The survival of tumor-bearing SCID mice treated with anti-CD20 mAbs. Groups of 10 SCID mice were injected intravenously with 3.5 × 106 Daudi (A) or Daudi-R cells (B). Five days after tumor cell inoculation, the mice were treated with rituximab or triple variant at a dose of 100 μg. For F(ab′)2 fragment treatment groups, groups of 10 SCID mice were injected with 3.5 × 106 Daudi-R cells intravenously on day 0 and then treated with 100 μg F(ab′)2 fragments intravenously on day 7. Additional 100-μg injections of F(ab′)2 were given intraperitoneally on day 7, intravenously on day 8, and intraperitoneally on day 9, to a total of 400 μg. (C) Groups of 10 SCID mice were injected intravenously with 107 Daudi-R cells. Five days after tumor cell inoculation, the mice were treated with rituximab or triple variant at the dose of 100 μg. The SCID/Daudi-R mice were treated with pan caspase inhibitor (Q-VD(OMe)-Oph) at a dose of 200 μg/day intraperitoneally 5 days a week for 3 weeks. (D) Samples of the IgG and F(ab′)2 fragments of the rituximab and the triple variant used in panel B were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis under reducing conditions. Note the absence of contaminating heavy (H) chains in both F(ab′)2 preparations.
