Denosumab is Effective for Controlling Serum Calcium Levels in Patients with Humoral Hypercalcemia of Malignancy Syndrome: A Case Report on Parathyroid Hormone-related Protein-producing Cholangiocarcinoma.

Hypercalcemia resulting in the elevation of serum parathyroid hormone-related protein (PTHrP) and suppression of serum PTH was observed in a patient with advanced cholangiocarcinoma (CCC) and multiple lymph node metastases. We confirmed humoral hypercalcemia of malignancy based on PTHrP-producing CCC. Chemotherapy with gemcitabine and cisplatin could not control the patient's serum PTHrP levels and the patient was affected with bisphosphonate-refractory hypercalcemia. We administered a single dose of denosumab, an anti-receptor activator of nuclear factor-kappaB ligand monoclonal antibody, and the patient's serum calcium levels remained close to the normal range for approximately 3 weeks without additional treatment.