Original Research ARTICLE
A non-interventional Clinical Trial assessing immune responses after Radiofrequency Ablation of Liver Metastases from Colorectal Cancer
- 1Other, Germany
- 2German Cancer Consortium, German Cancer Research Center (DKFZ), Germany
- 3Department of General, Visceral and Transplant Surgery, University Hospital Tübingen, Germany
- 4Institute of Medical Genetics and Applied Genomics, Tübingen University Hospital, Germany
- 5NGS Competence Center, Tübingen University Hospital, Germany
- 6Institute of Pathology, Charité - University Medicine Berlin, Germany
- 7Institute of Pathology, Heidelberg University Hospital, Germany
- 8Abteilung für Diagnostische und Interventionelle Radiologie, Universität Tübingen, Germany
- 9Department of Radiology, Minimally Invasive Therapies and Nuclear Medicine, SLK Clinics Heilbronn, Germany
- 10Institute of Pathology and Neuropathology, University Hospital Tübingen, Germany
- 11Instiute of Pathology, University of Marburg, Germany
Background: Radiofrequency ablation (RFA) is an established treatment option for malignancies located in the liver. RFA-induced irreversible coagulation necrosis leads to the release of danger signals and cellular content. Hence, RFA may constitute an endogenous in situ tumor vaccination, stimulating innate and adaptive immune responses, including tumor-antigen specific T cells. This may explain a phenomenon termed abscopal effect, namely tumor regression in untreated lesions evidenced after distant thermal ablation or irradiation. In this study, we therefore assessed systemic and local immune responses in individual patients treated with RFA.
Methods: For this prospective clinical trial, patients with liver metastasis from colorectal carcinoma (mCRC) receiving RFA and undergoing metachronous liver surgery for another lesion were recruited (n=9) during a 5-year period. Tumor and non-malignant liver tissue samples from six patients were investigated by whole transcriptome sequencing and tandem-mass spectrometry, characterizing naturally-presented HLA ligands. Tumor antigen-derived HLA-restricted peptides were selected by different predefined approaches. Further, candidate HLA ligands were manually curated. Peripheral blood mononuclear cells were stimulated in vitro with epitope candidate peptides, and functional T cell responses were assessed by intracellular cytokine staining. Immunohistochemical markers were additionally investigated in surgically resected mCRC from patients treated with (n=9) or without RFA (n=7).
Results: In all six investigated patients, either induced immune responses and/or pre-existing T cell immunity against the selected targets were observed. Multi-cytokine responses were inter alia directed against known tumor antigens such as cyclin D1 but also against a (predicted) mutation contained in ERBB3. Immunohistochemistry did not show a relevant influx of immune cells into distant malignant lesions after RFA treatment (n=9) as compared to the surgery only mCRC group (n=7).
Conclusions: Using an individualized approach for target selection, RFA induced and/or boosted T cell responses specific for individual tumor antigens were more frequently detectable as compared to previously published observations with well-characterized tumor antigens. However, the witnessed modest RFA-induced immunological effects alone may not be sufficient for the rejection of established tumors. Therefore, these findings warrant further clinical investigation including the assessment of RFA combination therapies e.g. with immune stimulatory agents, cancer vaccination and/or immune checkpoint inhibitors.
Keywords: T cell, Radiofrecuency ablation, TIL (tumor infiltrating lymphocytes), neoantigen, Immune infiltrates, Tumor antigen
Received: 18 Mar 2019;
Accepted: 10 Oct 2019.
Copyright: © 2019 Löffler, Nussbaum, Jaeger, Jurmeister, Budczies, Pereira, Clasen, Kowalewski, Mühlenbruch, Königsrainer, Beckert, Ladurner, Wagner, Bullinger, Groß, Schroeder, Sipos, Königsrainer, Stevanovic, Denkert, Rammensee, Gouttefangeas and Haen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Sebastian P. Haen, Other, Tübingen, Germany, email@example.com