64Cu-Tz-SarAr

64Cu-Tz-SarAr is a diagnostic radiopharmaceutical designed for pretargeted positron emission tomography (PET) imaging, primarily in oncology. It consists of a tetrazine (Tz) moiety conjugated to the sarcophagine chelator SarAr, which is radiolabeled with copper-64 (^64Cu). The agent is used as part of a two-step pretargeting strategy where an antibody modified with trans-cyclooctene (TCO)—such as hu5B1-TCO or huA33-TCO—is first administered to target tumor-associated antigens (e.g., CA19-9 or A33 antigen). After sufficient time for antibody accumulation and clearance from non-target tissues, 64Cu-Tz-SarAr is injected and rapidly binds to the TCO-modified antibody at the tumor site via bioorthogonal click chemistry. This approach enables high-contrast PET imaging by reducing background signal and radiation exposure to healthy tissue due to rapid renal clearance of unbound tracer. The technology was developed at Memorial Sloan Kettering Cancer Center and has been evaluated in Phase 1 clinical trials for imaging gastrointestinal neoplasms, metastatic pancreatic cancer, and other solid tumors expressing relevant antigens[1][2][4][5].