirus infections and the known role of 3CLpro as an antiviral target), would further drive such explorations.

However, without specific secondary references identified in the "Prior art" section to combine with Pfizer's disclosure, a detailed "combination of prior art references" argument for obviousness under 35 U.S.C. § 103 cannot be fully elaborated as requested. The invalidation of the patent under 35 U.S.C. § 102 (anticipation) already provides the strongest possible legal basis for its unenforceability.