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Court Finds Prior Art “Toxic” to Claims for HIV Vaccine

01-1094
April 05, 2002

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Last Month at the Federal Circuit - May 2002

Judges: Bryson (author), Rader, and Schall

In In re Sastry, No. 01-1094 (Fed. Cir. Apr. 5, 2002), the Federal Circuit affirmed a decision by the Board that the claims in the patent application of Jagannadha K. Sastry et al., directed to a peptidebased HIV vaccine comprising a combination of two peptides, were unpatentable for obviousness.

In Sastry’s claimed invention, the first peptide was designed to induce the body’s cell-mediated immune response by stimulating cytotoxic T cells (“CTL”). Sastry broadly claimed this first peptide as one that is “able to stimulate the formation or enhance the activity of cytotoxic T cells that are capable of killing MHC-matched target cells that have the peptide on their surface.”

The second peptide was provided to limit the spread of HIV to uninfected T cells (i.e., T-helper cells) to properly assist an immune response against the virus. This second peptide was selected from among four different peptides. Three of these peptides were defined as “HIV infection-inhibiting” that were derived from different portions of the HIV envelope protein. The fourth was defined as a “T helper cell-inducing” peptide having certain structural properties recited in the claims.

During prosecution, the Examiner rejected all of the claims as obvious over U.S. Patent No. 5,128,319 to Arlinghaus and a number of other references (including a 1988 journal article by Takahashi and a 1989 journal article by Javaherian). The Examiner contended that Arlinghaus taught the first peptide and the various other references taught the second peptide. On appeal to the Board, Sastry argued that there was no motivation to make the combination proposed by the Examiner, but the Board sustained the Examiner’s rejection.

On appeal to the Federal Circuit, Sastry conceded that the prior art references taught both the first and second peptides recited in the claims. However, Sastry again argued that there was no motivation to combine the references. Sastry interpreted Arlinghaus as suggesting that CTL-inducing peptides should not be used if they induce a significant antibody-mediated response. Sastry then contended that Arlinghaus actually taught away from the proposed combination of prior art references since the HIV infection-inhibiting (i.e., second) peptides described by Javaherian (and several of the other references) would induce a significant antibody response. Accordingly, Sastry argued that the combination of a “CTL inducing peptide” with either a “HIV infection-inhibiting peptide” or a “T helper cellinducing peptide” was a nonobvious combination.

The Federal Circuit disagreed, noting that Arlinghaus actually provided a roadmap for making the claimed combination. In its analysis, the Court found that Arlinghaus not only taught the first peptide, but also the second. According to the Court, Arlinghaus suggested a “plurality of active peptides,” including those with “the capacity to induce cytotoxic T cell activation to the native HIV protein,” thus disclosing Sastry’s first peptide. As for the second peptide, the Court noted that Arlinghaus clearly contemplated the use of more than one type of active peptide and identified two such peptides taught by Arlinghaus. These two peptides disclosed by Arlinghaus were identical to two HIV infectioninhibiting (i.e., second) peptides that were listed in Sastry’s application.

Given the significant overlap between Sastry and Arlinghaus, the Court opined that the Board could have based its rejection of Sastry on anticipation rather than obviousness. To not do so, however, did not constitute error on the part of the Board. Accordingly, the Federal Circuit affirmed the Board’s rejection of Sastry’s application as being obvious in view of the cited prior art.