isotype control antibody known not to bind mb 231 cells was administered intraperitoneally at a volume of 300 microliters after dilution from the stock concentration with a diluent that contained 2 7 mm kcl 1 mm kh 2 po 4 137 mm nacl and 20 mm na 2 hpo 4 the antibodies were then administered once per week for a period of 7 weeks in the same fashion tumor growth was measured about every seventh day with calipers for up to 8 weeks or until individual animals reached the canadian council for animal care ccac end points body weights of the animals were recorded for the duration of the study at the end of the study all animals were euthanised according to ccac guidelines ar36a36 11 1 completely prevented tumor growth and reduced tumor burden in a preventative in vivo model of human breast cancer on day 56 post implantation 6 days after the last treatment dose the mean tumor volume in the ar36a36 11 1 treated group was 0 percent of the tumor volume in the isotype control treated group p 0 0002 t test fig5 there were no clinical signs of toxicity throughout the study body weight measured at weekly intervals was a surrogate for well being and failure to thrive.