FANCB and neoplasm: In contrast, Fab-IH18-PEG showed increased circulation time compared with Fab-IH18 (the concentration 24 h p.i. was 2.03 ± 0.30%ID/g), causing the TBR to remain lower than for the other two constructs (8.22 ± 1.32, p = 0.0005 and p < 0.0001 compared to mIgG1 after 72 h and Fab after 24 h, respectively), while tumor accumulation for Fab-IH18-PEG after 24 h was significantly higher than Fab-IH18 (16.55 ± 2.80%ID/g, p < 0.0001).