Targeting the β2 -adrenergic receptor increases chemosensitivity in multiple myeloma by induction of apoptosis and modulating cancer cell metabolism

While multi-drug combinations and continuous treatment have become standard for multiple myeloma, the disease remains incurable. Repurposing drugs that are currently used for other indications could provide a novel approach to improve the therapeutic efficacy of standard multiple myeloma treatments. Here, we assessed the anti-tumor effects of cardiac drugs called β-blockers as a single agent and in combination with commonly used anti-myeloma therapies. Expression of the β ₂-adrenergic receptor correlated with poor survival outcomes in patients with multiple myeloma. Targeting the β ₂-adrenergic receptor (β ₂AR) using either selective or non-selective β-blockers reduced multiple myeloma cell viability, and induced apoptosis and autophagy. Blockade of the β ₂AR modulated cancer cell metabolism by reducing the mitochondrial respiration as well as the glycolytic activity. These effects were not observed by blockade of β ₁-adrenergic receptors. Combining β ₂AR blockade with the chemotherapy drug melphalan or the proteasome inhibitor bortezomib significantly increased apoptosis in multiple myeloma cells. These data identify the therapeutic potential of β ₂AR-blockers as a complementary or additive approach in multiple myeloma treatment and support the future clinical evaluation of non-selective β-blockers in a randomized controlled trial.