PD-L1 Copy Number Variation Does Not Correlate With PD-L1 Expression or Response to Anti-PD-1 Immunotherapy In Patients With Advanced Melanomas.

Predicting the response to PD-1/PD-L1 immune checkpoint blockade in patients with metastatic melanoma remains challenging. In this study, we have investigated for the relationships between PD-L1 expression, PD-L1 copy number variations, and the response to anti-PD-1 therapies. We studied the formalin-fixed paraffin-embedded tumor samples of 36 patients with metastatic melanoma using PD-L1 immunohistochemistry (IHC) and PD-L1/chromosome 9 fluorescent in situ hybridization (FISH).