This study investigates the effectiveness of an investigational medication in treating children with a type of blood cancer called CD22 positive B acute lymphoblastic leukemia (B-ALL) that has either come back after treatment or does not respond to treatment. B-ALL is a cancer of the white blood cells, and CD22 is a protein found on the surface of some of these cancer cells. The study aims to see how well the investigational medication works in achieving a response, which means the cancer decreases or goes away, after one cycle of treatment.

Participants in the study will receive the investigational medication and will undergo various medical procedures to monitor their response to the treatment. These procedures may include blood tests and bone marrow samples to check the presence of cancer cells. The study will also track any side effects experienced by the participants.

• Who can participate: Children with relapsed or refractory CD22 positive B acute lymphoblastic leukemia can participate. They must have a certain level of cancer cells in their bone marrow and meet other specific medical criteria.
• Study details: Participants will receive an investigational medication and be monitored for their response. A placebo is not used.