United States: Substitute Claims Upheld As Prior Art Is Inapplicable To Pharmaceutical Compositions

In Hope Medical Enterprises Inc., v. Fennec Pharmaceuticals Inc.,¹ the Board's Final Written Decision (FWD) found that Petitioner had not demonstrated that claims to a method for synthesizing anhydrous sodium thiosulfate (STS) were unpatentable for obviousness. More specifically, Petitioner Hope Medical filed a petition requesting an inter partes review (IPR) of U.S. Patent No. 10,792,363 (the '363 patent). The '363 patent claims methods for synthesizing STS and pharmaceutical compositions of anhydrous STS. After institution of the IPR, Patent Owner Fennec filed a motion to amend; submitted a statutory disclaimer of claims 1–17, 19, and 21–27; requested to cancel claims 18 and 20; and proposed revised substitute claims 28 and 29.

The cases involved a unique combination of issues from the parties and the Board. These included Patent Owner Fennec Pharmaceuticals waiving its Preliminary Response, disclaiming nearly all challenged claims, filing a Noncontingent Motion to Amend followed by a Revised Noncontingent Motion to Amend after Preliminary Guidance from the Board, and not relying on any expert declaration in support of its position. As for Petitioner Hope Medical, a central premise of its expert's position was found to be factually inaccurate and contradicted by Petitioner's prior statements during prosecution of its own patent related to the same technology. Petitioner also failed to provide any additional expert testimony to address new limitations added in Patent Owner's substitute claims. Lastly, in a rare decision, the Chief Administrative Patent Judge found good cause to extend the one-year period for issuing a FWD based on the revised motion to amend² and then, as noted, the Board granted Patent Owner's motion to amend with substitute claims—also a rare event³—and ruled that Petitioner Hope Medical did not demonstrate that proposed substitute claims were unpatentable.

Motion to Amend Claims

Petitioner's motion to amend sought to add revised substitute claims 28 and 29 which included multiple purity limitations to the recited method of synthesizing anhydrous STS.

As a threshold determination under 35 U.S.C. § 316(d) and 37 C.F.R. § 42.121 prior to addressing unpatentability, the Board determined that the substitute claims met the four statutory and regulatory requirements. First, the motion to amend proposed a "reasonable number of substitute claims"— two substitute claims for two canceled claims. Second there was "support in the original disclosure" for the additional limitations of the substitute claims. Third, the substitute claims "respond[ed] to a ground of unpatentability. And forth, the "scope of the claims" was narrowed as compared to the original claims.

No Motivation to Combine

Incorrect Expert Testimony Mischaracterized the Prior Art: The Board determined that "the evidence relied on by Petitioner does not support Petitioner's position that a POSITA would have been motivated to combine" the cited references. Petitioner's argument relied on expert testimony (Dr. Robin Rogers) that it would have been obvious to combine two prior art references because "[b]oth references disclose synthesis of sodium thiosulfate pentahydrate." (Emphasis added.) However, the expert's testimony was admitted by Petitioner to be incorrect⁴ as one reference (Sherman, a patent assigned on its face to Petitioner) taught synthesis of STS pentahydrate and the other (Levenson) taught synthesis of sodium thiosulfate heptahydrate. The Board further found that, as noted by Patent Owner, the argument advanced by Petitioner's expert was inconsistent with Petitioner's statements during prosecution of Sherman that distinguished Levenson as "not provid[ing] any teaching with respect to [STS] pentahydrate."

The Board found that "Petitioner is left with insufficient evidence to support its proposed obviousness combination," and that because Petitioner failed to demonstrate a motivation to combine the invention was not shown to be obvious.

Prior Art Was Not Suitable for Synthesis of a Pharmaceutical Composition: Petitioner argued that a POSITA would have been motivated to combine four prior art references to rendered obvious the substitute claims of the amended '363 patent. However, one of the references taught using cetylpyridinium bromide, which the Board found a POSITA would have understood to be "to be an unacceptable surface-active agent for synthesis of a pharmaceutical composition, based on its material safety data sheet." The Board reasoned that because Petitioner "fail[ed] to address the concerns about [] cetylpyridinium bromide" Petitioner further failed to carry its burden of proof.

Patent Owner's substitute claims included purity clauses limiting the amounts of residual impurities including sulfite. Petitioner "did not submit any declaration following Patent Owner's addition of the residual sulfite limitations in [the] proposed substitute claims." Additionally, one of the cited prior art references taught manufacture of STS for photographic processes "where a small amount of sulfite is unimportant." The Board ruled that "Petitioner[] fail[ed] to address the concerns about [] sulfite amount," thus, Petitioner's "contention as to reasonable expectation of success in achieving the residual sulfite limitation in claims" is "unsupported."

Take Away

First, while the PTAB rarely grants motions to amend, well supported substitute claims can save a patent. Patent drafters should include as much detail as possible in the specification so that claims can be narrowed if necessary. Second, errors in expert testimony and failure to address limitations of substitute claims can result in a failure to carry the burden of proof. In this case, the expert's erroneous testimony that mischaracterized the prior art as relating to STS and the petitioner's failure to address the purity limitations of the substitute claims left the petitioner without enough evidence to carry their burden of proof and as a result, the patent was upheld.

Footnotes

1. IPR2022-00125, Pap. 38 (P.T.A.B. Sept. 1, 2023)

2. IPR2022-00125, Pap. 35 (P.T.A.B. April 18, 2023)

3. See  Patent Trial and Appeal Board Motion to Amend (MTA) Study Update through March 31, 2023 (https://www.uspto.gov/sites/default/files/documents/mta_installment_8_.pdf?utm_campaign=subscriptioncenter&utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=)

4. IPR2022-00125, Pap. 32 (P.T.A.B. April 10, 2023)

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