CD274 and thymoma: A lack of a difference in survival between PD-L1 positive and negative TETs has also been described by Katsuya et al. [63] Considering the correlation of PD-L1 expression by tumor cells with the likelihood of response to anti-PD-1/PD-L1 therapy [64], immune checkpoint inhibitors might be a novel treatment option for unresectable or relapsed thymomas and thymic carcinomas.