Enanta Pharmaceuticals, Inc. · NASDAQ:ENTA
Enanta Pharmaceuticals — 13th International RSV Symposium 2025
16 slides from Enanta Pharmaceuticals's conference presentation, Mar 14, 2025
Slide 1: EDP-323 Oral L-Protein Inhibitor for RSV: Phase 2a Human Viral Challenge Study Results
EDP-323, a First-in-Class, Once-Daily, Oral Non-Nucleoside L-Protein, Replication Inhibitor Antiviral for the Treatment of RSV: Results From a Phase 2a Human Viral Challenge Study John P. DeVincenzo1, Alaa Ahmad1, Shijie Chen1, Brandon Löndt2, Alex Mann2, Julie Mori2, Andrew Catchpole2, Scott T. Rot
Slide 2: Disclosure of Relevant Financial Relationships and Acknowledgments
Disclosure of Relevant Financial Relationships and Acknowledgments Disclosures • JPD, AA, SC, and STR are employees of Enanta Pharmaceuticals and hold Enanta Pharmaceuticals stock • BL, AM, JM, and AC are employees of hVivo and hold hVivo stock Acknowledgments • Authors thank those who chose to volu
Slide 3: EDP-323: First-in-Class, Oral, Once Daily, L-Protein Inhibitor for RSV Infection
EDP-323: First-in-Class, Oral, Once Daily, L-Protein Inhibitor for the Treatment of RSV Infection • Significant unmet need for RSV antiviral therapies despite availability of prophylaxis1 – Complementary to effective preventive vaccines and monoclonal antibodies – See late breaker poster #253, Huang
Slide 4: Unique Properties of EDP-323 Mechanism of Action
Unique Properties of EDP-323 Mechanism of Action Detailed in Poster #161: In Vitro Characterization of Respiratory Syncytial Virus Inhibitors • EDP-323 maintained antiviral effect even when dosed up through 3 days post-infection in a 3D primary human airway epithelial cell system1,4 – Antiviral effe
Slide 5: Study Overview
Study Overview Objective • Evaluate the PK profile, safety, and antiviral activity of multiple doses of EDP-323 in a human RSV challenge study* among healthy adults1 Description • Randomized, double-blind, placebo-controlled human viral challenge (RSV-A Memphis 37b strain) Phase 2a study† Population
Slide 6: Study Design and Endpoints
Study Design and Endpoints Randomization Quarantine in Facility 1:1:1 Before Dosing Initiation After Dosing Initiation Follow-Up Study Inoculation Study Dosing for Study Study Day Screening Day -2/-1 Day Days 2 to ≤5 5 days Day 12 28 Admission Viral Monitor for infection EDP-323 or Discharge Final s
Slide 7: Participant Disposition
Participant Disposition Day 0 Inoculated with RSV-A Memphis 37b virus (n=142) Self-removed from quarantine due to personal reasons (n=1) Day 2 to Day 5 Randomized and Dosed (n=141) TEAE Safety Population Placebo QD x 5D EDP-323 600 mg QD x 5D EDP-323 600 mg LD + 200 mg QD x 4D (n=47) (n=47) (n=47) 9
Slide 8: Summary of Demographics
Summary of Demographics • Demographics were balanced across study arms EDP-323 EDP-323 Placebo High Dose Low Dose (n=47) (n=47) (n=47) Age, years, median (Q1, Q3) 28 (24, 33) 26 (24, 30) 27 (23, 30) Sex, male, n (%) 32 (68.1) 30 (63.8) 28 (59.6) Race, White, n (%) 39 (83.0) 35 (74.5) 38 (80.9) Q, qu
Slide 9: Summary of PK and Safety Outcomes
Summary of PK and Safety Outcomes PK - EDP-323 mean trough plasma concentrations were maintained at 16- to 35-fold above protein-adjusted EC90 against both RSV-A and RSV-B subtypes – See Poster #153, Elmore et al – PK and PK/PD Evaluations of Human Viral Challenge Study Safety - The frequency of TEA
Slide 10: Mean Viral Load Over Time and AUC by qRT-PCR
Mean Viral Load Over Time and AUC by qRT-PCR Primary Efficacy Endpoint: AUC (ITT-I Population) • EDP-323 showed 85% (high dose) and 87% (low dose) greater mean reductions in viral load AUC vs placebo (P <0.0001) – No statistically significant differences between the 2 EDP-323 dosing regimens 6 EDP-3
Slide 11: Mean Viral Load Over Time and AUC by Viral Culture
Mean Viral Load Over Time and AUC by Viral Culture Secondary Efficacy Endpoint: AUC (ITT-I Population) • EDP-323 showed 98% (high dose) and 97% (low dose) greater mean reductions in viral load AUC vs placebo (P <0.0001) – No statistically significant differences between the 2 EDP-323 dosing regimens
Slide 12: Mean Total Symptom Score and AUC
Mean Total Symptom Score and AUC Secondary Efficacy Endpoint: AUC (ITT-I Population) • EDP-323 showed 66% (high dose) and 78% (low dose) greater mean reductions in total symptom score AUC vs placebo (P <0.0001) – No statistically significant differences between the 2 EDP-323 dosing regimens 4 EDP-32
Slide 13: Viral Dynamics in Human RSV Challenge Studies: Fusion vs Polymerase Inhibitor
Viral Dynamics in Human RSV Challenge Studies (Memphis-37b) Fusion Inhibitor vs Polymerase Inhibitor Viral Load (qPCR) Viral Load (Culture) 5 3.0 Fusion Inhibitor (RV521) 4 (log10 PFU/mL) ±SE Mean Viral Load (log10 PFUe/mL) ±SE Mean Viral Load 2.0 RV521 350mg PO BID x 5 days (n=16) 3 RV521 200mg PO
Slide 14: EDP-323 RSV Human Challenge Study Conclusions
EDP-323 RSV Human Challenge Study Conclusions • Well tolerated with safety profile similar to placebo • Mean trough plasma concentrations maintained at 16- to 35-fold above protein-adjusted EC90 • Primary and key secondary endpoints achieved with statistical significance at both dose levels vs place
Slide 15: Poster Presentation: Zelicapavir for Treatment of RSV Infection in Young Children
Poster Presentation: Zelicapavir for Treatment of RSV Infection in Young Children A Phase-2, Double-Blind, Placebo-Controlled, LS Mean Change (± SE) From Baseline in Viral Load in Prespecified mITT-3 Population* Measured by qRT-PCR International Trial of Zelicapavir for Treatment of RSV Infection in
Slide 16: Thank you!
ii: Enanta Pharmaceuticals Great Chemistry Cures Thank you! a
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