Method of treatment obvious based on selection of compound from large list of compounds.

This appeal to the Patent Trial and Appeal Board (the “Board”) involved claims to the treatment of cutaneous T cell lymphoma.  Ex Parte Alain H. Rook et al., 2017 Pat. App. LEXIS 6518 (PTAB). The main claim on appeal, from U.S.S.N. 12/159,058, read:

3. A method of treating a patient with cutaneous T cell lymphoma, the method comprising:

administering to the patient an amount of a pharmaceutical composition comprising N-[4-(4-amino-2-ethyllH-imidazo [4,5-c]quinolin-l-yl)butyl] methanesulfonamide effective for ameliorating at least one symptom or clinical sign of cutaneous T cell lymphoma.

The Examiner rejected the claim over a single prior art reference, US 6,677,349 B1 to Griesgraber. Griesgraber had discovered a number of compounds that stimulated INF-α and TNF-α activity and stated that this discovery:

suggests that compounds of the invention are useful in treating diseases such as, but not limited to, viral diseases including . . . cutaneous T-cell lymphoma.

Griesgraber had no clinical data that his compounds would actually treat cutaneous T-cell lymphoma, but simply hypothesized that the compounds could do so based on their ability to stimulate INF-α and TNF-α, and the involvement of these two cytokines in immune responses.

One of the compounds that Griesgraber disclosed was N-[4-(4-amino-2-ethyllH-imidazo [4,5-c]quinolin-l-yl)butyl] methanesulfonamide.  Griesgraber disclosed the compound in a data set that included INF-α and TNF-α data for 270 compounds.

The Applicant argued that Griesgraber disclosed too many compounds, and too many diseases, to believe that every one of the compounds would be effective for the treatment of cutaneous T-cell lymphoma.  According to the Applicant, a worker of ordinary skill would not have had a reasonable expectation of successfully treating cutaneous T-cell lymphoma based on Griesgraber’s broad disclosure of numerous compounds, given the varying in vitro activity exhibited by these compounds and the range of diseases potentially treatable based on this in vitro activity.   

The Board rejected this argument because the Applicant was arguing against a bedrock tool of patent examination, flowing from cases such as Merck & Co. v. Biocraft Laboratories, Inc., 874 F.2d 804, 807 (Fed. Cir. 1989) and In re Corkill, 771 F.2d 1496 (Fed. Cir. 1985) As the Federal Circuit stated in Merck:

That the [prior art reference] discloses a multitude of effective combinations does not render any particular formulation less obvious. This is especially true because the claimed composition is used for the identical purpose taught by the prior art.

The fact that Griesgraber taught the identical purpose, cutaneous T-cell lymphoma, doomed the appeal.

The Board did, however, give some pointers on how to avoid an obviousness rejection under these circumstances.  The Board stated:

Appellants have provided no evidence that a particular threshold level of induction of cytokine production is necessary to achieve treatment, nor do they claim a particular response must be achieved; claim 3 recites “effective for ameliorating at least one symptom or clinical sign of cutaneous T cell lymphoma.”

If the patent application had been drafted with the clinical trial in mind, and the claim recited the clinical response that FDA would have required to grant approval, the claim would not have recited the “identical purpose” disclosed by Griesgraber, as stated by the Merck court, and it might have been patentable. The Applicant could have increased its chances of securing a patent even further by marshalling evidence that other compounds that exhibited Griesgraber's INF-α/TNF-α activity failed to produce this clinical response.