PDCD1 and extranodal nasal NK/T cell lymphoma: V-domain immunoglobulin suppressor of T cell activation (VISTA) has also been explored as a factor which predicted negative response to the usage of PD-1 inhibitors in NKTCL, and presents as a target for future therapeutics whereby VISTA blockade could be used as a tool for increasing sensitivity to anti-PD-1 options (117).