The present invention relates to MSLN-specific binding constructs comprising a designed
ankyrin repeat domain with binding specificity for MSLN and a chelator capable of bonding to a
radionuclide, as well as to such MSLN-specific binding constructs comprising a half-life extending
moiety with binding specificity for
serum albumin. The invention further relates to methods of producing such radio-labelled MSLN-specific binding constructs, pharmaceutical compositions comprising such constructs, and the use of such constructs or pharmaceutical compositions in methods for treating, imaging or diagnosing diseases, such as
cancer.