Figure 1

Panitumumab immunogenicity testing strategy. Three validated assays were used to detect the presence of anti-panitumumab antibodies. All clinical study samples were tested in two screening immunoassays (an acid-dissociation ELISA and a Biacore-based biosensor assay) to detect antibodies capable of binding to panitumumab. Samples that tested above the assay threshold and demonstrated reduction in response in the drug-competition specificity assay were reported as positive for binding antibodies and tested further in a cell-based neutralizing antibody bioassay. Assay thresholds were based on the upper bound of a one-sided 95% reference interval for the distribution of signals generated by serum samples from healthy subjects or cancer patients. S/N, signal-to-noise ratio.