The purpose of this study is to test an experimental approach called cell therapy for neuroblastoma or retinoblastoma. This study will take a patient's own white blood cells (T cells) and change them to turn against the cancer. These cells are an experimental treatment and have not been approved by the FDA. CAR T cells have been used to treat other cancers, but GPC2 CAR T cells have not been administered to human patients prior to this clinical trial.

If they choose to participate in this study, active participation will last approximately 12 months. Participants will also be asked to sign consent to a separate long term follow-up protocol to monitor their health for up to 15 years after their last GPC2 CAR T treatment.

This study will assess the safety and effectiveness of GPC2 CAR T cells. Overall, approximately 45 subjects will be enrolled on this study.

This study involves taking a study drug called CUDC-907. CUDC-907 is an oral drug that blocks certain proteins in tumor cells; these proteins may be important in the growth of some cancers. The overall goals of this study are to evaluate the side effects and benefits of CUDC-907 in patients with relapsed or treatment refractory solid tumor, brain tumor, or lymphoma, and to determine the best dose of CUDC-907 for children and adolescents. This study will also look at the levels of CUDC-907 in the blood over time after a dose.