IGF1 and breast cancer: However, pegvisomant administered (intra-peritoneal (IP)) in Nude mouse model of colorectal cancer over 30-days at 60 mg/kg lowered IGF1 by 57 to 64% (65), while a 14-days treatment (IP) at 250 mg/kg reduced IGF1 in Nude mouse model of breast cancer by 70 to 80% (66).