This clinical trial is focused on studying a type of blood cancer called Acute Lymphoblastic Leukemia (ALL), specifically in children who have experienced a high-risk first relapse. The study is comparing a new treatment using a medication called Inotuzumab Ozogamicin with a standard treatment known as ALLR3. The purpose of the study is to determine if Inotuzumab Ozogamicin is more effective than the standard treatment in helping children with this type of leukemia.

Participants in the study will receive either Inotuzumab Ozogamicin or the standard treatment. Inotuzumab Ozogamicin is given as an infusion, which means it is administered directly into the bloodstream through a vein. The study will last for a period of up to 28 days, during which the effects of the treatment will be closely monitored. Other medications that may be used in the study include Dexamethasone, Pegaspargase, Vincristine Sulfate, and Mitoxantrone Hydrochloride, which are commonly used in treating leukemia.

The study aims to see if the new treatment can help achieve a state where no cancer cells are detectable in the blood, known as minimal residual disease-negative status. This is an important goal in treating leukemia, as it indicates a better response to treatment. The study will also look at other outcomes, such as the time it takes for the disease to progress, the duration of response to treatment, and overall survival rates. Participants will be monitored for any side effects or adverse events during the study period.