On Aug. 27, 2020, Federal Circuit affirmed PTAB’s decision which found antifungal MoU/composition patents invalid as obvious.
Flatwing pharmaceuticals filed IPRs on US 9,549,938, US 9,566,289,
US 9,566,290, and US 9,572,823 patents. These patents are listed in orange book
for KERYDIN® (Tavaborole) topical solution, which is marketed by Anacor
pharmaceuticals. KERYDIN® is indicated for the treatment of onychomycosis, or
fungal infection, of the toenails due to Trichophyton
rubrum or Trichophyton mentagrophytes.
Claim 2 of the ’823 patent is representative and it is dependent upon claim 1.
1. A method of
delivering a compound, in a human, from a dorsal layer of a nail plate to a
nail bed to treat onychomycosis caused by Trichophyton rubrum or Trichophyton
mentagrophytes, the method comprising: contacting the dorsal layer of the nail
plate with a pharmaceutical composition comprising a compound that penetrates
the nail plate, the compound being [tavaborole] or a pharmaceutically
acceptable salt thereof, thereby treating onychomycosis due to Trichophyton
rubrum or Trichophyton mentagrophytes.
2. The method of claim
1, wherein the pharmaceutical composition is in the form of a topical solution
comprising 5% w/w of [tavaborole],
and wherein the pharmaceutical composition further comprises ethanol and
propylene glycol.
The Board issued final written decisions concluding that the
challenged claims would have been obvious over a combination of WO1995/033754 (Austin),US
2002/0165121 (Brehove), and US 6,224,887 (Samour). Austin discloses tavaborole
as fungicides which shows antifungal activity against several fungi. Brehove
discloses topical compositions of organoboron compounds and results showing
nail penetration and antifungal activity for compositions of organoboron compounds
formulated in petroleum jelly or mineral oil at 10% or 25% concentration.
Samour discloses topical formulations of other antifungal compounds, such as
econazole, at concentrations of 5% by weight. The Board found that Austin,
Brehove, and Samour each teach antifungal compositions at concentration ranges
that overlap 5%, that a skilled artisan would have been able to make the
claimed composition of tavaborole using known techniques, and that formulation
of tavaborole, even as a boron-containing compound, would not have been
unpredictable.
Court’s
analysis:
During appeal, Anacor argued that the Board erred in determining
that the claimed composition would have been obvious as the product of routine
optimization. Specifically, Anacor argued that it would not have been obvious
to formulate the claimed composition, as organoborons are quite reactive
compounds. Second, Samour teaches away from a 5%-econazole composition in favor
of a 10%-econazole composition.
Federal Circuit with respect to teaching away argument said
that Samour discloses several small experiments to determine the effect of
econazole concentration on nail penetration. The results indicate that
10%-econazole compositions provide greater nail penetration than the
5%-econazole compositions, but the effect is modest overall and depends on
other variables, such as excipients. Samour ultimately claims compositions with
concentrations of 1 to 10% econazole. Court said that Samour’s teachings barely
even suggest a “preference for an alternative” approach—let alone discourage a
skilled artisan from pursuing a 5%-antifungal composition, as is required for a
reference to teach away.
With respect to special technical challenges in formulating organoborons
compounds, court found Anacor’s arguments unpersuasive. Flatwing’s expert said that
the claimed composition could have been made according to well-known
formulation techniques, and tavaborole’s potential reactivity as an organoboron
compound would not have been an important consideration. Moreover, the inventors evidently did not
consider formulating organoborons a great challenge, as the specification does
not offer any guidance beyond citation of well-known guides to pharmaceutical
formulation. Furthermore, there is no
dispute that a skilled artisan would have appreciated that concentration is a
result-effective variable, such that one could optimize nail penetration by
routine experimentation within a predictable range of concentrations.
Therefore, the selection of 5% as the concentration of a tavaborole composition
would have been obvious to a skilled artisan.
Thus, the Board did not err in determining that creating a
tavaborole topical composition would have been obvious.