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Invalidity affirmed on double patenting grounds; inequitable conduct finding vacated

July 24, 2007
Post by Blog Staff

In the second of two rulings yesterday, the Federal Circuit found the patent on Toprol-XL® (a drug used to treat hypertension, angina, and congestive heart failure) invalid based on obviousness-type double patenting, affirming summary judgment on the issue.

The court vacated and remanded the grant of summary judgment of unenforceability due to inequitable conduct, as the district court improperly equated a motivation to deceive with an intent to deceive. This the court proceeded to this issue even though it had affirmed the invalidity of the patent because it noted that the Federal Circuit has not yet resolved the issue of whether a terminal disclaimer can reinstate the validity of a patent invalid due to obviousness-type double patenting by filing a terminal disclaimer during litigation.

During the development of the patents on Toprol-XL®, there were several issues relating to inventorship that were never resolved (or brought to the attention of the USPTO) regarding the U.S. patents. Two scientists who were employed by Astrazeneca left the company to join Lejus Medical. Lejus filed a patent application in Sweden and a subsequent U.S. application describing "delayed and extended release dosage forms of pharmaceutical compositions, including metoprolol succinate."

Once Astrazeneca noticed publication of the Swedish application, it began a transfer of ownership proceeding at the Swedish Patent Office, contending that another of its scientists had actually invented the compound. That proceeding was eventually settled, with Lejus agreeing to divide claims to "metoprolol succinate" and to "a pharmaceutical composition, characterized in that the active substance is metoprolol succinate," and the divided claims were assigned to Astrazeneca. Lejus retained the rights to the original U.S. application that did not include the divided claims, however the issue of inventorship was never resolved.

Astrazeneca was eventually issued two patents relevant to the invention, and Lejus retained one. Only one of Astrazeneca's patents, the '154 patent, is relevant to the appeal, as Astrazeneca did not appeal the finding of invalidity of the other patent.

The court affirmed the finding of obviousness-type double patenting between the '154 patent and Lejus' '318 patent. The only claim of the '154 patent claims "metoprolol succinate." The relevant claim of the '318 patent, as construed by the district court, claims:

an oral pharmaceutical composition that has (i) a core that contains metoprolol succinate (or one of several other drugs), (ii) the core is surrounded by an inner coating that allows a controlled release of metoprolol succinate, and (iii) an outer coating that resists dissolving in the stomach with the goal of releasing the metoprolol succinate close to or within the colon.

Based on this construction, the '318 patent claims a species of the genus claimed in the '154 patent, as the '318 patent claims metoprolol succinate in the context of a specific pharmaceutical composition, whereas the '154 patent simply claims metoprolol succinate. As a result, the claims were properly held invalid on grounds of obviousness-type double patenting, as while the claims do not cover the same invention, they are not patentably distinct. As explained by the court:

in this case, Claim 1 of the '154 Patent claiming a compound (A1) is an obvious variation of Claim 8 of the ’318 Patent claiming a composition comprised of one compound of an enumerated list (A1, A2, A3, etc.), an inner layer (B), and an outer layer (C). Specifically, it would have been an obvious variation of Claim 8 of the '318 Patent to omit the inner layer (B) and the outer layer (C).

The court also traversed some old CCPA precedent asserted by Astrazeneca, but found that because the CCPA always sat en banc, a later decision controlled that was contrary to Astrazeneca's position.

The court next addressed the unenforceability finding, as it is an open question before the Federal Circuit "whether a patentee may reinstate the validity of a patent by filing a terminal disclaimer during litigation." Here, the issue turned on the fact that the USPTO was never informed of the possible inventorship issue. The district court found an intent to deceive because:

Astra had a strong incentive to not disclose the dispute. If a patent examiner had learned of the dispute and found Nitenberg to be the sole inventor of metoprolol succinate, the '897 patent application would not have been entitled to priority to the January 1985 United States application.

The Federal Circuit held it was error to infer an intent to deceive based on an incentive to deceive. This was particularly the case here because there was contrary evidence in the deposition of Astrazeneca's in-house patent counsel, who testified that he did not know of and was not concerned about the incentives identified by the district court. As a result, the finding of unenforceability was vacated and remanded for further consideration.

Judge Schall dissented in part, and would have reversed the finding of obviousness-type double patenting.

Given the Federal Circuit's observation that the effect of filing a terminal disclaimer during litigation is still an open question, it seems reasonably likely that this case may appear before the Federal Circuit again to address that issue.

To read the full decision in In re Metoprolol Succinate Patent Litig., click here.


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