CONTRADICTING EVIDENCE: Our immunohistochemical analysis of one of the patients (case #2) showed a high level of PD-L1 expression (up to 70%), and that patient received pembrolizumab as second-line therapy. However, the patient showed disease progression after only 2 cycles of treatment, suggesting a lack of efficacy.

Herein, we describe treatment for a thymic carcinoma with high expression of PD-L1....After 3 cycles of pembrolizumab treatment, the size of the anterior mediastinal tumor and metastatic lesions of the right pleura notably decreased, indicating a partial response...pembrolizumab therapy has been ongoing for 8 cycles, and no serious adverse event or tumor progression has been observed.