Additional Study Information: The goal of this study is to determine at what dose the study treatment (ASP9801) is safe and tolerated in study participants with cancer who have tumors that cannot be removed (unresectable) or have spread (metastasized) to a different part of the body. This will be done by enrolling small groups of participants to receive different doses of the study treatment, starting with a very small dose and gradually increasing. The dose amount you receive will depend on the group you are assigned to. When the safe dose is identified, it will be used to evaluate if the treatment causes tumors to shrink in participants. During this period, participants will be continuously assessed to determine if ASP9801 is safe and tolerated by participants taking it. ASP9801 will be given by an injection directly into the tumor. Cancers include: Bladder cancer, colon cancer, rectal cancer, cervical cancer, skin cancer, melanoma, prostate cancer, stomach cancer, and testicular cancer.