For example, the PD-L1 assay developed as a biomarker for pembrolizumab studies uses an antibody against the 22C3 region of PD-L1 and a ‘proportional score’ of ≥1 % (melanoma) for PD-L1-positive disease, which has been observed in 80 % of melanoma tumors [32, 36]. The gene discussed is CD274; the disease is melanoma.