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Tumor-reactive clonotype dynamics dictate clinical response to TIL therapy in melanoma [TCR-Seq]

ABSTRACT: Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TILs) is effective in cancer patients, yet the profiles, specificity and dynamics of tumor clonotypes remain opaque. Using single-cell RNA/TCR-sequencing, clonotypes were tracked from baseline tumors to ACT products (ACTP) and post-ACT blood and tumor samples from 13 metastatic melanoma patients (NCT03475134). Furthermore, a predictor of tumor-reactive clonotypes was derived from the transcriptomic profiles of tumor-specific or bystander clones. Patients with clinical responses had tumors enriched in tumor-reactive TILs, preferentially expanding in-vitro to generate larger and more tumoricidal products and preferentially re-infiltrating tumors post-ACT. Conversely, lack of responses was associated with tumors devoid of tumor-reactive clonotypes and with cell products mostly composed of blood-borne clonotypes. The exhaustion state characterizing intratumoral tumor-reactive TILs was attenuated during in-vitro expansion and restored after tumor re-engraftment only in responders. Thus, tumor-reactive clonotypes drive clinical response to TIL therapy, providing insight to select patients or improve TILs’ culture.

ORGANISM(S): Homo sapiens

PROVIDER: GSE234352 | GEO | 2023/08/01

REPOSITORIES: GEO

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Project description:Background: Anti-tumor immunity is highly heterogeneous between individuals; however, underlying mechanisms remain elusive, despite their potential to improve personalized cancer immunotherapy. Head and neck squamous cell carcinomas (HNSCCs) vary significantly in immune infiltration and therapeutic responses between patients, demanding a mouse model with appropriate heterogeneity to investigate mechanistic differences. Methods: We developed a unique HNSCC mouse model to investigate underlying mechanisms of heterogeneous anti-tumor immunity. This model system may provide a better control for tumor-intrinsic and host-genetic variables, thereby uncovering the contribution of the adaptive immunity to tumor eradication. We employed single-cell T-cell receptor (TCR) sequencing coupled with single-cell RNA sequencing to identify the difference in TCR repertoire of CD8 tumor infiltrating lymphocytes (TILs) and the unique activation states linked with different TCR clonotypes. Results: We discovered that genetically identical wild-type recipient mice responded heterogeneously to the same SCC tumors orthotopically transplanted into the buccal mucosa. While tumors initially grew in 100% of recipients and most developed aggressive tumors, ~25% of recipients reproducibly eradicated tumors without intervention. Heterogeneous anti-tumor responses were dependent on CD8 T cells. Consistently, CD8 TILs in regressing tumors were significantly increased and more activated. Single-cell TCR-sequencing revealed that CD8 TILs from both growing and regressing tumors displayed evidence of clonal expansion compared with splenic controls. However, top TCR clonotypes and TCR specificity groups appear to be mutually exclusive between regressing and growing TILs. Furthermore, many TCRa/TCRb sequences only occur in one recipient. By coupling single-cell transcriptomic analysis with unique TCR clonotypes, we found that top TCR clonotypes clustered in distinct activation states in regressing vs. growing TILs. Intriguingly, the few TCR clonotypes shared between regressors and progressors differed greatly in their activation states, suggesting a more dominant influence from tumor microenvironment than TCR itself on T cell activation status. Conclusions: We reveal that intrinsic differences in the TCR repertoire of TILs and their different transcriptional trajectories may underlie the heterogeneous anti-tumor immune responses in different hosts. We suggest that anti-tumor immune responses are highly individualized and different hosts employ different TCR specificities against the same tumors, which may have important implications for developing personalized cancer immunotherapy.

Project description:Tumor-Infiltrating Lymphocytes (TILs) are composed by several immune subpopulations including NK, NKT, Tab, Tgd and B cells. Although some of these cells can have antitumoral activities, there is also a large number of cells which are not tumor-specific,known as bystander cells. These cells may not have a direct role in the antitumoral response but could lead to a modulation of the immune response after time. Recent studies have described fatal encephalitis and myocarditis in cancer patients after immune checkpoint therapies, in which EBV-specific T cells may be involved. Since EBV is able to infect B cells and epithelial cells, both present in the primary tumor site, the first events of these fatal responses could be a consequence of a dysregulation of the immune system in the tumor microenvironment, although this have not been deeply studied. Thus, the main objectives of this study are (i) to use EBV-transformed B cells from the tumor site as a model to study the tumor-infiltrating EBV+ B cells and (ii) to use these EBV-derived B cells to study the relationship with autologous T cells isolated from the tumor site. T cells from TILs have been isolated from a triple negative breast cancer patient before neoadjuvancy and were expanded directly from the biopsy. A Patient-Derived Xenograft (PDX) generated from the breast tumor, progressed into a lymphocytic neoplasm. EBVtransformed B cells were obtained from this PDX (PDX-derived B cells). T Cell Receptor high-throughput sequencing has been used to monitor the clonotypes present in the different samples. We have found 43 clonotypes infiltrating the PDX-562 tissue and 18 of them were also present in the human biopsy or in the biopsy-derived T cell cultures. 5 of these sequences were found in one of the biopsy-derived T cells analyzed. Thus, PDXderived B cells have been used as antigen presenting cells to expand these cells. Few clonotypes were obtained after expansions, although the analysis of the middle CDR3 have revealed a similar pattern with the 18 sequences from the PDX sample. Furthermore, peptides presented by HLA have been eluted from PDX-derived B cells, followed by MS analysis. Peptides obtained derived from 31 different proteins and >40% are cancerrelated in terms of expression.

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Tumor-reactive clonotype dynamics dictate clinical response to TIL therapy in melanoma [TCR-Seq]

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