Purdue Pharma (Purdue) has filed a petition for a writ of certiorari challenging a recent Federal Circuit decision upholding the invalidation of several Purdue patents on grounds of obviousness.
The decision, and the subsequent April 30, 2025 petition, underscore the importance for practitioners to ground secondary considerations in evidence when rebutting an obviousness rejection to a claimed invention.
Case background
A patent claim is considered obvious if the differences between the claim and prior art would have made the claim’s subject matter obvious to a person of ordinary skill in the art at the time of the invention. 35 U.S.C. § 103. To challenge a patent on these grounds, the challenger must show that a person of ordinary skill in the relevant art would have been motivated to combine or modify the prior art to achieve the claimed invention and had a reasonable expectation of success in doing so. Procter & Gamble Co. v. Teva Pharms. USA, Inc., 566 F.3d 989, 994 (Fed. Cir. 2009).
To determine a patent’s obviousness, courts consider several factors, including the level of ordinary skill in the art; the scope and content of the prior art; the differences between the claims and the prior art; and secondary considerations of nonobviousness, such as commercial success, long-felt but unmet needs, failure of others, and unexpected results. Prometheus Labs., Inc. v. Roxane Labs., Inc., 805 F.3d 1092, 1097 (Fed. Cir. 2015).
The underlying technology involved Purdue’s formulation of extended-release oxycodone, sold as OxyContin. Purdue’s patents covering the formulation itself expired in 2013. To overcome safety concerns from the US Food and Drug Administration (FDA) surrounding oxycodone abuse, Purdue created an “abuse resistant” formula of oxycodone in 2010. This version of the drug was harder to crush and more viscous when mixed with liquids, making it more difficult for would-be substance abusers to snort or incorporate into intravenous injections. Purdue also changed the chemical formulation to reduce the level of toxic byproducts in the final drug. These developments paved the way for several patents, including US Patent Nos. 9,763,933 ('933 patent), 9,775,808 ('808 patent), 9,763,886 ('886 patent), and 9,522,919 ('919 patent).
District court litigation
Although these patents were still active, Accord Healthcare, a manufacturer of generic pharmaceuticals, filed an abbreviated new drug application to begin selling its version of an OxyContin-like painkiller in 2020. Purdue subsequently sued for infringement of the patents listed above, after which a bench trial was held on the sole subject of validity. The district court held all asserted claims to be invalid, finding that the manufacture of polyethylene oxide (PEO) matrix tablets formed with simultaneous compression and heating – a technique related to the one Purdue used to make its abuse-resistant oxycodone – was obvious over prior art. Purdue Pharma L.P. v. Accord Healthcare, Inc., 669 F. Supp. 3d 286, 297 (D. Del. 2023).
Purdue appeals to the Federal Circuit
Following its loss at the district court, Purdue appealed to the US Court of Appeals for the Federal Circuit. One of its primary arguments was that the district court erred in dismissing the evidence of secondary considerations of nonobviousness, especially that of commercial success. Purdue Pharma L.P. v. Accord Healthcare, Inc., No. 2023-1953, 2024 U.S. App. LEXIS 32817, at *26 (Fed. Cir. 2024).
More specifically, Purdue argued that "reformulated OxyContin—with abuse deterrent qualities—has had commercial success" and that "detailed evidence establish[es] a nexus between OxyContin's commercial success and its abuse-deterrent features.” The alleged nexus was that “after Purdue reformulated OxyContin, [the] FDA concluded that original OxyContin was withdrawn from the market because of safety concerns related to its abuse. [The] FDA also prohibited all non-abuse-deterrent extended-release oxycodone products . . .." Id. at *28.
The Federal Circuit rejected this argument, finding no clear error in the district court’s conclusion. The district court had looked at expert testimony, which confirmed that the new anti-abuse OxyContin formulation simply replaced the original OxyContin, with all sales transferred to the new formulation. It had also found that "there was no demonstrated increase in the success of OxyContin relative to other opioids when the patented features were introduced." Id. at * 31 (citing Purdue Pharma, 669 F. Supp. 3d at 305). In other words, the district court found no nexus between the features of the claimed invention as embodied in the new OxyContin formulation and its commercial success. The Federal Circuit characterized Purdue’s position as “a bald assertion [] of commercial success unconnected to the patented features of the claimed invention.” Id. Based on this evidence, the Federal Circuit found no clear error in the district court’s decision to dismiss Purdue’s arguments related to the secondary consideration of commercial success and ultimately hold the patent claims invalid. Purdue Pharma, U.S. App. LEXIS 32817, at *28.
Purdue appeals to the Supreme Court
In response to the Federal Circuit’s verdict, Purdue filed a petition for a writ of certiorari. In the petition, Purdue argues that in applying the “nexus” test for secondary considerations of nonobviousness, the Federal Circuit’s recent decisions show a “troubling trend” of systematically negating “a critical check against hindsight bias in determining whether a patent is ‘obvious’ – and therefore invalid – under 25 U.S.C. § 103.” Purdue argues this trend has destabilized the patent system and “swung the pendulum too far in the direction of invalidating patents earned through hard work, ingenuity, and investment.”
Litigants are encouraged to keep these developments in mind when analyzing obviousness issues, especially those concerning drug formulations. Though nonprecedential, the Federal Circuit’s decision highlights the importance of establishing a nexus between the claimed invention and any alleged secondary considerations of nonobviousness. The Supreme Court’s pending decision of whether to grant certiorari will be noteworthy regardless of the outcome.
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