Fig. 5

Effect of refametinib and pictilisib combined treatment after tumor progression due to lapatinib plus trastuzumab therapy in HER2-amplified colon cancer xenograft models. a-b SW48-HER2 and LIM1215-HER2 were injected into right flank of nude mice. After 2 weeks from subcutaneous injection, mice were divided in four groups and treated for 26 weeks. Group 1: ctrl. Group 2: lapatinib (30 mg/kg every day, o.g.) and trastuzumab (10 mg/kg twice a week, i.p.) were administrated in combination. Group 3: refametinib (25 mg/kg every day, o.g.) and pictilisib (75 mg/Kg every day, o.g.) were administrated in combination. Group 4: mice were treated with combination of lapatinib (30 mg/kg every day, o.g.) and trastuzumab (10 mg/kg twice a week, i.p.) until progression (defined as > 30% increment of tumor volume from baseline). After tumor progression of group 4, mice were treated in second-line with combination of refametinib and pictilisib. c Tumor samples were collected and total protein extracts were subjected to immunoblotting with all antibodies, as described in materials and methods section. Anti-tubulin antibody was used for normalization of protein extract content