PD-1 in cancer: Dr. Jekyll and Mr. Hyde

T cell non-Hodgkin lymphomas (NHL) represent about 6% of non-cutaneous lymphomas and 65% of cutaneous lymphomas (1). Recent insights into the genetic landscape of nodal T cell NHL have led to an update in their classification (2). Despite this advance, peripheral T cell lymphomas (PTCL) still show morphologic, phenotypic, genetic and prognostic heterogeneity. Combinations of deep sequencing and transcriptomic analyses have identified mutations of epigenetic regulators, tumor suppressor genes and, interestingly, gain of function mutations of the T cell receptor (TCR) pathway (3,4)