Cinacalcet for the Treatment of Humoral Hypercalcemia of Malignancy: An Introductory Case Report with a Pathophysiologic and Therapeutic Review

: Hypercalcemia is an ominous development in the course of malignancy associated with a mean survival of only several months. A majority of cases of hypercalcemia are related to humoral hypercalcemia of malignancy (HHM), where hypercalcemia is caused by increased levels of circulating parathyroid hormone-related protein (PTHrP). Mainstay treatments in the management of HHM are intravenous fluids, intravenous bisphosphonates, and subcutaneous denosumab, although hypercalcemia oftentimes recurs despite these efforts. We present a case of advanced non-small cell lung cancer with PTHrP-mediated hypercalcemia that proved resistant to standard therapy. A trial of oral cinacalcet was initiated and improved calcium levels for 2 months despite a progressive rise in PTHrP and prior to subsequent disease progression. Based on the current body of literature, we propose that this calcium-lowering effect of cinacalcet occurs due to a potential effect on renal calcium excretion.