Assay signal as an alternative to titer for assessment of magnitude of an antidrug antibody response

Background: Titer methods are commonly used to characterize the magnitude of an antidrug antibody response. Assay S/N is an appealing alternative, but the circumstances under which use of signal-to-noise (S/N) is appropriate have not been well defined. Results: We validated both titer and S/N-based methods for several therapeutics. S/N correlated strongly with titer both in aggregate and when examined on a per subject basis. Analysis of impact of antibody magnitude on pharmacokinetics yielded the same result using either method. Each assay demonstrated excellent precision, good linearity, and adequate drug tolerance. Conclusion: Under these circumstances, assay S/N is a valid alternative to titer for assessment of the magnitude of an antidrug antibody response.