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Lead Characterization

In vitro characterization


WuXi Biologics can provide a variety of high throughput, high sensitivity and high content in vitro assays. 

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 qualification method development (Specificity, linearity and range, accuracy, precision)
  • Antigen-antibody binding assay 


    • Protein-based ELISA/SPR
    • Cell-based FACS
    • Dual binding of bispecific Ab (protein-protein, cell-protein and cell-cell)
    • CART (cell-protein, cell-cell and FACS)
    • 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)
  • Reporter gene assay (RGA)


    • Immune Checkpoint RGA
    • Bispecific RGA
    • Fc Effector Function RGA: ADCC and ADCP


  • Translocation imaging assay
  • PBMC activation


    • Anti-CD3/CD28 stimulation
    • Super antigen stimulation (SEA and SEB)
    • Cytokine release detection


  • T/NK/B cell activation and expansion
  • Tumor dependent immune system activation


    • BsAb (e.g., CD3xTAA),  reporter gene assay, cytokine release assay 


  • Fc dependent killing and phagocytosis assay


    • ADCP (FACS, RGA)
    • CDC


  • Fc independent killing


    • PBMC/CD8+ T  cell killing (CD3×TAA bispecific Ab)
    • T cell specific killing
    • NK cell-mediated killing 
    • CAR-T cell killing 


  • Proliferation assay (CFSE/BrdU/CellTiter-Glo®)
  • Cell panel screening (Viability/proliferation)
  • 3D culture assay (Proliferation, killing)
  • Cell cycle analysis
  • Apoptosis assay


    • PI/Annexin V 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 (Cell Titer 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/Luminex
  • 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 Lymphocyte Reaction (MLR)
  • Antigen specific MLR/T cell recall assay (CMV, TT)
  • CD4+ T cell exhaustion
  • Regulatory T cell assay


    • In vitro expansion
    • T cell activation-suppression assay


  • Angiogenesis assay 
  • Tubulin formation (Incucyte®)
  • Osteoclast formation
  • Hemagglutination
  • Metabolic diseases
  • CNS


    • Primary neuron culture, neurite outgrowth
    • Blood brain barrier (BBB) Transcytosis assay
  • Epitope mapping by ELISA peptide mapping (linear epitope)
  • Epitope mapping by alanine scan (conformational epitope)

In vivo efficacy study and ex vivo study

WuXi Biologics offers a variety of animal models to support biologics efficacy study and IND filing. 


  • Tumor models


    • Syngeneic models
    • CDX models
    • Humanized models
    • GVHD models


  • Autoimmune disease models
  • IVIS spectrum platform
  • Ex vivo studies


    • Cytokine assays
    • Histology platform
    • TIL assay

PK/PD and Exploratory Toxicology

Mouse, rat, cynomolgus monkey PK, ADA and exploratory toxicology studies.

Early-stage developability assessment

WuXi Biologics offers developability studies at the discovery  stage to support lead selection and reduce CMC development risk. These early-stage developability studies need just 5-10 mg samples and the studies take only 2-3 weeks to perform. 


Test Item
Analysis methods
Deamidation/ isomerization stress test UV, SEC-HPLC, cIEF, SPR for potency 1 week
Oxidation stress test UV, SEC-HPLC, HIC, SPR for potency 1 week
Melting temperature (Tm) DSF or DCS 3 days
Colloidal stability kD – (mL/g) DLS 1 week
Stressed thermal stability 40 ºC 1-2 week
Freeze/thaw stability  5x, -80 ºC /RT UV, SEC-HPLC, cIEF

1 week

Serum stability  

2 weeks