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Integrated Discovery Platform
From Concept to IND

Lead Optimization

Lead optimization is a critical step in the discovery stage of biologics therapeutics development. WuXi Biologics offers extensive lead assessment and optimization services for antibody therapeutics such as monoclonal (mAb), bispecific (bsAb), and multispecific (msAb) antibodies and other biologics including peptides, enzymes, soluble TCRs, TCR-T, cytokines, other soluble proteins and extracellular domains. Our team of experts work with you to establish the best path to optimize your molecule to its target and for its intended purpose.


WuXi Biologics has significant experience in the humanization of antibody therapeutics and our services utilize a best fit approach combined with structural modeling for back-mutation design. Our expertise and capabilities have been built upon completion of over 150 humanization projects with a success rate of >98%.

Key Features:


  • 8-10 weeks turnaround time
  • Post-translational modifications (PTM) removal in parallel


Affinity Optimization

WuXi Biologics offers antibody affinity optimization services through our well-established and highly-reliable parsimonious mutagenesis methodology. We also offer a phage/yeast library-based block-mutagenesis approach for affinity maturation of antibodies to cell-surface targets.

Key Features:


  • 3-4 months turnaround time
  • Mimics somatic hyper-mutations in natural antibody
  • Provides affinity improvement in dissociation constant ΚD: 10 – 1000 folds (up to picomolar affinity)
  • Tailored affinity optimization for association rate constant kon and dissociation rate constant koff
  • Includes simultaneous removal of post-translational modification (PTM) risks
  • Applicable for diverse biologics including antibodies, peptides, enzymes, soluble TCRs, TCR-T, cytokines, other soluble proteins and extracellular domains


Fc Selection and Engineering


WuXi Biologics offers high quality Fc selection and engineering services to generate Fc variants with desired effector functions and half-life.

Related services:


  • Engineering of novel Fc variants
  • Optimized Fc domain with enhanced antibody-dependent cell-mediated cytotoxicity (ADCC), extended half-life and improved thermostability (WuXi Biologics patent pending)
  • Binding affinity test to Fc receptors, FcRn, C1q
  • ADCC/ADCP/CDC assays



WuXi Biologics offers pH-sensitivity antibody engineering to increase Tumor Associated Antigen (TAA) targeting specificity and to minimize on-target off-tumor toxicity.

Key Features:


  • Standard timeline: 3 months turnaround time
  • Design and construction of pH sensitive synthetic library (combination of histidine and other charged residues)
  • Panning and screening under different pH conditions
  • Simultaneous removal of post-translational modification (PTM) risks
  • Optimization of other conditional biologics such as ATP, GSH and enzyme dependency

Early-stage Developability Assessment


WuXi Biologics offers developability studies at the discovery stage to support lead selection and reduce future CMC development risk. These early-stage developability studies require just 5-10 mg of sample material and the studies are rapid, taking only 2-3 weeks to perform.

After developability assessment, if any characteristics need to be improved, our team of experts can offer a full set of developability improvement services to meet your needs.


Test item​ Analysis / Methods​ Duration
Deamidation/Isomerization stress test​ UV, SEC-HPLC, icIEF, SPR for potency​ 1 week
Oxidation stress test​ UV, SEC-HPLC, icIEF, SPR for potency​ 1 week
Melting temperature (Tm)​ DSF or DSC​ 3 days​
Colloidal stability kD (mL/g)​ DLS​ 1 week
Stressed thermal stability​ 40℃​ 1-2 week​s
Freeze/Thaw stability​ 5x, -80℃/RT, UV, SEC-HPLC, cIEF​ 1 week
Serum stability​ ELISA / FACS binding​ 2 weeks​
Self-interaction (nm)​ AC-SINS​​ 1 week
Non-specific binding (BVP score)​ BVP ELISA​ 1 week