Life science
Medical & healthcare, Companion diagnostic test

Peripheral T cell receptor repertoire features predict durable responses to anti-PD-1
inhibitor monotherapy in advanced renal cell carcinoma
Department of Urology, Graduate School of Medicine
Assistant Professor Taigo Kato

https://researchmap.jp/taigokato

Professor Norio Nonomura

https://researchmap.jp/read0185096

Life science

Abstract
Immune checkpoint inhibitors (ICIs) had benefits to cancer patients via systemic T cell-mediated anti-cancer immune response.
Thus, we need to clarify the dynamic of peripheral T cell repertoiresas non-invasive predictive biomarkers to select responders to ICIs.
We collected tumors and PBMCs from 25 advanced kidney cancers, before and after anti-PD-1 therapy. We applied a next-generation sequencing to characterize T cell receptor (TCR) alphaand beta repertoires, and found responders showed expansion ofcertain T cell clones in the peripheral blood as evidenced by thesignificant decrease of diversity index and increase in the numberof expanded TCR clones at 1 month after treatment. We also foundthese expanded peripheral TCR clones were significantly sharedwith tumor-infiltrating T cells in responders, which may recognize
cancer antigens. Expression analysis revealed significantly elevated transcriptional levels of GZMB, Perforin, CD39, and PD-1 inresponders, markers of cancer antigen-specific T cells.
In conclusion, TCR repertoire analysis can be a potential tool for
personalized immunotherapy to identify peripheral surrogate markers for predicting clinical responses to ICIs.

▍ Background & Results
Immunotherapies such as immune checkpoint inhibitors (ICIs)
have revolutionized cancer treatment. However, the clinical effectof ICIs is still limited and identification of a predictive biomarker iscritically important for the precision medicine, which can select patients likely to have clinical benefit from ICIs.
In our study, a total of 25 advanced kidney cancer patientstreated with PD-1 antibody (Nivolumab) were enrolled and definedas the patients of responder (CR, PR and long SD, n = 15) andnon-responder (short SD and PD, n = 10) by RECIST criteria. We
collected tumor tissues and peripheral blood mononuclear cells(PBMCs) before and 1, 3, 6 months after starting treatment. We
applied a next generation sequencing approach to characterize T
cell receptor (TCR) repertoires using mRNA isolated from tumor tissues and PBMCs. To assess clonality of T cells, the diversity indexof TCR was calculated according to complementarity-determining
region 3 sequences. In addition, we calculated the number of expanded T cell clones in PBMCs after starting PD-1 antibody.
Through TCR repertoire analysis, in the PBMCs 1 month afterstarting PD-1 antibody, we found that significant decrease of diversity index in responder group. We also found that the numberof expanded T cell clones in PBMCs was significantly higher in responder group, suggesting that PD-1 antibody could induce strong
immune reactions in PBMCs with oligoclonal expansion of T cells.
Interestingly, some of abundant TCR clonotypes in PBMCs werealso detected in tumor tissues, indicating that these TCR clonotypes might recognize cancer-specific antigens.

ICIs. In the future, we can identify T cell clones that are significantly
increased in responders, leading to the development of neoantigen-specific cytotoxic T cells therapy as personalized immunotherapy.

Figure 1: For TCR repertoire analysis, we have a novel platform to read T cell
receptor using next-generation sequencing approach. We extracted mRNA fromtissue and peripheral blood, and amplified TCR legion with specific primer. And
then, we read TCR cDNA with next-generation sequencing and obtained data will
be analyzed with our own developed algorism Tcrip.

Figure 2: Diversity index for TCR alpha and TCR beta were significantly decreased at 1 month after the treatment in responders compared to that in non-responders, suggesting that responders had expansion of certain T cell clones
even in blood samples, not in tumor tissues. These expanded clones at 1 month
were significantly sustained at 3 and 6 months after treatment in responders, suggesting responders had long-lasting anti-cancer immune response.

▍ Significance of the research and Future perspective
Our findings revealed that the changes of diversity index of TCR
and expanded T cell clones in PBMCs by TCR repertoire analysis
can be early and concise markers to predict favorable response forFigure 3: Graphical abstract

P a t e n t
Tr e a t i s e

Kato, Taigo; Kiyotani, Kazuma; Tomiyama, Eisuke et al. Peripheral T cell receptor repertoire features predict durable responses to anti-PD-1 inhibitor
monotherapy in advanced renal cell carcinoma. Oncoimmunology. 2021 Jan 19; 10(1): 1862948. doi: 10.1080/2162402X.2020

URL
K e y w o r d renal cell carcinoma, immune checkpoint inhibitor, t cell receptor, next-generation sequencing, biomarker