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 an investigational cellular therapy called Afamitresgene Autoleucel. The overall goal of this study is to find out how safe and effective this cellular therapy is in treating people that have been diagnosed with synovial sarcoma, malignant peripheral nerve sheath tumors (MPNST), neuroblastoma or osteosarcoma that has grown or returned after being treated.

This study involves taking a study drug called ALRN-6924. ALRN-6924 is an investigational cancer treatment that activates p53, which suppresses the growth of tumors by blocking proteins in the cell called MDM2 and MDMX that inhibit p53 from doing its job. The overall goals of this study are to evaluate the side effects and benefits of ALRN-6924 in patients with relapsed or treatment refractory solid tumor or brain tumor, and to determine the best dose of ALRN-6924 for children and adolescents. This study will also look at how the body breaks down ALRN-6924 by measuring the amount of ALRN-6924 in the blood over time after a dose.

This study enrolls patients between 5 and 40 years of age with a diagnosis of any sarcoma that has progressed on or relapsed after upfront initial therapy. The purpose of this study is to find the best dose of a drug called cabozantinib ("the study drug") to give to patients in combination with a routine chemotherapy drug called ifosfamide.

This study aims to explore a new type of magnetic resonance imaging (MRI) called Chemical Exchange Saturation Transfer (CEST) in children aged 6-18 years with brain tumors. An MRI is a machine that takes detailed pictures of the brain. The CEST MRI used in this study is still being tested and has not been approved by the FDA yet. The study wants to find out if this new type of MRI can help doctors evaluate brain tumors. CEST MRI creates images using water molecules and protons in the brain. Early research shows that CEST could be helpful in understanding brain tumor changes.

This study will enroll 5 participants.

The purpose of this research study is to determine if certain markers in your blood are increased over the duration of your chemotherapy, especially as you get sicker, such as developing a severe infection (sepsis) or severe respiratory failure (acute respiratory distress syndrome).

This study involves taking a study drug called INBRX-109. The overall goal of the study is to find out how safe and effective the study drug is in treating people that have been diagnosed with advanced or metastatic Ewing sarcoma or SDH-deficient solid tumor/Gastrointestinal Stromal Tumor (GIST).

This study enrolls patients with newly diagnosed differentiated thyroid cancer (papillary thyroid cancer or follicular thyroid cancer) that has spread to the lungs and has a genetic mutation called and NTRK fusion. The study involves taking a study drug called larotrectinib for approximately 6 months prior to receiving radioiodine therapy (RAI). The overall goal of this study is to find out if taking the study drug before RAI works better than receiving RAI alone (the usual standard of care treatment).

This study involves taking a study drug called lurbinectedin. The overall goal of this study is to see if different doses of lurbinectedin are safe and effective at treating children and young adults with recurrent or relapsed solid tumors, including Ewing Sarcoma.

This is a clinical trial for patients with neuroblastoma that has returned (relapsed) or has not responded to standard treatment. The patients will have a biopsy of their tumor that will be tested for genetic changes and then matched to available drugs. If the results from the testing show molecular features in the tumor that allow for study treatment, patients will be invited for further testing to see if they are eligible for new treatments. Experimental therapies are all taken orally and may consist of one drug or a combination of drugs