Enanta Pharmaceuticals Advances RSV Treatment Pipeline and Expands Immunology Portfolio with Three Novel Targets
核心洞察
Enanta's zelicapavir demonstrated clinically meaningful improvement in RSV symptom resolution with a 6.7-day benefit for high-risk patients in Phase 2b trials, leading to Phase 3 enabling activities.
The company announced its third immunology program targeting MRGPRX2 (搜索), a mast cell receptor, with prototype inhibitors showing nanomolar potency and potential for treating chronic inflammatory diseases.
EDP-978 (搜索), an oral KIT (搜索) inhibitor for chronic spontaneous urticaria (搜索), is on track for IND filing in Q1 2026, while EPS-3903 (搜索), a STAT6 inhibitor for atopic dermatitis (搜索), targets IND submission in H2 2026.
Enanta Pharmaceuticals has provided comprehensive updates on its research and development programs, highlighting significant progress in both respiratory syncytial virus (搜索) (RSV) treatment and immunology therapeutics. The clinical-stage biotechnology company announced positive Phase 2b results for its lead RSV candidate and unveiled a new immunology program targeting mast cell-driven inflammatory diseases.
RSV Program Shows Clinical Promise
Zelicapavir, Enanta's oral, once-daily RSV N-protein (搜索) inhibitor, demonstrated clinically meaningful improvements in the Phase 2b RSVHR study conducted in high-risk adult outpatients. The trial included elderly patients and those with asthma (搜索), chronic obstructive pulmonary disease (搜索), or congestive heart failure (搜索). Results showed a 6.7-day benefit in time to complete resolution of all 13 RSV symptoms for the HR3 population (patients with congestive heart failure, chronic obstructive pulmonary disease, or age 75 or older) compared to placebo.
The drug also achieved a 7.2-day improvement in time to complete resolution on the 29-parameter total RiiQ™ symptom scale for the HR3 population. The study met key secondary endpoints, including reduction in hospitalization and antiviral effects. Zelicapavir has been dosed in more than 700 people to date and maintains a favorable safety profile.
Enanta is continuing Phase 3 enabling activities, including discussions with the FDA on adult Phase 3 trial design and overall registration path. The company expects to align with the FDA on Phase 3 design in Q2 2026 and prepare for a Phase 3 study in high-risk adults in H2 2026.
The company's second RSV candidate, EDP-323, an oral RSV L-protein (搜索) inhibitor, showed potential for post-exposure prophylaxis. Data presented in October demonstrated EDP-323's effectiveness in preventing RSV infection when initiated up to five days after RSV exposure in human challenge studies.
New MRGPRX2 Program Targets Mast Cell Diseases
Enanta announced its third immunology program targeting MRGPRX2 (搜索), a non-canonical G-protein-coupled receptor expressed predominantly on mast cells. Inhibiting MRGPRX2 may address multiple chronic inflammatory diseases including urticaria (搜索), asthma (搜索), and prurigo nodularis (搜索).
The company's prototype MRGPRX2 (搜索) inhibitors demonstrate nanomolar potency with EC50 values of 1-2nM in cellular assays and prevent skin mast cell activation in humanized MRGPRX2 mouse models. These prototypes show high selectivity for MRGPRX2 versus other GPCRs and exhibit favorable ADME properties supporting once-daily dosing. Enanta expects to select a development candidate in the second half of 2026.
Advancing KIT and STAT6 Inhibitor Programs
EDP-978 (搜索), Enanta's novel oral KIT (搜索) inhibitor clinical candidate for chronic spontaneous urticaria (搜索) and other mast cell-driven diseases, demonstrates nanomolar potency in binding and cellular assays with sub-nanomolar activity in vivo. The compound shows high selectivity for KIT versus other kinases and favorable ADME properties. The company is on track to submit an IND in Q1 2026 with Phase 1 data expected in Q4 2026.
EPS-3903 (搜索), nominated in November as the lead STAT6 inhibitor development candidate for atopic dermatitis (搜索), exhibits nanomolar activity in binding and cellular assays with high selectivity for STAT6. The compound shows rapid, continuous, and complete (>90%) inhibition of phosphorylated STAT6 after oral dosing in mice.
In preclinical disease models, EPS-3903 (搜索) demonstrated efficacy comparable to dupilumab. In a house dust mite asthma (搜索) model, treatment resulted in complete (>90%) inhibition of lung pSTAT6 and decreased inflammation comparable to dupilumab, including reductions in eosinophils and TARC in the lung and serum IgE. In an MC903 atopic dermatitis (搜索) mouse model, EPS-3903 showed complete (>90%) inhibition of pSTAT6 in skin and spleen, with robust decreases in serum IgE. The company targets IND filing in H2 2026.
Corporate Developments and Financial Position
In August 2025, Enanta filed a patent infringement action in the Unified Patent Court of the European Union against Pfizer and its subsidiaries regarding European Patent No. EP 4 051 265 in connection with Paxlovid manufacture, use, and sale in 18 EU member states. A hearing is expected within the UPC's 12-month target, with an update anticipated in H2 2026.
"Building on the progress we achieved in our RSV and immunology portfolios this past year, we enter 2026 with strong momentum as we continue to expand our pipeline and deliver on key milestones," said Jay R. Luly, Ph.D., President and Chief Executive Officer. "With programs in KIT (搜索), STAT6 and MRGPRX2 (搜索) inhibition, we are leveraging our proven expertise in small molecule drug discovery and development to build a leading immunology portfolio focused on type 2 immune driven diseases."
The company maintains a strong cash position with runway expected to fund operations into fiscal 2029, supported by continuing retained royalties from its hepatitis C collaboration with AbbVie (搜索).