Prednisone Recruiting Phase 1 Trials for Diffuse Large B-Cell Lymphoma Activated B-Cell Type / Diffuse Large B-Cell Lymphoma Germinal Center B-Cell Type / High Grade B-Cell Lymphoma With MYC and BCL2 and/or BCL6 Rearrangements / T-Cell/Histiocyte-Rich Large B-Cell Lymphoma / High Grade B-Cell Lymphoma, Not Otherwise Specified / Diffuse Large B-Cell Lymphoma, Not Otherwise Specified / Lymphoma, Large B-Cell, Diffuse (DLBCL) Treatment