Circulating biomarkers of response to systemic treatments in advanced hepatocellular

Hepatocellular carcinoma (HCC), is one of the most common causes of cancer related-death worldwide, with more of 50% of patients diagnosed at an advanced stage. Systemic therapies, including tyrosine kinase inhibitor such as sorafenib, regorafenib, lenvatinib and cabozantinib and combination therapies including immunotherapy (durvalumab and tremelimumab) or immunotherapy and angiogenesis inhibitor (atezolizumab and bevacizumab) are the standard of care for patients with advanced stage HCC. A response to systemic treatment is observed in less than 30% of patients. No biomarkers of treatment response are currently available for HCC, except for high serum levels of alpha-fetoprotein (AFP) that predict the response to ramucirumab. The aim of my project was to evaluate different circulating biomarkers of response to sorafenib and atezolizumab-bevacizumab. First, we explored the dynamics of endothelial progenitor cells (EPC), bone marrow-derived cells that contribute to the process of neovascularization, in 16 HCC patients receiving sorafenib. Five different EPC populations (CD34 total, CD34+CD133+, CD34+KDR+, CD34+CD133+KDR+, CD34+CD133-KDR-) were evaluated. EPC levels significantly decreased after eight weeks of treatment in patients who obtained a clinical benefit (radiological response or stable disease) whereas no significant differences were found in those who progressed. In addition, patients who obtained a clinical benefit from sorafenib had almost twice as many CD34+ CD133+ cells at baseline compared to patients who had disease progression. Next, we explored early variation of serum AFP as a potential surrogate biomarker of prognosis in patients treated with atezolizumab-bevacizumab. We observed that an AFP reduction of 20% at 3 weeks of treatment was associated with longer overall survival and progression free survival, showing a potential role as a biomarker of response. In addition, we demonstrated that the combination of AFP early response with the assessment of liver function using the albumin-bilirubin (ALBI) grade refines the prediction of outcomes in these patients, identifying four groups with different prognosis. In another project, we searched for mutations in circulating tumor DNA (ctDNA) in 772 plasmas collected at various tumor stages (BCLC 0 to C) from 173 patients with HCC treated by different therapies. We observed that 40.2% of plasma samples collected when HCC was active were mutated, with increased frequencies of mutation in case of intermediate and advanced stage. Interestingly, among patients with mutations detected in ctDNA, approximately one-third had low serum AFP level, suggesting that ctDNA could provide additional value as a biomarker. A good concordance was found between mutations detected in tumor and in ctDNA. Next, we observed that detection of mutations in ctDNA was associated with a worse overall survival and recurrence free survival in patients treated by percutaneous ablation. Moreover, the detection of mutations in two or three genes in ctDNA was linked to recurrence outside Milan criteria, suggesting the potential role of ctDNA as a surrogate marker of tumor aggressiveness. We also assessed the early dynamics of ctDNA before (H0) and after (H24) locoregional treatment, observing a higher level of ctDNA and detectable mutations at H24, suggesting that cell necrosis induced by locoregional treatment sensitizes the detection of mutations in the blood. Finally, we studied 356 plasma samples collected at the beginning of systemic treatment and we detected at least one mutation in 60% of samples with higher frequencies for TERT promoter followed by TP53 and CTNNB1. Notably, in patients treated with atezolizumab-bevacizumab, the persistence over time of the mutation(s) detected in ctDNA at baseline was associated with radiological progression.