The ratio of brain to liver glucose activity and disease activity in multiple myeloma

Changes in metabolic activity in tumor cells is one of the hallmarks of cancer. Cancer cells exhibit the Warburg effect with high glucose consumption for their energy needs. This provides the basis for imaging using ¹⁸F-2-deoxy-D-glucose for positron emission tomography to assess tumor burden and response to therapy. We postulated that metabolically active tumors may compete with the brain for glucose uptake and evaluated glucose uptake in the brain and liver in patients with multiple myeloma in various states of response and relapse. The ratio of brain to liver glucose activity (B2LR) mirrors disease activity in myeloma, predicts the presence of extramedullary disease and is also predictive of a short response to chimeric antigen receptor T cell therapy. Patients with a low B2LR also have an inferior survival compared to patients with persistently higher B2LR values. Our simple metabolic ratio has prognostic implications in myeloma and other tumors.