9Y8X | pdb_00009y8x

OC43 Mpro with EGT710

• PDB DOI: https://doi.org/10.2210/pdb9Y8X/pdb

• Classification: HYDROLASE
• Organism(s): Human coronavirus OC43
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2025-09-11 Released: 2025-12-24 
• Deposition Author(s): Knapp, M.S., Ornelas, E.
• Funding Organization(s): Not funded

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.12 Å
• R-Value Free: 
  0.265 (Depositor), 0.235 (DCC) 
• R-Value Work: 
  0.215 (Depositor), 0.207 (DCC) 
• R-Value Observed: 
  0.217 (Depositor) 

Starting Model: experimental

Literature

Preclinical characterization of EGT710, an oral non-peptidomimetic reversible covalent SARS-CoV-2 main protease inhibitor.

Moquin, S.A., Lakshminarayana, S.B., Balavenkatraman, K.K., Schiller, H., Claas, A., Bhhatarai, B., Loisios-Konstantinidis, I., Vulic, K., Kurhade, C., Kalveram, B.K., Chen, J.Y., Zou, J., Xie, X., Tandeske, L., Dovala, D., Ornelas, E., Knapp, M.S., Fuller, D., Nguyen, Z., Barkan, D.T., Bebrevska, L., Wright, S.K., Busby, S.A., Blais, J., Shi, P.Y., Gaudet, S., Bergeron, R., Yu, H., Zack, J., Sarko, C., Gu, F., Bradner, J.E., Tallarico, J.A., Diagana, T.T., Papillon, J.P.N.

(2025) NPJ Drug Discov 2

• PubMed: 42380487 
• DOI: https://doi.org/10.1038/s44386-025-00030-5
• Primary Citation Related Structures: 
  9Y8W, 9Y8X


• PubMed Abstract: 
  

  EGT710 is an orally bioavailable non-peptidomimetic reversible covalent coronavirus main protease (Mpro) inhibitor with low nM cellular activity against SARS-CoV-2. Twice daily dosing of 10 mg/kg of EGT710 decreased lung viral load in a mouse model of SARS-CoV-2 infection to below the limit of detection. Resistance selection resulted in the emergence of several Mpro mutations, with recombinant viruses containing L50F + E166A substitutions showing the largest shift in potency. Development of a viral kinetics model using viremia data from clinical trials, along with a human physiologically based pharmacokinetic model, predicted efficacy in humans with once daily oral doses of >360 mg. EGT710 displays favorable pharmacokinetic properties and an acceptable in vitro and in vivo safety profile, with human exposures at the recommended clinical dose of 600 mg predicted to be below the no adverse effect level in preclinical toxicology studies. Together, EGT710 has a promising preclinical profile and has completed a Phase I study.

---

Organizational Affiliation: 
• Biomedical Research, Novartis, Emeryville, CA, USA. [e-mail].
Biomedical Research, Novartis, Emeryville, CA, USA.
Biomedical Research, Novartis, Basel, Switzerland.
Biomedical Research, Cambridge, MA, USA.
Frontier Medicines, Boston, MA, USA.
Development, Novartis, Cambridge, MA, USA.
University of Texas Medical Branch, Galveston, TX, USA.
Pfizer, Pearl River, NY, USA.
Glaxo Smith Kline, Rockville, MD, USA.
Biomedical Research, Novartis, East Hanover, NJ, USA.
Amgen, Thousand Oaks, CA, USA.
Sanofi, Cambridge, MA, USA.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Biological Assembly Evidence: gel filtration

Macromolecule Content 

• Total Structure Weight: 33.89 kDa 
• Atom Count: 2,359 
• Modeled Residue Count: 297 
• Deposited Residue Count: 303 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
3C-like proteinase	A	303	Human coronavirus OC43	Mutation(s): 1  Gene Names: Pp1ab
UniProt
Find proteins for U3M6R3 (Human coronavirus OC43) Explore U3M6R3  Go to UniProtKB:  U3M6R3

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
A1CBU	B [auth A]	(4S)-4-(iminomethyl)-3-(isoquinolin-4-yl)-1-[6-(trifluoromethyl)pyridin-3-yl]imidazolidin-2-one C19 H14 F3 N5 O XZYITQWBMBTCLK-BUTILUPYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.12 Å
• R-Value Free:  0.265 (Depositor), 0.235 (DCC) 
• R-Value Work:  0.215 (Depositor), 0.207 (DCC) 
• R-Value Observed: 0.217 (Depositor) 

Space Group: P 4₃ 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 92.77	α = 90
b = 92.77	β = 90
c = 69.771	γ = 90

Software Package:

Software Name	Purpose
BUSTER	refinement
Aimless	data scaling
XDS	data reduction
PHASER	phasing
PDB_EXTRACT	data extraction

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2025-12-24 
Deposition Author(s): Knapp, M.S., Ornelas, E.

---

Funding Organization	Location	Grant Number
Not funded	United States	--

Revision History  

• Version 1.0: 2025-12-24
  Type: Initial release
  
• Version 1.1: 2026-07-15
  Changes: Database references