Classical Hodgkin's lymphoma in children is very sensitive to treatment with PD-1 inhibitors. The cause is a genetic change in the 9p24.1 region, which leads to excessive production of PD-L1 and PD-L2 proteins on tumor cells. PD-1 inhibitors block this pathway, allowing the immune system to better recognize and destroy tumor cells. In children with relapsed or difficult-to-treat (refractory) Hodgkin's lymphoma, significant effectiveness of this treatment was observed. Based on these results, the use of PD-1 blockade is also being considered as a first-line treatment. The goal of using PD-1 inhibitors in the first line is to achieve a cure with less long-term burden and damage caused by classical chemotherapy and radiation.