CD274 and AL amyloidosis: Previously, a constitutive oncogenic pathway has been reported to drive PD-L1 expression through signal transducer and activator of transcription 3 (STAT3) signaling in lymphoma cells.11 In addition, STAT3 signaling is known to be a downstream target of CKS1B activation in multiple myeloma cells.9 We hypothesized that CKS1B regulates PD-L1 expression by activating STAT3.