CD274 and melanoma: In agreement with correlative data reported for other solid tumours, the latter studies in melanoma showed that tracking changes in circulating levels of EXO‐PD‐L1 was associated with disease activity and progression (Ricklefs et al., 2018; Theodoraki et al., 2018) and predicted response to immune therapy (Chen et al., 2018; Cordonnier et al., 2020).