PDCD1LG2 and non-Hodgkin lymphoma: Second, HL is characterized by the genetic alterations in 9p24.1 that result in copy gain and overexpression of PD-L1 and PD-L2, with an increase in copy gain or amplification of 9p24.1 in more than 97% of newly diagnosed HL biopsy specimens.392,393 Third, infection with Epstein-Barr virus (EBV) is common in HL patients and also causes PD-L1 to be overexpressed, which is one of the key mechanisms by which the virus could persist in the host.394 In contrast, NHL does not display a high frequency of 9p24.1 alterations, thus the efficacy of ICI decreased for NHL patients.395