CD106 in tumor-specific exhausted CD8+ T cells mediates immunosuppression by inhibiting TCR signaling

T cell exhaustion is a major contributor to immunosuppression in the tumor microenvironment (TME). Blockade of key regulators of T cell exhaustion, such as PD-1, can reinvigorate tumor-specific T cells and activate anti-tumor immunity in various types of cancer. Here, we identified that CD106 was specifically expressed in exhausted CD8+ T cells in the TME using single-cell RNA-sequencing. High CD106 expression in the TME in clinical samples corresponded to improved response to cancer immunotherapy. CD106 in tumor-specific T cells suppressed anti-tumor immunity both in vitro and in vivo, and loss of CD106 in CD8+ T cells suppressed tumor growth and improved response to PD-1 blockade. Mechanistically, CD106 inhibited T-cell receptor (TCR) signaling by interacting with the TCR/CD3 complex and reducing its surface expression. Together, these findings provide insights into the immunosuppressive role of CD106 expressed in tumor-specific exhausted CD8+ T cells, identifying it as a potential biomarker and therapeutic target for cancer immunotherapy.

Soluble immune checkpoint factors reflect exhaustion of antitumor immunity and response to PD-1 blockade

BACKGROUNDPrecise stratification of patients with non-small cell lung cancer (NSCLC) is needed for appropriate application of PD-1/PD-L1 blockade therapy.METHODSWe measured soluble forms of the immune-checkpoint molecules PD-L1, PD-1, and CTLA-4 in plasma of patients with advanced NSCLC before PD-1/PD-L1 blockade. A prospective biomarker-finding trial (cohort A) included 50 previously treated patients who received nivolumab. A retrospective observational study was performed for patients treated with any PD-1/PD-L1 blockade therapy (cohorts B and C), cytotoxic chemotherapy (cohort D), or targeted therapy (cohort E). Plasma samples from all patients were assayed for soluble immune-checkpoint molecules with a highly sensitive chemiluminescence-based assay.RESULTSNonresponsiveness to PD-1/PD-L1 blockade therapy was associated with higher concentrations of these soluble immune factors among patients with immune-reactive (hot) tumors. Such an association was not apparent for patients treated with cytotoxic chemotherapy or targeted therapy. Integrative analysis of tumor size, PD-L1 expression in tumor tissue (tPD-L1), and gene expression in tumor tissue and peripheral CD8+ T cells revealed that high concentrations of the 3 soluble immune factors were associated with hyper or terminal exhaustion of antitumor immunity. The combination of soluble PD-L1 (sPD-L1) and sCTLA-4 efficiently discriminated responsiveness to PD-1/PD-L1 blockade among patients with immune-reactive tumors.CONCLUSIONCombinations of soluble immune factors might be able to identify patients unlikely to respond to PD-1/PD-L1 blockade as a result of terminal exhaustion of antitumor immunity. Our data suggest that such a combination better predicts, along with tPD-L1, for the response of patients with NSCLC.TRIAL REGISTRATIONUMIN000019674.FUNDINGThis study was funded by Ono Pharmaceutical Co. Ltd. and Sysmex Corporation.

Hepatitis C virus NS5B triggers an MDA5-mediated innate immune response by producing dsRNA without the replication of viral genomes

During the replication of viral genomes, RNA viruses produce double-stranded RNA (dsRNA), through the activity of their RNA-dependent RNA polymerases (RdRps) as viral replication intermediates. Recognition of viral dsRNA by host pattern recognition receptors - such as retinoic acid-induced gene-I (RIG-I)-like receptors and Toll-like receptor 3 - triggers the production of interferon (IFN)-β via the activation of IFN regulatory factor (IRF)-3. It has been proposed that, during the replication of viral genomes, each of RIG-I and melanoma differentiation-associated gene 5 (MDA5) form homodimers for the efficient activation of a downstream signalling pathway in host cells. We previously reported that, in the non-neoplastic human hepatocyte line PH5CH8, the RdRp NS5B derived from hepatitis C virus (HCV) could induce IFN-β expression by its RdRp activity without the actual replication of viral genomes. However, the exact mechanism by which HCV NS5B produced IFN-β remained unknown. In the present study, we first showed that NS5B derived from another Flaviviridae family member, GB virus B (GBV-B), also possessed the ability to induce IFN-β in PH5CH8 cells. Similarly, HCV NS5B, but not its G317V mutant, which lacks RdRp activity, induced the dimerization of MDA5 and subsequently the activation of IRF-3. Interestingly, immunofluorescence analysis showed that HCV NS5B produced dsRNA. Like HCV NS5B, GBV-B NS5B also triggered the production of dsRNA and subsequently the dimerization of MDA5. Taken together, our results show that HCV NS5B triggers an MDA5-mediated innate immune response by producing dsRNA without the replication of viral genomes in human hepatocytes.

Stem-like progenitor and terminally differentiated TFH-like CD4+ T cell exhaustion in the tumor microenvironment

Immune checkpoint inhibitors exert clinical efficacy against various types of cancer through reinvigoration of exhausted CD8+ T cells that attack cancer cells directly in the tumor microenvironment (TME). Using single-cell sequencing and mouse models, we show that CXCL13, highly expressed in tumor-infiltrating exhausted CD8+ T cells, induces CD4+ follicular helper T (TFH) cell infiltration, contributing to anti-tumor immunity. Furthermore, a part of the TFH cells in the TME exhibits cytotoxicity and directly attacks major histocompatibility complex-II-expressing tumors. TFH-like cytotoxic CD4+ T cells have high LAG-3/BLIMP1 and low TCF1 expression without self-renewal ability, whereas non-cytotoxic TFH cells express low LAG-3/BLIMP1 and high TCF1 with self-renewal ability, closely resembling the relationship between terminally differentiated and stem-like progenitor exhaustion in CD8+ T cells, respectively. Our findings provide deep insights into TFH-like CD4+ T cell exhaustion with helper progenitor and cytotoxic differentiated functions, mediating anti-tumor immunity orchestrally with CD8+ T cells.

Low frequency of intracranial progression in advanced NSCLC patients treated with cancer immunotherapies

Intracranial metastases are common in nonsmall-cell lung cancer (NSCLC) patients, whose prognosis is very poor. In addition, intracranial progression is common during systemic treatments due to the inability to penetrate central nervous system (CNS) barriers, whereas the intracranial effects of cancer immunotherapies remain unclear. We analyzed clinical data to evaluate the frequency of intracranial progression in advanced NSCLC patients treated with PD-1 blockade therapies compared with those treated without PD-1 blockade therapies, and found that the frequency of intracranial progression in advanced NSCLC patients treated with PD-1 blockade therapies was significantly lower than that in patients treated with cytotoxic chemotherapies. In murine models, intracranial rechallenged tumors after initial rejection by PD-1 blockade were suppressed. Accordingly, long-lived memory precursor effector T cells and antigen-specific T cells were increased by PD-1 blockade in intracranial lesions. However, intracranial rechallenged different tumors are not suppressed. Our results indicate that cancer immunotherapies can prevent intracranial progression, maintaining long-term effects intracranially as well as systemically. If intracranial recurrence occurs during the treatment with PD-1 blockade therapies, aggressive local therapies could be worthwhile.

Immunologic Significance of CD80/CD86 or Major Histocompatibility Complex-II Expression in Thymic Epithelial Tumors

Introduction

Unresectable or recurrent thymic epithelial tumors (TETs) have a poor prognosis, and treatment options are limited. This study aimed to investigate the immunologic significance of CD80/CD86 or major histocompatibility complex class II (MHC-II) expression in TETs, as potential predictive biomarkers for immune checkpoint inhibitors (ICIs).

Methods

We analyzed CD80, CD86, MHC class I (MHC-I), and MHC-II expression in TETs using immunohistochemistry and investigated their association with T-cell infiltration or ICI efficacy. In addition, we generated CD80- or MHC-II-expressing mouse tumors, evaluated the effects of ICIs, and analyzed tumor-infiltrating lymphocytes. We also performed tumor-rechallenge experiments in vivo.

Results

We found that approximately 50% and 30% of TETs had high expression of CD80/CD86 and MHC-II in tumor cells, respectively, and that this expression was related to T-cell infiltration in clinical samples. In mouse models, both CD80 and MHC-II increase the effects of ICIs. In addition, senescent T cells and long-lived memory precursor effector T cells were significantly decreased and increased, respectively, in tumor-infiltrating lymphocytes from CD80-expressing tumors, and rechallenged tumors were completely rejected after the initial eradication of CD80-expressing tumors by programmed cell death protein 1 blockade. Indeed, patients with CD80-high thymic carcinoma had longer progression-free survival with anti-programmed cell death protein 1 monoclonal antibody.

Conclusions

Half of the TETs had high expression of CD80/CD86 or MHC-II with high T-cell infiltration. These molecules could potentially increase the effects of ICIs, particularly inducing a durable response. CD80/CD86 and MHC-II can be predictive biomarkers of ICIs in TETs, promoting the development of drugs for such TETs.

Combination therapy with hydrogen peroxide and irradiation promotes an abscopal effect in mouse models

Hydrogen peroxide (H2 O2 ) induces oxidative stress and cytotoxicity, and can be used for treating cancers in combination with radiotherapy. A product comprising H2 O2 and sodium hyaluronate has been developed as a radiosensitizer. However, the effects of H2 O2 on antitumor immunity remain unclear. To investigate the effects of H2 O2 , especially the abscopal effect when combined with radiotherapy (RT), we implanted murine tumor cells simultaneously in two locations in mouse models: the hind limb and back. H2 O2 mixed with sodium hyaluronate was injected intratumorally, followed by irradiation only at the hind limb lesion. No treatment was administered to the back lesion. The H2 O2 /RT combination significantly reduced tumor growth at the noninjected/nonirradiated site in the back lesion, whereas H2 O2 or RT individually did not reduce tumor growth. Flow cytometric analyses of the tumor-draining lymph nodes in the injected/irradiated areas showed that the number of dendritic cells increased significantly with maturation in the H2 O2 /RT combination group. In addition, analyses of tumor-infiltrating lymphocytes showed that the number of CD8+ (cluster of differentiation 8) T cells and the frequency of IFN-γ+ (interferon gamma) CD8+ T cells were higher in the noninjected/nonirradiated tumors in the H2 O2 /RT group compared to those in the other groups. PD-1 (programmed death receptor 1) blockade further increased the antitumor effect against noninjected/nonirradiated tumors in the H2 O2 /RT group. Intratumoral injection of H2 O2 combined with RT therefore induces an abscopal effect by activating antitumor immunity, which can be further enhanced by PD-1 blockade. These findings promote the development of H2 O2 /RT therapy combined with cancer immunotherapies, even for advanced cancers.

High Expression of MHC Class I Overcomes Cancer Immunotherapy Resistance Due to IFNγ Signaling Pathway Defects

IFNγ signaling pathway defects are well-known mechanisms of resistance to immune checkpoint inhibitors. However, conflicting data have been reported, and the detailed mechanisms remain unclear. In this study, we have demonstrated that resistance to immune checkpoint inhibitors owing to IFNγ signaling pathway defects may be primarily caused by reduced MHC-I expression rather than by the loss of inhibitory effects on cellular proliferation or decreased chemokine production. In particular, we found that chemokines that recruit effector T cells were mainly produced by immune cells rather than cancer cells in the tumor microenvironment of a mouse model, with defects in IFNγ signaling pathways. Furthermore, we found a response to immune checkpoint inhibitors in a patient with JAK-negative head and neck squamous cell carcinoma whose HLA-I expression level was maintained. In addition, CRISPR screening to identify molecules associated with elevated MHC-I expression independent of IFNγ signaling pathways demonstrated that guanine nucleotide-binding protein subunit gamma 4 (GNG4) maintained MHC-I expression via the NF-κB signaling pathway. Our results indicate that patients with IFNγ signaling pathway defects are not always resistant to immune checkpoint inhibitors and highlight the importance of MHC-I expression among the pathways and the possibility of NF-κB-targeted therapies to overcome such resistance.

Abstract 1099: Combined treatment with direct hydrogen peroxide administration and irradiation promotes an abscopal effect in mouse models

Background: Hydrogen peroxide (H2O2) causes oxidative stress and cytotoxicity and may be used in cancer therapy in combination with radiotherapy (RT). Indeed, H2O2 has been clinically developed as a radiosensitizer (development code: KRC-01). However, effects of H2O2 on antitumor immunity remain unclear. In this study, we investigated the effects, especially an abscopal effect, using mouse models.

Material and Method: We used MC-38 (mouse colon cancer) and B16F10 (mouse melanoma) cell lines. Tumor cells were implanted simultaneously in two locations; hind legs and back of mice. A self-made radiation shielding device was used to prevent irradiation of the tumors on the back. Only the hind legs were directly injected with a mixture of H2O2 and hyaluronic acid (KRC-01), and then irradiated. Immune cells in tumors or tumor draining lymph nodes were analyzed with flow cytometry.

Result: We compared tumor growth among four groups: control, irradiation alone, H2O2 alone, and combination groups. Compared to the other groups, the combination significantly reduced non-irradiated tumor growth (abscopal effect). In immunodeficient SCID mice, this effect was not observed. Flow cytometric analyses of tumor draining lymph nodes showed that dendritic cells were maturated in the combination groups compared to the others. In addition, CD8+ T cells were activated in the non-irradiated tumors from the combination group compared to the others.

Conclusion: Intratumoral H2O2 administration enhanced the abscopal effect through activating antitumor immunity by RT.

Citation Format: Naoya Kemmotsu, Li zhu, Youki Ueda, Hiromichi Dansako, Shinichi Toyooka, Joji Nagasaki, Yosuke Togashi. Combined treatment with direct hydrogen peroxide administration and irradiation promotes an abscopal effect in mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1099.

Abstract 707: High major histocompatibility complex class I expression overcomes cancer immunotherapy resistance due to interferon gamma signaling pathway defects

IFN-γ signaling pathway defects such as JAK mutations are well-known mechanisms of resistance to immune checkpoint inhibitors (ICIs). However, some patients respond to ICIs despite IFN-γ signaling pathway defects, and the detailed mechanisms remain unclear. Here, we created JAK-deleted cancer cell lines and evaluated antitumor immunity. As a result, several tumors responded to PD-1 blockade despite JAK deletion. Such sensitive tumors had high major histocompatibility complex class I (MHC-I) expression despite IFN-γ signaling pathway defects, whereas MHC-I expression was reduced by JAK deletion in resistant tumors. In particular, if cancer cells had high MHC-I expression despite defects in IFN-γ signaling pathways, chemokines that recruit effector T cells were mainly produced by immune cells rather than cancer cells in the tumor microenvironment. Accordingly, we found a response to ICIs in a patient with JAK-negative head and neck squamous cell carcinoma, whose human leukocyte antigen class I (HLA-I) expression level was maintained. In addition, clustered regularly interspaced short palindromic repeats (CRISPR) screening to identify molecules with elevated MHC-I expression independent of IFN-γ signaling pathways demonstrated that guanine nucleotide-binding protein subunit gamma 4 (GNG4) maintained MHC-I expression via the NF-κB signaling pathway. Our results indicate that patients with IFN-ɤ signaling pathway defects are not always resistant to ICIs, and highlight the importance of MHC-I expression among the pathways, including inhibitory effects on cellular proliferation or chemokine production, and the possibility of NF-κB-targeted therapies to overcome such resistance.

Citation Format: Katsushige Kawase, Shusuke Kawashima, Joji Nagasaki, Takashi Inozume, Hiromasa Yamamoto, Masahito Kawazu, Toyoyuki Hanazawa, Yosuke Togashi. High major histocompatibility complex class I expression overcomes cancer immunotherapy resistance due to interferon gamma signaling pathway defects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 707.

Somatic mutations can induce a noninflamed tumour microenvironment via their original gene functions, despite deriving neoantigens

BACKGROUND

Identifying biomarkers to predict immune checkpoint inhibitor (ICI) efficacy is warranted. Considering that somatic mutation-derived neoantigens induce strong immune responses, patients with a high tumour mutational burden reportedly tend to respond to ICIs. However, there are several conflicting data. Therefore, we focused on the original function of neoantigenic mutations and their impact on the tumour microenvironment (TME).

METHODS

We evaluated 88 high-frequency microsatellite instability (MSI-H) colorectal cancers and analysed the function of the identified neoantigenic mutations and their influence on programmed cell death 1 (PD-1) blockade efficacy. The results were validated using The Cancer Genome Atlas (TCGA) datasets.

RESULTS

We identified frameshift mutations in RNF43 as a common neoantigenic gene mutation in MSI-H tumours. However, loss-of-function RNF43 mutations induced noninflamed TME by activating the WNT/β-catenin signalling pathway. In addition, loss of RNF43 function induced resistance to PD-1 blockade even in neoantigen-rich tumours. TCGA dataset analyses demonstrated that passenger rather than driver gene mutations were related to the inflamed TME in diverse cancer types.

CONCLUSIONS

We propose a novel concept of "paradoxical neoantigenic mutations" that can induce noninflamed TME through their original gene functions, despite deriving neoantigens, suggesting the significance of qualities as well as quantities in neoantigenic mutations.

Resistance to immune checkpoint inhibitors and the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have contributed significantly to the treatment of various types of cancer, including skin cancer. However, not all patients respond; some patients do not respond at all (primary resistance), while others experience recurrence after the initial response (acquired resistance). Therefore, overcoming ICI resistance is an urgent priority. Numerous ICI resistance mechanisms have been reported. They are seemingly quite complex, varying from patient to patient. However, most involve T-cell activation processes, especially in the tumor microenvironment (TME). ICIs exert their effects in the TME by reactivating suppressed T cells through inhibition of immune checkpoint molecules, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1). Thus, this review focuses on the resistance mechanisms based on the T-cell activation process. Here, we classify the main mechanisms of ICI resistance into three categories based on (1) antigen recognition, (2) T-cell migration and infiltration, and (3) effector functions of T cells. By identifying and understanding these resistance mechanisms individually, including unknown mechanisms, we seek to contribute to the development of novel treatments to overcome ICI resistance.

Activated CTLA-4-independent immunosuppression of Treg cells disturbs CTLA-4 blockade-mediated antitumor immunity

Combination therapy with anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and anti-programmed death-1 (PD-1) monoclonal antibodies (mAbs) has dramatically improved the prognosis of patients with multiple types of cancer, including renal cell carcinoma (RCC). However, more than half of RCC patients fail to respond to this therapy. Regulatory T cells (Treg cells) are a subset of highly immunosuppressive CD4⁺ T cells that promote the immune escape of tumors by suppressing effector T cells in the tumor microenvironment (TME) through various mechanisms. CTLA-4 is constitutively expressed in Treg cells and is regarded as a key molecule for Treg-cell-mediated immunosuppressive functions, suppressing antigen-presenting cells by binding to CD80/CD86. Reducing Treg cells in the TME with an anti-CTLA-4 mAb with antibody-dependent cellular cytotoxicity (ADCC) activity is considered an essential mechanism to achieve tumor regression. In contrast, we demonstrated that CTLA-4 blockade without ADCC activity enhanced CD28 costimulatory signaling pathways in Treg cells and promoted Treg-cell proliferation in mouse models. CTLA-4 blockade also augmented CTLA-4-independent immunosuppressive functions, including cytokine production, leading to insufficient antitumor effects. Similar results were also observed in human peripheral blood lymphocytes and tumor-infiltrating lymphocytes from patients with RCC. Our findings highlight the importance of Treg-cell depletion to achieve tumor regression in response to CTLA-4 blockade therapies.

Survival outcomes and functional results of VOLTAGE-A: Preoperative chemoradiotherapy (CRT) and consolidation nivolumab (nivo) in patients (pts) with both microsatellite stable (MSS) and microsatellite instability–high (MSI-H) locally advanced rectal cancer (LARC)

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Background: In VOLTAGE-A, CRT (50.4 Gy with capecitabine of 1,650 mg/m2) followed by five cycles of consolidation Nivo (240 mg q2 weeks [W]) and radical surgery showed 30% of pathological complete response (pCR) in pts with MSS and 60% in MSI-H T3–4 NanyM0 LARC. Here, we report survival outcomes and functional results. Methods: All 39 MSS and 5 MSI-H pts were included in the VOLTAGE-A from Jan 2017 to Oct 2019. Survival outcomes, late adverse events, and patient-reported outcome measurements for urogenital and anal functions were analyzed. Urinary function was evaluated using the International Prostate Symptom Score (I-PSS) periodically at 1W, 1, 3, 6, and 12 months (M), postoperatively. Sexual function in sexually active male pts was evaluated using the International Index of Erectile Function (IIEF) score at 3, 6, and 12M, postoperatively. Anal function was evaluated using the Wexner score, low anterior resection syndrome (LARS) score, and fecal incontinence severity index (FISI) score at 1-year post-surgery. All functional scores were evaluated preoperatively. Results: With a median follow-up of 44.8M (range, 25.7-58.9M), the 3-year relapse-free survival (RFS) and 3-year overall survival (OS) rates were respectively 79.5% and 97.4% in MSS, and 100% each in MSI-H pts. Of the MSS pts, those with pCR, clinical CR (cCR) according to the MSKCC criteria, high PD-L1 expression (tumor proportion score [TPS] ≥1%), and CD8/eTreg ratios of ≥2.5 had a trend of better 3-year RFS and OS than those without. During the follow-up period, one patient developed CTCAE grade 3 immune-related colitis, which was diagnosed 20M after the last dose of Nivo. Postoperative functional results were acceptable in both populations; pre-surgical median I-PSS scores were 3, whereas postsurgical values were 5 (1W), 5.5 (1M), 5 (3M), 4 (6M), and 4 (12M); median IIEF score was 20 at pre-surgery and 6 (3M), 6 (6M), and 8 (12M) at post-surgery; median scores of Wexner, LARS, and FISI were 2, 23, and 7 at pre-surgery, and 9, 30, and 17 at 1-year post-surgery, respectively. Conclusions: Preoperative CRT followed by Nivo showed promising survival outcomes in both MSS and MSI-H LARC pts. The therapeutic effect of pCR, cCR, and certain biomarkers analyzed by pre-CRT samples could be used as prognostic predictors in MSS pts. Clinical trial information: NCT02948348 .[Table: see text]

[Clonal Evolution in the Tumor Microenvironment]

Cancer immunotherapy has shown efficacy in many types of cancer. However, there are many challenges, such as the difficulty in predicting therapeutic efficacy. In the tumor microenvironment, tumor cells evolve to escape the anti-tumor immune response and have capacity of proliferation, whereas immune cells also evolve along with tumor cells. Elucidating the detailed clonal evolution is helpful for the development of biomarkers for prediction of therapeutic effects and novel therapies. To elucidate clonal evolution in the tumor microenvironment, analyses at the single-cell level, rather than in bulks, is necessary for heterogeneous and highly diverse cell populations. Recently, single-cell sequencing can be used to analyze comprehensive gene expression, or it is possible to focus on specific regions, such as T-cell or B-cell receptor sequences. In addition, technologies have been developed that allow spatial analyses by a single-cell level while preserving tissue location information. Recently, new findings have been clarified using pre- and post-treatment samples from same patients to analyze the clonal progression of the tumor cells themselves and immune cells based on sequential changes in the tumor microenvironment.

Mechanisms of resistance to immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are effective for various types of cancer, and their application has led to paradigm shifts in cancer treatment. While many patients can obtain clinical benefits from ICI treatment, a large number of patients are primarily resistant to such treatment or acquire resistance after an initial response. Thus, elucidating the resistance mechanisms is warranted to improve the clinical outcomes of ICI treatment. ICIs exert their antitumor effects by activating T cells in the tumor microenvironment. There are various resistance mechanisms, such as insufficient antigen recognition by T cells, impaired T‐cell migration and/or infiltration, and reduced T‐cell cytotoxicity, most of which are related to the T‐cell activation process. Thus, we classify them into three main mechanisms: resistance mechanisms related to antigen recognition, T‐cell migration and/or infiltration, and effector functions of T cells. In this review, we summarize these mechanisms of resistance to ICIs related to the T‐cell activation process and progress in the development of novel therapies that can overcome resistance.

Mixed Response to Cancer Immunotherapy is Driven by Intratumor Heterogeneity and Differential Interlesion Immune Infiltration

Some patients experience mixed response to immunotherapy, whose biological mechanisms and clinical impact have been obscure. We obtained two tumor samples from lymph node (LN) metastatic lesions in a same patient. Whole exome sequencing for the both tumors and single-cell sequencing for the both tumor-infiltrating lymphocytes (TIL) demonstrated a significant difference in tumor clonality and TILs' characteristics, especially exhausted T-cell clonotypes, although a close relationship between the tumor cell and T-cell clones were observed as a response of an overlapped exhausted T-cell clone to an overlapped neoantigen. To mimic the clinical setting, we generated a mouse model of several clones from a same tumor cell line. Similarly, differential tumor clones harbored distinct TILs, and one responded to programmed cell death protein 1 (PD-1) blockade but the other did not in this model. We further conducted cohort study (n = 503) treated with PD-1 blockade monotherapies to investigate the outcome of mixed response. Patients with mixed responses to PD-1 blockade had a poor prognosis in our cohort. Particularly, there were significant differences in both tumor and T-cell clones between the primary and LN lesions in a patient who experienced tumor response to anti-PD-1 mAb followed by disease progression in only LN metastasis. Our results underscore that intertumoral heterogeneity alters characteristics of TILs even in the same patient, leading to mixed response to immunotherapy and significant difference in the outcome.

Significance

Several patients experience mixed responses to immunotherapies, but the biological mechanisms and clinical significance remain unclear. Our results from clinical and mouse studies underscore that intertumoral heterogeneity alters characteristics of TILs even in the same patient, leading to mixed response to immunotherapy and significant difference in the outcome.

A variety of 'exhausted' T cells in the tumor microenvironment

In T cell biology, 'exhaustion' was initially described as a hyporesponsive state in CD8 + T cells during chronic infections. Recently, exhaustion has been recognized as a T-cell dysfunctional state in the tumor microenvironment (TME). The term 'exhaustion' is used mainly to refer to effector T cells with a reduced capacity to secrete cytokines and an increased expression of inhibitory receptors. The upregulation of exhaustion-related inhibitory receptors, including programmed cell death protein 1 (PD-1), in such T cells has been associated with the development of tumors, prompting the development of immune checkpoint inhibitors. In addition to CD8 + T cells, CD4 + T cells, including the regulatory T (Treg) cell subset, perform a wide variety of functions within the adaptive immune system. Upregulation of the same inhibitory receptors that are associated with CD8 + T-cell exhaustion has also been identified in CD4 + T cells in chronic infections and cancers, suggesting a similar CD4 + T-cell exhaustion phenotype. For instance, high expression of PD-1 has been observed in Treg cells in the TME, and such Treg cells can play an important role in the resistance to PD-1 blockade therapies. Furthermore, recent progress in single-cell RNA sequencing has shown that CD4 + T cells with cytotoxic activity are also vulnerable to exhaustion. In this review, we will discuss novel insights into various exhausted T-cell subsets, which could reveal novel therapeutic targets and strategies to induce a robust antitumor immune response.

Preoperative Chemoradiotherapy plus Nivolumab before Surgery in Patients with Microsatellite Stable and Microsatellite Instability-High Locally Advanced Rectal Cancer

PURPOSE

Preoperative chemoradiotherapy (CRT) and surgical resection are the standard treatment for locally advanced rectal cancer (LARC). Combining immune checkpoint inhibitors with radiation suggests a promising approach for enhancing efficacy. We investigated the efficacy of CRT followed by nivolumab and surgery in patients with LARC.

PATIENTS AND METHODS

In phase I, we investigated the feasibility of sequentially combined CRT, 5 cycles of nivolumab, and radical surgery. In phase II, patients with microsatellite stable (MSS) and microsatellite instability-high (MSI-H) LARC were evaluated.

RESULTS

Three patients in phase I received full courses of CRT and nivolumab without dose modification; the schedule was recommended for phase II. A pathologic complete response (pCR) was centrally confirmed in 30% [11/37; 90% confidence interval (CI), 18%-44%] and 60% (3/5) of the MSS and exploratory MSI-H cohorts, respectively. While immune-related severe adverse events were observed in 3 patients, no treatment-related deaths were observed. In 38 patients with MSS who underwent surgery, pCR rates of 75% (6/8) and 17% (5/30; P = 0.004, Fisher exact test) were observed in those with programmed cell death ligand 1 (PD-L1) tumor proportion score ≥1% and <1%, respectively; IHC staining was performed using pre-CRT samples. In 24 patients with MSS, pre-CRT samples were analyzed by flow cytometry; pCR rates of 78% (7/9) and 13% (2/15; P = 0.003, Fisher exact test) were observed for CD8+ T cell/effector regulatory T cell (CD8/eTreg) ratios of ≥2.5 and <2.5, respectively, in tumor-infiltrating lymphocytes.

CONCLUSIONS

CRT followed by consolidation nivolumab could increase pCR. PD-L1 expression and an elevated CD8/eTreg ratio were positive predictors in patients with MSS LARC.

HLA Class I Analysis Provides Insight Into the Genetic and Epigenetic Background of Immune Evasion in Colorectal Cancer With High Microsatellite Instability

BACKGROUND & AIMS

A detailed understanding of antitumor immunity is essential for optimal cancer immune therapy. Although defective mutations in the B2M and HLA-ABC genes, which encode molecules essential for antigen presentation, have been reported in several studies, the effects of these defects on tumor immunity have not been quantitatively evaluated.

METHODS

Mutations in HLA-ABC genes were analyzed in 114 microsatellite instability-high colorectal cancers using a long-read sequencer. The data were further analyzed in combination with whole-exome sequencing, transcriptome sequencing, DNA methylation array, and immunohistochemistry data.

RESULTS

We detected 101 truncating mutations in 57 tumors (50%) and loss of 61 alleles in 21 tumors (18%). Based on the integrated analysis that enabled the immunologic subclassification of microsatellite instability-high colorectal cancers, we identified a subtype of tumors in which lymphocyte infiltration was reduced, partly due to reduced expression of HLA-ABC genes in the absence of apparent genetic alterations. Survival time of patients with such tumors was shorter than in patients with other tumor types. Paradoxically, tumor mutation burden was highest in the subtype, suggesting that the immunogenic effect of accumulating mutations was counterbalanced by mutations that weakened immunoreactivity. Various genetic and epigenetic alterations, including frameshift mutations in RFX5 and promoter methylation of PSMB8 and HLA-A, converged on reduced expression of HLA-ABC genes.

CONCLUSIONS

Our detailed immunogenomic analysis provides information that will facilitate the improvement and development of cancer immunotherapy.

Lactic acid promotes PD-1 expression in regulatory T cells in highly glycolytic tumor microenvironments

The balance of programmed death-1 (PD-1)-expressing CD8⁺ T cells and regulatory T (Treg) cells in the tumor microenvironment (TME) determines the clinical efficacy of PD-1 blockade therapy through the competition of their reactivation. However, factors that determine this balance remain unknown. Here, we show that Treg cells gain higher PD-1 expression than effector T cells in highly glycolytic tumors, including MYC-amplified tumors and liver tumors. Under low-glucose environments via glucose consumption by tumor cells, Treg cells actively absorbed lactic acid (LA) through monocarboxylate transporter 1 (MCT1), promoting NFAT1 translocation into the nucleus, thereby enhancing the expression of PD-1, whereas PD-1 expression by effector T cells was dampened. PD-1 blockade invigorated the PD-1-expressing Treg cells, resulting in treatment failure. We propose that LA in the highly glycolytic TME is an active checkpoint for the function of Treg cells in the TME via upregulation of PD-1 expression.

PD-1 blockade therapy promotes infiltration of tumor-attacking exhausted T cell clonotypes

PD-1 blockade exerts clinical efficacy against various types of cancer by reinvigorating T cells that directly attack tumor cells (tumor-specific T cells) in the tumor microenvironment (TME), and tumor-infiltrating lymphocytes (TILs) also comprise nonspecific bystander T cells. Here, using single-cell sequencing, we show that TILs include skewed T cell clonotypes, which are characterized by exhaustion (T_ex) or nonexhaustion signatures (T_non-ex). Among skewed clonotypes, those in the T_ex, but not those in the T_non-ex, cluster respond to autologous tumor cell lines. After PD-1 blockade, non-preexisting tumor-specific clonotypes in the T_ex cluster appear in the TME. Tumor-draining lymph nodes (TDLNs) without metastasis harbor a considerable number of such clonotypes, whereas these clonotypes are rarely detected in peripheral blood. We propose that tumor-infiltrating skewed T cell clonotypes with an exhausted phenotype directly attack tumor cells and that PD-1 blockade can promote infiltration of such T_ex clonotypes, mainly from TDLNs.

Transcript-targeted analysis reveals isoform alterations and double-hop fusions in breast cancer

Although transcriptome alteration is an essential driver of carcinogenesis, the effects of chromosomal structural alterations on the cancer transcriptome are not yet fully understood. Short-read transcript sequencing has prevented researchers from directly exploring full-length transcripts, forcing them to focus on individual splice sites. Here, we develop a pipeline for Multi-Sample long-read Transcriptome Assembly (MuSTA), which enables construction of a transcriptome from long-read sequence data. Using the constructed transcriptome as a reference, we analyze RNA extracted from 22 clinical breast cancer specimens. We identify a comprehensive set of subtype-specific and differentially used isoforms, which extended our knowledge of isoform regulation to unannotated isoforms including a short form TNS3. We also find that the exon-intron structure of fusion transcripts depends on their genomic context, and we identify double-hop fusion transcripts that are transcribed from complex structural rearrangements. For example, a double-hop fusion results in aberrant expression of an endogenous retroviral gene, ERVFRD-1, which is normally expressed exclusively in placenta and is thought to protect fetus from maternal rejection; expression is elevated in several TCGA samples with ERVFRD-1 fusions. Our analyses provide direct evidence that full-length transcript sequencing of clinical samples can add to our understanding of cancer biology and genomics in general.

TIGIT/CD155 axis mediates resistance to immunotherapy in patients with melanoma with the inflamed tumor microenvironment

BACKGROUND

Patients with cancer benefit from treatment with immune checkpoint inhibitors (ICIs), and those with an inflamed tumor microenvironment (TME) and/or high tumor mutation burden (TMB), particularly, tend to respond to ICIs; however, some patients fail, whereas others acquire resistance after initial response despite the inflamed TME and/or high TMB. We assessed the detailed biological mechanisms of resistance to ICIs such as programmed death 1 and/or cytotoxic T-lymphocyte-associated protein 4 blockade therapies using clinical samples.

METHODS

We established four pairs of autologous tumor cell lines and tumor-infiltrating lymphocytes (TILs) from patients with melanoma treated with ICIs. These tumor cell lines and TILs were subjected to comprehensive analyses and in vitro functional assays. We assessed tumor volume and TILs in vivo mouse models to validate identified mechanism. Furthermore, we analyzed additional clinical samples from another large melanoma cohort.

RESULTS

Two patients were super-responders, and the others acquired resistance: the first patient had a non-inflamed TME and acquired resistance due to the loss of the beta-2 microglobulin gene, and the other acquired resistance despite having inflamed TME and extremely high TMB which are reportedly predictive biomarkers. Tumor cell line and paired TIL analyses showed high CD155, TIGIT ligand, and TIGIT expression in the tumor cell line and tumor-infiltrating T cells, respectively. TIGIT blockade or CD155-deletion activated T cells in a functional assay using an autologous cell line and paired TILs from this patient. CD155 expression increased in surviving tumor cells after coculturing with TILs from a responder, which suppressed TIGIT⁺ T-cell activation. Consistently, TIGIT blockade or CD155-deletion could aid in overcoming resistance to ICIs in vivo mouse models. In clinical samples, CD155 was related to resistance to ICIs in patients with melanoma with an inflamed TME, including both primary and acquired resistance.

CONCLUSIONS

The TIGIT/CD155 axis mediates resistance to ICIs in patients with melanoma with an inflamed TME, promoting the development of TIGIT blockade therapies in such patients with cancer.

Highly immunogenic cancer cells require activation of the WNT pathway for immunological escape

[Figure: see text].

Single-Cell Analysis of the Multicellular Ecosystem in Viral Carcinogenesis by HTLV-1

High-dimensional single-cell landscape of immune alterations during HTLV-1 infection and leukemogenesis identifies hallmarks of premalignant and malignant T-cell states and the accompanying shift of systemic immune state toward myeloid and immunosuppressive.

Premalignant clonal expansion of human T-cell leukemia virus type-1 (HTLV-1)–infected cells occurs before viral carcinogenesis. Here we characterize premalignant cells and the multicellular ecosystem in HTLV-1 infection with and without adult T-cell leukemia/lymphoma (ATL) by genome sequencing and single-cell simultaneous transcriptome and T/B-cell receptor sequencing with surface protein analysis. We distinguish malignant phenotypes caused by HTLV-1 infection and leukemogenesis and dissect clonal evolution of malignant cells with different clinical behavior. Within HTLV-1–infected cells, a regulatory T-cell phenotype associates with premalignant clonal expansion. We also delineate differences between virus- and tumor-related changes in the nonmalignant hematopoietic pool, including tumor-specific myeloid propagation. In a newly generated conditional knockout mouse model recapitulating T-cell–restricted CD274 (encoding PD-L1) gene lesions found in ATL, we demonstrate that PD-L1 overexpressed by T cells is transferred to surrounding cells, leading to their PD-L1 upregulation. Our findings provide insights into clonal evolution and immune landscape of multistep virus carcinogenesis.

Importance of lymph node immune responses in MSI-H/dMMR colorectal cancer

Patients with colorectal cancers (CRCs) generally exhibit improved survival through intensive lymph node (LN) dissection. However, recent progress in cancer immunotherapy revisits the potential importance of regional LNs, where T cells are primed to attack tumor cells. To elucidate the role of regional LN, we investigated the immunological status of nonmetastatic regional LN lymphocytes (LNLs) in comparison with those of the tumor microenvironment (tumor-infiltrating lymphocytes; TILs) using flow cytometry and next-generation sequencing. LNLs comprised an intermediate level of the effector T cell population between peripheral blood lymphocytes (PBLs) and TILs. Significant overlap of the T cell receptor (TCR) repertoire was observed in microsatellite instability–high/mismatch repair–deficient (MSI-H/dMMR) CRCs with high tumor mutation burden (TMB), although limited TCRs were shared between nonmetastatic LNs and primary tumors in microsatellite stable/MMR proficient (MSS/pMMR) CRC patients with low TMB. In line with the overlap of the TCR repertoire, an excessive LN dissection did not provide a positive impact on long-term prognosis in our MSI-H/dMMR CRC cohort (n = 130). We propose that regional LNs play an important role in antitumor immunity, particularly in MSI-H/dMMR CRCs with high TMB, requiring care to be taken regarding excessive nonmetastatic LN dissection in MSI-H/dMMR CRC patients.

Translational research of VOLTAGE-A: Efficacy predictors of preoperative chemoradiotherapy and consolidation nivolumab in patients with both microsatellite stable and microsatellite instability-high locally advanced rectal cancer

100

Background: In VOLTAGE-A, chemoradiotherapy (CRT; 50.4Gy with capecitabine, 1,650mg/m2) followed by five cycles of consolidation nivolumab (nivo) (240mg q2 weeks) showed 30% pathological complete response [pCR; AJCC tumor regression grade (TRG) 0] and 38% major pathological responses (AJCC TRG 0-1) in patients with microsatellite stable (MSS) locally advanced primary rectal cancer (LARC). In addition, 60% pCR was observed in patients with microsatellite instability-high (MSI-H) LARC. In this study, we aimed to determine the predictive biomarkers for efficacy of sequential preoperative CRT and consolidation nivo. Methods: Serial tumor biopsies were performed at four time points:pre-CRT; post-CRT; post-3 cycles of nivo; and pre-surgery. We analyzed the immune status of the patients by flow cytometry using the collected tumor-infiltrating lymphocytes (TILs) dissociated from tumor samples. Whole exome and RNA sequencing analyses were conducted using the extracted DNA and RNA from tumor, respectively. The PD-L1 status of tumor samples was also evaluated by in vitro diagnostic immunohistochemistry staining. Results: Of the 38 MSS patients whose PD-L1 tumor proportion score (TPS) was analyzable in pre-CRT samples, the pCR rates were 67% (6/9) and 17% (5/29) in positive (≥1%) and negative PD-L1 status (p = 0.009), respectively. Among the 24 MSS patients whose samples were serially collected, the pCR rates according to CD8+ T cells/effector regulatory T cells (CD8/eTreg) ratio in TILs of pre-CRT samples ≥2.5 and < 2.5 were 78% (7/9) and 13% (2/15), respectively (p = 0.003). The CD8/eTreg ratio in TILs was consistently high in patients with pCR during the study treatments. Ki-67 and PD-1 expression by CD8+ T cells in TILs was significantly high in pre-CRT samples from patients TRG 0-1. Conversely, in patients with TRG 2-3, CTLA-4 expression by both CD4+ T cells and CD8+ T cells in TILs was significantly high after five cycles of nivo, suggesting the potential resistance mechanisms of nivo monotherapy. Of the 21 MSS patients whose consensus molecular subtype (CMS) was analyzable, those with CMS1 and CMS3 tumors achieved 100% (2/2) and 60% (4/6) TRG 0-1, respectively. In contrast, patients with CMS2 and CMS4 tumors achieved 43% (3/7) and 29% (2/7) TRG 0-1, respectively. The tumor mutational burden (TMB) of pre-CRT samples in five MSI-H patients was higher than that in the 24 MSS patients (median: 13.2 vs. 0.99 mutation/Mbp, p < 0.0001). Among MSS patients, TMB was higher in patients with TRG 0-1 than in patients with TRG 2-3 (median: 1.45 vs. 0.84 mutation/Mbp, p = 0.016). Conclusions: Positive PD-L1 TPS; high CD8/eTreg ratio; Ki-67, PD-1, and CTLA-4 expression by CD8+ T cells in TILs; CMS 1 or 3; and high TMB can be good predictors of efficacy of preoperative CRT followed by nivo. Clinical trial information: NCT02948348.

HSP90 inhibition overcomes EGFR amplification-induced resistance to third-generation EGFR-TKIs

Background

Patients with non‐small cell lung cancer (NSCLC) harboring activating EGFR mutations are sensitive to epidermal growth factor receptor‐tyrosine kinase inhibitors (EGFR‐TKIs) but inevitably develop resistance to the inhibitors mostly through acquisition of the secondary T790M mutation. Although third‐generation EGFR‐TKIs overcome this resistance by selectively inhibiting EGFR with EGFR‐TKI‐sensitizing and T790M mutations, acquired resistance to third‐generation EGFR‐TKIs invariably develops.

Methods

Next‐generation sequencing (NGS) and fluorescence in situ hybridization (FISH) analysis were performed in an EGFR T790M‐mutated NSCLC patient who had progressed after a third‐generation EGFR‐TKI, TAS‐121. EGFR‐mutated cell lines were subjected to a cell proliferation assay and western blotting analysis with EGFR‐TKIs and a heat shock protein 90 (HSP90) inhibitor.

Results

NGS and FISH analysis revealed EGFR amplification in the resistant cancer cells. While EGFR L858R/T90M‐mutated cell line was sensitive to osimertinib or TAS‐121 in vitro, EGFR‐overexpressing cell lines displayed resistance to these EGFR‐TKIs. Western blot analysis showed that EGFR phosphorylation and overexpression of EGFR in cell lines was not suppressed by third‐generation EGFR‐TKIs. In contrast, an HSP90 inhibitor reduced total and phosphorylated EGFR and inhibited the proliferation of resistant cell lines.

Conclusions

EGFR amplification confers resistance to third‐generation EGFR‐TKIs which can be overcome by HSP90 inhibition. The results provide a preclinical rationale for the use of HSP90 inhibitors to overcome EGFR amplification‐mediated resistance.

Vaginal Transmission of Cancer from Mothers with Cervical Cancer to Infants

Two cases of pediatric lung cancer (in 23-month-old and 6-year-old boys) resulting from mother-to-infant transmission of uterine cervical tumors were incidentally detected during routine next-generation sequencing of paired samples of tumor and normal tissue. Spontaneous regression of some lesions in the first child and slow growth of the tumor mass in the second child suggested the existence of alloimmune responses against the transmitted tumors. Immune checkpoint inhibitor therapy with nivolumab led to a strong regression of all remaining tumors in the first child. (Funded by the Japan Agency for Medical Research and Development and others; TOP-GEAR UMIN Clinical Trials Registry number, UMIN000011141.).

Site-Specific and Targeted Therapy Based on Molecular Profiling by Next-Generation Sequencing for Cancer of Unknown Primary Site: A Nonrandomized Phase 2 Clinical Trial

Importance

Although profiling of gene expression and gene alterations by next-generation sequencing (NGS) to predict the primary tumor site and guide molecularly targeted therapy might be expected to improve clinical outcomes for cancer of unknown primary site (CUP), to our knowledge, no clinical trial has previously evaluated this approach.

Objective

To assess the clinical use of site-specific treatment, including molecularly targeted therapy based on NGS results, for patients with CUP.

Design, Setting, and Participants

This phase 2 clinical trial was conducted at 19 institutions in Japan and enrolled 111 previously untreated patients with the unfavorable subset of CUP between March 2015 and January 2018, with 97 patients being included in the efficacy analysis. Eligibility criteria included a diagnosis of unfavorable CUP after mandatory examinations, including pathological evaluation by immunohistochemistry, chest-abdomen-pelvis computed tomography scans, and a positron emission tomography scan.

Interventions

RNA and DNA sequencing for selected genes was performed simultaneously to evaluate gene expression and gene alterations, respectively. A newly established algorithm was applied to predict tumor origin based on these data. Patients received site-specific therapy, including molecularly targeted therapy, according to the predicted site and detected gene alterations.

Main Outcomes And Measures

The primary end point was 1-year survival probability. Secondary end points included progression-free survival (PFS), overall survival (OS), objective response rate, safety, efficacy according to predicted site, and frequency of gene alterations.

Results

Of 97 participants, 49 (50.5%) were women and the median (range) age was 64 (21-81) years. The cancer types most commonly predicted were lung (21 [21%]), liver (15 [15%]), kidney (15 [15%]), and colorectal (12 [12%]) cancer. The most frequent gene alterations were in TP53 (45 [46.4%]), KRAS (19 [19.6%]), and CDKN2A (18 [18.6%]). The 1-year survival probability, median OS, and median PFS were 53.1% (95% CI, 42.6%-62.5%), 13.7 months (95% CI, 9.3-19.7 months), and 5.2 months (95% CI, 3.3-7.1 months), respectively. Targetable EGFR mutations in tumor specimens were detected in 5 patients with predicted non-small-cell lung cancer (5.2%), 4 of whom were treated with afatinib; 2 of these patients achieved a durable PFS of longer than 6 months.

Conclusions and Relevance

This study's findings suggest that site-specific treatment, including molecularly targeted therapy based on profiling gene expression and gene alterations by NGS, can contribute to treating patients with the unfavorable subset of CUP.

Trial Registration

UMIN Identifier: UMIN000016794.

Blockade of EGFR improves responsiveness to PD-1 blockade in EGFR-mutated non-small cell lung cancer

The clinical efficacy of anti-PD-1 (programmed cell death-1) monoclonal antibody (mAb) against cancers with oncogenic driver gene mutations, which often harbor a low tumor mutation burden, is variable, suggesting different contributions of each driver mutation to immune responses. Here, we investigated the immunological phenotypes in the tumor microenvironment (TME) of epidermal growth factor receptor (EGFR)-mutated lung adenocarcinomas, for which anti-PD-1 mAb is largely ineffective. Whereas EGFR-mutated lung adenocarcinomas had a noninflamed TME, CD4⁺ effector regulatory T cells, which are generally present in the inflamed TME, showed high infiltration. The EGFR signal activated cJun/cJun N-terminal kinase and reduced interferon regulatory factor-1; the former increased CCL22, which recruits CD4⁺ regulatory T cells, and the latter decreased CXCL10 and CCL5, which induce CD8⁺ T cell infiltration. The EGFR inhibitor erlotinib decreased CD4⁺ effector regulatory T cells infiltration in the TME and in combination with anti-PD-1 mAb showed better antitumor effects than either treatment alone. Our results suggest that EGFR inhibitors when used in conjunction with anti-PD-1 mAb could increase the efficacy of immunotherapy in lung adenocarcinomas.

The potential application of PD-1 blockade therapy for early-stage biliary tract cancer

Biliary tract cancer (BTC) is an aggressive cancer with a poor prognosis partially due to the limited success in developing novel therapies, including molecularly targeted therapies and immunotherapies. Programmed cell death-1 (PD-1) blockade therapy is less effective against BTCs, necessitating further studies to understand the detailed immunological status of the tumor microenvironment (TME) in BTC. Here, we examined the immunological status of the TME in 37 BTCs with early- to late-stage disease, especially focusing on PD-1+CD8+ T cells. PD-1+CD8+ T cells, which are reportedly associated with the clinical response to PD-1 blockade therapy, were frequently observed in early-stage BTC and decreased with disease progression. Imaging mass cytometry for representative PD-1+CD8+TIL-high and -low patients demonstrated that tumor-infiltrating PD-1+CD8+ T cells were localized adjacent to tumor cells, whereas PD-1-CD8+ T cells were detected mainly in the stroma of the TME. In a mouse model, PD-1 expression by tumor-infiltrating CD8+ T cells was higher in smaller tumors and decreased with tumor growth. Consequently, large tumors became resistant to PD-1 blockade, while small tumors containing higher numbers of PD-1+CD8+ T cells were sensitive. We propose the important role of tumor-infiltrating PD-1+CD8+ T cells in anti-tumor immunity and the potential application of PD-1 blockade therapy for early-stage BTC.

The PD-1 expression balance between effector and regulatory T cells predicts the clinical efficacy of PD-1 blockade therapies

Immune checkpoint blockade has provided a paradigm shift in cancer therapy, but the success of this approach is very variable; therefore, biomarkers predictive of clinical efficacy are urgently required. Here, we show that the frequency of PD-1⁺CD8⁺ T cells relative to that of PD-1⁺ regulatory T (T_reg) cells in the tumor microenvironment can predict the clinical efficacy of programmed cell death protein 1 (PD-1) blockade therapies and is superior to other predictors, including PD ligand 1 (PD-L1) expression or tumor mutational burden. PD-1 expression by CD8⁺ T cells and T_reg cells negatively impacts effector and immunosuppressive functions, respectively. PD-1 blockade induces both recovery of dysfunctional PD-1⁺CD8⁺ T cells and enhanced PD-1⁺ T_reg cell-mediated immunosuppression. A profound reactivation of effector PD-1⁺CD8⁺ T cells rather than PD-1⁺ T_reg cells by PD-1 blockade is necessary for tumor regression. These findings provide a promising predictive biomarker for PD-1 blockade therapies.

Enhanced tumor response to radiotherapy after PD-1 blockade in metastatic gastric cancer

BACKGROUND

Immune checkpoint inhibitors may enhance the efficacy of radiotherapy (RT) in cancer treatment but the effect remains unknown in metastatic gastric cancer (mGC). This study aimed to compare the tumor shrinkage by palliative RT for mGC patients with or without previous exposure to anti-PD-1 therapy.

METHODS

Data of 36 mGC patients who had received palliative RT from April 2013 to May 2019 were analyzed. Primary tumor responses were evaluated through a volumetric measurement-based method using computed tomography (CT) and endoscopic responses were evaluated in patients who underwent endoscopy before and after RT. Tumor microenvironment (TME) immune status was investigated by analyzing tumor-infiltrating lymphocytes by flow cytometry.

RESULTS

Among 36 patients, 18 had previous exposure to anti-PD-1 before RT showing no significant differences in baseline characteristics with the other 18 patients without exposure to anti-PD-1 treatment. Tumor responses were observed in 28% (5/18) and none (0/18) in the anti-PD-1-exposed vs. naïve group, respectively (P = 0.045). Five out of eight patients in the anti-PD-1-exposed group, who underwent endoscopy after RT showed partial response, but none in the anti-PD-1-naïve patients showed response (P = 0.026). Increase in the CD8⁺ T cell/effector regulatory T cell ratio in TILs after anti-PD-1 therapy was noted in three responders to RT, but not in the other three non-responders.

CONCLUSIONS

Prior exposure to anti-PD-1 therapy increases tumor response to RT. Immune profiling suggests that anti-PD-1 therapy may enhance the efficacy of RT by immunoactivation in the TME.

Multicenter Phase I/II Trial of Napabucasin and Pembrolizumab in Patients with Metastatic Colorectal Cancer (EPOC1503/SCOOP Trial)

PURPOSE

This is a phase I/II trial to assess the efficacy and safety of napabucasin plus pembrolizumab for metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Phase I was conducted to determine the recommended phase 2 dose (RP2D) in a dose escalation design of napabucasin (240 to 480 mg twice daily) with 200 mg pembrolizumab every 3 weeks. Phase II included cohort A (n = 10, microsatellite instability high, MSI-H) and cohort B (n = 40, microsatellite stable, MSS). The primary endpoint was immune-related objective response rate (irORR). PD-L1 combined positive score (CPS), genomic profiles, and the consensus molecular subtypes (CMS) of colorectal cancer were assessed.

RESULTS

A total of 55 patients were enrolled in this study. In phase I, no patients experienced dose-limiting toxicities, and napabucasin 480 mg was determined as RP2D. The irORR was 50.0% in cohort A and 10.0% in cohort B. In cohort B, the irORR was 0%, 5.3%, and 42.9% in CPS < 1, 1≤ CPS <10, and CPS ≥ 10, respectively. Patients with objective response tended to have higher tumor mutation burden than those without. Of evaluable 18 patients for CMS classification in cohort B, the irORR was 33.3%, 0%, 33.3%, and 33.3% in CMS1, CMS2, CMS3, and CMS4, respectively. The common grade 3 or higher treatment-related adverse events included fever (10.0%) in cohort A and decreased appetite (7.5%) and diarrhea (5.0%) in cohort B.

CONCLUSIONS

Napabucasin with pembrolizumab showed antitumor activity with acceptable toxicities for patients with MSS mCRC as well as MSI-H mCRC, although it did not meet the primary end point. The impact of related biomarkers on the efficacy warrants further investigations in the additional cohort.See related commentary by Nusrat, p. 5775.

An Oncogenic Alteration Creates a Microenvironment that Promotes Tumor Progression by Conferring a Metabolic Advantage to Regulatory T Cells

Only a small percentage of patients afflicted with gastric cancer (GC) respond to immune checkpoint blockade (ICB). To study the mechanisms underlying this resistance, we examined the immune landscape of GC. A subset of these tumors was characterized by high frequencies of regulatory T (Treg) cells and low numbers of effector T cells. Genomic analyses revealed that these tumors bore mutations in RHOA that are known to drive tumor progression. RHOA mutations in cancer cells activated the PI3K-AKT-mTOR signaling pathway, increasing production of free fatty acids that are more effectively consumed by Treg cells than effector T cells. RHOA mutant tumors were resistant to PD-1 blockade but responded to combination of PD-1 blockade with inhibitors of the PI3K pathway or therapies targeting Treg cells. We propose that the metabolic advantage conferred by RHOA mutations enables Treg cell accumulation within GC tumors, generating an immunosuppressive TME that underlies resistance to ICB.

Association between the mutational smoking signature and the immune microenvironment in lung adenocarcinoma

OBJECTIVES

Mutational signatures associated with tobacco smoking (mutational smoking signatures: SS) are characterized mainly by C > A mutations. The aim of this study was to characterize the association between the tumor immune microenvironment and the SS in lung adenocarcinoma.

METHODS

Lung adenocarcinomas surgically resected from 96 patients, for which whole exome sequencing data was available, were included in the study. We extracted the SS from whole exome sequencing data, calculated the weights of SS using deconstructSigs, and compared the clinicopathological features of SS positive (SS+) and negative (SS-) adenocarcinomas. We selected 18 tumor pairs from SS + and SS- adenocarcinomas (sex, EGFR mutation, and tumor size-matched) and examined the expression of five immune markers (CD20, CD8, FOXP3, CD204, and PD-L1) by immunohistochemistry.

RESULTS

Of 96 specimens, there were 33 (34 %) SS + adenocarcinoma tumors. The smoking index significantly correlated with the weight of the SS (R = 0.43). Between SS + and SS- tumors, there was no significant difference in clinicopathological factors excluding smoking history. Immunohistochemistry revealed that the number of FOXP3 + T cells in SS + adenocarcinomas was significantly higher than that in the SS- adenocarcinomas (median number 58 vs. 36, p < 0.01). Also, the number of CD20 + B cells in SS + adenocarcinomas was significantly higher than that in the SS- adenocarcinomas (median number 77 vs. 29, p < 0.01); however; these phenomena could not be confirmed when stratified by smoking history.

CONCLUSION

In lung adenocarcinoma, SS is associated with an immunosuppressive tumor microenvironment.

Short-term results of VOLTAGE-A: Nivolumab monotherapy and subsequent radical surgery following preoperative chemoradiotherapy in patients with microsatellite stable and microsatellite instability-high locally advanced rectal cancer

4100

Background: Chemoradiotherapy (CRT) followed by radical surgery (S) is standard therapy for patients (pts) with locally advanced rectal cancer (LARC). Sequential use of an anti-PD-1 antibody after radiation demonstrates synergistic effects in in vivo models, and an anti-PD-1 antibody is effective in pts with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). We studied nivolumab (nivo) and radical S following CRT (50.4 Gy with capecitabine 1,650 mg/m2) in T3–4 NanyM0 LARC. Methods: After the quality-assured CRT, 240 mg q2 weeks x 5 cycles of nivo and radical S were investigated. In cohort A-1, for pts with microsatellite stable (MSS) LARC, the primary endpoint was a centrally confirmed pathological complete response (pCR) rate using AJCC tumor regression grading. The estimated required sample size assuming null and alternative hypotheses pCR = 10% and 30% was 37 pts, with a 1-sided alpha of 5% and power of 90%. In Cohort A-2, 5 pts with MSI-H LARC were included in an exploratory manner. Results: From Jan/2017 to Oct/2019, a targeted number of pts was included and assessed. In cohort A-1, 30% (11/37; 90% CI 18-44%) of pCR (AJCC grade (gr) 0) rate and 38% (14/37) of major pathological response (MPR) (AJCC gr 0+1) rate were observed. Clinical CR was observed in one additional pt (3%) refusing S after nivo. In cohort A-2, 60% (3/5) of pCR rate and 60% (3/5) of MPR rate were observed. As of Jan/2020, only 2 pts (1 local and 1 metastatic) in cohort A-1 and none in cohort A-2 recurred. Immune-related severe adverse events were observed in 3 pts (gr 3 myasthenia, gr 3 interstitial nephritis, and gr 2 peripheral motor neuropathy); all fully recovered and received radical S. During the follow-up period, one additional pt with gr 2 colitis was observed. No treatment-related deaths were observed. Conclusions: Promising pCR rates of 30% and 60%, with mild toxicities, were shown in MSS and MSI-H LARC pts treated with nivo plus radical S after CRT, suggesting the candidate therapy for the future non-surgical approach. Clinical trial information: NCT02948348 .

Translational research of voltage-A1: Efficacy predictors of preoperative chemoradiotherapy and subsequent nivolumab monotherapy in patients with microsatellite-stable locally advanced rectal cancer

4073

Background: In VOLTAGE-A1, after 5 cycles of nivolumab (240 mg q2 weeks) plus radical surgery following chemoradiotherapy (CRT; 50.4 Gy with capecitabine 1,650 mg/m2), a major pathologic response is observed in 38% (AJCC tumor regression grade 0-1) of 37 patients with microsatellite-stable locally advanced primary rectal cancer. Here, biomarkers for predicting the efficacy of this treatment were investigated. Methods: Serial tumor biopsies and blood collections were performed at 4 time points; before CRT, after CRT, after 3 cycles of nivolumab, and before surgery. Tumor-infiltrating lymphocytes (TILs) and DNA/RNA were extracted from tumor samples, and peripheral blood mononuclear cells (PBMCs) were extracted from blood samples. We analyzed the immune status of the patients by flow cytometry using the collected TILs and PBMCs. Whole exome and RNA sequencing analyses were conducted using the extracted DNA and RNA, respectively. The PD-L1 status of tumor samples was also evaluated by in vitro diagnostic immunohistochemistry staining. Results: Among the 24 patients whose samples were serially collected, 11 (46%) were AJCC grade 0-1 and 13 were 2-3. Before CRT, effector regulatory T (eTreg) cells in TILs were higher in patients with AJCC grade 2-3, and both the CD8+ T cell/eTreg cell ratio in TILs and PD-L1-positive tumor cells (≥1%) were higher in patients with AJCC grade 0-1 (p = 0.047, p = 0.083, respectively). Ki67 expression by CD8+ T cells in TILs was higher before CRT in patients with AJCC grade 0-1 (p = 0.037) and increased after CRT in all patients. Patients with consensus molecular subtype (CMS) 1 and CMS3 achieved AJCC grade 0-1 at rates of 100% (2/2) and 60% (4/6), respectively. In contrast, patients with CMS2 and CMS4 achieved AJCC grade 0-1 at rates of 43% (3/7) and 29% (2/7), respectively. The tumor mutation burden of pre-CRT samples was significantly higher in patients with AJCC grade 0-1 (median 1.45/MB) than in patients with AJCC grade 2-3 (0.84/MB) (p = 0.016). Conclusions: A higher CD8+ T cell/eTreg cell ratio, PD-L1-positive, Ki67 expression by CD8+ T cells in TILs, CMS1 or 3, and higher tumor mutation burden are good predictors of the efficacy of the sequential combination of CRT and nivolumab. Further results will be reported in the meeting. Clinical trial information: NCT02948348 .

NGSCUP: Phase II trial of site-specific treatment based on gene expression and mutation profiling by next generation sequencing (NGS) for patients (pts) with cancer of unknown primary site (CUP)

e15577

Background: Although gene profiling is a promising diagnostic technique to determine the tissue of origin for pts with CUP, we reported that site-specific treatment based on gene profiling using microarray did not result in an improvement the survival compared with empirical therapy in the previous randomized phase 2 trial (Hayashi, et. al, JCO 2019). Recently, we have established new integrative diagnostic system combined the gene expression from RNA-sequencing and mutation/copy number variation data from targeted genomic-sequencing using NGS. We have performed a single-arm phase 2 study to assess the efficacy of site-specific therapy determined by this system in previously untreated pts with CUP. Methods: Comprehensive gene profiling was performed by NGS, and an established algorithm was applied to predict tumor origin. Pts with CUP was received site-specific chemotherapy determined by the predicted site. The primary endpoint was one-year survival rate. Results: A total of 111 pts was enrolled and all had sufficient biopsy tissue for gene profiling. Efficacy analysis was performed for 97 pts who received site-specific treatment. Cancer types most commonly predicted were lung (21%), liver (15%), kidney (15%), and colorectal cancer (12%). The one-year survival rate, median overall survival (OS), and progression free survival (PFS) was 53.1% (95%CI, 42.6-62.5%), 13.7 months (95% CI, 9.3-19.7 months), and 5.2 months (95% CI, 3.3-7.1 months), respectively. Median OS (15.7 versus 11.0 months, P = .078) and PFS (5.5 versus 2.8 months, P = .019) were better for predicted tumor types categorized as more responsive types than for less responsive ones. Conclusions: Site-specific treatment based on NGS demonstrated promising efficacy. Pts with CUP predicted to have more responsive tumor types had longer survival compared with pts with less responsive tumor types, suggesting that molecular tumor profiling by both DNA and RNA testing contributes to the management of pts with CUP. Clinical trial information: UMIN051180009.

Regorafenib Plus Nivolumab in Patients With Advanced Gastric or Colorectal Cancer: An Open-Label, Dose-Escalation, and Dose-Expansion Phase Ib Trial (REGONIVO, EPOC1603)

PURPOSE

This is a phase Ib trial of regorafenib plus nivolumab for gastric and colorectal cancer.

PATIENTS AND METHODS

Enrolled patients received regorafenib plus nivolumab in a dose-finding part to estimate the maximum tolerated dose. Additional patients were enrolled in a dose-expansion part. Regorafenib of 80-160 mg was administered once daily for 21 days on/7 days off with nivolumab 3 mg/kg every 2 weeks. The primary end point was dose-limiting toxicity (DLT) during the first 4 weeks to estimate the recommended dose.

RESULTS

Fifty patients (25 each with gastric and colorectal cancer) were enrolled. All patients had received ≥ 2 previous lines of chemotherapy, including anti-angiogenetic inhibitors in 96% of patients. Seven patients with gastric cancer had previously been treated with immune checkpoint inhibitors. One patient had microsatellite instability-high colorectal cancer, whereas the remaining patients had microsatellite stable or mismatch repair-proficient tumors. Three DLTs (grade 3 colonic perforation, maculopapular rash, and proteinuria) were observed with regorafenib 160 mg; none were observed with 80 or 120 mg. During the dose-expansion part, regorafenib dose was reduced from 120 to 80 mg because of frequent maculopapular rash. The common grade ≥ 3 treatment-related adverse events were rash (12%), proteinuria (12%), and palmar-plantar erythrodysesthesia (10%). Objective tumor response was observed in 20 patients (40%), including 11 with gastric cancer (44%) and 9 with colorectal cancer (36%). Median progression-free survival was 5.6 and 7.9 months in patients with gastric and colorectal cancer, respectively.

CONCLUSION

The combination of regorafenib 80 mg plus nivolumab had a manageable safety profile and encouraging antitumor activity in patients with gastric and colorectal cancer, which warrants additional investigations in larger cohorts.

TENERGY: multicenter phase II study of Atezolizumab monotherapy following definitive Chemoradiotherapy with 5-FU plus Cisplatin in patients with unresectable locally advanced esophageal squamous cell carcinoma

BACKGROUND

The standard treatment for patients with unresectable locally advanced esophageal squamous cell carcinoma (ESCC) is definitive chemoradiotherapy (CRT) using 5-FU plus cisplatin. However, complete response (CR) rates are low at 11-25%, resulting in 9-10 months of median overall survival (OS). An improved therapeutic efficacy by combining immunotherapy with radiation has been reported in patients with locally advanced non-small cell lung cancer. The results using ESCC cell lines suggest sequential treatment with anti-PD-L1 agents soon after completion of CRT is the most effective combination.

METHODS

TENERGY trial is a multicenter, phase II, proof-of-concept study to assess the efficacy and safety of atezolizumab following definitive CRT in patients with locally advanced ESCC. The main inclusion criteria are unresectable locally advanced ESCC without distant metastasis, completion of 60 Gy of radiation plus two concomitant cycles of chemotherapy (cisplatin 70 mg/m2 on day 1 and 5-FU 700 mg/m2 on days 1-4, every 28 days), and adequate organ function. Within 6 weeks after CRT, participants will start taking 1200 mg of atezolizumab every three weeks and continue until 12 months or disease progression. The primary endpoint is the confirmed CR rate by the investigator's assessment. Secondary endpoints include overall response rate, progression-free survival (PFS), OS, adverse events, and confirmed CR rate by central assessment. We will enroll 50 patients (40 with primary locally advanced ESCC and 10 with postoperative locoregionally recurrent ESCC). We will obtain biopsies from the primary site and will collect blood at 3 time points (before CRT, after CRT, and four weeks after the start of atezolizumab) for an exploratory biomarker study. We will analyze the phenotype of immune-competent cells, neoantigens, tumor mutational burden, PD-L1 status, and Human Leukocyte Antigen haplotyping.

DISCUSSION

The synergistic efficacies of the sequential combination of CRT and atezolizumab should improve the CR rate, resulting in survival improvement for patients with unresectable locally advanced ESCC. Because CRT is a standard treatment option for patients with early stage to locally advanced ESCC, the sequential combination of CRT and atezolizumab has the potential to change the standard ESCC treatments.

TRIAL REGISTRATION

UMIN000034373, 10/04/2018 and EPOC1802.