The Federal Circuit has launched an assault on common claiming techniques in pharma and chemical patents. In October 2019 the Federal Circuit issued two opinions, the first was HZNP Medicines1 involving the limitation "consisting essentially of" and the second, Idenix2 , striking at Markush Groups. This post concerns the HZNP decision. On February 25 the Federal Circuit denied HZNP's request for a rehearing and rehearing en banc. According the Drug Patent Watch reported there were 244 drug patents using the language "consisting essentially of," a number which seems low based on my experience.
The term "consisting essentially of" is a transition phrase midway between "comprising" and "consisting of." These phrases are often used when defining a multi-component composition such as a drug formulation, herbicidal formulations, lubricant compositions. In patent claims the phrase "consisting essentially of" has a distinct meaning. It is mid-way between the closed limitation "consisting of" and the open term "comprising."2 The skilled claim drafter will use the phrase "consisting essentially" when listing components of a multi-component composition or when specifying the steps in a process. This is a signal that the claim is open to including additional non-listed components or steps "that that do not materially affect the basic and novel properties of the invention.4 " The challenge is how does one know which unlisted components or steps "do not materially affect the basic and novel properties of the invention."
Usually the patent specification will describe the properties of the invention. If adding an unlisted component does not adversely affect the objective then it's included in the claim coverage. The HZNP opinion used claim 49 from U.S.P. 8,252,838 ('838) as representative of the formulation claims. The formulation claims were directed a formulation for delivering diclofenac sodium topically to the knee to treat the pain of osteoarthritis of the knee:
49. A topical formulation consisting essentially of:
1–2% w/w diclofenac sodium;
40–50% w/w DMSO;
23–29% w/w ethanol;
10–12% w/w propylene glycol;
hydroxypropyl cellulose; and
water to make 100% w/w, wherein the topical formulation has a viscosity of 500–5000 centipoise.
The Court focused on the term "essentially" which left the claim open only to components which did not materially affect the basic and novel properties of the invention. The lower court identified in the patent what it termed 5 basic and novel properties:
1. Better drying time than prior art formulation
2. Higher viscosity
3. Increased transdermal penetration
4. Greater pharmacokinetic absorption
5. Favorable stability.
The specification had sections discussing each property. The problem was with the better drying time property. Data was presented both when applied to a human knee and in vitro as compared to the prior art formulation. In the in vitro test one of the inventive compositions exhibited worse drying properties over 1 hour than the prior art but when applied to a human knee the inventive compositions were "almost completely dry" while the after the same 30 minutes a "significant amount" of the formulation was left. Since the tests gave inconsistent results the affirmed the lower court decision that the inconsistent results that the term between drying time did not have single meaning so the POSITA would not know what standard to use to evaluate the drying time. If one did not know how to evaluate the drying time then one could not determine if adding an disclosed additive would "materially affect the basic and novel properties" of the formulation5 .
While the Court's conclusion seems reasonable in the abstract, the data teaches the POSITA that in evaluating drying time the in vitro test was not reliable and gave false negatives.
The message is simple, when using the term "consisting essentially of" make certain that for every advantage of the claimed definition there is a clear method for determine if a composition has the advantage. Here had the patent drafter simply advised that the in vivo gave more consistent results a different result might well been reached.
1 HZNP Medicines LLLC v. Actavis Laboratories UT, Inc,, 940 F.3d 680 (Fed. Cir. 2019), reh'g and reh'g en banc denied (February 25, 2020)
2 Idenix Pharms. LLC v. Gilead Scis., Inc., 941 F.3d 1149 (Fed. Cir. 2019)
3 AK Steel Corp. v. Sollac & Ugine, 344 F.3d 1234, 1239 (Fed. Cir. 2003)
4 PPG Indus. v. Guardian Indus. Corp., 156 F.3d 1351, 1354 (Fed. Cir. 1998)
5 Honeywell Int'l, Inc. v. U.S.I.T.C., 341 F.3d 1332 (Fed. Cir. 2003). Claim indefinite where there were multiple ways of measuring a property and each gave different results
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