Endocrine Abstracts

Denosumab is a MAB currently licensed for use in treatment of osteoporosis. It is designed to inhibit RANK ligand to prevent bone breakdown by osteoclasts. Its use for treatment of malignant hypercalcaemia is still to be fully investigated.

We present the case of a 71-year-old south Asian gentleman with recurrent resistant hypercalcaemia secondary to follicular non-Hodgkin’s lymphoma. Calcitriol levels were elevated which was thought to be lymphoma related. Despite numerous administrations of bisphosphonates including pamidronate and monthly zolendronate, the patient’s calcium levels remained elevated around 3.11 mmol/l even reaching 4.6 mmol/l.

Owing to significant elevation of calcium and resistance to conventional methods (including dexamethasone), denosumab 60 mg s.c. was administered as a means of controlling the hypercalcaemia. The patient’s calcium remained elevated on discharge and up to 1 month later. Approximately 1 month following administration the patient’s calcium levels were recorded within the normal range (2.13 mmol/l) however it began to decrease further over the course of the next few weeks and the patient became significantly hypocalcaemic (1.58 mmol/l) requiring calcium supplementation.

There is currently limited literature on the use of denosumab in managing hypercalcaemia in malignancy and it is only licensed for preventing skeletal related events in bone metastases from solid tumours and myeloma. There is no literature on its use in lymphoma. This case highlights the difficulties in managing malignant hypercalcaemia and offers an effective new therapeutic option in the form of denosumab. It also highlights the importance of regular follow up to monitor calcium levels as there is the possibility of a delayed effect of denosumab in treating hypercalcaemia.

This is the first documented case of denosumab use in hypercalcaemia secondary to lymphoma. It also provides evidence of delayed hypocalcaemia as a side effect of denosumab therapy up to 1 month following administration.