Study to Investigate the Efficacy and Safety of RP1 in Adult Patients With Organ Transplants and Advanced Skin Malignancies

The purpose of this study is to assess the safety and efficacy of RP1 (administered into the tumor) in 90 patients who have received an organ transplant in the past and currently have skin cancer. The skin cancer is either locally advanced (large tumors in the skin, muscles or nerves) or metastatic (spread to other parts of the body). This study will consist of a 28-day Screening Period, a Treatment Period, and a Follow-up Period. During the Treatment Period, patients will be dosed with RP1 every two weeks for up to 2 years (104 weeks). Tumor measurements will be done approximately every 8 weeks (and additionally if needed) until progressive disease, start of subsequent anticancer therapy, or completion/discontinuation of the study. During the Follow-up Period, patients will visit the clinic at 30, 60, and 100-150 days after their last dose of RP1 for safety and quality of life assessments. Patients will continue follow-up for up to 3 years from the day of the last patient's first dose.