RecruitingPhase 2Drug trialAdding Dasatinib Or Venetoclax To Improve Responses In Children With Newly Diagnosed T-Cell Acute Lymphoblastic Leukemia (ALL) Or Lymphoma (T-LLY) Or Mixed Phenotype Acute Leukemia (MPAL)This is a clinical trial testing whether the addition of one of two chemotherapy agents, dasatinib or venetoclax, can improve outcomes for children and young adults with newly diagnosed T-cell acute lymphoblastic leukemia and lymphoma or mixed phenotype acute leukemia. Primary Objective * To evaluate if the end of induction MRD-negative rate is higher in patients with T-ALL treated with dasatinib compared to similar patients treated with 4-drug induction on AALL1231. * To evaluate if the end of induction MRD-negative rate is higher in patients with ETP or near-ETP ALL treated with venetoclax compared to similar patients treated with 4-drug induction on AALL1231. Secondary Objectives * To assess the event free and overall survival of patients treated with this therapy. * To compare grade 4 toxicities, event-free survival (EFS) and overall survival (OS) of patients treated with this therapy in induction and reinduction to toxicities of similar patients treated on TOT17.