CD38 and neoplasm: From the affinity measurement, RP02 bound to the purified CD38 with an apparent KD value of 8.6 × 10−9m and displayed a biphasic dissociation kinetics, much weaker than the KD value of the known scFv antibody 028 (0.65 × 10−9m) (Figure 2a,c), yet both showed similar efficacy in terms of tumor cell lysis (Figure 5a).