Over the past ten years, scientists have discovered how to use immune cells from cancer patients to fight their disease. Despite this progress, many children with cancer still do not respond to these treatments. This problem is especially relevant for children with solid cancers. The overall goal of this proposal is to address this gap in knowledge and make a new cancer treatment that can cure more childhood cancers, particularly solid cancers. In terms of cancer treatments, solid cancers have two main problems. First, solid cancers are big and hard for some therapies to break up. Second, the most successful new therapies using patient cells have to be made for each patient individually. Although this approach is safe, making new therapies for each new patient is expensive and takes a lot of time — time that children with aggressive solid cancers may not have. Building off of past successes, our team will use two types of anti-cancer treatments at the same time to overcome these problems. We will first do this work in animal models in order to learn both if our new double treatment is able to cure cancer and if it is safe in these lab animals. If our double treatment is successful in these animal studies, then we should be able to give it to children with cancer in the near future, offering hope to pediatric patients in need of new therapies for their solid tumors.