The age of the “blockbuster drug” is drawing to a close with an estimated $65 billion of drug revenue going off-patent in the next four years. Pharmaceutical companies are actively developing new strategies to cope with the expiration of the patents protecting their biggest products. One specific strategy involves patenting improved versions of existing products, such as novel pharmaceutical solid forms.
Pharmaceuticals can exist in numerous solid forms, including salts, solvates, polymorphs and co-crystals. From a pharmaceutical point of view, different solid forms of a drug can influence the drug’s characteristics, such as stability and potency. As a result, drug producers actively screen for, and identify, all potential pharmaceutical solid forms to avoid complications during the production process and product lifetime. Pharmaceutical companies have begun filing solid-form patent applications hoping to extend a product’s life-cycle through longer patent terms. The generic drug industry has also begun targeting unprotected solid forms as a means to potentially avoid patent infringement. Obstacles are being encountered in the patent office and the courts, with the major legal hurdles being anticipation (novelty), obviousness and enablement. This article will briefly discuss each of these hurdles and their effect on pending patent applications or patents claiming pharmaceutical solid forms.
Novelty is a requirement for patentability. Inventions lacking novelty are deemed “anticipated”, and thus are unpatentable. An invention is anticipated only if each and every element of the claimed invention is found, expressly or inherently, in the prior art. Prior art generally constitutes information that is publicly available, before a given date, which might be relevant to the invention being claimed. Inherent anticipation is often problematic for solid-form patents and patent applications. Inherent anticipation refers to when a prior art reference does not expressly disclose every limitation of a claimed invention, but any “missing” limitations are present, inherently, in the reference. For example, the Court of Appeals for the Federal Circuit held that a patent claiming an improved solid form was inherently anticipated by a prior art reference claiming a process for making the original solid form. The Court found that production of the original solid form inherently resulted in production of trace amounts of the improved form. Consequently, a company seeking to patent multiple solid forms of a particular drug should take the necessary precautions to determine whether a patent claiming their original solid form will anticipate any later patent applications claiming newly-developed solid forms.
Obviousness is closely related to anticipation, but may be generally easier to overcome for novel pharmaceutical solid forms. The patent laws state that a patent cannot be obtained if the subject matter sought to be patented is obvious to one of ordinary skill in the art, in view of the prior art. Obviousness rejections may be overcome through the production of evidence, such as unexpected results, failure of others or commercial success. The patent office and the courts require less evidence for highly-unpredictable technology, such as the development of co-crystals. Thus, if a person of ordinary skill in the art cannot predict the structures, properties or process of making a novel solid form, an obviousness rejection may be overcome by demonstrating that the formation of a particular solid form was unexpected.
Lastly, new pharmaceutical solid forms must meet the standard of enablement, which requires sufficient disclosure in the patent application, such that any person skilled in the art can make and use the invention without undue experimentation. Several factors are taken into consideration when determining the amount of experimentation necessary. As with obviousness, the patent office looks at the predictability of the art. The less predictable the claimed invention is, the greater the showing required to prove that the claimed invention is enabled. Generally, higher enablement requirements lead to a more narrow claim scope in pharmaceutical solid-form patents. For example, a TransForm Pharmaceutical patent application originally claiming a large genus of co-crystals had to be narrowed to only those co-crystal species that the patent office argued were enabled.
Despite the legal obstacles faced when patenting pharmaceutical solid forms, a number of patents have issued with several more patent applications being filed each month. In fact, a recent search of the United States Patent & Trademark Office databases for the term “co-crystal” resulted in 11 issued patents and 109 published applications claiming that particular solid form. For pharmaceutical companies to remain competitive and offset the loss of revenue associated with patent expiration, product life-cycle strategies should be developed to include the detection, protection and enforcement of novel pharmaceutical solid forms.
Gaby L. Longsworth, Ph.D., Esq., is a Director with the law firm of Sterne, Kessler, Goldstein & Fox P.L.L.C. She concentrates her practice in patent law. Christopher B. Ferenc, Esq., is an associate with the law firm of Sterne, Kessler, Goldstein & Fox P.L.L.C. He concentrates his practice in patent law. This article reflects the present thoughts of the authors, and should not be attributed to Sterne, Kessler, Goldstein & Fox P.L.L.C. or any of its former, current, or future clients. The content is for purposes of discussion and should not be considered legal advice.