A Phase 1-1b Study to Evaluate the Safety, Efficacy and Dosimetry of Study Drug A9-3408 in Subjects With Metastatic Melanoma

This Phase 1 study is testing the safety, dosing, and early effectiveness of a new radioactive therapy called A9-3408 in people with advanced or metastatic melanoma (skin cancer that has spread) whose cancer has progressed after standard treatments. **You may be eligible if...** - You have been diagnosed with unresectable or metastatic melanoma confirmed by biopsy - Your cancer progressed after prior standard-of-care therapy - A specific PET scan shows uptake of a companion imaging agent in at least one measurable tumor - Your overall health and organ function are adequate - If you can become pregnant or are sexually active with someone who can become pregnant, you must use appropriate birth control **You may NOT be eligible if...** - You have not recovered from side effects of prior treatments - Your organ function does not meet the study's baseline requirements - You are pregnant Talk to your doctor to see if this trial is right for you.