Enanta Secures FDA Path for Zelicapavir Registrational Trial, Shifts Endpoints
The biotech's net loss narrowed to $0.45 a share from $1.06 a year earlier as R&D spending fell 31%.
Enanta Pharmaceuticals (ENTA) secured a registrational Phase 2b/3 trial pathway for its oral RSV antiviral zelicapavir following a successful End-of-Phase 2 meeting with the FDA, with the adult study set to begin in the fourth quarter of 2026. The milestone marks a significant pivot from the prior quarter, when the company was still conducting enabling activities and exploring potential business development partnerships for the program.
The trial design reflects lessons from earlier clinical work. The registrational adult study will use a 7-day dosing regimen, up from the 5-day course tested in the prior Phase 2b RSVHR trial, and will measure time to complete resolution of all 13 RSV symptoms via the RiiQ instrument rather than the 4-symptom LRTD resolution endpoint that failed to demonstrate an effect. The Phase 2b portion will enroll a minimum of 200 patients, with the Phase 3 portion sized at approximately 660.
Enanta also disclosed a Phase 2b pediatric trial of zelicapavir for the first time, to be initiated in the third quarter of 2026 with topline data expected in 2027, conducted in collaboration with the Penta Foundation and the AMS-PHPT Research Unit at Chiang Mai University. The company now estimates a global market opportunity of over $2 billion for an oral RSV antiviral across children and all high-risk adults, with U.S. revenue potential of $2.6 billion to $3.5 billion and an addressable patient population exceeding 3 million domestically.
Revenue for the fiscal second quarter ended March 31 was $17.2 million, up 15% from $14.9 million a year earlier, driven by increased AbbVie MAVYRET/MAVIRET product sales. That represented a sequential decline from fiscal first-quarter revenue of $18.6 million, which itself had risen 10% year over year. Full fiscal-year 2025 revenue totaled $65.3 million, down 3.4% from $67.6 million in fiscal 2024, reflecting lower AbbVie sales in the first nine months of that year.
Research and development expenses fell sharply, dropping 31% to $19.4 million in the fiscal second quarter from $28.1 million a year prior, as decreased RSV clinical trial costs more than offset higher immunology program spending. The cost reduction helped narrow the net loss to $13.1 million, or $0.45 a share, from $22.6 million, or $1.06 a share, in the year-ago quarter. Interest expense nearly doubled to $3.3 million from $1.7 million, driven by higher royalty revenue triggering larger payments under the company's OMERS arrangement.
Cash and cash equivalents stood at $227.0 million as of March 31, down $14.9 million from $241.9 million at the end of December. The December balance had been bolstered by a $74.8 million public offering in October 2025 that added 7.475 million shares at $10.00 each, lifting weighted average shares outstanding to approximately 29.0 million from 21.4 million a year earlier.
Separately, Enanta's EDP-978 KIT inhibitor dosed its first Phase 1 participant in April 2026, with topline data still expected in the fourth quarter of the year. The zelicapavir safety database now encompasses more than 700 subjects. A Federal Circuit decision in the company's Pfizer patent litigation is anticipated by the end of September 2026, with a UPC hearing scheduled for September 29.