CD38-specific hcAbs prolong the survival of mice bearing CD38-expressing CA46 tumors. Kaplan-Meier plot of overall survival of SCID mice intravenously injected with CA46-luc cells. SCID mice (n = 7/group) received weekly i.p. treatments (2 mg/kg, arrows) with CD38-specific heavy chain antibodies WF211-hcAb, MU1067-hcAb, JK36-hcAb, isotype control (l-15-hcAb), or daratumumab as described in Fig. 5. Overall survival of mice treated with hcAbs or daratumumab was significantly longer as compared to mice receiving isotype control treatment (p≤0.0001 and p=0.002, respectively). Overall survival of mice treated with the CD38-specific hcAbs was longer than that of mice receiving daratumumab treatment. This difference was significant for JK36-hcAb (p=0.003) and WF211-hcAb (p=0.031), but not for MU1067-hcAb (p=0.110). Log rank test was used for statistical analysis. Epitope specificities of CD38-specific antibodies are indicated in parentheses. Results are representative of three independent experiments.