A 68-year-old man comes to his physician with a 2-month history of progressive back pain, fatigue, anorexia, and weight loss. He has a past medical history of hypertension, diabetes mellitus, and hyperlipidemia. He appears pale. His temperature is 37.3^oC (99.1^oF), pulse is 78/min, respirations are 12/min, and blood pressure is 128/78 mm Hg. Initial laboratory results reveal a hemoglobin level of 7.2 g/dL (13.5-17.5), creatinine of 1.5 mg/dL (0.6-1.2), calcium of 11.6 mg/dL (8.4-10.2), and beta2-microglobulin of 4.3 mg/L (0.70-1.80). Fluorescence in situ hybridization (FISH) shows a 17p deletion. X-rays show multiple lytic bone lesions. Which of the following is the most appropriate next step in his management?