Multiple obvious paths still obvious – Federal Court
On February 26, 2015 Justice Barnes released his public reasons dismissing the second of Janssen’s prohibition applications in respect of Teva’s generic version of the multiple myeloma drug VELCADE, this application dealing with Canadian Patent No. 2,203,936.
The 936 Patent claims a broad genus of boronic acid dipeptides, including the compound bortezomib, all said to be effective inhibitors of the proteasome and having therapeutic utility in treating cancer. The claims asserted by Janssen concerned only the compound bortezomib.
Selection patent
The prior art included WO 904, a patent application that disclosed a genus of boronic acid compounds also said to be useful to inhibit the proteasome. The genus was defined to include elements that could be selected so as to make up the bortezomib molecule. Janssen argued that bortezomib was not a selection from the WO 904 genus because one structural element of bortezomib, a pyrazinecarbonyl N-terminal blocking, fell outside the definition in WO 904 of potential N-terminal blocking groups. Justice Barnes agreed with Teva’s position that WO 904 disclosed a genus of compounds that includes bortezomib and that the 936 Patent is therefore a section patent.
Justice Barnes rejected Janssen’s argument that a skilled person would face challenges in choosing the elements required to assemble the bortezomib molecule and that the prior art taught way from these choices. Although choices were required to be made, those choices were rendered obvious by the teaching of WO 904. A person of skill is not doing anything inventive when he chooses options provided in a prior patent to build a molecule that he expects will work.
Bortezomib does not possess a property of a special character or a substantial advantage over the genus from which it was selected. Janssen’s argument that the choices made by the inventors were the best of those available was not borne out by the evidence. It did not matter that WO 904 did not specifically describe bortezomib. It was sufficient that bortezomib was included in the genus of previously claimed compounds so that, in the absence of some special or unexpected advantage favouring bortezomib, the compound cannot be reclaimed.
Obviousness
Even if the pyrazinecarbonyl group was not an element of the genus claimed in WO 904, its selection was obvious. The use of pyrazinecarbonyl groups for N-terminal protection of peptides was known in the prior art. The argument that the choice of a pyrazinecarbonyl protecting group was inventive was belied by the definition of the protecting group in the 936 Patent which states that any of the known categories of protecting groups can be employed. Justice Barnes rejected the evidence of Janssen’s expert witness that the pyrazinecarbonyl moiety provided some enhanced efficacy to the active part of the bortezomib molecule, finding that he was outside of his area of expertise. The non-inventive nature of the selection of the blocking group was confirmed by the evidence of an inventor that the choice was left to chemists based on what was available or catalogued and was a matter of routine benchwork.
Teva was represented by Aitken Klee LLP.
A copy of Justice Barnes’ Reasons for Judgment can be found here.