317 T cell receptor (TCR)-based cellular therapy for fibrolamellar HCC

Résumé fourni par la source

Background Fibrolamellar carcinoma (FLC) is a rare and often lethal liver cancer that primarily affects children and young adults without cirrhosis. There is no standard systemic treatment for FLC and the median survival for patients with advanced, unresectable FLC is approximately 12 months. The FLC transcriptome is characterized by an in-frame fusion of exon 1 of DNAJB1 with exons 2-10 of PRKACA, the catalytic subunit of protein kinase A (PKA), leading to expression of a chimeric protein, DNAJ-PKAc that has thus far been ‘undruggable’ due to unacceptable on-target toxicity. Our overall goal is to target this ‘undruggable’ oncogenic driver using T Cell Receptor (TCR)-Based cellular therapy.Methods We are performing a clinical trial of a peptide-based therapeutic vaccine targeting DNAJ-PKAc, in combination with the immune checkpoint inhibitors nivolumab and ipilimumab. We analyzed PBMCs from a subset of patients who demonstrated a clinical response to this immune-based combination therapy to identify TCRs with specificity for DNAJ-PKAc. We further characterized these TCRs functionally by their HLA specificity, affinity, cytotoxicity and cytokine production profiles using various co-culture systems.Results To identify fusion specific T cell receptors (TCRs) generated in response to the vaccine patient peripheral lymphocytes were expanded and 10x single cell transcriptomic with paired TCR sequencing was performed. Candidate TCRs were reconstructed and expressed in T cells prior to co-culturing with HLA matched antigen presenting cells that were pulsed with DNAJ-PKAc peptides to verify fusion specificity via flow cytometry for T cell activation. To measure affinity this co-culture system was utilized with varying concentrations of peptide. To measure cytotoxicity tumor cells expressing the fusion and matched HLA were co-cultured with T cells expressing candidate TCRs and an Incucyte was used to monitor tumor cell death over several days. We identified several TCRs recognizing DNAJ-PKAc-derived peptides in the context of class II HLAs, including HLA-DRB1*13:01 and HLA-DRB3*01. The TCRs recognize DNAJ-PKAc with variable HLA specificity, TCR affinity, in vitro cytotoxicity and cytokine response profiles. In general, TCRs with specificity for DNAJ-PKAc presented in the context of HLA-DRB1*13:01 were higher affinity than those recognizing HLA-DRB3*01. We also found that a TCRs affinity was not predictive of its killing capacity in vitro.Conclusions This work identifies and characterizes multiple TCRs from several patients with specificity for DNAJ-PKAc. Our data provides evidence that the therapeutic efficacy of a peptide-based therapeutic vaccine may be mediated by a CD4 T cell response, and provides potential candidates for off-the-shelf TCR therapy for FLC.Trial Registration NCT04248569Ethics Approval J19140/IRB00222681 Johns Hopkins IRB Participants gave informed written consent before taking part in the study.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.