Lead Pb 203-MP0712

**Semantic type:** Indicator, Reagent, or Diagnostic Aid|Pharmacologic Substance

**Definition:** A half-life engineered radioconjugate composed of MP0712, a designed ankyrin repeat proteins (DARPin)-based agent targeting the tumor-associated antigen (TAA) delta-like protein 3 (DLL3), conjugated, through the bifunctional, macrocyclic chelating agent DOTAM (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic amide; TCMC), to the gamma-emitting radioisotope lead Pb 203, with potential use as an imaging agent for DLL3-expressing tumor cells during single photon emission computed tomography (SPECT)/computed tomography (CT). Upon administration of lead Pb 203-MP0712, the DARPin moiety targets and binds to DLL3 expressed on tumor cells. Upon SPECT/CT, the DLL3-expressing tumor cells can be visualized and detected. DLL3, a Notch pathway protein, is overexpressed on a variety of cancer cell types. It plays a key role in embryonic development and in tumor initiation and proliferation. DARPins are small, have favorable pharmacokinetics, allow for high tumor uptake and penetration, and have high binding affinity. MP0712 also binds to human serum albumin, which extends the half-life of MP0712.

**Synonyms:** - 203Pb-DOTAM-MAM279 - 203Pb-MP0712 - 203Pb-labeled MP0712 - DLL3-targeting 203Pb-based DARPin Imaging Agent MP0712 - Lead Pb 203 MP0712 - Lead Pb 203-DOTAM-MAM279 - Lead Pb 203-labeled DLL3-targeting DARPin Imaging Agent MP0712 - Pb203-DOTAM-MAM279