The present invention relates to a composition for enhancing T-cell function or for treating a T-cell dysfunctional disorder, the composition comprising, consisting or consisting essentially of a lysine specific demethylase (LSD) inhibitor (which may be a MAO inhibitor or phenelzine) and a Programmed cell death protein- 1 (PD-1) binding antagonist (which may be an antibody, preferably nivolumab, pembrolizumab, lambrolizumab or pidilizumab).