BACKGROUND. Sorafenib is an oral antiangiogenic agent administered in advanced-stage hepatocellular carcinoma (HCC). Based on preclinical and human studies, we hypothesized that, in addition to its antiangiogenic properties, sorafenib may beneficially reduce the extent of the immunosuppressive network in HCC patients. To test this hypothesis, we examined whether alterations in the immunosuppressive burden of advanced-stage HCC patients correlated with clinical outcome.
METHODS. In before and after sorafenib treatment, blood samples collected from 19 patients with advanced HCC, the frequency of PD-1+ T cells, Tregs, and myeloid derived suppressor cells (MDSC) were quantified by multiparameter FACS. Cytokine levels in plasma were determined by ELISA.
RESULTS. Overall survival (OS) was significantly impacted by the reduction in the absolute number of both CD4+PD-1+ T cells and CD8+PD-1+ T cells following sorafenib treatment. Significant decreases in the frequency and absolute number of Foxp3+ Tregs were also observed, and a statistically significant improvement in OS was noted in patients exhibiting a greater decrease in the number of Foxp3+ Tregs. The ratio of CD4+CD127+PD-1– T effector cells to CD4+Foxp3+PD-1+ Tregs was significantly increased following treatment with sorafenib. Increased frequency of CD4+CD127+ T effector cells in the posttreatment samples significantly correlated with OS.
CONCLUSION. This study is the first to our knowledge to demonstrate the potent immunomodulatory effects of sorafenib therapy on PD-1+ T cells and Tregs and the ensuing correlation with survival. These phenotypes could serve as predictive biomarkers to identify HCC patients who are likely to benefit from sorafenib treatment.
TRIAL REGISTRATION. Registration is not required for observational studies.
FUNDING. This study was supported by NCI Core Grant to RPCI (NIH P30 CA016056) and discretionary funds to Y. Thanavala.