APG-115 Alone or in Combination With APG-2575 in Children With Recurrent or Refractory Neuroblastoma or Solid Tumors

This study tests APG-115 — a drug that reactivates the body's natural cancer-fighting protein (p53) — alone or combined with APG-2575 (a drug that blocks cancer cell survival signals) in children with neuroblastoma or other solid tumors that have returned or stopped responding to treatment. **You may be eligible if...** - Your child has relapsed or treatment-resistant neuroblastoma or another solid tumor - Your child has measurable or trackable areas of disease - Your child has adequate organ function - Your child has a performance score of 50 or higher (Lansky scale) - Expected survival is at least 3 months - Tumor tissue samples are available or can be obtained **You may NOT be eligible if...** - Your child has uncontrolled infection or severe organ failure - Your child is pregnant or breastfeeding, or a fertile female/male not willing to use contraception - Your child has received certain other investigational treatments recently Talk to your doctor to see if this trial is right for you.