PTAB invalidates Anacor’s Tavaborole patents

A big blow for Anacor as its two patents got invalidated by PTAB. Anacor hold patent rights on its oxaborole antifungal drug Tavaborole which got approved by FDA in 2014.(KERYDIN SOLUTION 5%).


Tavaborole was patented as a product in US 5,880,188 A which had expired. The drug was later licensed to Anacor, which initiated the trails and succeded to bring the drug into the market.


Anacor have few or more patents claiming composition and approved indication. The snapshot of Tavaborole OB has given below:


IPR petitions

Coalition For Affordable Drugs has filed IPR petitions for US 7,582,621 B2 (IPR2015-01776) and US 7,767,657 B2 (IPR2015-01785).

us ‘621 claims a method of treating onychomycosis in a human, said method comprising administering to the human a therapeutically effective amount of 1,3-dihydro-5-fluoro-1-hydroxy-2,1-benzoxaborole, or a pharmaceutically acceptable salt thereof, sufficient to treat said onychomycosis.

US ‘657 claims a pharmaceutical formulation, comprising:

(a) 1,3-dihydro-5-fluoro-1-hydroxy-2,1-benzoxaborole, or a salt thereof; and
(b) a pharmaceutically acceptable excipient
wherein said pharmaceutical formulation is for topical administration to an animal suffering from an infection by a microorganism.
Prior art considered for  US 7,582,621 B2 Prior art considered for  US 7,767,657 B2
Austin WO 95/33754 (Dec. 14, 1995; Ex. 1002) Chaudhuri U.S. 6,143,794 (Nov. 4, 2000; Ex. 1004)
Brehove, US 2002/0165121 A1, (Nov. 7, 2002; Ex. 1003). Samour U.S. 6,224,887 (May 1, 2001; Ex. 1005)
Freeman WO 03/009689 (Feb. 6, 2003; Ex. 1003) Friedman U.S. 7,074,392 (Jul. 11, 2006; Ex. 1006)
Atlas U.S. 5,498,407 (Mar. 12, 1996; Ex. 1007)
Shapiro U.S. 3,816,472 (June 11, 1974; Ex. 1008)
Austin WO 95/33754 (Dec. 14, 1995; Ex. 1002)
Freeman WO 03/009689 (Feb. 6, 2003; Ex. 1003)

Scope of the prior art:

Austin relates to various oxaborole derivatives and their use as fungicides for the protection of plastic materials. Austin specifically claims Tavaborole. Along with a number of different preferred oxaboroles, Austin discloses tavaborole as Example 64, as well as the results of a study showing tavaborole has effective antifungal activity against five different fungi: Aspergillus niger, Aureobasidium pullulans, Candida albicans (“C. albicans”), Gliocladium roseum, and Penicillium pinophylum.

Brehove relates to the topical treatment of nail infections such as onychomycosis caused by bacteria, fungi, and other pathogens. Brehove explains that onychomycosis is a nail disease typically caused by C. albicans, Trichophyton mentagrophytes, Trichophyton rubrum (“T. rubrum”), or Epidermpophyton floccusum.

Freeman discloses phenylboronic acid (PBA) and related boronic acid compounds that are used for treating fungal infections such as onychomycosis. Freeman identifies T. rubrum as one of the most common dermatophyte causes of onychomycosis. Freeman also identifies non-dermatophytes, “especially Candida Sp.,” as another cause of onychomycosis.

Chaudhuri is directed to topical formulations for treating nail fungal diseases. Chaudhuri states that treating onychomycosis can be difficult and that it would be advantageous to have a topical formulation capable of penetrating the nail barrier and treating nail fungal diseases. In particular, Chaudhuri provides an example containing 5–20% weight propylene glycol, 20–80% weight ethanol, and 0.5 to 15% weight antifungal. Id. at 8:57–9:10.

Samour describes a nail lacquer formulation that is effective for the treatment or prevention of fungal infections, such as onychomycosis. Samour teaches that an effective amount of active antifungal agent preferably ranges from 1 to 10% by weight of the composition.

Friedman describes a topical sustained release composition for delivery of antifungal agents to nails. Friedman describes a number of methacrylic polymers for use as a film-forming polymer and describes plasticizers, such as dibutyl sebacate, with a preferable weight ratio of plasticizer to polymer of about 0.4:1 to about 0.3:1.

Atlas describes the use of hydrogel polymers as excellent carriers for the release of drugs.

Shapiro describes antifungal compounds for treating fungal infections. Shapiro teaches that its antifungal compounds are effective against fungi including Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton verrucosum, and Microsporum gypseum.

Having considered the parties’ arguments and evidence, PTAB has evaluated all of the evidence together to make a final determination of obviousness and concluded that the petitioner has shown by a preponderance of the evidence that claims of US ‘621 and US ‘657 are unpatentable as obvious over the cited references.

Anacor may file an appeal to CAFC.


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