FDPS and Hypercalcemia: It is worthy of note that treatment of cells with nitrogen-containing bisphosphonate (N-BP) drugs used for hypercalcemia of malignancy or osteoporosis, such as zoledronic acid, alendronate, ibandronate and pamidronate, inhibits farnesyl diphosphate synthase (FDPS), resulting in intracellular accumulation of IPP and DMAPP that stimulate γδ T cells.