CD274 and plasma cell myeloma: Lenalidomide is an immunomodulatory drug with direct anti-tumour activity via binding to cereblon (CRBN) to inhibit downstream NF-kB signaling, and also indirect effects in the tumour microenvironment through multifaceted functions on different immune cells [237], including downregulation of PD-L1 on the surface of lymphoma and myeloma cells [238,239].