Denosumab for the treatment of bisphosphonate-refractory hypercalcemia of malignancy (HCM).

e20512 Background: HCM, caused primarily by tumor-induced bone resorption, is treated with intravenous (IV) bisphosphonates (BisP), but patients (pts) can relapse or become refractory. Denosumab binds to RANK ligand (RANKL) to inhibit osteoclast-mediated bone resorption. Methods: In this single-arm, open-label, proof-of-concept study, pts with HCM (corrected serum calcium [CSC] >12.5 mg/dL [CTCAE grade ≥3]) despite IV BisP treatment ≥7 and ≤30 days before screening received subcutaneous denosumab 120 mg on days 1, 8, 15, and 28, then every 4 weeks. The primary endpoint was the proportion of pts with CSC ≤11.5 mg/dL (CTCAE grade ≤1) within 10 days of denosumab initiation. Results: The study enrolled33 pts (64% men; mean age 60 years; 76% with advanced solid tumors, 39% with bone metastases [BM]), with a median (25th, 75th percentile [Q1, Q3]) follow-up of 56 (18, 79) days. Median (Q1, Q3) baseline CSC was 13.7 (13.2, 14.2) mg/dL; 19 pts (58%) had HCM symptoms. Median (Q1, Q3) time from last BisP treatment ...