Monday, October 28, 2013

Is a Dosage Range Unpatentable as Being a Method of Medical Treatment?

Bayer Inc v Cobalt Pharmaceuticals Company / drospirenone (NOC) 2013 FC 1061 Hughes J
            YAZ / drospirenone / 2,179,728

As noted in my overview post, the Drospirenone decision is notable primarily as a development in the law relating to the patentability of methods of medical treatment, as Hughes J held four of the five claims at issue to be invalid on this basis.

Claims 1, 2, 6,7 and 8 were at issue [124]. All but Claim 8 were held to be invalid [162]. Claim 1, which is representative of the invalid claims, was as follows:

1. Use of an oral dosage form comprising an estrogen selected from

2.0 to 6.0 mg of 17-estradiol and
0.015 to 0.020 mg of ethinylestradiol;

and a gestagen selected from

0.05 to 0.075 mg of gestodene,
0.075 to 0.125 mg of levonorgestrel,
0.06 to 0.15 mg of desogestrel,
0.06 to 0.15 mg of 3-ketodesogestrel,
0.2 to 0.3 mg of norgestimate,
>0.35 to 0.75 mg of norethisterone,
0.1 mg of drospirenone to a drospirenone dose equivalent to 0.075 mg of gestodene, and
0.1 mg of cyproterone acetate to a cyproterone acetate dose equivalent to 0.075 mg of gestodene;

for contraception for a female of reproductive age who has not yet reached premenopause, by administration of the form of dosage for 23 or 24 days, beginning on day one of the menstrual cycle, followed by 5 or 4 pill-free or placebo pill days, for a total of 28 days in the administration cycle.

Claim 2 restricted the estragen to ethinylestradiol, Claim 6 restricted the gestagen to one of the two listed in Claim 1, and Claim 7 was similar to Claim 1, but with somewhat more restricted dose ranges [158].

Claim 8, held to be valid, was as follows:

8. Use according to claim 1, whereby the estrogen is present in a dose of 20 µg of ethinylestradiol or an equivalent dose of 17-estradiol and the gestagen is present in a dose of 75 µg of gestodene or an equivalent dose of levonorgestrel, cyproterone acetate or drospirenone.

As noted by Hughes J, in contrast with the first four claims, “Claim 8 is restricted to a single dosage (not a range) of one of two estrogens; and a single dosage, not a range, of one of three gestagens” [159].

After referring to his Cobalt / zoledronate (NOC) 2013 FC 985 decision (blogged here) as summarizing the law, Hughes J held Claim 1, 2, 6 and 7 invalid for the following reasons (my emphasis):

[160 In the present case, all claims are clearly expressed in terms of use for a contraceptive. All claims except claim 8 provide for a range of dosages for one or both of the estrogen and gestagen components.

[162] The point, however, is not whether a commercial product is provided with fixed dosages and regimens. The point is, what do the claims say? All claims at issue are use claims, not product claims. All but claim 8 claim the use as a contraceptive of a two-component drug with each component to be selected from a choice of components, and with each component to be furnished at a dosage within a range of dosages. Claims 1, 2, 6 and 7 are not proper subject matter for a Canadian patent, as they do not claim a vendible product; they provide for a choice to be made by those prescribing or providing contraceptive drugs to choose between a variety of components and a variety of dosage ranges. Only claim 8 survives, as it is directed to a single dosage of each of two compounds.

Hughes J evidently wrote Cobalt / zoledronate with Drospirenone in mind, so the contrast between Claim 8 and the other four claims is directly reflected in the second pair of contrasting claims he identified at [91]-[92] of that decision:

• the substance X in the form of a 5 mg tablet for the treatment of Y [patenable]
• the use of substance X in a dosage range between A and B for the treatment of X [unpatentable].

From this, it follows directly that Claim 8 is patentable while the others are unpatentable. Drospirenone is helpful in explaining why Hughes J is of the view that claims to a dosage range are unpatentable, namely that “they provide for a choice to be made by those prescribing or providing contraceptive drugs to choose between a variety of components and a variety of dosage ranges” [162]. The implication is that by providing for a choice to be made, this implicates the professional skill of the prescribing doctor: (and see [161]).

I see two problems with this analysis. First, there is a distinction between a patent which requires the use of professional skill to practice the invention, and one in which professional skill may be exercised, but is not required, while practicing the invention. In Drospirenone, Hughes J held the claims to be useful, which implies that any combination with the specified range would work as an effective contraceptive. Professional skill might be exercised in practising the invention, to reduce side effects, for example, but in principle professional skill is not necessary to practice the invention effectively. Consider an analogy to a selection patent, in which the genus patent specifies that a broad range of compounds is effective for a particular purpose. It might well require professional skill, whether that of a doctor or engineer, depending on the patent, to get the most out of the invention; and if sufficient skill is required in choosing the best species, this might even be the basis for a valid selection patent. But the fact that professional skill is normally exercised in the practice of the genus patent, does not make the genus patent invalid. In this case, the patent does not “provide” for a choice to be made, in the sense of requiring a choice to practice the invention effectively, but rather it allows for a choice to be made. Put another way, elsewhere in this decision, Hughes J accepted that the word “about” is not vague and implies a range of about 10% around the specified value [103-06]. It would be possible to cover the entire range specified by Claim 1, by claims framed similarly to Claim 8, except to dosages “about” a single dosage. While this would require a very large number of claims, the difference between this multiplicity of specific dosage claims, and a single claim to a range of dosages, is purely formal. In summary, many patentable inventions allow for the exercise of professional skill in their implementation, and this alone does not make the claims invalid. While Claim 1 certainly allows for the exercise of professional skill, it does not seem to me to require it.

Moreover, even the suggestion that a claim is invalid if it requires the exercise of medical skill, is very difficult to reconcile with Wellcome / AZT 2002 SCC 77 which upheld a Claim 22 to the use of “an effective amount” of AZT. Surely choosing an effective amount of AZT implicates the professional skill of a doctor or pharmacist just as much as choosing from a specified range. Indeed, more skill is required by the AZT claim, because, as just noted, in this case any selection within the range specified by the ‘728 patent would work, whereas in the AZT claim, professional skill must be exercised to select an effective amount. (See also my post on Cobalt / zoledronate, making a similar point.)

More broadly, what is wrong with a claim which requires the exercise of professional skill? Many claims are of this nature, and the question is normally treated as one of sufficiency. It is well established that a claim requiring the exercise of professional skill is not invalid for that reason, so long as undue experimentation is not required. As discussed in my previous post, there may be a sense that the exercise of professional skill is inherently nebulous, but if that is the real objection, it should be dealt with directly, by invalidating for insufficiency or ambiguity, claims where the professional skill required by the claim is of a nature that is not described or cannot be reliably replicated.

If the objection relates to the exercise of medical skill in particular, we must ask what distinguishes medical skill from other professional skills. One answer is that there is a policy argument to be made that a physician should not be prevented from treating her patient to the best of her ability by fear of a patent action. But if that is the real objection, the better response is to address it directly, by providing a defence for physicians, as in the US under 35 USC § 287(c)(1). That is surely a policy decision for the legislature; and in any event, this policy goal is not aided by Hughes J’s distinction between dosage ranges and a single dosage; to the extent that the compositions encompassed by any of the Claims are “used” by the prescribing physician, allowing claims to specific dosages exposes physicians to liability; Claim 8 would be infringed by a physician who determines that the dosage specified by that claim is appropriate for her patient.

Ultimately, it seems to me that the distinction between a dosage range and a specific dosage is a formalism which lacks a a clear policy rationale, and is inconsistent with Wellcome / AZT.

It is also very disappointing to see the apparent resurrection, both in this decision [162] and in Cobalt / zolendronate and the case-law discussed therein, of the long-discredited “vendible product” test for patentable subject matter. This test was created by Morton J in Re GEC's Application, (1942) 60 RPC 1 at 4, where he stated that “a method or process is a manner of manufacture if it (a) results in the production of some vendible product or (b) improves or restores to its former condition a vendible product or (c) has the effect of preserving from deterioration some vendible product to which it is applied.” The list is curiously specific, if it is an attempt to reconcile difficult cases on narrow factual grounds – though Morton J did not cite specific authority for this proposition, referring merely to “cases cited to me”. But it is more bluntly described as legal gerrymandering, aimed at reaching a particular result on the facts. There is no unifying principle, either stated or apparent. While the phrase “vendible product” is repeated, it is not truly a unifying concept, as not every invention that affects a vendible product is patentable; only certain effects are within the scope of the rule. In particular, on the facts of the case, Morton J held that using a known compound for extinguishing a fire did not fall within the rule as stated, apparently because preserving a vendible product from fire does not amount to “preserving from deterioration.” This invisibly fine distinction was evidently developed for the purpose of allowing Morton J to hold the invention unpatentable. The application at issue was for a patent on a method of extinguishing incendiary bombs by means of a concentrated aqueous solution of a known substance (zinc chloride). Legal realism provides the most obvious explanation for the rule: the case was decided in the middle of World War II, just after the Blitz, and Morton J did not want the inventor to be able to hold London to ransom. While this is no doubt a reasonable concern, it does not warrant re-writing the law of patentable subject matter. In Canada today, this concern could be addressed by s 19 of the Act.

Regardless of the explanation for Morton J’s decision in Re GEC's Application, it is no longer good law. Morton J held that the claims in question on the basis that they were “nothing more than claims for a new use of an old substance, such use not being, in my view, a manner of manufacture.” This holding, which was made immediately after his statement of the vendible production rule, and which is apparently his application of that rule on the facts, is directly inconsistent with Shell Oil[1982] 2 SCR 536, the leading SCC decision on patentable subject matter, which upheld the patentability of a new use for an old compound. Even prior to that, the vendible product rule itself has been effectively expunged from the law by the penetrating analysis of the High Court of Australia in NRDC (1961) 102 CLR 252 (HCA). For more discussion of the vendible product rule, see my article, The Rule Against Abstract Claims: History and Principles, 26 CIPR 205 at 224-25 (draft version here).

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