However, the use of anti-PD-1 mAbs in SS is still debated since, secondary T-cell neoplasia in patients undergoing PD-1 blockade for their primary tumor, (9–11), as well as rapid disease progression in patients with T-cell leukemia/lymphoma treated with anti-PD-1 mAbs have also been documented (23–25). Here, PDCD1 is linked to synovial sarcoma.