The anti-proliferative side effects of AEE788, a tyrosine kinase inhibitor blocking both EGF- and VEGF-receptor, are liver-size-dependent after partial hepatectomy in rats.

BACKGROUND: Blocking of EGFR signaling by the tyrosine kinase inhibitor AEE788 was well tolerated and did not inhibit liver regeneration after standard 70% partial hepatectomy (PH) in a rat model, as demonstrated previously. However, serum levels of AEE788 at POW1 were 3-fold higher than in the non-resected control group. Therefore, we expanded theses studies to a model of extended 90%PH to investigate the role of liver size for the metabolism of AEE788 and its potential influence on side effects, liver regeneration and liver remodeling.

METHOD: Rats treated with 50 mg/kg AEE788 or solvent every other day orally were subjected to 90%PH. Animals were sacrificed at 1, 2, 7 and 28 days after PH. We measured plasma and liver levels of AEE788 and assessed anti-proliferative side effects, liver regeneration, and liver architecture.

RESULT: Liver regeneration and liver architecture were not impaired by AEE788 treatment after 90%PH. 90%PH caused a clinically relevant drug accumulation within 1 week of treatment (AEE788 serum and tissue levels: 90%PH*>70%PH*>normal control, *p < 0.05), suggesting a liver-size-dependent metabolism of the drug. Drug accumulation after 90%PH was associated with severe side effects (delayed body weight recovery, diarrhea, impaired hair growth) within 1 week of treatment.

CONCLUSION: Treatment with AEE788 could be a potential strategy for adjuvant treatment after oncological liver resection, as liver regeneration was not impaired. Our results suggest a liver-size-dependent metabolism of AEE788 leading to drug accumulation and subsequently to severe side effects. It calls for therapeutic drug monitoring in the early postoperative phase after extended resection.