Sorafenib and hepatocellular carcinoma: is alpha-fetoprotein a biomarker predictive of tumor biology and primary resistance?

Lay abstract Alpha-fetoprotein (AFP) is a plasma protein commonly used as a tumor marker for hepatocellular carcinoma. Sorafenib is a targeted therapy used to block the growth of cancer cells in several ways. It affects various proteins on the surface of cancer cells as well as targets inside the cell. Some of these targets are involved in tumor angiogenesis (growth of new blood vessels). In the present analysis, elevated AFP plasma levels before starting sorafenib therapy were correlated with inferior survival compared with patients with low AFP levels, thus suggesting a possible role of AFP in resistance to sorafenib therapy. Using a specific antibody, the authors also studied the expression on cancer cells of VEGFR2, which is a protein involved in angiogenesis and one of the targets of sorafenib. No correlation was found between AFP level and VEGFR2 expression. The underlying mechanisms involved in resistance to sorafenib therapy still need to be clarified and deserve further studies. Background: Alpha-fetoprotein (AFP) is the only biomarker with proven prognostic value in advanced hepatocellular carcinoma. Preliminary data indicate crosstalk between AFP and VEGF signaling. Methods: The authors looked at 69 patients with advanced hepatocellular carcinoma who were previously tested for VEGFR2 expression, had available baseline AFP serum concentrations and were treated with sorafenib within clinical trials. Results: Shorter progression-free survival and overall survival were associated with increased AFP level and elevated VEGFR2 staining. At multivariate analysis of AFP level was the only independent prognostic factor for progression-free survival and overall survival. Conclusion: The authors' study confirms the adverse prognostic role of elevated baseline AFP and also suggests a possible role of AFP in primary resistance to sorafenib therapy.