SPDL1 and melanoma: Soluble PD-L1 can be produced by transcribed PD-L1 splice variants, of which four variants have been identified in melanoma.8 9 Metalloproteases ADAM10 and ADAM17 can also cleave the PD-L1 ectodomain from tumour cells and extracellular vesicles (EVs) to form soluble programmed death ligand 1 (sPD-L1).10 Lastly, tumour cells release extracellular vesicles expressing programmed death ligand 1 (evPD-L1).11