Patently Obvious? The English High Court Considers Drug Development Practices in Teva v Bayer On 8 October 2021, Mr. Justice Mellor handed down his judgment in (1) Teva Pharmaceutical Industries Limited (2) Teva UK Limited v Bayer Healthcare LLC [2021] EWHC 2690 (Pat). The decision follows existing case law to find that the chemical formulation of a drug developed by Bayer (a salt form of sorafenib, sorafenib tosylate, used in the treatment of cancer) was the obvious outcome that would result from the routine drug development by the hypothetical Skilled Team (comprising individuals skilled in the art). This follows the previous Supreme Court decision in Actavis v ICOS¹, in which the Court arrived at a similar conclusion. While there were other claims for the use of sorafenib tosylate salt orally, or the use for the treatment of cancer, claim 12 of the patent in suit, EP (UK) 2305255 (Patent), was for the chemical formulation for the sorafenib tosylate salt per se.
Obvious actions for the Skilled Team Would the Skilled Team attempt to formulate a soluble form of sorafenib? In Teva v Bayer, the closest prior art was an article about sorafenib in the journal Endocrine-Related Cancer, entitled “Discovery of a novel Raf kinase inhibitor”, written by authors from Onyx, Bayer, and Chiron. The judgment refers to this article as “Lyons” (after one of the principal authors); Lyons was published prior to the priority date of the Patent. Lyons disclosed the preliminary results of phase I clinical trials for sorafenib. Lyons referenced the dosage and chemical structure of the drug (and that it had been successful for oral administration in humans),
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but did not disclose that sorafenib tosylate salt was the salt form of sorafenib that was used. Indeed, Lyons did not mention which salt form of sorafenib had been used in the trials. In para. 126, Mellor J. found that: “Lyons provided the Skilled Team with a strong (but not irresistible) motivation to investigate this chemical entity with a view to identifying a formulated drug, preferably for oral administration to humans. The point is that from the starting point of Lyons, the Skilled Team (and the Skilled Formulator in particular) had their CGK routine tests, considerations and analysis to work with.” Consistent with the tests set out in Windsurfing² and Pozzoli³, the Skilled Team was held to include a person skilled in drug formulation (the Skilled Formulator). Accordingly, the crucial question to be answered was: In the standard course of drug development, would the Skilled Team have tested and selected sorafenib tosylate for clinical formulation? If so, then sorafenib tosylate per se would be obvious.
Given that Lyons disclosed to the Skilled Formulator that a sufficiently soluble formulation of sorafenib was possible, the judge was not persuaded by the defendant’s expert’s suggestion that the Skilled Team would have found overcoming the low solubility level of sorafenib to be “an extremely challenging project” (para. 127) and that this would have meant that seeking to identify a suitably soluble sorafenib salt would not have been obvious. The Skilled Team would know that a soluble salt form of sorafenib must exist, because an orally administered tablet was used in the clinical trials described in Lyons. The Skilled Formulator, Mellor J. concluded, would therefore have been motivated to carry out a salt screen to identify and find that suitably soluble form. Would the Skilled Team have used the tosylate salt in its salt screen? This is the question at the heart of this case (as confirmed by the judge at para. 129). Mellor J. paid close attention to each party’s expert, and quoted each at length in his judgment; he eventually concluded
