Arseniy was diagnosed with leukemia in December 2022. The boy received an accurate diagnosis of B-lymphoblastic leukemia by April 2023. The child began treatment in accordance with the protocol and experienced morphological remission in June 2023. The boy's treatment protocol was altered in October, and in November 2023, he was able to achieve molecular genetic remission. Arseniy was on maintenance therapy starting on 27.12.2023. Doctors recommended that the child needs to continue taking dasatinib intermittently at 50 mg / 100 mg per day. Due to the absence of a medicine, but it is necessary to take the medicine in conjunction with the underlying disease, Arseniy was supported through the «Medicines and medical equipment» program.