Messenger RNA electroporated hepatitis B virus (HBV) antigen-specific T cell receptor (TCR) redirected T cell therapy is well-tolerated in patients with recurrent HBV-related hepatocellular carcinoma post-liver transplantation: results from a phase I trial.

Background And Aims: Liver transplantation (LT) is the primary curative option for cirrhotic patients with early-stage hepatocellular carcinoma (HCC). However, tumor recurrence occurs in 15-20% of cases with unfavorable prognosis. We have developed a library of T cell receptors (TCRs) specific for different hepatitis B virus (HBV) antigens, restricted by different molecules of human leucocyte antigen (HLA)-class I, to redirect T cells against HBV antigens (Banu in Sci Rep 4:4166, 2014). We further demonstrated that these transiently functional T cells specific for HBV obtained through messenger RNA (mRNA) electroporation can eliminate HCC cells expressing HBV antigens in vitro and in vivo (Kah in J Clin Invest 127:3177-3188, 2017). A phase I clinical trial for patients with HCC recurrence post-liver transplant was conducted to assess the safety, tolerability, and anti-tumor efficacy of transiently functional HBV-TCR T cells. Here, we report the clinical findings with regard to the safety and anti-tumor efficacy of mRNA electroporated HBV-specific TCR-T cells. (ClinicalTrials.gov identifier: NCT02719782).

Patients And Methods: A total of six patients with HBV-positive recurrent HCC post-liver transplant and HLA-matched to TCR targeting hepatitis B surface antigen (HBsAg) or hepatitis B core antigen (HBcAg) (HLA-A*02:01/HBsAg, HLA-A*11:01/HBcAg, HLA-B*58:01/HBsAg or HLA-C*08:01/HBsAg) were enrolled in this study. The primary objective was to assess the safety of short-lived mRNA electroporated HBV-TCR T cells based on the incidence and severity of the adverse event (AE) graded per National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), Version 4.0. The secondary objective was to determine the effectiveness of HBV-TCR T cells as per RECIST 1.1 criteria. Patients were followed up for survival for 2 years post-end of treatment.

Results: The median age of the six patients was 35.5 years (range: 28-47). The median number of HBV-TCR T cell infusions administered was 6.5 (range: 4-12). The treatment-related AE included grade 1 pyrexia. This study reported no cytokine release syndrome nor neurotoxicity. One patient remained alive and five were deceased at the time of the data cutoff (30 April 2020).

Conclusion: This study has demonstrated that multiple infusions of mRNA electroporated HBV-specific TCR T cells were well-tolerated in patients with HBV-positive recurrent HCC post-liver transplant.