Pharmacokinetics Not Laws of Nature in Disguise

A recent decision from the U.S. District Court for the District of Delaware highlights an unsuccessful, yet creative Section 101 challenge. This case concerns a generic challenge for the brand-name drug Myrbetriq®, indicated for overactive bladder (OAB). Myrbetriq® uses an active ingredient called mirabegron, and its maker, Astellas Pharma, holds several patents covering the drug's formulation and how it works.

Astellas asserted four patents against Abbreviated New Drug Application filers Ascent Pharmaceuticals, MSN Pharmaceuticals and MSN Laboratories.

• The '780 Patent and '409 Patent. These cover the composition of the drug: specific sustained-release tablet formulations containing mirabegron, along with particular excipients (such as polyethylene oxide and polyethylene glycol), designed to dissolve at a specific rate. The claims of these patents require that the "drug dissolution rate from the pharmaceutical composition is 39% or less after 1.5 hours and at least 75% after 7 hours," and the "drug dissolution rate from the pharmaceutical composition is 39% or less after 1.5 hours and at least 75% after 7 hours," respectively.
• The '451 Patent and '189 Patent. These cover methods of treatment: administering mirabegron in a sustained-release formulation to treat OAB, with a key feature being a "reduced food effect" compared to an immediate-release version. (In other words, whether you take the pill with or without food doesn't swing the drug's absorption nearly as much.)

Among other things, Ascent argued that all four patents are invalid under Section 101: that the dissolution profile required by the patents simply mirrors the natural transit time of a pill through the small intestine, which is about three to four hours. In other words, Ascent was saying the patents were really just claiming a natural phenomenon (how long it takes the pill to move through the gut) dressed up in pharmaceutical clothing. Ascent's expert specifically characterized the claimed formulations as "quite ordinary, quite conventional" sustained-release tablets.

Astellas understandably disagreed and argued as to each patent group:

The Composition Claims (Claims 9 and 13 of the '780 Patent, Claim 5 of the '409 Patent) are directed to a pharmaceutical composition; a manmade tablet requiring a specific non-natural drug (mirabegron), specific non-natural excipients with particular characteristics, at specific doses, exhibiting a specific dissolution profile.

The Method Claims (Claim 20 of the '780 Patent, Claims 5 and 6 of the '451 Patent, Claims 4 and 19 of the '189 Patent) are directed to a specific method of treatment for a specific medical condition (OAB), in specific patients, using a specific non-natural drug, at specific doses, to achieve a specific clinical outcome (including a reduced food effect).

Senior Judge Joseph Bataillon of the District of Delaware held that Ascent failed to demonstrate by clear and convincing evidence that any asserted claim was invalid under Section 101. Judge Bataillon found that the Composition Claims are directed to "nonnatural compositions created using a nonnatural drug and nonnatural excipients." They pass Alice Step One. Relying on Vanda Pharmaceuticals Inc. v. West-Ward Pharmaceuticals, Judge Bataillon also held that the Method Claims are directed to "a specific method of treatment for specific patients using a specific compound at specific doses to achieve a specific outcome." They also pass Alice Step One.

Because no claims were directed to patent-ineligible subject matter, the court never needed to reach Alice Step Two.

The Section 101 ruling here is notable for a couple of reasons:

1. Pharmaceutical Composition and Method-of-Treatment Claims Continue to Hold Up Well Under Alice/Mayo.When claims are directed to specific, engineered formulations of synthetic drugs, rather than merely observing or describing a natural relationship, courts consistently find them patent-eligible. The key is specificity: specific drug, specific excipients, specific doses, specific dissolution profiles, specific clinical outcomes.
2. The "Natural Phenomenon in Disguise" Argument Has Limits.Ascent tried to reframe the dissolution profile as just a reflection of natural intestinal transit time, but the court looked at the claims as a whole instead of one isolated parameter in order to find that the overall invention was directed to human-engineered pharmaceutical technology, not nature.

In the end, Astellas's patents survived multiple other invalidity grounds, and the court entered judgment that all four patents were infringed. Ascent's proposed generic version of Myrbetriq® will have to wait.