Tagworks’ technology enables the in vivo actuation of tagged antibodies through systemic and selective chemical manipulation in vivo. This In Vivo Chemistry technology, based on a bioorthogonal chemical reaction between a tag and a probe, improves the efficacy of several established antibody-based imaging and therapy approaches. Tagged antibodies are allowed to circulate and accumulate at their target site. After clearance from non-target areas, a chemical probe is administered which binds to and actuates the tagged antibody, boosting the signal-to-background ratio or therapeutic window of antibody pharmaceuticals, such as those used in Radioimmunoimaging and –therapy and Antibody-Drug Conjugate therapy.