New effective therapies are greatly needed for metastatic uveal melanoma, the most common ocular malignancy, which has a very poor prognosis with a median survival of <1 year. The melanocortin 1 receptor (MC1R) is expressed in 94% of uveal melanoma. MC1R is not expressed in normal tissues of concern for toxicity. We have previously reported a MC1R specific ligand (MC1RL) with high affinity and selectivity for MC1R. Ac-225 is a therapeutic radionuclide that emits 4 alpha particles in the decay chain. The aim of this study is to use MC1RL as a targeting scaffold for development of a radiopharmaceutical by conjugation of Ac-225 chelate.