Alveolar Soft Part Sarcoma (ASPS) is a rare, but deadly cancer of soft tissue (such as muscle, nerves, or fat) that primarily strikes adolescents and young adults. ASPS is caused by a mutation in which two different chromosomes mispair and fuse to make a new cancer-causing gene. Because ASPS grows slowly and painlessly, patients often don’t notice anything until the tumor has already metastasized, leaving few treatment options and a high likelihood of mortality within 5 years. In order to advance treatments, we developed a mouse model of ASPS using the human version of the cancer gene to replicate its biology as closely as possible to humans. These mouse tumors develop in various tissues, but grow most rapidly in the central nervous system (both brain and retina). We realized that the tumors growing in the retina may provide a rare opportunity to directly visualize tumor growth and closely monitor tumor responses to treatment, using the sophisticated imaging tools of ophthalmology, available to us at our University’s Moran Eye Center. The ability to visually track blood vessel recruitment and immune cell behavior during ASPS tumor growth and treatment is an exciting possibility that will expand our understanding of mechanisms that ASPS uses to evade therapy. Using this approach, we will test a promising therapeutic that targets a biological process called SUMOylation, a feature in many cancers (including ASPS) that is associated with tumor aggression and treatment failure.