Integrated characterisation of anti-tumour immunity following neoadjuvant immunotherapy of hepatocellular carcinoma

Background Surgery can be a potentially curative treatment for early-stage hepatocellular carcinoma (HCC). However, 70% patients relapse within 2-years after resection. To improve this outcome, a potential role of immunotherapy in the neoadjuvant setting is currently under investigation.

PRIME-HCC (NCT03682276) is a phase Ib study testing the combination of ipilimumab (anti-cytotoxic T-lymphocyte antigen 4) and nivolumab (anti-programmed death 1) in 32 patients with early-phase HCC, undergoing surgical resection.

Studies conducted with immune checkpoint inhibitors (ICI) in the neoadjuvant setting can provide unique data from the analysis of surgical specimens and biological samples of responders and non-responders, with the aim of identifying possible predictive factors of response to ICI.

Aims The overarching aim of this proposal is to aid identification of mechanisms of action of immunotherapy taking advantage of a unique biorepository of clinical samples collected as part of the neoadjuvant clinical trial PRIME-HCC. We will test the hypothesis that ICI response can be related to CD8+ T cells exhaustion.

Methods I will extensively analyze biological samples collected during the study, including tumour tissue (pre-ICI and post-surgery), peripheral blood mononuclear cells (PBMCs), serum, plasma and stool aliquots.

I will focus on three main correlates of exhaustion: 1) I will evaluate tumour-infiltrating lymphocytes using multiparameter mass cytometry and using the Nanostring PanCancer Immune Panel for a complete immune-profiling of the malignancy.

Relative expression of immune exhaustion markers will be analysed in relationship with response to treatment and recurrence-free survival. 2) I will perform a longitudinal assessment of T-cell receptor beta-chain repertoire in peripheral blood lymphocytes by sequencing of CDR3 region to assess for dynamic changes in clonality of the T-cell response. 3) I will perform gut microbiome characterization by sequencing of 16S rRNA gene from stool DNA to correlate bacterial phylogeny with the characteristics of the anti-tumour immune response.

Impact of the research results The results of the research will help to optimize the use of ICI in HCC, by facilitating identification of patients who are more likely to respond to treatment and spare non-responders from unnecessary and potentially life-threatening toxicity.

It will improve understanding of ICI-responsiveness focusing on an exclusive treatment setting, with broader reaching implications transferable to other oncological indications where ICIs are standard of care.