Enanta Pharmaceuticals, Inc. v. Pfizer Inc.

Enanta Pharmaceuticals, Inc. v. Pfizer Inc. The Federal Circuit affirmed, holding that the provisional application's disclosure of a —NHC(O)—C2-C12-alkyl substituent did not provide written description support for the later-claimed —NHC(O)—C1-alkyl subject matter. Because the patent was not entitled to the provisional filing date, Pfizer's intervening nirmatrelvir disclosure anticipated the claims. The decision underscores that even a seemingly small chemical range change in a priority document can defeat priority where the earlier application does not itself disclose the later-claimed subject matter. Affirmed summary judgment of invalidity. The asserted patent claimed coronavirus replication inhibitors and sought priority to a provisional application filed before Pfizer's public nirmatrelvir disclosure. The provisional listed the relevant substituent as —NHC(O)—C2-C12-alkyl, while the later patent used —NHC(O)—C1-C12-alkyl, which would cover nirmatrelvir's C1 alkyl group. The Federal Circuit treated the issue as written description for priority, not as a district court's power to correct an obvious typographical error in an issued patent. Expert testimony pointing to an alleged typo elsewhere in the provisional did not create a fact dispute that the provisional disclosed or conveyed possession of the C1 alkyl substituent. Because Enanta did not dispute anticipation if priority failed, the loss of priority supported summary judgment of anticipation. § 102 § 112(a) precedential § 103 § 102 § 112(a) precedential § 103 § 102 § 112(a) precedential