Application of the Reverse Doctrine of Equivalents to Amgen v. Hoechst Marion, Inc.

A Markman hearing was held and the court construed the main elements of the claim as follows: the term 'vertebrate cells' meant 'cells from an animal having a backbone;' the term 'non-human DNA seq- uences' meant 'DNA sequences that are not part of the human genome;' and the term 'DNA encoding erythropoietin' meant 'DNA which encodes human erythropoietin.' Id. at 89. Thereafter, the court determined that TKT's cells literally infringed claim 1 by finding that: 1) TKT's cells are vertebrate cells; 2) TKT's cells have non-human DNA sequences that control transcription; 3) TKT's cells contain DNA encoding EPO; and 4) TKT's cells meet the other limitations of claim 1. Id. at 117-119.

The following demonstrates a hypothetical analysis of how TKT may have raised the Reverse Doctrine of Equivalents as a defense to avoid liability for patent infringement. This analysis does not attempt to address the likelihood of success of this defense or the various reasons TKT had in not asserting the same.

As a preliminary note, it does not appear that any court has addressed the issue of whether an earlier performed claim construction analysis bears any weight on a Reverse Doctrine of Equivalents analysis. It is logical, however, that a Reverse Doctrine of Equivalents analysis should not be influenced by an earlier claim construction. A claim construction analysis is performed without reference to the accused device to ascertain what level of protection should be afforded a particular claim, relative to the invention itself, the specification, the prosecution history and the prior art. It is only after the claims have been construed that they are compared with the accused device. In contrast, a Reverse Doctrine of Equivalents analysis is performed with reference to the accused device and asks whether it is fair to hold the accused device liable for literal infringement. It is an inquiry of fairness that has been necessitated by the limitation of language. Thus, when the patent issued, it may have been proper for the patent to include a particular claim, given the state of the art and the specific invention. However, when that claim is asserted against an accused device, the court may recognize that the claim encompasses more than the patentee actually contributed. (This may appear as a lack of enablement/written description problem, but, depending on the court's perspective, it need not be so. The court may determine that the patentee's invention merited the scope of the claims at the time of patenting, but it is not fair to invalidate the claims because of later developments. Rather than invalidating the claims, the court could simply conclude that the accused invention is not liable for the literal infringement. Thus, the Reverse Doctrine of Equivalents can advance the judicial bias against invalidating patents.)

Since the court is recognizing the limitation of language and is evaluating the question of infringement from an equity perspective, it is fair for the court to step beyond the literal language of the claims and ascertain the principle of the invention without reference to the asserted claims.

Further, the Reverse Doctrine of Equivalents itself dictates that the analysis should proceed without reference to the claims. The doctrine provides that it is not fair to hold an accused device that literally falls within the scope of the asserted claim(s) liable if it is so far changed in principle from the patented article that it performs the same or a similar function in a substantially different way. The standard makes clear that it is the principle of the invention that must be evaluated and compared and does require that the claims be consulted to evaluate liability under the Reverse Doctrine of Equivalents.

Returning to TKT's defense, TKT would attempt to satisfy the first step of the test by demonstrating that its cells are substantially different in principle than the principle of the Amgen cells. TKT would argue that the principle of the Amgen cells is a non-human cell containing an exogenous EPO gene and non-human sequences controlling the expression of the EPO gene, wherein the controlling sequences are located adjacent to the EPO gene. Even though claim 1 is much broader than this principle, TKT would assert that the disclosure of the '349 patent does not teach anything broader than this principle. Further, a consideration of the prosecution history of the '349 patent and related patents may reveal additional comments and statements supporting this or a more restrictive principle.

TKT would advance that the principle of its cells are human cells containing an endogenous EPO gene and non-human controlling sequences located upstream from the EPO gene, in a position not necessarily adjacent to the EPO gene. Such an interpretation, TKT would continue, is clearly supported by the evidence of record and is consistent with TKT's invention. Because the principles are substantially different, TKT likely could have been able to satisfy the first step of the test.

TKT would then attempt to demonstrate that its cells operate in a substantially different way than the way in which the Amgen's cells operate. TKT would argue that Amgen's cells produce EPO by obtaining a non-human cell that does not contain the EPO gene, inserting into that cell the EPO gene and also inserting into the cell, at a location adjacent to the EPO gene, non-human sequences that control expression of the EPO gene, and thereafter using the non-human control sequences to activate the EPO gene.

In contrast, TKT would then demonstrate that it produces EPO by obtaining a human cell that contains the EPO gene and then inserting at a location upstream, and not necessarily adjacent to, the EPO gene non-human sequences that control expression of the EPO gene, and thereafter causing the control sequences to express the EPO gene. TKT would argue that these two modes of producing EPO are substantially different. Therefore, because the TKT cells are substantially different in principle from the Amgen cells and because the TKT cells operate in a substantially different way from the Amgen cells, TKT might have been able to avoid liability for infringement of claim 1.

Justin S. Rerko is a patent agent with Pearne & Gordon LLP and graduated from Case Western Reserve University School of Law in May, 2003. He focuses on biotechnology and mechanical engineering. Michael Garvey, a partner with Pearne & Gordon LLP, also contributed to this article.

In the previous issue, we discussed the principle of the Reverse Doctrine of Equivalents and provided several illustrations of cases that have addressed the same. In this issue, we apply the principle to the Amgen, Inc. v. Hoechst Marion , Inc. case, wherein the defendants Hoecht Marion and Transkarayotic Therapies (collectively 'TKT') were found liable for infringing several of Amgen's patents. Amgen, Inc. v. Hoechst Marion, Inc., 126 F. Supp. 2d 69 (D. Mass. 2001). Although the Reverse Doctrine of Equivalents defense was not raised, this article discusses how this doctrine might have relieved TKT of liability.

Although Amgen asserted a number of patents against TKT, this article focuses on claim 1 of U.S. Patent No. 5,756,349 (the '349 patent), the text of which is as follows:

1. Vertebrate cells which can be propagated in vitro and which are capable upon growth in culture of producing erythropoietin in the medium of their growth in excess of 100 U of erythropoietin per 106 cells in 48 hours as determined by radioimmunoassay, said cells comprising non-human DNA sequences that control transcription of DNA encoding human erythropoietin.

(Erythropoietin is a protein that stimulates the production of red blood cells.)

Amgen's Technology: By taking advantage of recombinant DNA techniques, Amgen developed a method for producing human erythropoietin (EPO) in quantities previously unattainable by purification from bodily fluids. In short, Amgen removes the gene that encodes EPO from a cell naturally containing the gene and then introduces (transfects) it with non-human control sequences (SV40 viral promoter) into a Chinese Hamster Ovary (CHO) cell. Relative to the CHO cells, the promoter DNA and the human EPO gene are exogenous because the promoter and the EPO gene do not naturally reside in the CHO cells. Amgen, 126 F. Supp. 2d at 55.

TKT's Technology: TKT also developed a method of producing human EPO. However, rather than transfecting a cell with an exogenous EPO gene, TKT manipulates the endogenous human EPO gene where it naturally resides in a human cell. The EPO gene is endogenous relative to the cells used by TKT because the EPO gene naturally resides in those cells. To facilitate the manipulation, TKT inserts a control element (a cytomegalovirus (CMV) promoter) upstream from the EPO gene. Additionally, TKT homologously recombines its CMV promoter into the cells, as opposed to the heterologous recombination used by Amgen, and TKT inserts its CMV promoter at a position farther upstream than the position at which Amgen inserts the SV40 promoter.

A Markman hearing was held and the court construed the main elements of the claim as follows: the term 'vertebrate cells' meant 'cells from an animal having a backbone;' the term 'non-human DNA seq- uences' meant 'DNA sequences that are not part of the human genome;' and the term 'DNA encoding erythropoietin' meant 'DNA which encodes human erythropoietin.' Id. at 89. Thereafter, the court determined that TKT's cells literally infringed claim 1 by finding that: 1) TKT's cells are vertebrate cells; 2) TKT's cells have non-human DNA sequences that control transcription; 3) TKT's cells contain DNA encoding EPO; and 4) TKT's cells meet the other limitations of claim 1. Id. at 117-119.

The following demonstrates a hypothetical analysis of how TKT may have raised the Reverse Doctrine of Equivalents as a defense to avoid liability for patent infringement. This analysis does not attempt to address the likelihood of success of this defense or the various reasons TKT had in not asserting the same.

As a preliminary note, it does not appear that any court has addressed the issue of whether an earlier performed claim construction analysis bears any weight on a Reverse Doctrine of Equivalents analysis. It is logical, however, that a Reverse Doctrine of Equivalents analysis should not be influenced by an earlier claim construction. A claim construction analysis is performed without reference to the accused device to ascertain what level of protection should be afforded a particular claim, relative to the invention itself, the specification, the prosecution history and the prior art. It is only after the claims have been construed that they are compared with the accused device. In contrast, a Reverse Doctrine of Equivalents analysis is performed with reference to the accused device and asks whether it is fair to hold the accused device liable for literal infringement. It is an inquiry of fairness that has been necessitated by the limitation of language. Thus, when the patent issued, it may have been proper for the patent to include a particular claim, given the state of the art and the specific invention. However, when that claim is asserted against an accused device, the court may recognize that the claim encompasses more than the patentee actually contributed. (This may appear as a lack of enablement/written description problem, but, depending on the court's perspective, it need not be so. The court may determine that the patentee's invention merited the scope of the claims at the time of patenting, but it is not fair to invalidate the claims because of later developments. Rather than invalidating the claims, the court could simply conclude that the accused invention is not liable for the literal infringement. Thus, the Reverse Doctrine of Equivalents can advance the judicial bias against invalidating patents.)

Since the court is recognizing the limitation of language and is evaluating the question of infringement from an equity perspective, it is fair for the court to step beyond the literal language of the claims and ascertain the principle of the invention without reference to the asserted claims.

Further, the Reverse Doctrine of Equivalents itself dictates that the analysis should proceed without reference to the claims. The doctrine provides that it is not fair to hold an accused device that literally falls within the scope of the asserted claim(s) liable if it is so far changed in principle from the patented article that it performs the same or a similar function in a substantially different way. The standard makes clear that it is the principle of the invention that must be evaluated and compared and does require that the claims be consulted to evaluate liability under the Reverse Doctrine of Equivalents.

Returning to TKT's defense, TKT would attempt to satisfy the first step of the test by demonstrating that its cells are substantially different in principle than the principle of the Amgen cells. TKT would argue that the principle of the Amgen cells is a non-human cell containing an exogenous EPO gene and non-human sequences controlling the expression of the EPO gene, wherein the controlling sequences are located adjacent to the EPO gene. Even though claim 1 is much broader than this principle, TKT would assert that the disclosure of the '349 patent does not teach anything broader than this principle. Further, a consideration of the prosecution history of the '349 patent and related patents may reveal additional comments and statements supporting this or a more restrictive principle.

TKT would advance that the principle of its cells are human cells containing an endogenous EPO gene and non-human controlling sequences located upstream from the EPO gene, in a position not necessarily adjacent to the EPO gene. Such an interpretation, TKT would continue, is clearly supported by the evidence of record and is consistent with TKT's invention. Because the principles are substantially different, TKT likely could have been able to satisfy the first step of the test.

TKT would then attempt to demonstrate that its cells operate in a substantially different way than the way in which the Amgen's cells operate. TKT would argue that Amgen's cells produce EPO by obtaining a non-human cell that does not contain the EPO gene, inserting into that cell the EPO gene and also inserting into the cell, at a location adjacent to the EPO gene, non-human sequences that control expression of the EPO gene, and thereafter using the non-human control sequences to activate the EPO gene.

In contrast, TKT would then demonstrate that it produces EPO by obtaining a human cell that contains the EPO gene and then inserting at a location upstream, and not necessarily adjacent to, the EPO gene non-human sequences that control expression of the EPO gene, and thereafter causing the control sequences to express the EPO gene. TKT would argue that these two modes of producing EPO are substantially different. Therefore, because the TKT cells are substantially different in principle from the Amgen cells and because the TKT cells operate in a substantially different way from the Amgen cells, TKT might have been able to avoid liability for infringement of claim 1.

Justin S. Rerko is a patent agent with Pearne & Gordon LLP and graduated from Case Western Reserve University School of Law in May, 2003. He focuses on biotechnology and mechanical engineering. Michael Garvey, a partner with Pearne & Gordon LLP, also contributed to this article.