This research study is testing the best dose of an investigational medication called CART-19 cells for people with certain medical conditions. CART-19 cells are a type of treatment made from a person's own cells, which are changed to help fight disease. This study is in two parts. In the second part, they will use a specific dose level to treat more people and make sure it is safe and works well. Everyone in the study will get treatment over three days, with a different amount each day. They will need to be checked for at least three months after the first treatment.
- Length: At least 3 months of follow-up.
- Visits: Several visits for treatment and follow-up.
- Eligibility: Must have received and responded to the first treatment, and then had a return of symptoms.
Participants will be given the investigational medication through a process called split dosing, where the treatment is given in parts over a few days. If you are considering participating, remember that this study involves multiple visits and follow-up checks.