$ENTA

Enanta Pharmaceuticals has begun its Phase IIb/III RESOLVE trial for zelicapavir, an RSV treatment. The trial will assess safety and efficacy in high-risk adults. Initial results are expected in 2027. The FDA has granted zelicapavir fast track designation. Earlier trials showed promising results, including reduced symptom duration and hospitalization rates.

Enanta Pharmaceuticals laid off 37 employees, reducing its workforce from 120, to align with strategic priorities. The company is focused on antiviral and immunology treatments, with key trials expected to report data soon. Enanta's revenue for the last quarter was $14.4 million, all from royalties, and it had $211.5 million in cash reserves.

ENANTA PHARMACEUTICALS INC (ENTA) filed an SEC Form 8-K — Results of Operations and Financial Condition. Exhibit 99.1 Enanta Pharmaceuticals Reports Financial Results for its Fiscal Third Quarter Ended June 30, 2026 • Dosing Initiated in LOTUS, a Phase 2b Pediatric Trial of Zelicapavir; Topline Data Expected in 2027 • On Track to Initiate RESOLVE, a Registrational Phase 2b/3 High-Ri

The US Federal Circuit affirmed that every claim in Enanta Pharmaceuticals’ patent on a coronavirus protease inhibitor is invalid in Enanta Pharmaceuticals, Inc. v. Pfizer Inc. (Fed. Cir. June 23, 2026). The court said Enanta’s provisional did not disclose the relevant C1 alkyl range, so Pfizer’s April 6, 2021 nirmatrelvir (Paxlovid) presentation was prior art. Paxlovid earned about $19B in 2022.

The Federal Circuit, in Enanta Pharmaceuticals v. Pfizer, held Enanta’s patent could not claim priority to an earlier provisional filing because the provisional described a C2-C12 alkyl range, while the issued claims covered C1-C12. Pfizer’s intervening disclosure of nirmatrelvir (Paxlovid) was treated as prior art, anticipating and invalidating Enanta’s claims under 35 U.S.C. §112.

The Federal Circuit in Enanta Pharmaceuticals v. Pfizer (June 23, 2026) affirmed that Pfizer’s Paxlovid-related U.S. Patent No. 11,358,953 cannot claim the provisional application’s July 20, 2020 priority because the provisional lacked written-description support for later claims. The court said changing alkyl range C2 to C1 was not supported, making Pfizer’s nirmatrelvir disclosure prior art and invalidating the asserted claims.

Enanta Pharmaceuticals appealed a Massachusetts court ruling that its U.S. Patent No. 11,358,953 was invalid, finding the patent improperly broadened “substituted” alkyls from C2-C12 to C1-C12 and that Pfizer’s later public disclosure anticipated the claims. The Federal Circuit affirmed, ruling the provisional lacked written description support for C1 alkyl coverage.

A Fed. Cir. decision in Enanta Pharmaceuticals v. Pfizer (No. 2025-1427, June 23, 2026) held that Enanta’s ’953 coronavirus replication inhibitor patent could not claim priority to its July 20, 2020 provisional because the provisional’s “-NHC(O)-C2-C12-alkyl” did not support the later “-NHC(O)-C1-C12-alkyl” claim scope. Pfizer’s April 6, 2021 nirmatrelvir disclosure then anticipated the claims, leading to invalidity.

The Federal Circuit (Enanta Pharms. v. Pfizer) affirmed summary judgment that Enanta’s U.S. Patent No. 11,358,953 is invalid for lack of priority and anticipation by Pfizer’s COVID-19 drug Paxlovid’s active ingredient nirmatrelvir. Courts held Enanta’s July 20, 2020 provisional did not provide written-description support for the later ’953 claims.

ENANTA PHARMACEUTICALS INC (ENTA) filed an SEC Form 8-K — Entry into a Material Definitive Agreement. EX-1.1 2 d123412dex11.htm EX-1.1 EX-1.1 Exhibit 1.1 OPEN MARKET SALE AGREEMENT SM July 2, 2026 JEFFERIES LLC 520 Madison Avenue New York, New York 10022 Ladies and Gentlemen: Enanta Pharmaceuticals, Inc., a Delaware corporation (the “ Company ”), proposes, subject to the terms an