A novel combination of bortezomib, lenalidomide, and clarithromycin produced stringent complete response in refractory multiple myeloma complicated with diabetes mellitus – clinical significance and possible mechanisms: a case report

BACKGROUND: In general, dexamethasone is a required component drug in various combination chemotherapies for treating multiple myeloma, and its efficacy has been widely recognized. However, administration of dexamethasone is known to cause various adverse effects including hyperglycemia which requires insulin therapy. During the course of treatment, we developed a novel effective dexamethasone-free combination regimen and evaluated it for its effect in multiple myeloma. CASE PRESENTATION: We report a case of 68-year-old Japanese woman with refractory advanced Bence-Jones-λ type multiple myeloma associated with diabetes mellitus. Various combination regimens were carried out, but the response to some regimens was insufficient or others containing dexamethasone, although effective, were inappropriate to continue due to aggravation of diabetes mellitus. Thus, we developed a dexamethasone-free, short dosing-period regimen consisting of bortezomib, lenalidomide, and clarithromycin. This regimen was found to be highly effective and succeeded in achieving stringent complete response. CONCLUSIONS: The successful dexamethasone-free regimen clearly shows that dexamethasone is not a requisite component in treating multiple myeloma, and it can be substituted with clarithromycin. This regimen is particularly useful for treating patients with multiple myeloma associated with diabetes mellitus.