4-1BB Agonism Averts TIL Exhaustion and Licenses PD-1 Blockade in Glioblastoma and Other Intracranial Cancers.

The success of checkpoint blockade against glioblastoma (GBM) has been disappointing. Anti-PD-1 strategies may be hampered by severe T-cell exhaustion. We sought to develop a strategy that might license new efficacy for checkpoint blockade in GBM. We characterized 4-1BB expression in tumor-infiltrating lymphocytes (TIL) from human GBM. We implanted murine tumor models including glioma (CT2A), melanoma (B16), breast (E0771), and lung carcinomas intracranially and subcutaneously, characterized 4-1BB expression, and tested checkpoint blockade strategies in vivo. Our data reveal that 4-1BB is frequently present on nonexhausted CD8+ TILs in human and murine GBM. In murine gliomas, 4-1BB agonism and PD-1 blockade demonstrate a synergistic survival benefit in a CD8+ T-cell-dependent manner. The combination decreases TIL exhaustion and improves TIL functionality. This strategy proves most successful against intracranial CT2A gliomas. Efficacy in all instances correlates with the levels of 4-1BB expression on CD8+ TILs, rather than with histology or with intracranial versus subcutaneous tumor location. Proffering 4-1BB expression to T cells licenses combination 4-1BB agonism and PD-1 blockade in models where TIL 4-1BB levels had previously been low and the treatment ineffective. Although poor T-cell activation and severe T-cell exhaustion appear to be limiting factors for checkpoint blockade in GBM, 4-1BB agonism obviates these limitations and produces long-term survival when combined with anti-PD-1 therapy. Furthermore, this combination therapy is limited by TIL 4-1BB expression, but not by the intracranial compartment, and therefore may be particularly well-suited to GBM.

Woroniecka KI ，Rhodin KE ，Dechant C ，Cui X ，Chongsathidkiet P ，Wilkinson D ，Waibl-Polania J ，Sanchez-Perez L ，Fecci PE ... -  《-》

Immune Checkpoint Inhibitor-induced Reinvigoration of Tumor-infiltrating CD8(+) T Cells is Determined by Their Differentiation Status in Glioblastoma.

Immune checkpoint inhibitors (ICI) are used for the treatment of various cancers, but clinical trials of anti-programmed cell death protein 1 (PD-1) with patients with recurrent glioblastoma (GBM) have failed to show clinical benefits. In this study, we examined the differentiation status of CD8+ tumor-infiltrating lymphocytes (TIL) from patients with primary GBM and their reinvigoration by ICIs to understand the nature of T-cell exhaustion in GBM. We isolated TILs from 98 patients with newly diagnosed GBM and examined the expression of immune checkpoint receptors and T-cell transcription factors using flow cytometry. TILs were ex vivo stimulated with anti-CD3 in the presence of anti-PD-1 and/or anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) and their proliferation assessed. CD8+ TILs had significantly increased expression of immune checkpoint receptors, including PD-1 and CTLA-4, compared with peripheral blood CD8+ T cells. Among CD8+ TILs, PD-1+ cells exhibited more terminally differentiated phenotypes (i.e., EomeshiT-betlo) than PD-1- cells. These data were confirmed by analyzing NY-ESO-1157-specific CD8+ TILs. Evaluating the proliferation of CD8+ TILs after ex vivo stimulation with anti-CD3 and anti-PD-1, we found that proliferation inversely correlated with the percentage of EomeshiT-betlo cells among PD-1+CD8+ TILs. When anti-CTLA-4 was used in combination with anti-PD-1, an additional increase in CD8+ TIL proliferation was observed in patients with low percentages of EomeshiT-betlo CD8+ TILs, who responded well to anti-PD-1 in ex vivo assays, but not in patients with high percentages of EomeshiT-betlo CD8+ TILs, who did not respond to anti-PD-1. In primary GBM, the differentiation status of CD8+ TILs determines their reinvigoration ability upon ICI treatment.

Park J ，Kwon M ，Kim KH ，Kim TS ，Hong SH ，Kim CG ，Kang SG ，Moon JH ，Kim EH ，Park SH ，Chang JH ，Shin EC ... -  《-》

T-Cell Exhaustion Signatures Vary with Tumor Type and Are Severe in Glioblastoma.

Purpose: T-cell dysfunction is a hallmark of glioblastoma (GBM). Although anergy and tolerance have been well characterized, T-cell exhaustion remains relatively unexplored. Exhaustion, characterized in part by the upregulation of multiple immune checkpoints, is a known contributor to failures amid immune checkpoint blockade, a strategy that has lacked success thus far in GBM. This study is among the first to examine, and credential as bona fide, exhaustion among T cells infiltrating human and murine GBM.Experimental Design: Tumor-infiltrating and peripheral blood lymphocytes (TILs and PBLs) were isolated from patients with GBM. Levels of exhaustion-associated inhibitory receptors and poststimulation levels of the cytokines IFNγ, TNFα, and IL2 were assessed by flow cytometry. T-cell receptor Vβ chain expansion was also assessed in TILs and PBLs. Similar analysis was extended to TILs isolated from intracranial and subcutaneous immunocompetent murine models of glioma, breast, lung, and melanoma cancers.Results: Our data reveal that GBM elicits a particularly severe T-cell exhaustion signature among infiltrating T cells characterized by: (1) prominent upregulation of multiple immune checkpoints; (2) stereotyped T-cell transcriptional programs matching classical virus-induced exhaustion; and (3) notable T-cell hyporesponsiveness in tumor-specific T cells. Exhaustion signatures differ predictably with tumor identity, but remain stable across manipulated tumor locations.Conclusions: Distinct cancers possess similarly distinct mechanisms for exhausting T cells. The poor TIL function and severe exhaustion observed in GBM highlight the need to better understand this tumor-imposed mode of T-cell dysfunction in order to formulate effective immunotherapeutic strategies targeting GBM. Clin Cancer Res; 24(17); 4175-86. ©2018 AACRSee related commentary by Jackson and Lim, p. 4059.

Woroniecka K ，Chongsathidkiet P ，Rhodin K ，Kemeny H ，Dechant C ，Farber SH ，Elsamadicy AA ，Cui X ，Koyama S ，Jackson C ，Hansen LJ ，Johanns TM ，Sanchez-Perez L ，Chandramohan V ，Yu YA ，Bigner DD ，Giles A ，Healy P ，Dranoff G ，Weinhold KJ ，Dunn GP ，Fecci PE ... -  《-》

TIGIT and PD-1 Immune Checkpoint Pathways Are Associated With Patient Outcome and Anti-Tumor Immunity in Glioblastoma.

Glioblastoma (GBM) remains an aggressive brain tumor with a high rate of mortality. Immune checkpoint (IC) molecules are expressed on tumor infiltrating lymphocytes (TILs) and promote T cell exhaustion upon binding to IC ligands expressed by the tumor cells. Interfering with IC pathways with immunotherapy has promoted reactivation of anti-tumor immunity and led to success in several malignancies. However, IC inhibitors have achieved limited success in GBM patients, suggesting that other checkpoint molecules may be involved with suppressing TIL responses. Numerous IC pathways have been described, with current testing of inhibitors underway in multiple clinical trials. Identification of the most promising checkpoint pathways may be useful to guide the future trials for GBM. Here, we analyzed the The Cancer Genome Atlas (TCGA) transcriptomic database and identified PD1 and TIGIT as top putative targets for GBM immunotherapy. Additionally, dual blockade of PD1 and TIGIT improved survival and augmented CD8+ TIL accumulation and functions in a murine GBM model compared with either single agent alone. Furthermore, we demonstrated that this combination immunotherapy affected granulocytic/polymorphonuclear (PMN) myeloid derived suppressor cells (MDSCs) but not monocytic (Mo) MDSCs in in our murine gliomas. Importantly, we showed that suppressive myeloid cells express PD1, PD-L1, and TIGIT-ligands in human GBM tissue, and demonstrated that antigen specific T cell proliferation that is inhibited by immunosuppressive myeloid cells can be restored by TIGIT/PD1 blockade. Our data provide new insights into mechanisms of GBM αPD1/αTIGIT immunotherapy.

Raphael I ，Kumar R ，McCarl LH ，Shoger K ，Wang L ，Sandlesh P ，Sneiderman CT ，Allen J ，Zhai S ，Campagna ML ，Foster A ，Bruno TC ，Agnihotri S ，Hu B ，Castro BA ，Lieberman FS ，Broniscer A ，Diaz AA ，Amankulor NM ，Rajasundaram D ，Pollack IF ，Kohanbash G ... -  《Frontiers in Immunology》

Focal radiation therapy combined with 4-1BB activation and CTLA-4 blockade yields long-term survival and a protective antigen-specific memory response in a murine glioma model.

Belcaid Z ，Phallen JA ，Zeng J ，See AP ，Mathios D ，Gottschalk C ，Nicholas S ，Kellett M ，Ruzevick J ，Jackson C ，Albesiano E ，Durham NM ，Ye X ，Tran PT ，Tyler B ，Wong JW ，Brem H ，Pardoll DM ，Drake CG ，Lim M ... -  《PLoS One》