Fig. 3.

Heterocombinations of antibodies to EGFR and HER2 are endowed with enhanced antitumor activities. (A) BXPC3 xenografts were implanted and mice randomized into groups of eight animals, essentially as in the legend to Fig. 1. The indicated antibodies to HER2 (431 and 12) and the 565 antibody to EGFR, were injected into the peritoneum either singly (160 µg per mouse per injection, total: 480 µg per mouse) or in combinations (80 µg of each mAb per mouse per injection; total: 480 µg per mouse). Three injections were performed on days 7, 14, and 21, and the fractions of tumor-free mice were determined on day 84. (B–D) Mice bearing palpable BXPC3 tumors were randomized and each group of eight animals was injected with the indicated mAbs seven times, at 8 d intervals, into the peritoneum. Antibodies were used either singly (160 µg per mouse per injection, total: 1,120 µg per mouse) or in combinations (80 µg of each mAb per mouse per injection; total: 1,120 µg per mouse). Tumor volumes were monitored and their average ± SEM are presented, along with the P values comparing combined treatments with single mAb injections. The arrow in each panel marks the last injection of antibodies.