CTLA4 and brain glioma: To improve the BBB permeability of cytotoxic T-lymphocyte associated antigen 4 (a-CTLA-4) and programmed cell death-1 (a-PD-1) for immunotherapy of brain glioma, Ljubimova and co-workers described a nanoscale immunoconjugate system.360 The immunoconjugate was obtained by covalently attaching antibodies (a-CTLA-4 IgG2b, or a-PD-1 IgG) to poly(β-L-malic acid) polymers, with pre-conjugation of anti-mouse transferrin receptor antibody, and trileucine.