The aim of this project is to apply radiotherapy using antibodies labelled with radionuclides, so called radioimmunotherapy (RIT), to realize molecularly specific delivery of cytotoxic radiotherapy to disseminated disease sites in prostate cancer and AR-positive breast cancer. In previous work, we have successfully pioneered technology that enables targeting antigens secreted by luminal tissues, opening a new class of cancer tissue-specific targets including widely used circulating biomarkers. The antibodies are labelled with 89Zr for PET imaging, 111In for SPECT and 177Lu for therapy. Nanoparticle conjugated antibodies will enable simultaneous imaging with MRI,PET,SPECT, US and optical imaging. In this project, the described infrastructure will be used for precise external therapy of prostate and prostate cancers in small animals in order to facilitate the interpretation of the RIT results, enable a better understanding of the biological mechanism and lay the ground for optimized therapy that can be translated into the clinic. Our project has direct and broad translational impact for management of advanced PCa. Radiolabelled antibody as 177Lu-hu11B6 targets and accumulates specifically at the prostate (ie. remnant post-resected tissue) and disseminated PCa tissue. Clinical-grade good manufacturing practice (cGMP) DOTA-conjugated humanized 11B6 has entered production , and radiolabelled hu11B6 could motivate a major shift to treat advanced PCa in patients. A clinical phase-1 trial of hu11B6 in prostate cancer patients for imaging with PET is currently planned for early 2017. Based on the localization and biokinetic properties then dosimetry calculations will form the basis for future clinical therapy studies.