District Court Finds Claims Directed to Method for Analyzing Enoxaparin Sample to Be Patent Eligible

Last month, in Momenta Pharmaceuticals, Inc. v. Amphastar Pharmaceuticals, Inc., District Judge Nathaniel M. Gorton of the U.S. District Court for the District of Massachusetts allowed a motion for judgment as a matter of law filed by Plaintiffs Momenta Pharmaceuticals, Inc. and Sandoz Inc. ("Momenta") contending that two affirmative defenses asserted by Defendants Amphastar Pharmaceuticals, Inc. and International Medication Systems, Ltd. ("Amphastar") were inapplicable.  Amphastar had asserted the affirmative defenses of patent ineligible subject matter and indefiniteness in response to Momenta's claim that Amphastar's sale of generic enoxparain products infringed U.S. Patent No. 7,575,886.  The instant post addresses Amphastar's affirmative defense of patent ineligible subject matter.

The '886 patent is directed at a set of manufacturing quality control processes that ensure that each batch of generic enoxaparin includes the individual sugar chains characteristic of enoxaparin sodium, which is marketed under the brand name LOVENOX.  Representative claim 1 of the '886 patent recites:

1.  A method for analyzing an enoxaparin sample for the presence or amount of a non naturally occurring sugar associated with peak 9 of FIG. 1 that results from a method of making enoxaparin that included β-eliminative cleavage with a benzyl ester and depolymerization, comprising:
    providing an enoxaparin sample that has been exhaustively digested with two or more heparin degrading enzymes;
    using a separation method to determine, in the enoxaparin sample that has been contacted with two or more heparin degrading enzymes, the presence of a structural signature associated with the non naturally occurring sugar associated with peak 9 of FIG. 1 that results from a method of making enoxaparin that includes β-eliminative cleavage with a benzyl ester and depolymerization;
    making a determination about the enoxaparin sample based upon a comparison of the determination of the presence of a structural signature associated with the non naturally occurring sugar associated with peak 9 to a reference standard for enoxaparin, and
    determining the presence of the structural signature associated with the non naturally occurring sugar associated with peak 9 of FIG. 1 in a second batch of enoxaparin, to thereby analyze the enoxaparin sample.

Two days after Amphastar received FDA approval to market its generic enoxaparin product, Momenta filed a complaint alleging that Amphastar infringed the '886 patent by manufacturing generic enoxaparin for commercial sale using its patented method.  After twice reaching the Federal Circuit (see "Momenta Pharmaceuticals, Inc. v. Amphastar Pharmaceuticals, Inc. (Fed. Cir. 2012)" and "Momenta Pharmaceuticals, Inc. v. Teva Pharmaceuticals USA Inc. (Fed. Cir. 2015)"), the case returned to the District Court where Amphastar moved for summary judgment of invalidity (on the grounds of lack of patent eligible subject matter and indefiniteness) and non-infringement, and Momenta cross-moved for summary judgment of dismissal of the equitable defenses of waiver and estoppel.  In a decision issued in June (see Memonrandum & Order), the District Court denied the motions filed by both Amphastar and Momenta.

With regard to Amphastar's motion for summary judgment of lack of patent eligible subject matter, Amphastar argued that each of the four steps of the claimed method for analyzing an enoxaparin sample involves patent ineligible subject matter.  In particular, Amphastar contended that the first step of the claimed process involves the digestion of enoxaparin, which is a law of nature, the second step involves the identification and separation of that natural process, and the third and fourth steps involve the comparison between the tested product and a standard product, which are comparisons of abstract ideas.  In response, Momenta countered that the exhaustive digestion of enoxaparin in the first step, which requires exposure of the enoxaparin sample to a chemical cocktail for a certain time and at a specific temperature, does not occur naturally, and that the process results in a mixture of long and short sugar chains that do not individually exist in nature.  Momenta also disputed Amphstar's assertion that the second, third, and fourth steps of the claimed process rendered the claimed process patent ineligible.  In denying Amphastar's motion, the District Court determined that after "[v]iewing the facts in the light most favorable to Momenta," Momenta had persuaded the Court "that the '886 patent '[is] directed to a new and useful method' of ensuring the quality of enoxaparin."

Turning to Momenta's motion for judgment as a matter of law on Amphastar's affirmative defense of patent ineligible subject matter, the District Court once again faced the issue of the patent eligibility of asserted claims.  The Court began by outlining the two-step framework for determining patent eligible subject matter set forth in Mayo Collaborative Servs. v. Prometheus Labs., Inc., 132 S. Ct. 1289, 1293 (2012).  In the first step, the Court must determine whether the claims are "directed" to a patent ineligible concept, such as a natural law, natural phenomenon or abstract idea, and if the claims are so directed, then the Court must determine whether the elements of the invention "transform" the claims into an application eligible for a patent.  In allowing Momenta's motion, the District Court determined that:

Because the '886 patent "[is] directed to a new and useful method" of ensuring the quality of enoxaparin and involves a series of laboratory steps rather than a law of nature or abstract idea, this Court concludes that the asserted claims involve patentable subject matter. See CellzDirect, 827 F.3d at 1048.

Momenta Pharmaceuticals, Inc. v. Amphastar Pharmaceuticals, Inc. (D. Mass. 2017)
Memorandum & Order by District Judge Gorton