Characterization of the cryoablation-induced immune response in kidney cancer patients

ABSTRACT

Cryoablation is one of treatment modalities for kidney cancer and is expected to induce strong local immune responses as well as systemic T-cell-mediated immune reactions that may lead to the regression of distant metastatic lesions. Thus, the characterization of T cell repertoire and immune environment in tumors before and after treatment should contribute to the better understanding of the cryoablation-induced anticancer immune responses. In this study, we collected tumor tissues from 22 kidney cancer patients, before cryoablation and at 3 mo after cryoablation. In addition, blood samples were collected from 14 patients at the same time points. We applied a next generation sequencing approach to characterize T cell receptor β (TCRB) repertoires using RNAs isolated from tumor tissues and peripheral blood mononuclear cells. TCRB repertoire analysis revealed the expansion of certain T cell clones in tumor tissues by cryoablation. We also found that proportions of abundant TCRB clonotypes (defined as clonotypes with ≥ 1% frequency among total TCRB reads) were significantly increased in the post-cryoablation tissue samples than those of pre-cryoablation tumor samples. Some of these TCRB clonotypes were found to be increased in peripheral blood. Expression analysis of immune-related genes in the tissues of pre- and post-cryoablation showed significantly elevated transcriptional levels of CD8⁺, CD4⁺, Granzyme A (GZMA), and CD11c along with a high CD8/FOXP3 ratio in the post-cryoablation tissue samples. Our findings revealed that cryoablation could induce strong immune reactions in tumors with oligoclonal expansion of antitumor T cells, which circulate systemically.

KEYWORDS:

• Cryoablation
• immune response
• kidney cancer
• next generation sequencing
• T cell receptor

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Acknowledgments

We thank Dr. Mutsumi Tsuchiya for samples processing and data collection. We also thank Drs. Rui Yamaguchi, Seiya Imoto, and Satoru Miyano in The University of Tokyo for developing the algorithm of TCR repertoire analysis and helpful support in data management. The super-computing resource (http://sc.hgc.jp/shirokane.html) was provided by Human Genome Center, the Institute of Medical Science, The University of Tokyo.

Author Contributions

Y.N. planned and supervised the entire project; J.P. provided the study design and the working hypothesis and completed the article; T.K. designed the study, conducted experiments, performed data analysis, and drafted the article; T.I. conducted experiments and performed data analysis; Y.I. and K.K. conducted data analysis and provided scientific advice; N.N. and U.M. provided the study design and completed the article; A.N. performed data analysis and provided scientific advice; H.H. and K.O. performed cryoablation and completed the article.