Our Patent Case Summaries provide a weekly summary of the precedential patent-related opinions issued by the Court of Appeals for the Federal Circuit and the opinions designated precedential or informative by the Patent Trial and Appeal Board.
Enanta Pharmaceuticals, Inc. v. Pfizer Inc.
No. 2025-1427 (Fed. Cir. (D. Mass.) June 23, 2026). Opinion by Lourie, joined by Bryson and Chen.
Enanta sued Pfizer, alleging Pfizer’s Paxlovid® product infringed Enanta’s patent directed to compounds and methods of inhibiting coronavirus replication activity. The patent claimed priority to a provisional application filed before Pfizer publicly disclosed nirmatrelvir, which was later incorporated into Pfizer’s accused Paxlovid® product.
Pfizer moved for summary judgment of anticipation, arguing that the asserted patent was not entitled to the provisional application’s filing date because the provisional disclosed a substituent with a C2-C12 alkyl range, whereas the asserted patent claimed a corresponding C1-C12 alkyl range, with “[t]he subscripted numbers identify[ing] the number of carbon atoms in the alkyl group.” The district court granted summary judgment for Pfizer, concluding that the C2 of the provisional was not an obvious typographical error that it could correct. Enanta appealed.
The Federal Circuit affirmed. The court explained that the priority issue turned on written description, not on standards governing correction of errors in issued patents. The question was whether there was a genuine dispute of material fact as to whether the provisional’s disclosure of a C2-C12 alkyl range provided written description support for the claimed C1 alkyl group. Applying the written description standard, the Federal Circuit ruled that the provisional application did not “convey to a skilled artisan that the inventors possessed” the C1 alkyl substituent at the time of the provisional filing. The court reasoned that “C2 is simply different from C1,” and that the provisional application expressly disclosed a range of chemical moieties beginning with two carbon atoms while omitting the one-carbon alkyl group later claimed.
The court rejected Enanta’s reliance on expert testimony identifying a purported typographical error elsewhere in the provisional application as creating a genuine dispute of material fact, explaining that the testimony did not show that the specific disputed substituent disclosed in the provisional conveyed possession of the C1 alkyl group.
The Federal Circuit similarly rejected Enanta’s arguments based on other C1 alkyl disclosures in the provisional application. The court emphasized that “entitlement to a filing date … extends only to that which is disclosed,” and the provisional disclosed only a C2-C12 alkyl. The court further explained that “a disclosure of one chemical compound, or integer in this case, cannot necessarily be a disclosure of another, even one close by structurally.”
Because the provisional application did not disclose the C1 alkyl substituent, Enanta’s asserted patent was not entitled to the provisional application’s priority date. And because Enanta did not dispute anticipation absent the earlier priority date, the Federal Circuit affirmed the district court’s summary judgment of anticipation.
Light & Wonder, Inc. v. Evolution Malta Limited
Nos. IPR2025-01072, -01073, -01078 (PTAB June 22, 2026) (designated precedential on June 22, 2026). Decision by Squires.
Evolution filed a motion to terminate multiple instituted IPRs in view of a related district court decision involving the same parties. The Patent Trial and Appeal Board denied the motion, reasoning that “it lacked the authority to terminate the IPRs for discretionary reasons.” Evolution then sought guidance on “how to request Director Review,” and the Director agreed that “the Director Review rule does not expressly permit” review of a decision denying a motion to terminate.
The Director explained, however, that “changed circumstances can surface after the deadline to file a request for Director Review [of an institution decision] has elapsed but before trial has progressed meaningfully.” Recognizing that sua sponte Director Review “is not always the most efficient process, and parties should be able to seasonably raise issues affecting institution,” the Director announced that, going forward, the Office would waive the fourteen-day deadline for requesting Director Review of a decision to institute a trial and extend “the deadline from fourteen days to thirty days.”
The Director also stated that, in “exceptional circumstances, the Office may extend the deadline … so long as trial has not progressed meaningfully.” Exceptional circumstances may include “dismissal of all or substantially all claims in a co-pending litigation, findings of fact and conclusions of law that render all or substantially all challenged claims invalid in litigation, and a violation of a Sotera stipulation.”
In this case, the Director initiated sua sponte review rather than require Evolution to file a request for Director Review at that stage. Before the IPR petitions were filed, the district court dismissed Evolution’s infringement claims without prejudice, finding the challenged claims patent ineligible under 35 U.S.C. § 101, but allowing Evolution to amend. After the Board instituted the IPRs, the district court granted Light & Wonder’s renewed motion to dismiss with prejudice and again ruled that the challenged claims were directed to patent-ineligible subject matter under § 101. Because all challenged claims “now stand invalid,” the Director concluded that maintaining the IPRs to review the claims for patentability on other grounds would be “unnecessary and inefficient.”
The Director also rejected Light & Wonder’s arguments that the IPRs should proceed because the Federal Circuit might reverse the district court’s § 101 ruling and because much of the IPR work had been completed. The Director explained that, if the Federal Circuit reversed, raising invalidity in district court on remand “is the better and more efficient approach.” The Director also noted that reply and sur-reply briefing remained pending and that “the Board has not yet expended resources on oral arguments or a final written decision.”
The Director vacated the Board’s institution decisions, denied the petitions, and ordered that no trial be instituted.