An acid test for metformin.

Lactic acid export from highly glycolytic cancer cells is critical to maintain cellular homeostasis. The identification of syrosingopine as an inhibitor of the lactate transporters monocarboxylate transporter (MCT) 1 and the tumor-induced isoform MCT4 suggests a potential therapeutic intervention. In a recent issue of this journal, Van der Vreken, Oudaert I and colleagues showed that syrosingopine, together with another drug metformin, had a synergistic effect in killing cultured multiple myeloma (MM) cell lines, primary MM blasts from patients, and in a mouse MM model. The antidiabetic drug metformin is currently also being investigated for anticancer efficacy. The synthetic lethality of these two drugs, which have good safety records and are approved for noncancer indications, raises the possibility of their combination for clinical anticancer therapy. © 2023 The Author. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.