PDCD1 and neoplasm: However, interestingly, when we divided the patients into two groups according to the positivity of tumour cell surface PD-L1 (Fig. 3a), the results showed that the levels of circulating PD-1/CD80+ sEVs positively correlated with those of PD-L1+ sEVs in patients with PD-L1-positive tumour cells (Fig. 3b).