PDCD1LG2 and lung adenocarcinoma: Shinchi et al. observed longer progression-free survival (PFS) in lung adenocarcinoma patients with positive PD-L2 expression (Shinchi et al. 2019), while another retrospective study reported that the high expression of PD-L2 on tumor cells was associated with a poor prognosis for patients (Takamori et al. 2019).