Developing an antibody tag with improved pharmacokinetics and stability allowed Tagworks to achieve increased tumor uptake of a radiolabeled pretargeting probe. Even though this adapted tag exhibited a slight loss in reactivity, its use in a antibody (CC49-TCO) conjugate demonstrated a longer clearance half-life, improved tumor accumulation and increased in vivo stability. The overall result was a 50% increase in tumor uptake as well as increased tumor/non-tumor ratios of the radiolabeled tetrazine probe. Read the Tagworks paper "Trans-cyclooctene tag with improved properties for tumor pretargeting with the Diels-Alder reaction" in Mol. Pharmaceutics 2014, 11(9). doi:10.1021/mp500725a