There is significant interest in identifying high-affinity therapeutic antibodies with desirable biophysical properties during early antibody discovery. The most important biophysical properties are solubility, folding stability and viscosity, and these are frequently assayed in common formulation buffers. Nevertheless, the biophysical properties of antibodies in serum are also important because aggregation in serum can lead to immunogenicity and low activity, and non-specific interactions with serum proteins can lead to fast antibody clearance. Therefore, we are developing a method based on affinity-capture self-interaction nanoparticle spectroscopy (AC-SINS) for assaying the stability and specificity of mAbs in serum that is compatible with large numbers of dilute and unpurified antibodies common during early antibody discovery. Our approach uses gold nanoparticles coated with polyclonal anti-human antibodies to immobilize human mAbs, and the relative propensity of immobilized mAbs to self-associate or interact with serum proteins is evaluated via the plasmon wavelength of the gold conjugates. We find that evaluating the plasmon wavelengths of antibody conjugates over a wide range of mAb concentrations – from low subsaturating levels that do not fully coat the particles to saturating levels – enables robust discrimination between mAbs with high and low stability in serum. Moreover, we find that samples containing antibody aggregates can be discriminated from those that do not, which should enable direct monitoring of antibody aggregation in serum. We are currently optimizing and validating this approach for identifying antibodies with high serum stability. <br/>

Rapid screening of monoclonal antibody stability in serum using affinity-capture self-interaction nanoparticle spectroscopy

249th National Meeting (2015)

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