The role of c-MET inhibitors in advanced hepatocellular carcinoma: now and future

Recent advancements in improving the efficacy and safety of chimeric antigen receptor (CAR)-T cell therapy for hepatocellular carcinoma

The liver is one of the most frequent sites of primary malignancies in humans. Hepatocellular carcinoma (HCC) is one of the most prevalent solid tumors with poor prognosis. Current treatments showed limited efficacy in some patients, and, therefore, alternative strategies, such as immunotherapy, cancer vaccines, adoptive cell therapy (ACT), and recently chimeric antigen receptors (CAR)-T cells, are developed to offer better efficacy and safety profile in patients with HCC. Unlike other ACTs like tumor-infiltrating lymphocytes (TILs), CAR-T cells are equipped with engineered CAR receptors that effectively identify tumor antigens and eliminate cancer cells without major histocompatibility complex (MHC) restriction. This process induces intracellular signaling, leading to T lymphocyte recruitment and subsequent activation of other effector cells in the tumor microenvironment (TME). Until today, novel approaches have been used to develop more potent CAR-T cells with robust persistence, specificity, trafficking, and safety. However, the clinical application of CAR-T cells in solid tumors is still challenging. Therefore, this study aims to review the advancement, prospects, and possible avenues of CAR-T cell application in HCC following an outline of the CAR structure and function.

Chimeric Antigen Receptor T Cell Therapy for Hepatocellular Carcinoma: Where Do We Stand?

Hepatocellular carcinoma (HCC) remains a global health challenge that urgently calls for innovative therapeutic strategies. Chimeric antigen receptor T cell (CAR T) therapy has emerged as a promising avenue for HCC treatment. However, the therapeutic efficacy of CAR T immunotherapy in HCC patients is significantly compromised by some major issues including the immunosuppressive environment within the tumor, antigen heterogeneity, CAR T cell exhaustion, and the advanced risk for on-target/off-tumor toxicity. To overcome these challenges, many ongoing preclinical and clinical trials are underway focusing on the identification of optimal target antigens and the decryption of the immunosuppressive milieu of HCC. Moreover, limited tumor infiltration constitutes a significant obstacle of CAR T cell therapy that should be addressed. The continuous effort to design molecular targets for CAR cells highlights the importance for a more practical approach for CAR-modified cell manufacturing. This review critically examines the current landscape of CAR T cell therapy for HCC, shedding light on the changes in innate and adaptive immune responses in the context of HCC, identifying potential CAR T cell targets, and exploring approaches to overcome inherent challenges. Ongoing advancements in scientific research and convergence of diverse treatment modalities offer the potential to greatly enhance HCC patients' care in the future.

Hepatocellular carcinoma patients with high circulating cytotoxic T cells and intra-tumoral immune signature benefit from pembrolizumab: results from a single-arm phase 2 trial

BACKGROUND

A limited number of studies have characterized genomic properties of hepatocellular carcinoma (HCC) patients in response to anti-PD-1 immunotherapy.

METHODS

Herein, we performed comprehensive molecular characterization of immediate (D-42 to D-1) pre-treatment tumor biopsy specimens from 60 patients with sorafenib-failed HCC in a single-arm prospective phase II trial of pembrolizumab. Objective response rate was the primary efficacy endpoint. We used whole-exome sequencing, RNA sequencing, and correlative analysis. In addition, we performed single-cell RNA sequencing using peripheral blood mononuclear cells.

RESULTS

The overall response rate of pembrolizumab in sorafenib-failed HCC patients was 10% ([6/60] 95% CI, 2.4-17.6). In a univariate analysis using clinicopathological features, female gender, PD-L1 positivity, and low neutrophil-to-lymphocyte ratio (NLR) were identified as contributing factors to pembrolizumab response. Somatic mutations in CTNNB1 and genomic amplifications in MET were found only in non-responders. Transcriptional profiles through RNA sequencing identified that pembrolizumab responders demonstrated T cell receptor (TCR) signaling activation with expressions of MHC genes, indicating increased levels of T cell cytotoxicity. In single-cell sequencing from 10 pre- and post-treatment peripheral blood mononuclear cells (PBMCs), patients who achieved a partial response or stable disease exhibited immunological shifts toward cytotoxic CD8+ T cells. Conversely, patients with progressive disease showed an increased number of both CD14+ and CD16+ monocytes and activation of neutrophil-associated pathways.

CONCLUSIONS

Taken together, HCC patients with infiltration of cytotoxic T cells, along with increased active circulating CD8+ T cells during pembrolizumab treatment and down-regulation of neutrophil-associated markers, significantly benefited from pembrolizumab treatment.

TRIAL REGISTRATION

NCT#03163992 (first posted: May 23, 2017).