Making a Mosaic of Obscure Prior Art Is Permissible in Obviousness Attack under Hospira

Biogen Canada Inc v Taro Pharmaceuticals Inc 2020 FC 621 Manson J

            2,562,277 / fampidrine sustained release / FAMPYRA / NOC action

As outlined in my last post, the 277 patent, owned by Acorda and licenced to Biogen, relates to the use of sustained release fampidrine for improving walking in a person with multiple sclerosis (MS). In this decision Manson J held the 277 patent, to be anticipated and obvious, ultimately because the inventors had themselves disclosed the invention in a financial filing prior to the claim date. My last post dealt with anticipation. This post deals with obviousness. This case is the first clear application of the FCA’s holding in Hospira that the state of the art for the purpose of an obviousness attack includes all prior art, not just that which would be reasonably discoverable. For convenience, I’ll refer to prior art that is not part of the cgk or reasonably discoverable, as “obscure prior art.” Importantly, Manson J appears to have been of the view that it is permissible to mosaic various pieces of obscure prior art.

The prior art included a financial filing referred to as Acorda S-1, that disclosed results from a small clinical trial undertaken by Acorda, the MS-F201 trial, as well as the protocol for a second trial that was planned (the MS-F202 trial) [36, 122]. This was held to anticipate. It was also invoked in support of obviousness, along with the Goodman References (also disclosing the same trials), and a publication reporting the pharmacokinetic properties of fampridine SR (“Hayes”). Given the very small gap between this prior art and claimed invention, the holding that the claims were obvious in light of these references followed fairly directly [181-200].

The key issue on obviousness was not bridging the gap between the prior art and the claimed invention, but whether the prior art references were properly part of the state of the art. In particular, it was not established that any of these references would have been part of the common general knowledge or discoverable in a reasonably diligent search. As Manson J noted, prior to codification of the non-obviousness requirement in s 28.3, “citable prior art for obviousness was limited to that which would have been found by the POSITA in a reasonably diligent search” [152]. However, in Hospira 2020 FCA 30 the FCA held that “it is an error to exclude prior art from the obviousness analysis simply because it would not have been located in a reasonably diligent search” [153]. Biogen objected to this as being contrary to the intent of s 28.3, but as Manson J pointed out, “The Federal Court of Appeal’s decision in Hospira is both clear and binding on this Court. Prior art will not be excluded from the obviousness analysis solely because the POSITA would not have found it after a reasonably diligent search” [154]. Consequently, Manson J considered the prior art at issue to be part of the state of the art for an obviousness attack, without consideration of whether it would have been reasonably discoverable [163-64, 166].

That much follows directly from Hospira. But there was an important point left open in Hospira, where the FCA stated (my emphasis):

[86] The likelihood that a prior art reference would not have been located by a PSA may be relevant to consideration of step 4 of the obviousness analysis (whether differences between the state of the art and the inventive concept constitute steps which would have been obvious to the PSA) in that the uninventive PSA might not have thought to combine that prior art reference with other prior art to make the claimed invention.

In my post on Hospira, I said the following:

This indicates that there can be no mosaicing of prior art that is not available in a reasonably diligent search. Thus, obviousness can be assessed over the common general knowledge alone, or over one item of broader prior art plus cgk, but not over two items of broader public art plus cgk. I believe that this is essentially the UK position.

In other words, I read Hospira as saying that while one element of obscure prior art could be combined with the traditional state of the art (cgk or material reasonably discoverable), it was not necessarily permissible to combine two elements of obscure prior art, on the view that a POSITA who did not know about a piece of obscure prior art would not think to combine it with another piece of obscure prior art which she also did not know about.

However, Manson J did not read this paragraph the same way. He stated

[193] Following the Federal Court of Appeal’s guidance in Hospira that it may be relevant to consider the likelihood that a prior art reference would not have been located by the POSITA at this stage of the obviousness analysis, I am satisfied that the POSITA would have combined the pharmacokinetic parameters taught in Hayes 2003 with the fixed doses of 10 mg bid taught in the Acorda S-1. Both references report information on the Elan fampridine SR composition, and the Acorda S-1 states that the pharmacokinetic characteristics of fampridine SR in subjects with MS had been established in earlier trials sponsored by Elan.

There was no suggestion that either Hayes 2003 of Acorda S-1 were part of the cgk or were reasonably discoverable: in light of Manson J’s holding that it was wrong to exclude prior art from the obviousness analysis for that reason, he simply never addressed the question.

Consequently, in Biogen v Taro, Manson J did mosaic two elements of obscure prior art. He was evidently of the view that the only inquiry mandated by Hospira [86] is whether the POSITA, with both elements of prior art in hand, would find it obvious to combine them.

Manson J’s interpretation of Hospira [86] is certainly reasonable, but I like to think my interpretation is reasonable as well, so it’s not clear, at least to me, what the FCA intended. Presumably the point will be clarified by the FCA soon enough. If Manson J’s reading is correct, then the state of the art available for an obviousness attack in Canadian law now goes beyond what is available in either the US or the UK (at least as I understand the law in those jurisdictions.)