Extending Patent Protection: Strategies for Minimizing Patent Term Loss Due to Double Patenting

A patent provides its owner the right to exclude others during the term of the patent from using, making, offering to sell, selling or importing the patented invention without authorization. Patent protection is critical for biotechnology and pharmaceutical innovations because of the substantial time, efforts and costs spent in developing and commercializing such innovations. Maximizing patent term for such innovations, especially for successful products, will help biotechnology and pharmaceutical companies recoup investments and increase profitability.

A useful strategy for extending the life cycle of a product is to file additional patent applications for related inventions, such as new formulations, combinations and uses, to extend patent protection for the product. ¹Spruill, M. & Cunningham M., International BioPharm, March 1, 2005. However, pursuing patent protection in multiple applications may give rise to double patenting issues, potentially invalidating later issued patents and defeating the purpose of filing the additional applications. Court decisions on invalidating patents covering well-known drugs (e.g., antidepressant drug Prozac, ²Eli Lilly & Co. v. Barr Labs., Inc., 251 F.3d 955, 58 U.S.P.Q.2d 1865 (Fed. Cir. 2001) 62 PTCJ 120, 6/8/01. blood pressure drug Toprol-XL, ³In re Metoprolol Succinate Litig., 494 F.3d 1011, 83 U.S.P.Q.2d 1545 (Fed. Cir. 2007) 74 PTCJ 403, 8/3/07. anti-inflammatory drug Celebrex ⁴Pfizer, Inc. v. Teva Pharm. USA. Inc., 518 F.3d 1353, 86 U.S.P.Q.2d 1001 (Fed. Cir. 2008) 75 PTCJ 500, 3/14/08. and cancer drug Gemzar ⁵Sun Pharm. Indus. v. Eli Lilly & Co., 611 F.3d 1381, 95 U.S.P.Q.2d 1797 (Fed. Cir. 2010) 80 PTCJ 480, 8/6/10.) or their uses highlight such a risk.

For those unwary, double patenting presents a potential trap for losing patent term. Thus, it is important to develop strategies for minimizing patent term loss due to double patenting when filing and prosecuting patent applications.

A Primer on Double Patenting

Rules against double patenting prevent a patent owner from obtaining more than one patent for either the same invention or an obvious modification of the same invention. ⁶In re Longi, 759 F.2d 887, 892, 225 U.S.P.Q. 645 (Fed. Cir. 1985). The prohibition of obtaining more than one patent for the same invention is provided in 35 U.S.C. §101, and thus is referred to as “statutory double patenting.” The prohibition of obtaining more than one patent for an obvious modification of the same invention is a judicially created doctrine, and is referred to as “obviousness-type double patenting.”

The primary rationale for the prohibition against obviousness-type double patenting is to prevent unjustified extension of patent term. A second patent directed to essentially the same invention should not last longer than the first patent. This doctrine was developed when patents lasted 17 years from their issue date. Without double patenting deterrence, a patentee would be able to extend patent protection by obtaining a second patent, which would inevitably last longer.

However, even for applications filed on or after June 8, 1995, that have patent terms 20 years from their earliest claimed priority filing dates other than the filing dates of provisional or foreign applications, double patenting may still function to prevent improper extension of patent rights under certain circumstances. For example, a second patent may be entitled to a longer patent term adjustment resulting from delays in examining the application by the Patent and Trademark Office (PTO), and thus expire later than the first one if without double patenting.

Double patenting is a ground of rejection during examination of patent applications. It is also a ground for invalidating patents in litigation. Double patenting may arise between applications or patents having at least one common inventor, being commonly owned, or under a joint research agreement. ⁷USPTO. Manual of Patent Examining Procedure, 8th ed., rev. 9, §804 (USPTO, Alexandria, Va. 2012).

Under most circumstances, only the claims, not the specification, of an earlier patent may support a double patenting rejection or invalidation. ⁸Eli Lilly & Co. v. Teva Parenteral Medicines, Inc., 689 F.3d 1368, 1378-9, 104 U.S.P.Q.2d 1134 (Fed. Cir. 2012) 84 PTCJ 743, 8/31/12. If claims of two patents have identical scope, one patent may be invalidated in view of the other on the basis of statutory double patenting. The test for determining statutory double patenting is whether “one of the claims could be literally infringed without literally infringing the other.” ⁹In re Vogel, 422 F.2d 438, 422, 164 U.S.P.Q. 619 (C.C.P.A. 1970).

As to obvious-type double patenting, the analysis generally entails two steps. The first step construes the claim in the earlier patent and the claim in the later patent to determine the differences. The second step determines whether the differences render the claims patentably distinct from each other. The claims are not patentably distinct if the later claim is obvious over, or anticipated by, the earlier claim. ¹⁰Metoprolol Succinate, 494 F.3d at 1016.

One exception to double patenting is provided by 35 U.S.C. §121. When two or more patents result from a restriction requirement by the PTO, Section 121 insulates such patents from the charge of double patenting. ¹¹Applied Materials, Inc. v. Advanced Semiconductor Materials Am., Inc., 98 F.3d 1563, 1568, 40 U.S.P.Q.2d 1481 (Fed. Cir. 1996). More specifically, the PTO issues a restriction requirement when it believes that a patent application claims two or more independent or distinct inventions. If an applicant elects a single invention in the original application and files a divisional application to pursue another invention not elected in the original application, according to Section 121, patents issuing from the original application and the divisional application cannot be used against each other based on double patenting.

An applicant or a patentee may file a terminal disclaimer to overcome an obviousness-type double patenting rejection or challenge. A terminal disclaimer is a written statement that disclaims the period of the second patent that would extend beyond the expiration of the first patent. Thus, by requiring an applicant or patentee to file a terminal disclaimer, obviousness-type double patenting prevents extension of patent protection beyond the term of the first patent.

Strategies for Minimizing Patent Term Loss Due to Double Patenting

To minimize patent term loss due to double patenting, applicants should consider their overall patent strategies when filing and prosecuting multiple patent applications directed to related inventions.

File a single application that claims related inventions

An applicant should consider filing a single application that claims related inventions instead of filing separate applications directed to the related inventions individually. Filing a single application may trigger a restriction requirement if the PTO believes that the application claims multiple independent or distinct inventions. The applicant may file divisional applications to pursue inventions not elected in the original application. As long as the issued claims in the divisional applications are consonant with the claims in the original application that were subject to the restriction requirement, Section 121 shields the issued claims in the divisional applications from obviousness-type double patenting attacks.

Filing a single application that claims related inventions is advantageous over filing separate applications even if the claims in the separate applications are likely deemed as directed to independent or distinct inventions by the PTO if they were included in a single application. This is because a court may arrive at a conclusion different from that of the PTO when a patent is challenged based on double patenting.

For example, in Pfizer v. Teva, ¹²518 F.3d 1353. three patents-in-suit relate to the drug Celebrex. The PTO issued a restriction requirement in the application from which the first patent issued, asserting that the application contained three inventions: (1) certain non-steroidal anti-inflammatory drug (NSAID) compounds, including Celebrex, (2) compositions comprising the NSAID compounds, and (3) methods of treating inflammation or an inflammation-associated disorder using the NSAID compounds. In response to the restriction requirement, the applicant elected the first invention in that application, filed a divisional application to pursue the second invention and further filed a continuation-in-part (CIP) application to seek protection for the third invention.

The Federal Circuit held that even though the method claims in the CIP application were subject to the restriction requirement in the first application, Section 121 protection was only available to divisional applications, not to the CIP application. In addition, the court invalidated the third patent issuing from the CIP application based on double patenting in view of the second patent issuing from the divisional application despite the PTO indication that the composition claims in the second patent were patentably distinct from the method claims in the third patent by virtue of issuing the restriction requirement in the first application.

Thus, it would be safer to include claims directed to related inventions in a single application and file divisional applications if the PTO issues a restriction requirement than to assume that the related inventions are patentably distinct and voluntarily file separate applications directed to different inventions. In the latter case, an applicant will lose Section 121 protection against double patenting if the related inventions are eventually deemed as not patentably distinct by a court.

Claiming related inventions in a single application is critical to avoid double patenting if the related inventions are a new drug and a single use of the new drug. Doing so will trigger a restriction requirement if an examiner believes that the new drug and its use are distinct inventions. The restriction requirement will in turn entitle the applicant to invoke Section 121 protection against double patenting between the original application and a divisional application filed in response to the restriction requirement.

If instead, the applicant files two applications separately claiming the drug and its use, a later patent issued from one application would be invalidated on the ground of double patenting in view of an earlier patent issued from the other application. This is because an application claiming a new drug has to disclose at least one use of the drug to meet the utility and enablement requirements for patentability. If an applicant discovers only a single use of a new drug, such a use must be described in an application that claims the new drug.

Although generally the specification of an earlier patent cannot support a double patenting invalidation, the Federal Circuit has established an exception to this rule where claims directed to a method based on a single use of the drug were at issue. In Geneva v. GlaxoSmithKline, ¹³Geneva Pharm., Inc. v. GlaxoSmithKline, PLC, 349 F.3d 1373, 68 U.S.P.Q.2d 1865 (Fed. Cir. 2003) 67 PTCJ 94, 12/5/03. the court invalidated claims directed to a method of using clavulanic acid or its salt for treating antibiotic-resistant bacteria based on an earlier patent that claims potassium clavulanate and discloses but does not claim the same use. The court reasoned that because the single use claimed in the later patent was necessary to the patentability of the compound claimed in the earlier patent, such a disclosure need be considered to determine the scope of the compound claims of the earlier patent in double patenting analysis of the method claims of the later patent. ¹⁴Id. at 1386. Thus, the description of a single use of a new drug in an application that claims the new drug will be used to reject claims directed to the single use in another application unless the two applications are subject to Section 121 protection.

Similarly, claiming related inventions in a single application is also important to avoid double patenting if the related inventions are a new drug and multiple closely related uses of the new drug. As discussed above, in Pfizer, ¹⁵518 F.3d 1353. the court invalidated claims directed to methods of treating inflammation or an inflammation-associated disorder using certain NSAID compounds in view of an earlier patent that claims compositions comprising the NSAID compounds, and discloses but does not claim the same methods. Thus, the court extended the exception in Geneva to the situations where the earlier patent claims compositions and discloses multiple closely related uses of active compounds encompassed by the composition. Because of multiple uses disclosed in the earlier patent, the primary rationale for examining the specification of the earlier patent during double patenting analysis in Geneva was not applicable in Pfizer. Instead, the court focused on a more general statement of examining the specification of an earlier patent in determining the scope of compound claims of that patent in Geneva. ¹⁶Id. at 1363.

In view of Pfizer, to avoid double patenting, an application disclosing multiple closely related uses of a new drug must include method claims based on such uses, along with a claim directed to the new drug, to provoke a restriction requirement and to seek Section 121 protection.

Describe only claimed invention(s) in an application

As discussed above, from a double patenting perspective, it is desirable to file a single application that claims related inventions. However, an applicant may decide to file separate applications for related inventions individually due to other considerations. For example, filing separate applications may facilitate licensing different inventions to different entities. Also, including multiple inventions in a single application may sometimes cause the application to be unduly lengthy, which increases the filing and prosecution costs of the application and its divisional applications.

If an applicant decides to file separate applications to protect related inventions individually, to minimize the risk of double patenting, the applicant should describe in an application only inventions claimed in the application, not inventions claimed in another application. For example, if an applicant invents a drug and discovers two distinct uses of the drug, the applicant may decide to file two applications: one to claim the drug and the first use of the drug, and the other to claim the second use of the drug. In the first application, the applicant should describe the drug and the first use, but not the second use. In the second application, the applicant should describe the second use of the drug, but not the first use. Otherwise, the disclosure of the second use in the first application may be used to invalidate the claim directed to the second use in a patent issuing from the second application according to a recent Federal Circuit decision.

In Sun v. Eli Lilly, ¹⁷611 F.3d 1381. an earlier patent discloses gemcitabine and its antiviral and antitumor activities, but only claims gemcitabine and a method for using gemcitabine in treating Herpes viral infections. A later patent claims a method of treating cancer using gemcitabine. The Federal Circuit held the method claims in the later patent invalid for obviousness-type double patenting over the compound claim in the earlier patent in view of the disclosure of gemcitabine’s antitumor activity in the earlier patent.

File divisional applications, not continuation or continuation-in-part applications, in response to a restriction requirement

In response to a restriction requirement, an applicant should file a divisional application to preserve the availability of Section 121 protection so that the parent and the divisional applications will not be used against each other based on double patenting. Because the Federal Circuit has interpreted the term “divisional application” in Section 121 literally, Section 121 protection is not available to CIP applications or continuation applications, including those that are substantively divisional applications but are filed as continuation applications.

For example, as discussed above in Pfizer, the Federal Circuit held that Section 121 protection was not available to a CIP application even though the method claims in the CIP application were subject to a restriction requirement in the parent application. In Amgen v. Hoffman-La Roche, ¹⁸Amgen Inc. v. F. Hoffman-La Roche Ltd., 580 F.3d 1340, 1354, 92 U.S.P.Q.2d 1289 (Fed. Cir. 2009) 78 PTCJ 645, 9/25/09. the court held that applications filed in response to a restriction requirement and designated as “continuation applications,” could not be protected under Section 121, even though they met the definition of “divisional application” and could have been filed as divisional applications.

Although Section 121 does not protect continuation or continuation-in-part applications filed directly from an application subject to a restriction requirement, it provides protection for continuation and CIP applications descending from divisional applications. For example, in Applied Materials v. Advanced Semiconductor Materials, ¹⁹98 F.3d 1563. the Federal Circuit held that Section 121 protected a patent descending from a divisional application of an original application via a CIP application and three continuation applications from double patenting based on a patent issuing from the original application.

In addition to continuations and CIP applications of divisional applications, Section 121 also provides protection for divisional applications of divisional applications. For example, in Boehringer Ingelheim v. Barr Labs, ²⁰Boehringer Ingelheim Int’l GmbH v. Barr Labs., Inc., 592 F.3d 1340, 93 U.S.P.Q.2d 1417 (Fed. Cir. 2010) 79 PTCJ 345, 1/29/10. the patent at issue is a divisional application of its parent application, which in turn is a divisional application of another application, its grandparent application. The grandparent application was subjected to a restriction requirement listing 10 groups of inventions. The grandparent application issued with claims directed to one of the 10 groups and another subgroup. The parent application issued with claims directed to two other groups and one subgroup that belongs to the same group as, but does not overlap with, the subgroup of the grandparent application. The application at issue was granted with claims directed to four other groups.

The Federal Circuit held that Section 121 protection was available to prevent the parent application from being a reference application against the patent at issue. Thus, if an application contains multiple independent and distinct inventions according to a restriction requirement, an applicant does not have to file a divisional application for each of the multiple inventions. Section 121 protection is still available if an applicant files a divisional application that claims two or more inventions other than those claimed in the parent application. The applicant may further file one or more additional divisional applications of the divisional application if needed, and the further divisional applications may still enjoy Section 121 protection.

After filing a divisional application, an applicant should keep distinct inventions separate by not crossing the line of demarcation between the independent and distinct inventions that prompted the restriction requirement. ²¹Symbol Techs., Inc. v. Opticon, Inc., 935 F.2d 1569, 1579, 19 U.S.P.Q.2d 1241 (Fed. Cir. 1991). For example, Section 121 will not protect a divisional application if the divisional application is amended to include claims not consonant in scope to the original claims subject to restriction in the parent. ²²Id.

Summary

Double patenting is a complex area of patent law. Understanding double patenting is especially important to protecting biotechnology and pharmaceutical inventions for which multiple related applications are typically filed. Avoiding double patenting among such applications or subsequently issued patents is essential to minimizing patent term loss and maximizing the value of a patent portfolio.

To this end, an applicant should consider filing a single application that claims related inventions to trigger a restriction requirement and invoke Section 121 protection from double patenting invalidation among related applications or patents. However, if an applicant decides not to file a single application for related inventions due to other considerations, the applicant should describe in an application only inventions claimed in the application, not inventions claimed in other applications. In addition, in response to a restriction requirement, an applicant should file divisional applications, not continuation or CIP applications, and should maintain in the divisional applications the line of demarcation between the independent and distinct inventions that prompted the restriction requirement.