For instance, NSCLC patients with brain metastases showed longer overall survival with anti-PD-1 checkpoint blockade (Pembrolizumab) but only in patients where PD-L1+ stromal and immune cells were detectable (in at least 1% of cells); tumor specimens from responders also expressed higher levels of granzyme B and proinflammatory chemokines such as CXCL9 and 10 compared to non-responders [81]. Here, PDCD1 is linked to non-small cell lung carcinoma.