FCGRT and plasma cell myeloma: Additionally, higher linear clearance and lower predicted Ctrough of daratumumab at Cycle 3 Day 1 have been noted for RRMM patients with IgG versus non-IgG disease, likely due to competition for neonatal Fc receptor (FcRn) binding and protection from elimination between IgG M-protein secreted by myeloma cells and daratumumab; however, overall response rates with daratumumab were similar between IgG and non-IgG patients [26].