In Liquidia Technologies, Inc. v. United Therapeutics Corp., IPR2020-00770, Paper 45 (P.T.A.B. Oct. 8, 2021), the Patent Trial and Appeal Board ("PTAB") issued a Final Written Decision ("FWD") finding seven of the challenged claims unpatentable and two of the challenged claims not unpatentable.  


Petitioner challenged claims 1-9 of U.S. Patent No. 9,604,901 ("the '901 Patent") on two obviousness grounds: Phares and Moriarty/Phares. Claim 1, the only independent claim, read:

1. A pharmaceutical batch consisting of treprostinil or a salt thereof and impurities resulting from (a) alkylating a benzindene triol, (b) hydrolyzing the product of step (a) to form a solution comprising treprostinil, (c) contacting the solution comprising treprostinil from step (b) with a base to form a salt of treprostinil, (d) isolating the salt of treprostinil, and (e) optionally reacting the salt of treprostinil with an acid to form tresprostinil, and wherein the pharmaceutical batch contains at least 2.9 g of treprostinil or its salt.

Claims 6 and 7, the two claims that survived the inter partes review ("IPR") challenge to the '901 patent, read:

6. A method of preparing a pharmaceutical product from a pharmaceutical batch as claimed in claim 1, comprising storing a pharmaceutical batch of a salt of treprostinil as claimed in claim 1 at ambient temperature, and preparing a pharmaceutical product from the pharmaceutical batch after storage.

7. A method as claimed in claim 6, wherein the salt of treprostinil is a diethanolamine salt.

The examiner issued an anticipation rejection based on Moriarty during prosecution of the '901 patent. Since the claims are drafted in product-by-process format, determination of patentability is based only on the product without regard to the process. In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985). According to the examiner, "[a]lthough the method of Moriarty and the steps recited in the instant claims are not identical, the product obtained is the same." FWD at 10. The examiner also rejected claims as obvious over Moriarty and Phares.1 The applicant overcame the rejections with claim amendments and expert declarations.


The PTAB construed "pharmaceutical batch" in claim 1 to not require storage stability, contrary to Patent Owner's argument. Id. at 20. The PTAB also construed the terms "storing" and "storage" to require actual storage for a period of at least three months. Id. at 25.  This was different from the way the PTAB construed those terms in the Decision to Institute, which was largely based on the prosecution history of the parent patent. Id. at 20-21.  Finally, the PTAB construed claim 1 step (c) to require the solution formed in step (b) as the starting material for forming the salt in step (c) (not treprostinil isolated from step (b)). Id. at 27.

The PTAB found that Petitioner showed by a preponderance of evidence that claims 1-5, 8 and 9 were unpatentable as obvious over Moriarty and Phares. "Petitioner has shown that an ordinarily skilled artisan would have had a reason to combine Moriarty and Phares, and would have had a reasonable expectation of success when doing so." Id. at 34. "[W]e are persuaded that an ordinarily skilled artisan would have had a reason to start with the treprostinil free acid of Moriarty and convert it into a diethanolamine salt." Id. at 36. "Phares, even if it does not improve[] the purity, improves at least the bioavailability, of treprostinil of Moriarty..This provides a sufficient reason for a [POSA] to combine the teachings of Moriarty and Phares." Id. at 37. The PTAB noted that the motivation to combine does not have to be the same as that of the inventor. Id. Nor does the suggestion to combine have to be express in the prior art; it may come from the knowledge of one skilled in the art. Id. at 38. In the current case, the PTAB found sufficient motivation in the "universal" desire "to enhance commercial opportunities by improving a product or process." Id.

With respect to a reasonable expectation of success, the PTAB found that a well-known chemical purification technique in the prior art would have provided such reasonable expectation to a POSA. Id. at 43.

The PTAB rejected Patent Owner's objective evidence of nonobviousness as "conclusory at best," noting that Patent Owner did not "demonstrate how any alleged unexpected results were unexpected compared with the closest prior art." Id. at 46. Patent Owner's citations to the specification and expert declarations without explanation are insufficient. Nor did Patent Owner show that the alleged storage stability advantages were commensurate in scope with the claims. Id.

The conclusion regarding claims 6 and 7 was different. Although Petitioner argued that Phares inherently taught the "storing"/ "storage" limitation, the PTAB agreed with Patent Owner that Petitioner was confusing "relative thermodynamic stabilities with actual stability." Id. at 47. Phares taught Form A and Form B of treprostinil diethanolamine salt and that Form B appears to be "thermodynamically more stable" than the "metastable" Form A. Id. But "nothing in Phares suggests the salt would be stable for at least three months," as required by the PTAB's claim construction. Id. at 48. The PTAB rejected Petitioner's argument that such an understanding would have been within the level of ordinary skill at the time of the invention.  Id. at 48.


This case provides an example of a Petitioner successfully overcoming a 35 U.S.C. § 325(d) argument by convincing the PTAB that the examiner erred in her evaluation during prosecution. By addressing the potential § 325(d) issue in the petition and explaining the examiner's error and how the same references were being presented differently, Petitioner was able to avoid a discretionary denial under § 325(d).

This case reminds us that objective evidence of unexpected results must "demonstrate how any alleged unexpected results were unexpected compared with the closest prior art.

And we are reminded that the objective evidence is to be commensurate in scope with the claimed invention.


1 The PTAB rejected Patent Owner's arguments in its Preliminary Response that the IPR petition should be denied based on 35 U.S.C. § 325(d) because the examiner already considered Moriarty and Phares during prosecution. "Although it is undisputed that the Office considered both Phares and Moriarty during the prosecution of the '901 patent, we find that the examiner erred in evaluating these references." IPR2020-00770, Paper 7, at 7 (P.T.A.B. Oct. 13, 2020). In particular, "the examiner erred in relying on the applicant's argument on the improved purity profile to allow the challenged claims." Id. at 15.

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