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September 30, 2020by Christopher Bayne

A “product-by-process” limitation exists where a recited product, such as a composition or article, is defined in terms of the method used to manufacture the product.

In assessing patentability under U.S. patent law, product-by-process limitations are not limited to the manipulations of the recited method steps—but, instead, are limited by the structure implied by the method steps.  As explained by the Federal Circuit:

[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.

In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985), cited with approval in M.P.E.P. § 2113, para. I.

However, as explained in the Manual of Patent Examining Procedure (MPEP), the structure implied by the process steps of a product-by-process limitation should be considered especially (i) where the product can only be defined by the process steps, or (ii) where the manufacturing process steps would be expected to impart distinctive structural characteristics to the final product.  See M.P.E.P. § 2113, para. I (citing In re Garnero, 412 F.2d 276, 279, 162 USPQ 221, 223 (CCPA 1979)).

Despite these rules, issues of claim construction can occur when a product-by-process limitation is imbedded within a method claim.  Given that a method claim is limited by the manipulations of the recited method steps, should the process steps of a nested product-by-process limitation also be considered when assessing patentability?

On September 28, 2020, the Federal Circuit (“Court”) issued a precedential opinion in Biogen MA Inc. v. EMD Serono, Inc. leaving no doubt that the nesting of a product-by-process limitation within a method claim does not alter the rule described in Section 2113 of the MPEP.

Biogen MA, Inc. (“Biogen”) sued EMD Serono, Inc. and Pfizer, Inc. (collectively “Serono”) for infringing Biogen’s U.S. Patent Number 7,588,755 (the “`755 patent”) by the sale and marketing of Rebif, a recombinant interferon-β (“IFN-β”) product used for the treatment of Multiple Sclerosis (MS).

Claim 1 of the `755 patent, shown below, includes a nested product-by-process limitation defining a so-called “recombinant polypeptide” based on its production from a “recombinant DNA molecule” within a non-human host.

1. A method for immunomodulation or treating a viral condition[ ], a viral disease, cancers or tumors comprising the step of administering to a patient in need of such treatment a therapeutically effective amount of a composition comprising:

a recombinant polypeptide produced by a non-human host transformed by a recombinant DNA molecule comprising a DNA sequence selected from the group consisting of:

(a) DNA sequences which are capable of hybridizing to any of the DNA inserts of G-pBR322(Pst)/HFIF1, G-pBR322(Pst)/HFIF3 (DSM 1791), G-pBR322(Pst)/HFIF6 (DSM 1792), and G-pBR322(Pst)/HFIF7 (DSM 1793) under hybridizing conditions of 0.75 M NaCl at 68° C. and washing conditions of 0.3 M NaCl at 68° C., and which code for a polypeptide displaying antiviral activity, and

(b) DNA sequences which are de-generate as a result of the genetic code to the DNA sequences defined in (a);

said DNA sequence being operatively linked to an expression control sequence in the recombinant DNA molecule.

A central issue in Biogen MA was whether the district court should have applied the product-by-process analysis (i.e., M.P.E.P. § 2113) to the term “recombinant polypeptide” in Claim 1 of the `755 patent.

Under the product-by-process analysis, the recited method for producing the “recombinant polypeptide” in Claim 1—i.e., production using the “recombinant DNA molecule” in a “non-human host”—could not be used to distinguish prior art references teaching the use of native IFN-β to treat viral diseases.

On this issue, the Court held that the district court’s refusal to consider the respective structures of the “recombinant polypeptide” and the native polypeptide (IFN-β)—as opposed to their respective sources of production—ran afoul of the longstanding rule that “an old product is not patentable even if it is made by a new process.”  Amgen Inc. v. Hoffman-La Roche Ltd., 580 F.3d 1340 (Fed. Cir. 2009).  As explained by the Court:

We agree with Serono. The district court’s refusal to consider the identity of recombinant and native IFN-β runs afoul of the longstanding rule that “an old product is not patentable even if it is made by a new process.” Amgen, 580 F.3d at 1366. See also Gen. Elec. Co. v. Wabash Appliance Corp., 304 U.S. 364, 373 (1938) (“[A] patentee who does not distinguish his product from what is old except by reference, express or constructive, to the process by which he produced it, cannot secure a monopoly on the product by whatever means produced.”); Cochrane v. Badische Anilin & Soda Fabrik, 111 U.S. 293, 311 (1884) (“While a new process for producing [an old product] was patentable, the product itself could not be patented, even though it was a product made artificially for the first time.”); SmithKline Beecham Corp. v. Apotex Corp., 439 F.3d 1312, 1317 (Fed. Cir. 2006) (“It has long been established that one cannot avoid anticipation by an earlier product disclosure by claiming the same product . . . as produced by a particular process.”).

In line with Amgen, the Court found that the recombinant origin of the “recombinant polypeptide” does not confer novelty if the polypeptide itself is structurally identical to the corresponding native (non-recombinant) polypeptide (IFN-β) used in the prior art.  In the Court’s own words:

The nature of the origin or source of the composition recited in the claims at issue in this case is, in all relevant respects, identical to that considered in Amgen. As in Amgen, the recombinant origin of the recited composition cannot alone confer novelty on that composition if the product itself is identical to the prior art non-recombinant product. The requirements that the claimed polypeptide is “recombinant” and “produced by a non-human host transformed by a recombinant DNA molecule” (in the case of Claim 1 of the ’755 patent) describe the process by which the product, i.e. the “polypeptide,” is formed. These are not additional structural limitations. See Purdue Pharma L.P. v. Epic Pharma, LLC, 811 F.3d 1345, 1353 (Fed. Cir. 2016) (holding that because a source limitation of a composition “has no effect on its structure . . . [that] limitation . . . cannot be a structural limitation”). The key question for anticipation here, as in Amgen, is thus whether the recombinant product is identical to the prior art product—not whether the prior art product was made recombinantly.

The Court also reiterated that “nesting” a product-by-process limitation within a method of treatment claim does not affect the claim construction of the product-by-process limitation.  Consequently, as explained below, the process steps of a nested product-by-process limitation are not considered when assessing the patentability of the claimed method.

There is no logical reason why the nesting of a product-by-process limitation within a method of treatment claim should change how novelty of that limitation is evaluated. Indeed, we have previously applied product-by-process analysis to a nested limitation.  In Purdue Pharma, we interpreted a claim to “an oral dosage form comprising . . . oxycodone hydrochloride active pharmaceutical ingredient having less than 25 ppm 14-hydroxy[ ], wherein at least a portion of the 14-hydroxy [ ] is derived from 8α[ ] during conversion of oxycodone free base to oxycodone hydrochloride” as including a product-by-process limitation; namely, the 14-hydroxy as derived. Purdue Pharma, 811 F.3d at 1353 (emphasis omitted). Similar to our analysis here, the court in Purdue Pharma held that it was appropriate to focus on the identity of the products of the claimed and prior art processes, and not on the source limitation, in analyzing obviousness. See id. at 1353–54. The nesting of the product-by-process limitation within a method of treatment claim does not change the proper construction of the product-by-process limitation itself.

In addition to reversing the district court’s construction based on the source of the “recombinant polypeptide,” the Court also disagreed with the district court’s position that the three-dimensional structure of the “recombinant polypeptide” could be used to distinguish the native polypeptide.  First, the term “polypeptide” was defined in the `755 patent as a linear array of amino acids without reference to the three-dimensional structure. Second, although Claim 1 requires the polypeptide to display “antiviral activity,” it does not recite any specific folded three-dimensional structure that gives rise to that activity. Finally, the jury was never instructed that the three-dimensional structures of the respective peptides must be compared in order to assess anticipation.

Takeaways: Product-by-process limitations should always be construed based on the structure implied by the process steps—as opposed to the recited process steps—even when a product-by-process limitation is nested within a method claim.  But keep in mind that the process steps of a product-by-process limitation may be relevant especially (i) where the product can only be defined by the process steps, or (ii) where the manufacturing process steps would be expected to impart distinctive structural characteristics to the final product.

Circuit Judges:  P. NEWMAN, R. LINN, and T.M. HUGHES (Opinion by LINN).

Christopher Bayne

by Christopher Bayne

Christopher D. Bayne is a patent attorney having extensive experience with patent preparation and prosecution for both domestic and international clients. His practice includes, for example, drafting and filing patent applications, patent prosecution and appeals before the United States Patent and Trademark Office, reexamination practice, reissue practice, inter partes and post-grant review, third-party submissions, and providing legal opinions.