Even with billions of dollars of funding and the cumulative knowledge and experience of over a hundred years of experimental pharmacology, de novo discovery of effective and safe therapeutics remains a costly and risky endeavor. The number of unsuccessful attempts to obtain Food and Drug Administration (FDA) approval of drugs for specific indications is far greater than the number of successes. As a result, there is an extensive and ever growing list of “failed” drugs, most of which are ultimately abandoned by pharmaceutical companies.
More recently, failed drugs previously considered to be lost causes are being reconsidered as possible therapies for different indications than those for which they had originally been considered. Such drug “repurposing” provides researchers and clinicians with a cost-effective way to identify potential new therapies without needing to start from scratch. Many failed drugs have already established their relative safety in Phase I clinical trials, which can simplify and reduce the cost of obtaining FDA approval should a new indication be found. Drug repurposing is not limited to failed drugs but is also being considered for currently marketed drugs as well as “off patent” generic compounds to expand and extend their usefulness.
But because drug repurposing primarily concerns previously-known drugs, obtaining patent protection can be challenging. In some cases, a drug to be repurposed is still protected by a patent that can be acquired and/or in-licensed, but often the drug itself is not protected by patent. Without patent protection, commercialization of a repurposed drug (i.e., maximizing the potential beneficial impact of the drug) is not realistic. This article discusses certain issues to be considered when trying to obtain new patent protection for repurposed drugs. It should be expected that each attempt to patent a repurposed drug will have its own fact-specific challenges. Accordingly, the concepts discussed here are generalized and non-exhaustive.
The foundational inquiry for determining whether a repurposed drug can be patented in the United States is to consider whether, under 35 U.S.C. § 101, the drug constitutes patentable subject matter. Section 101, in relevant part, provides: “[w]hoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor …”[1] Repurposed drugs are often non-nature-based compositions of matter (i.e., synthetic compounds that are not naturally occurring) that can be used in useful processes (e.g., methods of treating a disease by administering to a patient in need thereof a therapeutically effective dose of a drug). Therefore, claims directed to repurposed drugs and methods of their use should not typically run afoul of § 101. Even repurposed drugs that are nature-based compositions of matter may still be patentable, for example, if recited in a method of treatment claim. Indeed, method of treatment claims reciting nature-based compositions of matter seem to be on more secure footing under § 101 in light of the recent decision in Vanda Pharmaceuticals Inc. v. West-Ward Pharmaceuticals,[2] at least because the United States Patent and Trademark Office has issued a recent memorandum to the Patent Examining Corps advising that the Patent Office intends to follow the legal reasoning in this case.[3] Nevertheless, care must be taken when drafting claims to avoid § 101 issues.
Another significant hurdle to overcome with respect to patenting repurposed drugs is 35 U.S.C. § 102. Section 102, as applied to a repurposed drug, requires that it was not previously patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before a patent application is filed to cover the repurposed drug. In other words, a claim to the repurposed drug itself must be novel, in that it must recite something not previously publicly known. Practically speaking, most composition of matter claims reciting only the repurposed drug will be excluded from patentability under § 102, because (almost by definition for a “repurposed” drug) the drug was previously known and thus its earlier public disclosure would be prior art to any subsequent patent filing. Accordingly, composition claims directed to the repurposed drug itself will likely be anticipated because they are not reciting anything new. Yet there are ways to overcome § 102 to obtain composition claims on repurposed drugs.
One useful approach for overcoming a § 102 rejection is to incorporate the repurposed drug into a composition that includes one or more other compounds to form a novel combination not previously known. Importantly, the claimed combination can be any practical combination that is novel for purposes of overcoming § 102. However, as discussed below, claims to pharmaceutical compositions that recite combinations with more than one key constituent (e.g., a therapeutically effective amount of a repurposed drug and a therapeutically effective amount of a second drug) are more likely to be patentable. Additional details...
