In our Case of the Week, the Federal Circuit revived Novartis’s US Patent No. 8,101,659 by reversing the district court’s decision which found the patent invalid for lack of written description. The Federal Circuit also affirmed the district court’s holding that the patent was not invalid for obviousness or enablement. The patent protects Entresto®a pharmaceutical drug for treating heart failure with reduced ejection fraction. Entresto is a combination drug composed of two others: valsartan and sacubitril. Valsartan is an angiotensin receptor blocker that reduces blood-vessel constriction, and sacubitril is a neutral endopeptidase inhibitor that also helps to reduce blood-vessel constriction, but by a different biological pathway. Together, the drugs provide superior treatment results than either drug alone. Representative claim 1 of the ’659 patent covers a pharmaceutical composition of the two drugs administered in combination in a ratio of about 1:1.
When MSN and other generic manufacturers filed an ANDA for a generic version of Entresto, Novartis sued for direct infringement of the ’659 patent claims. The term “administered in combination” in the claims was a major focus of claim construction. MSN argued the term limited the claims to the administration of the two drugs as two separate formulations—an interpretation that would protect MSN from infringement, since their proposed generic drug was a complex of both drugs prepared into one formulation. In contrast, Novartis argued the term “administered in combination” did not imply such a limitation. The district court agreed with Novartis, and referred to prosecution history which supported the position that the claims included compositions in which the drugs were administered non-separately and complexed.
During the bench trial, MSN argued the patent was invalid for obviousness, lack of written description, and lack of enablement.
For obviousness, MSN asserted the two drugs were known in the art before the priority date of the patent; therefore, it would have been obvious to a person of ordinary skill in the art to have combined them and expected superior results with the drug combination. However, the court noted that, although the two drugs were known in the art, sacubitril had never been administered to humans or tested in animal models, so its value in treating heart failure in humans was unknown. Thus, the district court concluded there would have been no motivation, or reasonable expectation of success, for a skilled artisan to select valsartan and sacubitril, specifically, for a combination treatment of heart failure at the time of filing. The Federal Circuit affirmed.
On the issues of lack of enablement and written description, MSN argued that, because the combination complex of valsartan and sacubitril was created after the filing date of the ’659 patent, it necessarily could not have been properly enabled or described in the patent. The district court disagreed with MSN on enablement because enablement is judged as of the priority date, and later-existing states of the art may not be properly considered in an enablement analysis. However, the court agreed with MSN when it considered written description by a similar logic: The fact that the complex of the drugs did not exist at the time of filing meant they could not have been properly described in the patent. Therefore, according to the district court, written description was lacking in the patent.
The Federal Circuit reversed the district court on written description and affirmed on enablement. Specifically, the Federal Circuit noted that the district court erred in conflating the analysis for patentability and infringement. Enablement and written description—a patentability analysis—must be evaluated on the patent claims themselves, not on their construction. Though the claims were construed not to be limited to the drugs in separate formulations for administration, the claims themselves were not directed to a single formulation complex of the drugs, but to a combination administration. Therefore, enablement and written description must be analyzed in light of the claims being directed to the drugs administered in combination. Under this proper analysis, the Federal Circuit noted the patent did enable and properly describe the patent claims as written. The Federal Circuit highlighted that post-filing improvements upon underlying technology, such as the improvement of complexing the two drugs into one formulation, should not be used to “reach back” and invalidate a patent that covers the underlying technology.
The full opinion can be found here.
By Ann Bernert
