ADRB2 and cancer: In a non-randomized, non-blinded clinical trial, non-indicated administration of propranolol upon cancer diagnosis was found to reduce the chance of relapse for melanoma.320 In another study, metastatic melanoma participants using nonselective β-AR inhibitors, instead of selective β1-AR antagonists, had an extended overall survival period after receiving therapy targeted with IL-2 plus CTLA-4 and/or PD-1 checkpoint inhibitors.321 The β-AR antagonist deserves to be investigated further, enabling it to be used more precisely in specific TME.