Understanding cancer immunobiology has been hampered by difficulty identifying cancer-specific T cells. Merkel cell polyomavirus (MCPyV) causes most Merkel cell carcinomas (MCCs). All patients with virus-driven MCC express MCPyV oncoproteins, facilitating identification of virus (cancer)-specific T cells. We studied MCPyV-specific T cells from 27 patients with MCC using MCPyV peptide-HLA-I multimers, 26-color flow cytometry, single-cell transcriptomics, and T cell receptor (TCR) sequencing. In a prospective clinical trial, higher circulating MCPyV-specific CD8 T cell frequency before anti-PD-1 treatment was strongly associated with 2-year recurrence-free survival (75% if detectable, 0% if undetectable, p = 0.0018; ClinicalTrial.gov: NCT02488759). Intratumorally, such T cells were typically present, but their frequency did not significantly associate with response. Circulating MCPyV-specific CD8 T cells had increased stem/memory and decreased exhaustion signatures relative to their intratumoral counterparts. These results suggest that cancer-specific CD8 T cells in the blood may play a role in anti-PD-1 responses. Thus, strategies that augment their number or mobilize them into tumors could improve outcomes.
Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.

Checkpoint inhibition (CPI) therapy and adoptive cell therapy with autologous tumor-infiltrating lymphocytes (TIL-based ACT) are the two most effective immunotherapies for the treatment of metastatic melanoma. While CPI has been the dominating therapy in the past decade, TIL-based ACT is beneficial for individuals even after progression on previous immunotherapies. Given that notable differences in response have been made when used as a subsequent treatment, we investigated how the qualities of TILs changed when the ex vivo microenvironment of intact tumor fragments were modulated with checkpoint inhibitors targeting programmed death receptor 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Initially, we show that unmodified TILs from CPI-resistant individuals can be produced, are overwhelmingly terminally differentiated, and are capable of responding to tumor. We then investigate these properties in ex vivo checkpoint modulated TILs finding that that they retain these qualities. Lastly, we confirmed the specificity of the TILs to the highest responding tumor antigens, and identified this reactivity resides largely in CD39+CD69+ terminally differentiated populations. Overall, we found that anti-PD-1 will alter the proliferative capacity while anti-CTLA4 will influence breadth of antigen specificity.
Copyright © 2023 Hulen, Friese, Kristensen, Granhøj, Borch, Peeters, Donia, Andersen, Hadrup, Svane and Met.

Given hepatitis B virus (HBV)-related hepatocellular carcinoma (HBV-HCC) exhibits unique gut microbiota characteristics and a significant immunosuppressive tumor microenvironment. Thus, a better understanding of the correlation between gut microbiota and the immunosuppressive response may help predict occurrence and prognosis of HBV-HCC.
Here, in a cohort of ninety adults (healthy control n=30, HBV-cirrhosis n=30, HBV-HCC n=30) with clinical data, fecal 16S rRNA gene sequencing, matched peripheral blood immune response with flow cytometry analysis. Correlation between the gut microbiome of significantly different in HBV-HCC patients and clinical parameters as well as the peripheral immune response was assessed.
We found that community structures and diversity of the gut microbiota in HBV-CLD patients become more unbalanced. Differential microbiota analysis that p:Acidobacteriota, p:Proteobacteria, p:Campilobacterota, f:Streptococcaceae, g:Klebsiella associated with inflammation were enriched. The beneficial bacteria of f:Clostridia UCG-014, f:Oscillospiraceae, f:_Rikenellaceae, g:_Barnesiella, g:Prevotella, g:Agathobacter were decreased. Functional analysis of gut microbiota revealed that lipopolysaccharide biosynthesis, lipid metabolism, butanoate metabolism were significantly elevated in HBV-CLD patients. Spearman's correlation analysis showed that Muribaculaceae, Akkermaniacaeae, [Eubacterium]_coprostanoligenes_group, RF39, Tannerellaceae have positive correlation with CD3+T, CD4+T and CD8+T cell counts while negatively correlated with liver dysfunction. Furthermore, paired peripheral blood showed a decreased proportion of CD3+T, CD4+T and CD8+T cells, while an increased T (Treg) cells. The immunosuppressive response of programmed cell death 1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), immune receptor tyrosine based inhibitor motor (ITIM) domain (TIGIT), T-cell immune domain, and multiple domain 3 (TIM-3) of CD8+T cells were higher in HBV-HCC patients. They were positively correlated with harmful bacteria, such as Actinobaciota, Myxococota, Streptococcaceae and Eubacterium coprostanoligenes.
Our study indicated that gut beneficial bacteria, mainly Firmicutes and Bacteroides appeared dysbiosis in HBV-CLD patients. They have negative regulation of liver dysfunction and T cell immune response. It provides potential avenues for microbiome-based prevention and intervention for anti-tumor immune effects of HBV-CLD.
Copyright © 2023 Yan, Zhang, Shi, Zhang, Zhu, Bi and Wang.

ADAPTeR is a prospective, phase II study of nivolumab (anti-PD-1) in 15 treatment-naive patients (115 multiregion tumor samples) with metastatic clear cell renal cell carcinoma (ccRCC) aiming to understand the mechanism underpinning therapeutic response. Genomic analyses show no correlation between tumor molecular features and response, whereas ccRCC-specific human endogenous retrovirus expression indirectly correlates with clinical response. T cell receptor (TCR) analysis reveals a significantly higher number of expanded TCR clones pre-treatment in responders suggesting pre-existing immunity. Maintenance of highly similar clusters of TCRs post-treatment predict response, suggesting ongoing antigen engagement and survival of families of T cells likely recognizing the same antigens. In responders, nivolumab-bound CD8+ T cells are expanded and express GZMK/B. Our data suggest nivolumab drives both maintenance and replacement of previously expanded T cell clones, but only maintenance correlates with response. We hypothesize that maintenance and boosting of a pre-existing response is a key element of anti-PD-1 mode of action.
Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.

Immune checkpoint inhibitors demonstrate clinical activity in many tumor types, however, only a fraction of patients benefit. Combining CD137 agonists with these inhibitors increases anti-tumor activity preclinically, but attempts to translate these observations to the clinic have been hampered by systemic toxicity. Here we describe a human CD137xPD-L1 bispecific antibody, MCLA-145, identified through functional screening of agonist- and immune checkpoint inhibitor arm combinations. MCLA-145 potently activates T cells at sub-nanomolar concentrations, even under suppressive conditions, and enhances T cell priming, differentiation and memory recall responses. In vivo, MCLA-145 anti-tumor activity is superior to immune checkpoint inhibitor comparators and linked to recruitment and intra-tumor expansion of CD8 + T cells. No graft-versus-host-disease is observed in contrast to other antibodies inhibiting the PD-1 and PD-L1 pathway. Non-human primates treated with 100 mg/kg/week of MCLA-145 show no adverse effects. The conditional activation of CD137 signaling by MCLA-145, triggered by neighboring cells expressing >5000 copies of PD-L1, may provide both safety and potency advantages.
© 2021. The Author(s).