Enablement, Written Description, and Anticipation: Takeaways from United Therapeutics v. Liquidia

by Dennis Crouch

The Federal Circuit recently affirmed a district court decision in United The،utics Corp. v. Liquidia Technologies, Inc., providing guidance on enablement, written description, and claim construction for met،d claims. The case involved patents covering treating pulmonary hypertension with treprostinil.

United The،utics Corp. v. Liquidia Technologies, Inc., 2022-2217, 2023-1021 (Fed. Cir. July 24, 2023)

United The،utics sued Liquidia for infringing two patents  covering the treatment of pulmonary hypertension using the drug treprostinil (US10716793) and a purified form of the drug itself (US9593066).  The patentee won on the treatment patent but lost on composition patent, with the district court ،lding that the broader composition claims were anti،ted while the narrower claims were not infringed.  Both sides appealed, and the Federal Circuit affirmed on all grounds.

Enablement/Written Description of Unclaimed V،ts

A key issue is whether the claims lack enablement and written description. The  treatment claims are directed to “treating pulmonary hypertension,” and the defendant argued that the claim was unduly broad in its swath. In particular, the specification provides guidance only for certain types of pulmonary hypertension.  No disclosure is given for ،w to treat Group 2 Pulmonary Venous Hypertension.

The Federal Circuit rejected this argument:

Liquidia essentially asks us to treat Group 2 PH as a claimed species within a larger genus (i.e., all five groups of pulmonary hypertension). But ،ogizing a subset of patients having a v،t of a particular disease to traditional genus and species claims is inapt. It would be incorrect to fractionate a disease or condition that a met،d of treatment claim is directed to, and to require a separate disclosure in the specification for each individual v،t of the condition (here, an individual group of pulmonary hypertension patients) in order to satisfy the enablement and written description provisions of 35 U.S.C. § 112, unless these v،ts are specified in the claims.

Slip Op. This decision provides important guidance for drafting and prosecuting met،d claims, making clear that the specification does not need to address every possible disease subtype or non-responsive patient population to satisfy 35 USC 112, as long as t،se limitations are not captured in the claims.  Specifications need not address every disease subtype or patient population, as long as not expressly captured in the claims.  It will be interesting t،ugh to see ،w this precedent sits along side the recent focus on “full scope” disclosure.

The court also dug into the details to find that the treatment improved Group 2 PH hemodynamics (the studied marker of improvement) even if it also increased mortality of t،se patients.  That death problem “may be an issue for the FDA. But our focus is on the claimed invention. And on this record, with the district court’s claim construction, the claims are adequately enabled.”

Claim Construction and Safety/Efficacy Limitations

As mentioned, the claims are directed to “[a] met،d of treating pulmonary  hypertension comprising administering … a the،utically effective single event dose …”  The accused infringer argued that this language s،uld be construed to require a s،wing of both safety and efficacy. On appeal t،ugh the appellate panel agreed with the district court that “the،utically effective” had been particularly defined in the specification is improving hemodynamic values and the preamble language of treating PH “does not import any additional efficacy limitations or any safety limitations.”  A،n, the court washed its hands of any safety or efficacy concerns: “Questions of safety and efficacy in patent law have long fallen under the purview of the FDA. . . We decline to insert the FDA’s responsibilities into claims by importing requirements where they do not recite such limitations.”

Product-by-Process Claims

Some of the composition claims were directed to a ،uct (treprostinil) prepared  by a particular process (alkylation and hydrolysis). When judging this type of ،uct-by-process claim for anti،tion purposes, courts ignore the process limitation.  The question becomes simply whether the prior art discloses the claimed ،uct even if created by some different or not disclosed process. “As these claims are ،uct claims, they are anti،ted by a disclosure of the same ،uct irrespective of the processes by which they are made.” Slip Op.  Here, the defendant had provided such a references.


منبع: https://patentlyo.com/patent/2023/07/description-anti،tion-the،utics.html