In vivo antitumor activity of CD20-Flex BiFP. (A) Groups of SCID mice were subcutaneously inoculated with 5×106 Daudi. When the tumors reached 8 to 10 mm in diameter, 10 mg/kg rituximab, Flex-Ig, CD20-Flex BiFP, or PBS was intravenously injected once weekly for 4 doses. Tumor size was measured 2-dimensionally with a caliper. (B-D) BALB/c mice were inoculated with A20-CD20 cells and then treated with rituximab, Flex-Ig, CD20-Flex BiFP, or rituximab combined with Flex-Ig (n = 25) (B). The antibody-treated tumor-free mice were then rechallenged with A20-CD20 (C) or A20 cells (D) subcutaneously in the opposite flank on day 42 (solid symbols). Naive mice were inoculated with A20-CD20 cells (middle) or A20 cells (right) as the control. The primary tumor material is examined through measurement of tumor size and IHC analysis. The graphs are representative of at least 5 experiments, each of which showed similar results.
