Monday, March 21, 2022

Allergan v Apotex / Risedronate Dosage Form — Overview

Allergan Inc v Apotex Inc 2022 FC 260 Kane J

2,602,188 / risedronate / ACTONEL DR

This very long decision—262 pages and 946 paragraphs—turns largely on its facts. The length of the decision is a consequence of Kane J’s very thorough recitation of the arguments and evidence. The main point of interest arises from the somewhat unusual claim.

Allergan’s 188 patent relates to a dosage form of a bisphosphonate for use in treating osteoporosis. Bisphosphonates were well known for use in treating osteoporosis. Bisphosphonates were known to have poor bioavailability. One specific known problem was significantly lower absorption when taken with food—the “food effect”. The food effect was thought to be due to bisphosphonates forming complexes with ions, such as calcium and magnesium, from the food in the stomach. (Bisphosphonates were known to be absorbed in the small intestine.) The standard way of addressing the food effect in the prior art was to prescribe the bisphosphonate to be taken while fasting. This gave rise to compliance problems [273].

Allergan came up with a solution to the food effect, namely a dosage form comprising a combination of bisphosphonate with EDTA in an enteric coating. The enteric coating allows everything to pass into the small intestine, where the EDTA—a known chelating agent—binds to the cations and prevents them from binding to the bisphosphonate. This means that the dosage would be equally effective whether given with food or after fasting. Accordingly, Claim 1 of the 188 patent was to “An oral dosage form of a bisphosphonate for use with or without food or beverage intake, comprising...” All the claims incorporated the “for use with or without food” limitation. The “with or without” food structure of the claim is a bit odd, as “or” is normally used to signal alternatives, so that it might have been separated into two claims, one claiming use with food and one without. But given that the purpose of the invention was to overcome the food effect, the experts agreed, and Kane J held, that the claim should be construed to mean that the oral dosage can used “either with food or without food or beverage at the preference of the patient” [228]. That seems right to me.

But there’s a catch. Giving EDTA without food can cause irritation of the esophageal lining. Even though this was apparently an uncommon and fairly minor problem, and did not affect efficacy in treating osteoporosis, the product monograph for Allergan’s product, ACTONEL DR, consequently specified that it should be taken with food. The Apotex PM was essentially identical [905]. Consequently, Kane J held that Apotex’s product did not infringe, either directly or by inducement, because it was not for use with or without food, but only with food [921].

Kane J’s construction seems right, given the phrase “for use with or without food” in the claim. But I am puzzled as to why the patentee included those words in the first place. Kane J said this:

[225] For the ‘188 Patent, the ability to use the oral dosage form either with food or without food is set out in the claim because its purpose is to overcome the food effect (which is the problem of the extremely low absorption of the bisphosphonate when taken with food as opposed to when taken fasted). The oral dosage can be taken either with food or without food at the choice of the patient and the treatment effect will be similar (i.e., pharmaceutically effective absorption). The invention of the ‘188 Patent signalled a significant change in the administration of oral bisphosphonates, hence the emphasis on this feature.

It’s true that the advance was to allow a formulation that can be taken without food as well as with it, and it may be that is what motivated the applicant to include this phrase. But that does not mean that this feature has to be included in the claim itself. (I should note that this explanation was not central to Kane J’s reasoning, as it was not disputed that “with or without food” was an essential element.) So long as the compound itself is new, the purpose need not be specified: if an inventor comes up with a new drug that is useful for curing cancer, they are entitled to claim the compound per se, without restricting it to the use in curing cancer. In this case, the claimed composition* was new: it was essentially a selection over the closest prior art, a prior Brazilian patent application referred to as BR 601: see eg [366], [372]. So I’m at a bit of a loss to explain why it was included.** If the phrase was indeed unnecessary, that suggests the possibility that “for use without or without food” is not an essential element, but this argument was not run by Allergan [188]. So I presume there was some reason for including the phrase that is not apparent from the decision. I wonder if the phrase might have been added to placate an obstinate examiner? I note that even if it was added in response to an objection, it is not clear that this precludes a finding of non-essentiality: see Actavis [2017] UKSC 48 UKSC.

Allegan also argued that “for use with or without food” should be construed as meaning only ‘suitable for’, not intended for. Kane J rejected this argument, which I’ll discuss at more length in my next post.

In light of this construction, infringement turned on the factual issue as to whether the PM instructed use with food, or whether taking with food was optional. Allergan’s argument was to the effect that a skilled person would recognize that it would be effective if taken without food, since the side effects were minor. Nonetheless, as Kane J found [905]–[922], the PM clearly and repeated instructed that the product should be taken with food: eg ““Do not take ACTONEL DR before food or on an empty stomach. . .” That this instruction was to avoid abdominal pain rather than to enable effective absorption does not change the fact that the product was for use with food. Apotex’s PM was the same, and so Apotex did not infringe directly or by inducement.

There are a couple of other points to note. One of the expert witnesses had been ‘blinded’, but Kane J was not impressed: “I note that the jurisprudence is mixed on the treatment of blinded evidence. I favour the approach noted in Janssen Inc v Apotex Inc, 2019 FC 1355 at paras 58-59 . . . that blinded opinions are not necessarily given greater weight just because they are blinded.”

Another point is that the most relevant prior art, a prior Brazilian patent application referred to as BR 601, was obscure prior art; that is, it was available to the public, but it would not have been found by a skilled person in a reasonably diligent search [634]. This raised on the facts the holding in Hospira 2020 FCA 30 that the state of the art for the purposes of an obviousness attack includes all prior art. In my post on Hospira, I suggested that this holding leaves open the question of whether obscure prior art can be mosaiced in an obviousness attack.

Kane J noted that

[635] In accordance with Hospira at para 86, it would be an error for the Court to exclude BR 601 from the mosaic of prior art because it would not be found by the skilled person in a reasonably diligent search.

[636] As guided by Hospira, the likelihood that BR 601 would not turn up (and, based on the evidence, it would not turn up) is relevant to the obvious to try test; i.e., would the skilled person have thought to combine BR 601 with the other prior art to bridge the differences between the state of the art and the invention?

She then noted that

[637] This is a tricky distinction when applied to the facts. If BR 601 is part of the prior art, then the differences between the state of the art and the invention would need to account for whatever can be distilled from BR 601 as part of the “state of the art”. However, if the skilled person would not have found BR 601, how can the skilled person consider it in the context of combining it with other prior art at the obvious to try stage of the analysis of obviousness? This is only possible in circumstances where the unknown prior art is handed to the skilled person. To avoid this dilemma and running afoul of Hospira, I have considered BR 601 as if it were prior art, but as noted, the “teaching” of BR 601 requires careful scrutiny.

Ultimately, Kane J did not have to wrestle too directly with this “tricky distinction”, because, as I read it, BR 601 simply would not make the 188 patent obvious, no matter how it was used. BR 601 was at best a broad genus than encompassed the claimed invention, but did not point to it with any specificity, and did not give any hint of the special advantages of the 188 dosage form.

*The original version of the post said the "compound" was new: that is not correct. It is the claimed composition that was new. 

**Since the composition was new, it seems to me that it could have been claimed as such, without that phrase, in the same way a new compound can be claimed without specifying the use. 

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