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Integrated Discovery Platform
From Concept to IND

In Vitro Lead Characterization

WuXi Biologics provides assay development services and offers comprehensive biologics screening and characterization throughout the lead preclinical candidate (PCC) drug selection process. Our biology team has extensive discovery experience with various targets and therapeutic modalities including but not limited to monoclonal (mAbs), bispecific (bsAbs) and multispecific (msAbs) antibodies, fusion proteins, and immunocytokines. Learn more about our in vitro characterization capabilities for ADCs.



Affinity by SPR (Surface Plasmon Resonance)​


  • Protein-Protein, protein-peptide, protein-small molecule binding affinity
  • Antibody and Fc-fusion protein binding affinity to Fc receptors​
  • Off-rate ranking
  • High-performance koff ranking for humanization and affinity maturation
  • High-throughput koff ranking for hybridoma screening


Bispecific antibody simultaneous binding​


  • Affinity to cell surface proteins by FACS​


Related SPR service​


  • Epitope binning​
  • SPR assay method development and qualification (specificity, linearity, range, accuracy, and precision)

Epitope Binning and Mapping


Peptide mapping, domain mapping and alanine scanning mutagenesis services are available to assist customers in obtaining antigen epitope information, including linear and conformational epitopes. We have successfully completed more than 30 epitope mapping projects for the benefit of our clients’ antibody drug design & discovery projects.

Peptide mapping (linear epitope)​


  • Mapping linear epitopes of a target protein
  • Screening antibodies that bind to a specific epitope
  • Timeline: 5~7 weeks


Domain mapping (domain epitope)


  • Positioning the binding domain of an antibody, especially for complex, high molecular weight antigens.​ ​
  • Classifying antibodies by differences in antigen-binding domains.​
  • Timeline: 5~7 weeks


Alanine Scanning Mutagenesis (both linear and conformational epitopes)​


  • Mapping epitopes at the amino acid level
  • Characterization of protein stability and expression
  • Timeline: 9-11 weeks


Functional Assays​


Biochemical Assay​s


​​​ ​

Test item​ Analysis methods​
Antigen-antibody binding assay
  • Protein based ELISA/SPR
  • Cell-based FACS​
  • Dual binding of bispecific Ab (protein-protein, cell-protein, cell-cell)​
  • RBC or platelets binding assay
Competition Assay
  • Ligand blocking (protein or cell-based, ELISA/FACS)​
  • Epitope binning (protein or cell-based, ELISA/FACS)​
Cross species/paralogue binding (protein or cell-based, ELISA, FACS)​
Signal Transduction (Phosphorylation)​
  • Western blot
  • p-ELISA
  • HTRF/AlphaLISA
  • ​ Intracellular staining (FACS)
cAMP signaling assay​
Enzymatic assays​
Receptor occupancy

Cellular Assay​s

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Test item​ Analysis methods​
Reporter gene assay (RGA)​
  • Immune Checkpoint RGA
  • Bispecific RGA
  • Fc Effector Function RGA: ADCC, ADCP​
Translocation imaging assay​
PBMC activation​
  • anti-CD3/CD28 stimulation​
  • Super antigen stimulation (SEA, SEB)​
  • Cytokine release detection​
T/NK/B cell activation and expansion​
Tumor dependent immune system activation​
  • BsAb (eg. CD3 x TAA), Reporter gene assay, Cytokine release assay​
Fc dependent killing and phagocytosis assay​
  • CDC​
Fc independent killing​
  • PBMC/CD8 T cell killing (CD3×TAA bispecific Ab)
  • T cell specific killing​
  • NK-mediated killing​
  • CAR-T killing​
Cytotoxicity assay (CellTiter-Glo)​
Bystander killing assay​
Proliferation assay (CFSE/BrdU/CellTiter-Glo)​
Cell panel screening (Viability/proliferation)​
3D culture assay (Proliferation, killing)​
Cell cycle analysis​
Apoptosis assay​
  • PI/AnnexinV staining FACS​
  • Caspase 3/7 activation (Luminescence)​
Monocyte survival​
Differentiation and polarization​
  • DC differentiation
  • Macrophage differentiation/polarization (M1/M2)​
  • T cell polarization (Th1, Th2, Th17, Treg)​
Antibody Internalization​
  • Direct detection by FACS/HCS​
  • Lysosome co-localization (Image)
  • pHrodo (Operetta, FACS)​
  • Fab-Zap assay (CellTiter-Glo)​
Cell Migration/Invasion Assay
  • ​Image based​
  • Transwell​
Surface marker profiling​
Target expression profiling on resting or activated cells​
Cytokine/chemokine profiling​
  • ELISA/AlphaLISA/Elispot/CBA
Ex vivo tumor and TIL profiling​
CAR-T cell activation​
  • CAR-T cell cytokine release
  • CAR-T cell proliferation​
CAR-T cell killing​
Allogeneic Mixed Lymphocytes Reaction (MLR)​
Antigen specific MLR/T cell recall assay (CMV, TT)​
T cell exhaustion​
Regulatory T cell assay​
  • in vitro expansion​
  • T cell activation-suppression assay​
Metabolic diseases​
Infectious disease​
  • Pseudovirus neutralization assay​
  • Antibody-dependent enhancement
In vitro safety evaluation​
  • Immunogenicity evaluation​
  • Pre-ADA evaluation​
  • Cytokine release assay (PBMC, whole blood)​
Developability evaluation​
  • Serum/plasma stability test (human, cyno, mouse)

For more information on our lead characterization services please Contact Us.