Dapsone – USA

Dapsone – USA

On July 16, 2021, in an unsealed opinion, Delaware Court granted Defendant’s motion on the pleading for non-infringement.

 

Plaintiff (Almirall) holds NDA for Aczone®(Dapsone) gel, 7.5%. Defendant (Torrent) filed ANDA with P-IV certification to market generic version of Aczone. Plaintiff sued Defendant for infringement of US 9,517,219 patent. The ‘219 patent describes and claims methods for treating acne vulgaris or rosacea by administering pharmaceutical compositions containing dapsone and certain inactive ingredients, specifically “a polymeric viscosity builder comprising acrylamide/sodium acryloyldimethyl taurate copolymer.” Torrent’s ANDA does not contain acrylamide/sodium acryloyldimethyl taurate copolymer (“A/SA,” also known as “Sepineo™ P 600”). Instead, it contains carbomer homopolymer type C, also known as “Carbopol®.”Torrent moved for judgment on the pleadings pursuant to Federal Rule of Civil Procedure 12(c), arguing that its proposed generic version of Almirall’ s drug does not infringe the ‘219 patent.

 

Court said that Torrent’s Rule 12(c) motion is grounded on the doctrine of argument-based prosecution history estoppel. During prosecution, Plaintiff clearly and unmistakably demonstrates surrendered Carbopol® as an equivalent for the claimed A/SA. The applicant stated:

The instant claims recite a new formulation of dapsone wherein the
active ingredient is about 7 .5 % w/w dapsone and an entirely new
thickening agent is employed. The new formulation of the
instant claims does not include a carbomer such as Carbopol®,
but instead utilizes as [sic] acrylamide/sodium acryloyldimethyl
taurate copolymer, also known as “Sepineo TM P 600″….

 

The applicant also argued that “the use of Sepineo TM P 600 as the sole thickening agent in a topical dermatological formulation” was one of the “three significant distinctions” between the claimed subject matter and the prior art. These unambiguous statements in the prosecution history meet the high bar for a “clear and unmistakable” surrender of Carbopol® as a possible equivalent for A/SA. Moreover, Almirall did not offer any persuasive argument as to how the statements in the prosecution history might mean anything other than what they plainly say. Almirall’s other arguments regarding discovery, claim construction, denial of same motion with other defendant also fail.

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