This new drug, called peptide alarm therapy (PAT), is injected directly into a tumor to stimulate immune cells to attack the tumor. This drug stimulates immune responses that people already have because of exposure to viral infections and/or vaccines. We found that, in mice, injection of this drug in combination with a PD-L1 inhibitor, a drug already approved by the FDA, eliminates tumors. This new drug can be used for different types of solid tumors and is expected to have few side effects. This is a first clinical trial of this new type of drug to determine if it is safe. This new type of drug may be effective against many different tumor types in adult or pediatric patients.