For tumor cells in the bispecific antibody simulations, the effective RO follows the bell shaped curve typical described in PK/PD models of these antibodies18,22 (Fig. 4A), where, effective RO increases to a maximum at a level similar to the EC50 RO of CD38 as measured in the typical way, then starts to decline as typical RO increases to full occupancy. The gene discussed is CD38; the disease is neoplasm.