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Merck Sharp & Dohme Corp. v. Hospira Inc.

Case Name: Merck Sharp & Dohme Corp. v. Hospira Inc., 14-cv-915-RGA, 2016 U.S. Dist. LEXIS 139721 (D. Del. Oct. 7, 2016) (Andrews, J.) 

Drug Product and Patent(s)-in-Suit: Invanz® (ertapenem); U.S. Patents Nos. 5,952,323 (“the ’323 patent”) and 6,486,150 (“the ’150 patent”)

Nature of the Case and Issue(s) Presented: Ertapenem is a highly unstable antibiotic, first claimed in U.S. Patent No. 5,478,820 (“the ’820 patent”). The two patents-in-suit, owned by Merck, related to a stable ertapenem composition and a method of stabilizing ertapenem (the ’323 patent) and a process for preparing a carbamate adduct of ertapenem (the ’150 patent).

Hospira filed an ANDA seeking to market a generic version of Invanz. Merck sued Hospira for patent infringement. After a bench trial, the court found the asserted claims of the ’323 patent valid and (based on Hospira’s stipulation) infringed. The Court also determined that the asserted claims of the ’150 patent were invalid as obvious in light of the prior art.

Why Merck Prevailed: Hospira argued that the asserted claims of the ’323 patent were anticipated by the ’820 patent. Although the ’820 patent did not teach a carbamate adduct, as required by the claims of the ’323 patent, Hospira urged that the adduct was inherently present and would form under the conditions disclosed in the ’820 patent. The court disagreed. The ’323 patent explicitly taught that the adduct would not form outside the pH range of 6.0-9.0. This pH range was not disclosed in the ’820 patent, nor would the procedure described in the patent—mixing alkali carbonate or bicarbonate at “an appropriate pH”—lead to a pH of 6.0-9.0. Thus, no adduct was formed, and the asserted claims were not anticipated.

Hospira’s obviousness arguments also did not persuade the court to find the ’323 patent invalid. Hospira’s prior art focused on imipenem and meropenem, similar compounds that were stable at a neutral pH. Hospira argued that one of ordinary skill, knowing that those compounds were stable at a neutral pH, would seek to stabilize ertapenem at a similar pH. But the court found that there were significant structural differences between Hospira’s prior-art compounds and ertapenem that would discourage one of skill from treating ertapenem the same as imipenem and meropenem. For example, imipenem could be isolated in a crystalline form at room temperature, whereas ertapenem must be kept at -20°C to be isolated in a solid form. Perhaps more importantly, imipenem was unable to form an adduct at any condition. Further, the court found that objective indicia weighed in favor of a finding of non-obviousness.

Concerning the ’150 patent, Hospira argued that the asserted claims would have been obvious to a person of ordinary skill at the time of invention. The court agreed. Although the claims described a process for preparing a carbamate adduct of ertapenem, that process was simply a recitation of routine manufacturing steps. Because the ’323 patent described a carbamate adduct product in detail, one of ordinary skill seeking to create the disclosed compound would simply utilize the routine steps claimed by the ’150 patent to make it. Thus, in light of the ’323 patent, the ’150 patent contained no inventive concept.

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