Comparison of METH and therapeutic protein serum concentrations (μM). A. Total METH serum concentration was approximately 44% of the scFv7F9Cys serum concentration, and AUC0→2hrs of the METH serum concentrations was determined to be 340 ng*hr/ml, B. In the PEGylated conjugate group, total METH serum concentrations were an average of 29% of the therapeutic protein concentration, with a METH AUC0→2hrs of 935 ng*hr/ml. Total AUC0→48hrs of scFv7F9Cys-PEG20K was 4326 ng*hr/ml. This is a 12.7-fold increase in total METH binding activity compared to scFv7F9Cys, which was only active through two hrs (AUC0→2hrs = 340 ng*hr/ml).