Portal branch ligation does not counteract the inhibiting effect of temsirolimus on extrahepatic colorectal metastatic growth

The mTor-inhibitor temsirolimus (TEM) has potent anti-tumor activities on extrahepatic colorectal metastases. Treatment of patients with advanced disease may require portal branch ligation (PBL). While PBL can induce intrahepatic tumor growth, the effect of PBL on extrahepatic metastases under TEM treatment is unknown. Therefore, we analyzed the effects of TEM treatment on extrahepatic metastases during PBL-associated liver regeneration. GFP-transfected CT26.WT colorectal cancer cells were implanted into the dorsal skinfold chamber of BALB/c-mice. Mice were randomized to four groups (n = 8). One was treated daily with TEM (1.5 mg/kg), PBS-treated animals served as controls. Another group underwent PBL of the left liver lobe and received daily TEM treatment. Animals with PBL and PBS treatment served as controls. Tumor vascularization and growth as well as tumor cell migration, proliferation and apoptosis were studied over 14 days. In non-PBL animals TEM treatment inhibited tumor cell proliferation as well as vascularization and growth of the extrahepatic metastases. PBL did not influence tumor cell engraftment, vascularization and metastatic growth. Of interest, TEM treatment significantly reduced tumor cell engraftment, neovascularization and metastatic groth also after PBL. PBL does not counteract the inhibiting effect of TEM on extrahepatic colorectal metastatic growth.