Moreover, Trichostatin A (an HDAC inhibitor) inhibits apoptosis of CD4+ T cells in the melanoma TME by suppressing NFAT1-regulated FasL expression, and therefore its combination with anti-CTLA4 could enhance the infiltration of CD4+ T cells and promote anti-tumor effects of anti-CTLA4 123. The gene discussed is HDAC9; the disease is neoplasm.