Hypocalcaemia in patients with metastatic bone disease (MBD) receiving denosumab (#195)
Aims: Hypocalcaemia is a known risk with antiresorptive therapy for skeletal complications of malignancy. Results from a combined analysis of hypocalcaemic events from three phase 3 trials of denosumab and zoledronic acid (ZA) in patients with MBD and data from post-marketing adverse event reports (AER) are presented.
Methods: Patients with solid tumours or multiple myeloma were randomised to denosumab 120mg SC Q4W or ZA 4mg IV (adjusted for renal function) Q4W. Daily calcium (≥500mg) and vitamin D (≥400IU) were recommended. Albumin-corrected serum calcium was measured Q4W by central lab. Hypocalcaemic events were collected as decreases in serum calcium and investigator-reported AEs. Post-marketing AER of hypocalcaemia included in the Amgen Global Safety database (AGS) were reviewed.
Results: 2841 and 2836 patients received denosumab and ZA, respectively. Median calcium levels for both treatment groups were similar over time. Among denosumab patients, hypocalcaemia was most common within 6 months of starting treatment, and more common in patients not taking calcium and vitamin D (15.8%) vs those who did (8.7%). Grade 3/4 (<1.75mmol/L) decreases in serum calcium were reported in 3.1% and 1.3% of denosumab and ZA patients, respectively. No fatal hypocalcaemia cases were reported in the trials. From May–Nov 2012, 37 cases of severe symptomatic hypocalcaemia were reported and recorded in the AGS; fatal outcomes were reported for 3 other patients with advanced cancers and various comorbidities.
Conclusions: Hypocalcaemia is a risk associated with antiresorptive therapy when treating bone metastases and myeloma. It occurred less often in patients taking calcium and vitamin D. Serum calcium and vitamin D levels should be checked and hypocalcaemia corrected prior to starting denosumab. Calcium levels should be monitored and calcium and vitamin D taken while receiving denosumab.
Body JJ et al. Hypocalcaemia in patients with metastatic bone disease receiving denosumab. J Clin Oncol 31,2013(suppl;abstr 9628). Reused with permission.©2012 American Society of Clinical Oncology. All rights reserved.