Safety and efficacy of bone-modifying agents among multiple myeloma patients: A retrospective cohort study

OBJECTIVE: To determine the incidence of skeletal-related events among multiple myeloma patients who received chemotherapy without a bone-modifying agent (zoledronic acid and denosumab) versus those who received chemotherapy with a bone-modifying agent. The secondary objective was to determine the incidence of skeletal-related events in patients without any prior history of skeletal-related events and who were treated with zoledronic acid every four weeks versus those who received zoledronic acid at an extended interval of every twelve weeks. Additional secondary objectives included the incidence of nephrotoxicity, hypocalcemia and osteonecrosis of the jaw in all patients. METHODS: This institutional review board-approved, retrospective cohort study included patients 18 to 89 years old with a diagnosis of multiple myeloma, who were being treated with chemotherapy between July 1, 2016 and October 31, 2019. Safety and efficacy were assessed through analysis of pertinent data collected: patient demographics, baseline skeletal-related events, development of new skeletal-related events, number and type of bone-modifying agent doses administered, and drug-related toxicities such as nephrotoxicity, hypocalcemia, and osteonecrosis of the jaw. RESULTS: A total of 73 patients were included. New skeletal-related events occurred in 12 patients (27%) in the chemotherapy without a bone-modifying agent group and in 5 patients (17%) in the chemotherapy with a bone-modifying agent group (OR = 0.56, 95% CI [0.172-1.8]; P = 0.32). The incidence of skeletal-related events was similar among patients receiving zoledronic acid every four weeks versus every twelve weeks in patients without a prior skeletal-related event (N = 0 vs. N = 2 respectively; P = 0.47). There were no statistically significant differences observed in each of the three secondary safety endpoints: incidence of hypocalcemia, nephrotoxicity and osteonecrosis of the jaw. CONCLUSION: Multiple myeloma patients receiving chemotherapy without a bone-modifying agent had higher rates of skeletal-related events compared to those being treated with chemotherapy and a bonemodifying agent. Our results highlight the benefit of utilizing bonemodifying agents for the prevention of skeletal-related events in all multiple myeloma patients being treated with chemotherapy.