In a recent memorandum order, Judge Sue L. Robinson granted patent infringement defendants Lupin Limited and Lupin Pharmaceuticals’ Rule 12(c) motion for judgment on the pleadings as to one claim of plaintiffs’ patent, and denied the motion as to other claims. See Senju Pharmaceutical Co., et al. v. Lupin Limited, et al., C.A. No. 11-271-SLR (consolidated), Slip Op. (D. Del. Dec. 7, 2012).
Plaintiffs alleged that defendants’ ANDA infringed two of their patents. Id. at 2. The parties had previously stipulated to the dismissal of all claims and counterclaims related to one patent, and defendants moved for judgment on the pleadings as to certain claims of the remaining patent (“the ’045 patent”). The ’045 patent “is directed to aqueous liquid pharmaceutical compositions comprising gatifloxacin and disodium edtate [(“EDTA”)], as well as various methods utilizing these compositions.” Plaintiffs had previously filed a request for reexamination of various claims of the ’045 patent and amended their complaint to allege infringement—by two of defendants’ ANDA applications—of the ’045 patent as reexamined. Id. at 2-3. The reexamination had resulted in, inter alia, an amended claim 6 and the addition of claims 12-16. See U.S. Patent No. 6,333,045 Ex Parte Reexamination Certificate.
In their motion, defendants alleged that the “narrower reexamined claims 6 and 12-16 of the ’045 patent are invalid for obviousness and that plaintiffs should be collaterally estopped from relitigating these claims based on this court’s findings in Senju Pharmaceutical Co. Ltd. v. Apotex Inc., 717 F. Supp. 2d 404, 419-27 (D. Del. 2010).” Senju Pharma., Slip Op. at 5. In this prior decision (“Apotex”, discussed here), the Court had construed “the EDTA concentration limitation [in “original claim 6”] to be from 0.001 to 0.2 w/v%.” Id. at 5 (citing Apotex at 419 & n.26, 421-23). Plaintiffs countered that the “reexamined claims [had] not been previously litigated and decided, because this court did not consider or determine the validity of a claim limited to 0.01 w/v% [EDTA]” in Apotex. Id. (internal citations and quotation marks omitted).
The Court accepted plaintiffs’ argument as to reexamined claims 6 and 12-16 after summarizing Apotex. Id. at 7. In Apotex it had held that “original claim 6 was obvious in light of the prior art as it ‘would lead one of ordinary skill in the art to reasonably expect that’” EDTA would be combined with gatifloxacin at the concentrations in original claim 6. Id. at 5-6 (quoting Apotex at 423). However, the Court now concluded that “[a]lthough in the ’045 patent the concentration of EDTA is limited to from 0.001 to 0.2 w/v%, this court did not specifically make findings for a claim with a limitation of 0.01 w/v% EDTA [in Apotex ] . . . . Moreover, plaintiffs did not fully litigate a claim with a limitation of 0.01 w/v% EDTA and [defendants have] not shown sufficient evidence that this limitation does not lend patentable significance to reexamined claims 6 and 12-16.” Id. at 7. In support of its conclusion, the Court cited 35 U.S.C. § 282 for the proposition that “a narrower claim is not rendered invalid by the invalidity of a broader claim.” Id. at 7 n.5. Accordingly, the Court denied the motion for judgment on the pleadings as to these reexamined claims.
The Court also rejected plaintiffs’ argument that its 2012 decision in the same Apotex case, discussed here, precluded the application of collateral estoppel, explaining that “[t]his court stated that claim preclusion applied to that case, not that issue preclusion could never apply.” Id. at 5 n.2.