Table 1.

Comparison of CD20 mAb construction, binding characteristics, and ability to activate complement

ConstructionCD20-binding efficiency (kD)FcγR affinity (kD)Complement activation
RituximabChimeric (murine Fab) WT human IgG1Fc+ (5–8) Faster off rate t1/2 = 0.7 h+ (660)+
OfatumumabFully human WT IgG1 Fc++ (3–6) Slow off rate t1/2 = 4 h+ (NA)++
ObinutuzumabHumanized Fab Defucosylated IgG1 Fc+ (4)++ (55)±
OcaratuzumabMutant humanized Fab Mutant human IgG1Fc++ (0.097) Slow off rate++ (NA)±
  • Abbreviations: Fab, variable region; Fc, fragment crystallizable; FcR, Kd data for FcRIII; Kd, dissociation constant in nmol/L; NA, not available; t1/2, half-life; WT, wild-type.