Dual PD-1 and CTLA-4 Checkpoint Blockade Promotes Antitumor Immune Responses through CD4+Foxp3- Cell-Mediated Modulation of CD103+ Dendritic Cells

Targeting cytotoxic lymphocyte antigen 4 (CTLA-4) in breast cancer

Breast cancer (BC) has a high mortality rate and is one of the most common malignancies in the world. Initially, BC was considered non-immunogenic, but a paradigm shift occurred with the discovery of tumor-infiltrating lymphocytes (TILs) and regulatory T cells (Tregs) in the BC tumor microenvironment. CTLA-4 (Cytotoxic T-lymphocyte-associated protein 4) immunotherapy has emerged as a treatment option for BC, but it has limitations, including suboptimal antitumor effects and toxicity. Research has demonstrated that anti-CTLA-4 combination therapies, such as Treg depletion, cancer vaccines, and modulation of the gut microbiome, are significantly more effective than CTLA-4 monoclonal antibody (mAB) monotherapy. Second-generation CTLA-4 antibodies are currently being developed to mitigate immune-related adverse events (irAEs) and augment antitumor efficacy. This review examines anti-CTLA-4 mAB in BC, both as monotherapy and in combination with other treatments, and sheds light on ongoing clinical trials, novel CTLA-4 therapeutic strategies, and potential utility of biomarkers in BC.

Roles of tissue-resident immune cells in immunotherapy of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common and lethal type of lung cancer, with limited treatment options and poor prognosis. Immunotherapy offers hope for improving the survival and quality of life of NSCLC patients, but its efficacy depends on the tumor immune microenvironment (TME). Tissue-resident immune cells are a subset of immune cells that reside in various tissues and organs, and play an important role in fighting tumors. In NSCLC, tissue-resident immune cells are heterogeneous in their distribution, phenotype, and function, and can either promote or inhibit tumor progression and response to immunotherapy. In this review, we summarize the current understanding on the characteristics, interactions, and roles of tissue-resident immune cells in NSCLC. We also discuss the potential applications of tissue-resident immune cells in NSCLC immunotherapy, including immune checkpoint inhibitors (ICIs), other immunomodulatory agents, and personalized cell-based therapies. We highlight the challenges and opportunities for developing targeted therapies for tissue-resident immune cells and optimizing existing immunotherapeutic approaches for NSCLC patients. We propose that tissue-resident immune cells are a key determinant of NSCLC outcome and immunotherapy response, and warrant further investigation in future research.

The mitotic spindle-related seven-gene predicts the prognosis and immune microenvironment of lung adenocarcinoma

PURPOSE

Abnormalities in the mitotic spindle have been linked to a variety of cancers. Data on their role in the onset, progression, and treatment of lung adenocarcinoma (LUAD) need to be explored.

METHODS

The data were retrieved from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Molecular Signatures Database (MSigDB), for the training cohort, external validation cohort, and the hallmark mitotic spindle gene set, respectively. Mitotic spindle genes linked to LUAD prognosis were identified and intersected with differentially expressed up-regulated genes in the training cohort. Nomogram prediction models were built based on least absolute shrinkage and selection operator (LASSO) regression, univariate cox, and multivariate cox analyses. The seven-gene immunological score was examined, as well as the correlation of immune checkpoints. The DLGAP5 and KIF15 expression in BEAS-2B, A549, H1299, H1975, and PC-9 cell lines was validated with western blot (WB).

RESULTS

A total of 965 differentially expressed up-regulated genes in the training cohort intersected with 51 mitotic spindle genes associated with LUAD prognosis. Finally, the seven-gene risk score was determined and integrated with clinical characteristics to construct the nomogram model. Immune cell correlation analysis revealed a negative correlation between seven-gene expression with B cell, endothelial cell (excluding LMNB1), and T cell CD8 + (p < 0.05). However, the seven-gene expression was positively correlated with multiple immune checkpoints (p < 0.05). The expression of DLGAP5 and KIF15 were significantly higher in A549, H1299, H1975, and PC-9 cell lines than that in BEAS-2B cell line.

CONCLUSION

High expression of the seven genes is positively correlated with poor prognosis of LUAD, and these genes are promising as prospective immunotherapy targets.

Tumor Mutational Burden in Breast Cancer: Current Evidence, Challenges, and Opportunities

Tumor mutational burden (TMB) correlates with tumor neoantigen burden, T cell infiltration, and response to immune checkpoint inhibitors in many solid tumor types. Based on data from the phase II KEYNOTE-158 study, the anti-PD-1 antibody pembrolizumab was granted approval for treating patients with advanced solid tumors and TMB ≥ 10 mutations per megabase. However, this trial did not include any patients with metastatic breast cancer; thus, several questions remain unanswered about the true role of TMB as a predictive biomarker of benefit to immune checkpoint inhibitor therapy in breast cancer. In this review, we will discuss the challenges and opportunities in establishing TMB as a predictive biomarker of benefit to immunotherapy in metastatic breast cancer.

Epigenetic regulation in the tumor microenvironment: molecular mechanisms and therapeutic targets

Over decades, researchers have focused on the epigenetic control of DNA-templated processes. Histone modification, DNA methylation, chromatin remodeling, RNA modification, and noncoding RNAs modulate many biological processes that are crucial to the development of cancers. Dysregulation of the epigenome drives aberrant transcriptional programs. A growing body of evidence suggests that the mechanisms of epigenetic modification are dysregulated in human cancers and might be excellent targets for tumor treatment. Epigenetics has also been shown to influence tumor immunogenicity and immune cells involved in antitumor responses. Thus, the development and application of epigenetic therapy and cancer immunotherapy and their combinations may have important implications for cancer treatment. Here, we present an up-to-date and thorough description of how epigenetic modifications in tumor cells influence immune cell responses in the tumor microenvironment (TME) and how epigenetics influence immune cells internally to modify the TME. Additionally, we highlight the therapeutic potential of targeting epigenetic regulators for cancer immunotherapy. Harnessing the complex interplay between epigenetics and cancer immunology to develop therapeutics that combine thereof is challenging but could yield significant benefits. The purpose of this review is to assist researchers in understanding how epigenetics impact immune responses in the TME, so that better cancer immunotherapies can be developed.

Intratumoral CD8+ T cells with a tissue-resident memory phenotype mediate local immunity and immune checkpoint responses in breast cancer

CD8⁺ tumor-infiltrating lymphocytes with a tissue-resident memory T (T_RM) cell phenotype are associated with favorable prognosis in patients with triple-negative breast cancer (TNBC). However, the relative contribution of CD8⁺ T_RM cells to anti-tumor immunity and immune checkpoint blockade efficacy in breast cancer remains unknown. Here, we show that intratumoral CD8⁺ T cells in murine mammary tumors transcriptionally resemble those from TNBC patients. Phenotypic and transcriptional studies established two intratumoral sub-populations: one more enriched in markers of terminal exhaustion (T_EX-like) and the other with a bona fide resident phenotype (T_RM-like). Treatment with anti-PD-1 and anti-CTLA-4 therapy resulted in expansion of these intratumoral populations, with the T_RM-like subset displaying significantly enhanced cytotoxic capacity. T_RM-like CD8⁺ T cells could also provide local immune protection against tumor rechallenge and a T_RM gene signature extracted from tumor-free tissue was significantly associated with improved clinical outcomes in TNBC patients treated with checkpoint inhibitors.

Immune checkpoint blockade induces gut microbiota translocation that augments extraintestinal antitumor immunity

Gut microbiota, specifically gut bacteria, are critical for effective immune checkpoint blockade therapy (ICT) for cancer. The mechanisms by which gut microbiota augment extraintestinal anticancer immune responses, however, are largely unknown. Here, we find that ICT induces the translocation of specific endogenous gut bacteria into secondary lymphoid organs and subcutaneous melanoma tumors. Mechanistically, ICT induces lymph node remodeling and dendritic cell (DC) activation, which facilitates the translocation of a selective subset of gut bacteria to extraintestinal tissues to promote optimal antitumor T cell responses in both the tumor-draining lymph nodes (TDLNs) and the primary tumor. Antibiotic treatment results in decreased gut microbiota translocation into mesenteric lymph nodes (MLNs) and TDLNs, diminished DC and effector CD8+ T cell responses, and attenuated responses to ICT. Our findings illuminate a key mechanism by which gut microbiota promote extraintestinal anticancer immunity.

Case report: Local cryoablation combined with pembrolizumab to eliminate lung metastases from ovarian clear cell carcinoma

Ovarian clear cell carcinoma has a high recurrence rate with poor prognosis and is generally not sensitive to conventional platinum-based chemotherapy. Its less frequent occurrence of mutations such as BRCA limited the targeted therapies. Immunotherapy is not currently recommended as a first-line agent for ovarian cancer, and most patients are not yet able to benefit from it. Cryoablation can be used to treat solid systemic tumors, including ovarian cancer metastases, and can produce a limited anti-tumor immune response. The anti-tumor effects of cryoablation combined with immunotherapy have not been adequately confirmed. This study reports a case of a patient with ovarian clear cell carcinoma who underwent conventional adjuvant chemotherapy after initially surgical resection of the tumor. Unfortunately, cancer recurred and metastasized to the abdominal wall. After a series of painful chemotherapy and a second surgery, the cancer was still not effectively controlled, and the patient developed extensive metastases in the lung. The patient’s PD-L1 expression level also did not support solo immunotherapy. We pioneered the use of cryoablation to first eradicate the most significant lesion in the upper lobe of the left lung and then combined it with the PD-L1 inhibitor pembrolizumab to treat the patient with immunotherapy, which resulted in the complete eradication of the other multiple metastases in the lung and saved the patient’s life. Although the precise mechanism of action has not yet been explored, we have reason to believe that the combination of cryoablation and immune checkpoint inhibitor has a powerful synergistic anti-tumor effect, which is yet to be confirmed by more basic research and clinical applications in the next step.

Monoclonal Antibodies to CTLA-4 with Focus on Ipilimumab

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4 or CD152) is a negative regulator of T-cell-mediated immune responses which plays a critical role in suppressing autoimmunity and maintaining immune homeostasis. Because of its inhibitory activity on T cells, CTLA-4 has been investigated as a drug target to induce immunostimulation, blocking the interaction with its ligands. The antitumor effects mediated by CTLA-4 blockade have been attributed to a sustained active immune response against cancer cells, due to the release of a brake on T cell activation. Ipilimumab (Yervoy, Bristol-Myers Squibb) is a fully human anti-CTLA-4 IgG1κ monoclonal antibody (mAb) that represents the first immune checkpoint inhibitor approved as monotherapy by FDA and EMA in 2011 for the treatment of unresectable/metastatic melanoma. In 2015, FDA also granted approval to ipilimumab monotherapy as adjuvant treatment of stage III melanoma to reduce the risk of tumour recurrence. The subsequent approved indications of ipilimumab for metastatic melanoma, regardless of BRAF mutational status, and other advanced/metastatic solid tumours always involve its use in association with the anti-programmed cell death protein 1 (PD-1) mAb nivolumab. Currently, ipilimumab is evaluated in ongoing clinical trials for refractory/advanced solid tumours mainly in combination with additional immunostimulating agents.

The importance of immune checkpoints in immune monitoring: A future paradigm shift in the treatment of cancer

The growth and development of cancer are directly correlated to the suppression of the immune system. A major breakthrough in cancer immunotherapy depends on various mechanisms to detect immunosuppressive factors that inhibit anti-tumor immune responses. Immune checkpoints are expressed on many immune cells such as T-cells, regulatory B cells (Bregs), dendritic cells (DCs), natural killer cells (NKs), regulatory T (Tregs), M2-type macrophages, and myeloid-derived suppressor cells (MDSCs). Immune inhibitory molecules, including CTLA-4, TIM-3, TIGIT, PD-1, and LAG-3, normally inhibit immune responses via negatively regulating immune cell signaling pathways to prevent immune injury. However, the up-regulation of inhibitory immune checkpoints during tumor progression on immune cells suppresses anti-tumor immune responses and promotes immune escape in cancer. It has recently been indicated that cancer cells can up-regulate various pathways of the immune checkpoints. Therefore, targeting immune inhibitory molecules through antibodies or miRNAs is a promising therapeutic strategy and shows favorable results. Immune checkpoint inhibitors (ICIs) are introduced as a new immunotherapy strategy that enhance immune cell-induced antitumor responses in many patients. In this review, we highlighted the function of each immune checkpoint on different immune cells and therapeutic strategies aimed at using monoclonal antibodies and miRNAs against inhibitory receptors. We also discussed current challenges and future strategies for maximizing these FDA-approved immunosuppressants' effectiveness and clinical success in cancer treatment.

Various Uses of PD1/PD-L1 Inhibitor in Oncology: Opportunities and Challenges

The occurrence and development of cancer are closely related to the immune escape of tumor cells and immune tolerance. Unlike previous surgical, chemotherapy, radiotherapy and targeted therapy, tumor immunotherapy is a therapeutic strategy that uses various means to stimulate and enhance the immune function of the body, and ultimately achieves the goal of controlling tumor cells.With the in-depth understanding of tumor immune escape mechanism and tumor microenvironment, and the in-depth study of tumor immunotherapy, immune checkpoint inhibitors represented by Programmed Death 1/Programmed cell Death-Ligand 1(PD-1/PD-L1) inhibitors are becoming increasingly significant in cancer medication treatment. employ a variety of ways to avoid detection by the immune system, a single strategy is not more effective in overcoming tumor immune evasion and metastasis. Combining different immune agents or other drugs can effectively address situations where immunotherapy is not efficacious, thereby increasing the chances of success and alternative access to alternative immunotherapy. Immune combination therapies for cancer have become a hot topic in cancer treatment today. In this paper, several combination therapeutic modalities of PD1/PD-L1 inhibitors are systematically reviewed. Finally, an analysis and outlook are provided in the context of the recent advances in combination therapy with PD1/PD-L1 inhibitors and the pressing issues in this field.

Identification of Two Subsets of Murine DC1 Dendritic Cells That Differ by Surface Phenotype, Gene Expression, and Function

Classical dendritic cells (cDCs) in mice have been divided into 2 major subsets based on the expression of nuclear transcription factors: a CD8⁺Irf8⁺Batf3 dependent (DC1) subset, and a CD8^-Irf4⁺ (DC2) subset. We found that the CD8⁺DC1 subset can be further divided into CD8⁺DC1a and CD8⁺DC1b subsets by differences in surface receptors, gene expression, and function. Whereas all 3 DC subsets can act alone to induce potent Th1 cytokine responses to class I and II MHC restricted peptides derived from ovalbumin (OVA) by OT-I and OT-II transgenic T cells, only the DC1b subset could effectively present glycolipid antigens to natural killer T (NKT) cells. Vaccination with OVA protein pulsed DC1b and DC2 cells were more effective in reducing the growth of the B16-OVA melanoma as compared to pulsed DC1a cells in wild type mice. In conclusion, the Batf3-/- dependent DC1 cells can be further divided into two subsets with different immune functional profiles in vitro and in vivo.

BET Inhibition Enhances TNF-Mediated Anti-Tumor Immunity

Targeting chromatin binding proteins and modifying enzymes can concomitantly affect tumor cell proliferation and survival, as well as enhance anti-tumor immunity and augment cancer immunotherapies. By screening a small-molecule library of epigenetics-based therapeutics, BET (Bromo- and Extra-Terminal domain) inhibitors (BETi) were identified as agents that sensitize tumor cells to the anti-tumor activity of CD8+ T cells. BETi modulated tumor cells to be sensitized to the cytotoxic effects of the pro-inflammatory cytokine TNF. By preventing the recruitment of BRD4 to p65-bound cis-regulatory elements, BETi suppressed the induction of inflammatory gene expression, including the key NF-κB target genes BIRC2 (cIAP1) and BIRC3 (cIAP2). Disruption of pro-survival NF-κB signaling by BETi led to unrestrained TNF-mediated activation of the extrinsic apoptotic cascade and tumor cell death. Administration of BETi in combination with T-cell bispecific antibodies (TCB) or immune checkpoint blockade increased bystander killing of tumor cells and enhanced tumor growth inhibition in vivo in a TNF-dependent manner. This novel epigenetic mechanism of immunomodulation may guide future use of BETi as adjuvants for immune oncology agents.

Type 1 conventional dendritic cells and interferons are required for spontaneous CD4+ and CD8+ T-cell protective responses to breast cancer

OBJECTIVES

To better understand how immune responses may be harnessed against breast cancer, we investigated which immune cell types and signalling pathways are required for spontaneous control of a mouse model of mammary adenocarcinoma.

METHODS

The NOP23 mammary adenocarcinoma cell line expressing epitopes derived from the ovalbumin model antigen is spontaneously controlled when orthotopically engrafted in syngeneic C57BL/6 mice. We combined this breast cancer model with antibody-mediated depletion of lymphocytes and with mutant mice affected in interferon (IFN) or type 1 conventional dendritic cell (cDC1) responses. We monitored tumor growth and immune infiltration including the activation of cognate ovalbumin-specific T cells.

RESULTS

Breast cancer immunosurveillance required cDC1, NK/NK T cells, conventional CD4+ T cells and CD8+ cytotoxic T lymphocytes (CTLs). cDC1 were required constitutively, but especially during T-cell priming. In tumors, cDC1 were interacting simultaneously with CD4+ T cells and tumor-specific CTLs. cDC1 expression of the XCR1 chemokine receptor and of the T-cell-attracting or T-cell-activating cytokines CXCL9, IL-12 and IL-15 was dispensable for tumor rejection, whereas IFN responses were necessary, including cDC1-intrinsic signalling by STAT1 and IFN-γ but not type I IFN (IFN-I). cDC1 and IFNs promoted CD4+ and CD8+ T-cell infiltration, terminal differentiation and effector functions. In breast cancer patients, high intratumor expression of genes specific to cDC1, CTLs, CD4+ T cells or IFN responses is associated with a better prognosis.

CONCLUSION

Interferons and cDC1 are critical for breast cancer immunosurveillance. IFN-γ plays a prominent role over IFN-I in licensing cDC1 for efficient T-cell activation.

Exercise Training Improves Tumor Control by Increasing CD8+ T-cell Infiltration via CXCR3 Signaling and Sensitizes Breast Cancer to Immune Checkpoint Blockade

The mechanisms behind the antitumor effects of exercise training (ExTr) are not fully understood. Using mouse models of established breast cancer, we examined here the causal role of CD8+ T cells in the benefit acquired from ExTr in tumor control, as well as the ability of ExTr to improve immunotherapy responses. We implanted E0771, EMT6, MMTV-PyMT, and MCa-M3C breast cancer cells orthotopically in wild-type or Cxcr3-/- female mice and initiated intensity-controlled ExTr sessions when tumors reached approximately 100 mm3 We characterized the tumor microenvironment (TME) using flow cytometry, transcriptome analysis, proteome array, ELISA, and immunohistochemistry. We used antibodies against CD8+ T cells for cell depletion. Treatment with immune checkpoint blockade (ICB) consisted of anti-PD-1 alone or in combination with anti-CTLA-4. ExTr delayed tumor growth and induced vessel normalization, demonstrated by increased pericyte coverage and perfusion and by decreased hypoxia. ExTr boosted CD8+ T-cell infiltration, with enhanced effector function. CD8+ T-cell depletion prevented the antitumor effect of ExTr. The recruitment of CD8+ T cells and the antitumor effects of ExTr were abrogated in Cxcr3-/- mice, supporting the causal role of the CXCL9/CXCL11-CXCR3 pathway. ExTr also sensitized ICB-refractory breast cancers to treatment. Our results indicate that ExTr can normalize the tumor vasculature, reprogram the immune TME, and enhance the antitumor activity mediated by CD8+ T cells via CXCR3, boosting ICB responses. Our findings and mechanistic insights provide a rationale for the clinical translation of ExTr to improve immunotherapy of breast cancer.

Transcriptomic and Immunophenotypic Characterization of Tumor Immune Microenvironment in Squamous Cell Carcinoma of the Oral Tongue

The tumor immune microenvironment of oral tongue squamous cell carcinoma may be accountable for differences in clinical behavior, particularly between different age groups. We performed RNA expression profiling and evaluated tumor infiltrating lymphocytes (TILs) and their T-cell subsets in order to assess the functional status of oral tongue squamous cell carcinoma tumor microenvironment and detect potentially clinically useful associations. Archival surgical pathology material from sixteen oral tongue squamous cell carcinoma patients was microscopically evaluated for TIL densities. RNA was extracted from macrodissected whole tumor sections and normal controls and RNA expression profiling was performed by the NanoString PanCancer IO 360 Gene Expression Panel. Immunostains for CD4, CD8 and FOXP3 were evaluated manually and by digital image analysis. Oral tongue squamous cell carcinomas had increased TIL densities, numerically dominated by CD4 + T cells, followed by CD8 + and FOXP3 + T cells. RNA expression profiling of tumors versus normal controls showed tumor signature upregulation in inhibitory immune signaling (CTLA4, TIGIT and PD-L2), followed by inhibitory tumor mechanisms (IDO1, TGF-β, B7-H3 and PD-L1). Patients older than 44 years showed a tumor microenvironment with increased Tregs and CTLA4 expression. Immunohistochemically assessed CD8% correlated well with molecular signatures related to CD8 + cytotoxic T-cell functions. FOXP3% correlated significantly with CTLA4 upregulation. CTLA4 molecular signature could be predicted by FOXP3% assessed by immunohistochemistry (R2 = 0.619, p = 0.026). Oral tongue squamous cell carcinoma hosts a complex inhibitory immune microenvironment, partially reflected in immunohistochemically quantified CD8 + and FOXP3 + T-cell subsets. Immunohistochemistry can be a useful screening tool for detecting tumors with upregulated expression of the targetable molecule CTLA4.

Immunotherapy for the Breast Cancer treatment: Current Evidence and Therapeutic Options

Breast cancer (BC) stands at the first position among all forms of malignancies found in women globally. The available therapeutic approaches for breast cancer includes chemotherapy, radiation therapy, hormonal therapy and finally surgery. Despite the conventional therapies, in recent years the advance immunology based therapeutics emerge a potential in breast cancer treatment, including immune checkpoint blockades, vaccines and in combination with other treatment strategies. Although, commonly used treatments like trastuzumab/pertuzumab for human epidermal growth factor receptor 2 (Her2) positive and hormone therapy for estrogen receptor (ER) positive and/or progesterone receptor (PR) positive BC are specific but triple negative breast cancer (TNBC) cases remain a great challenge for treatment measures. Immune checkpoint inhibitors (anti-PD-1/ anti-CTLA-4) and anti-cancer vaccines (NeuVax, Muc-1, AVX901, INO-1400 and CEA), either alone or in combination with other therapies have created new paradigm in therapeutic world. In this review, we highlighted the current immunotherapeutic aspects and their ongoing trials towards the better treatment regimen for BC.

The Multifaceted Role of Th1, Th9, and Th17 Cells in Immune Checkpoint Inhibition Therapy

During the last decade, immune checkpoint inhibition (ICI) has become a pillar of cancer therapy. Antibodies targeting CTLA-4 or PD-1/PD-L1 have been approved in several malignancies, with thousands of clinical trials currently underway. While the majority of cancer immunotherapies have traditionally focused on enhancing cytotoxic responses by CD8⁺ or NK cells, there are clear evidences that CD4⁺ T cell responses can modulate the immune response against tumors and influence the efficacy of ICI therapy. CD4⁺ T cells can differentiate into several subsets of helper T cells (Th) or regulatory T cells (Treg), with a wide range of effector and/or regulatory functions. Importantly, different Th subsets may have different and sometimes contrasting roles in the clinical response to ICI therapy, which in addition may vary depending on the organ and tumor niche. In this review, we discuss recent evidence that highlights how ICI therapy impacts Th1, Th9, and Th17 cells and vice versa. These data might be important designing better interventions that unleash the full potential of immune response against cancer.

Type I IFN Activating Type I Dendritic Cells for Antitumor Immunity

Immune checkpoint inhibitors are successful immunotherapy modalities that enhance CD8⁺ T-cell responses. Although T cells are initially primed in draining lymph nodes, the mechanisms that underlie their reactivation inside the tumor microenvironment are less clear. Recent studies have found that not only is the cross-priming of conventional type 1 dendritic cells (cDC1) required to initiate CD8⁺ T-cell responses during tumor progression, but it also plays a central role in immunotherapy-mediated reactivation of tumor-specific CD8⁺ T cells for tumor regression. Moreover, many cancer treatment modalities trigger type I IFN responses, which play critical roles in boosting cDC1 cross-priming and CD8⁺ T-cell reactivation. Inducing type I IFNs within tumors can overcome innate immune resistance and activate antitumor adaptive immunity. Here, we review recent studies on how type I IFN-cDC1 cross-priming reactivates CD8⁺ T cells and contributes to tumor control by cancer immunotherapy.

Emerging dynamics pathways of response and resistance to PD-1 and CTLA-4 blockade: tackling uncertainty by confronting complexity

Immune checkpoint inhibitors provide considerable therapeutic benefit in a range of solid cancers as well as in a subgroup of hematological malignancies. Response rates are however suboptimal, and despite considerable efforts, predicting response to immune checkpoint inhibitors ahead of their administration in a given patient remains elusive. The study of the dynamics of the immune system and of the tumor under immune checkpoint blockade brought insight into the mechanisms of action of these therapeutic agents. Equally relevant are the mechanisms of adaptive resistance to immune checkpoint inhibitors that have been uncovered through this approach. In this review, we discuss the dynamics of the immune system and of the tumor under immune checkpoint blockade emanating from recent studies on animal models and humans. We will focus on mechanisms of action and of resistance conveying information predictive of therapeutic response.

Innate myeloid cells in the tumor microenvironment

Cancer immunotherapies are receiving increasing approval in the clinic, but still only a fraction of patients benefit long-term. Understanding the most important mechanisms of immunotherapeutic resistance is critical for broader utility and benefit of cancer immunotherapy. While the tumor microenvironment (TME) is made up of many cell types, immunosuppressive monocytes/macrophages, granulocytes and myeloid derived suppressor cells interact with, and play a critical role in regulating the anti-tumor lymphocyte effector cells that mediate effective immunotherapies. Herein, we discuss the latest research that has identified and compared the importance of pro-tumor and immunosuppressive mechanisms that tumor infiltrating myeloid cells employ. Exploiting this new information may help to develop totally novel therapies to boost contemporary cancer immunotherapy.

Immune Checkpoint Inhibitors: New Weapons Against Medullary Thyroid Cancer?

Medullary thyroid carcinoma is a rare neuroendocrine neoplasm that originates from thyroid C cells. Surgery, with complete resection of the tumor, is the only curative approach. However, in most cases, the tumor recurs at locoregional or metastatic level. In this setting, the management remains challenging. In recent years, the immune checkpoint inhibitors have provided promise for changing the cancer treatment paradigm through the application of new approaches that enhance the body's natural antitumor defenses. The aim of this review is to summarize and discuss available data on efficacy and safety of the Food and Drug Administration-approved immune checkpoint inhibitors in patients with medullary thyroid carcinoma. After an extensive search, we found 7 useful data sources (one single-case report, one short article with very preliminary data, five ongoing registered clinical trials). Despite the lack of published evidence regarding the use of immune check point inhibitors, it must be considered that all the ongoing registered clinical trials saw first light in the last three years, thus indicating a growing interest of researchers in this field. Results coming from these trials, and hopefully, in the next future, from additional trials, will help to clarify whether this class of drugs may represent a new weapon in favor of patients with medullary thyroid carcinoma.

ONCR-177, an Oncolytic HSV-1 Designed to Potently Activate Systemic Antitumor Immunity

ONCR-177 is an engineered recombinant oncolytic herpes simplex virus (HSV) with complementary safety mechanisms, including tissue-specific miRNA attenuation and mutant UL37 to inhibit replication, neuropathic activity, and latency in normal cells. ONCR-177 is armed with five transgenes for IL12, FLT3LG (extracellular domain), CCL4, and antagonists to immune checkpoints PD-1 and CTLA-4. In vitro assays demonstrated that targeted miRNAs could efficiently suppress ONCR-177 replication and transgene expression, as could the HSV-1 standard-of-care therapy acyclovir. Although ONCR-177 was oncolytic across a panel of human cancer cell lines, including in the presence of type I IFN, replication was suppressed in human pluripotent stem cell-derived neurons, cardiomyocytes, and hepatocytes. Dendritic cells activated with ONCR-177 tumor lysates efficiently stimulated tumor antigen-specific CD8⁺ T-cell responses. In vivo, biodistribution analyses suggested that viral copy number and transgene expression peaked approximately 24 to 72 hours after injection and remained primarily within the injected tumor. Intratumoral administration of ONCR-177 mouse surrogate virus, mONCR-171, was efficacious across a panel of syngeneic bilateral mouse tumor models, resulting in partial or complete tumor regressions that translated into significant survival benefits and to the elicitation of a protective memory response. Antitumor effects correlated with local and distant intratumoral infiltration of several immune effector cell types, consistent with the proposed functions of the transgenes. The addition of systemic anti-PD-1 augmented the efficacy of mONCR-171, particularly for abscopal tumors. Based in part upon these preclinical results, ONCR-177 is being evaluated in patients with metastatic cancer (ONCR-177-101, NCT04348916).

Heterogeneous Tumor-Immune Microenvironments between Primary and Metastatic Tumors in a Patient with ALK Rearrangement-Positive Large Cell Neuroendocrine Carcinoma

Evolution of tumor-immune microenviroments (TIMEs) occurs during tumor growth and dissemination. Understanding inter-site tumor-immune heterogeneity is essential to harness the immune system for cancer therapy. While the development of immunotherapy against lung cancer with driver mutations and neuroendocrine tumors is ongoing, little is known about the TIME of large cell neuroendocrine carcinoma (LCNEC) or anaplastic lymphoma kinase (ALK) rearrangement-positive lung cancer. We present a case study of a 32-year-old female patient with ALK-rearrangement-positive LCNEC, who had multiple distant metastases including mediastinal lymph-node, bilateral breasts, multiple bones, liver and brain. Multiple biopsy samples obtained from primary lung and three metastatic tumors were analyzed by fluorescent multiplex immunohistochemistry. Tissue localizations of tumor-infiltrating lymphocytes in the tumor nest and surrounding stroma were evaluated. T cell and B cell infiltrations were decreased with distance from primary lung lesion. Although each tumor displayed a unique TIME, all tumors exhibited concomitant regression after treatment with an ALK-inhibitor. This study provides the first evidence of the coexistence of distinct TIME within a single individual with ALK-rearrangement-positive LCNEC. The present study contributes to our understanding of heterogeneous TIMEs between primary and metastatic lesions and provides new insights into the complex interplay between host-immunity and cancer cells in primary and metastatic lesions.

Combined use of microwave ablation and cell immunotherapy induces nonspecific immunity of hepatocellular carcinoma model mice

Microwave ablation (MWA) has been widely used in the treatment of solid tumors. Studies have been less conducted on the efficacy of MWA used with cell immunotherapy in treating hepatocellular carcinoma (HCC). The current study aimed at exploring the efficacy of MWA in combination with cell immunotherapy in treating HCC. Hepa1-6 HCC mice were treated by MWA, blockade, or the combined therapy (MWA used with blockade), or left untreated. Survival rates of the mice were plotted by Kaplan-Meier Curve, followed by log-rank test. 25 days after the operation, surviving mice were monitored for tumor recurrence, and tumor volumes were calculated every 5 days. Immunohistochemistry and flow cytometry were performed to detect the numbers of CD4⁺ and CD8⁺ cells in the tumors and spleens of mice. The expressions of related cytokines were detected and measured by ELISPOT and ELISA. The results showed that MWA combined with anti-PD-1/anti-CTLA-4 not only increased the survival time, protected the mice against tumor recurrence, but also enhanced the intratumoral infiltration of cytotoxic T lymphocyte and systemic T-cell immune responses induced by MWA through activation of synergistically specific antitumor immunity. In addition, the combined therapy increased T-helper 1 cell (Th1-type) cytokines, but reduced Th2-type cytokines, resulting in the polarization of Th1 cells. T-cell immune responses of HCC cells were activated by MWA. In addition, the combined therapy of MWA and anti-PD-1/anti-CTLA-4 induced Th1-type immune response, and showed specific antitumor immunity.

Preclinical platform for long-term evaluation of immuno-oncology drugs using hCD34+ humanized mouse model

BACKGROUND

Well-characterized preclinical models are essential for immune-oncology research. We investigated the feasibility of our humanized mouse model for evaluating the long-term efficacy of immunotherapy and biomarkers.

METHODS

Humanized mice were generated by injecting human fetal cord blood-derived CD34+ hematopoietic stem cells to NOD-scid IL2rγnull (NSG) mice myeloablated with irradiation or busulfan. The humanization success was defined as a 25% or higher ratio of human CD45+ cells to mice peripheral blood mononuclear cells.

RESULTS

Busulfan was ultimately selected as the appropriate myeloablative method because it provided a higher success rate of humanization (approximately 80%) and longer survival time (45 weeks). We proved the development of functional T cells by demonstrating the anticancer effect of the programmed cell death-1 (PD-1) inhibitor in our humanized mice but not in non-humanized NSG mice. After confirming the long-lasting humanization state (45 weeks), we further investigated the response durability of the PD-1 inhibitor and biomarkers in our humanized mice. Early increase in serum tumor necrosis factor α levels, late increase in serum interleukin 6 levels and increase in tumor-infiltrating CD8+ T lymphocytes correlated more with a durable response over 60 days than with a non-durable response.

CONCLUSIONS

Our CD34+ humanized mouse model is the first in vivo platform for testing the long-term efficacy of anticancer immunotherapies and biomarkers, given that none of the preclinical models has ever been evaluated for such a long duration.

The role of dendritic cells for therapy of B-cell lymphoma with immune checkpoint inhibitors

Immune checkpoint blocking (ICB) is a promising new tool of cancer treatment. Yet, the underlying therapeutic mechanisms are not fully understood. Here we investigated the role of dendritic cells (DCs) for the therapeutic effect of ICB in a λ-MYC-transgenic mouse model of endogenously arising B-cell lymphoma. The growth of these tumors can be effectively delayed by antibodies against CTLA-4 and PD-1. Tumor-infiltrating DCs from mice having received therapy showed an upregulation of costimulatory molecules as well as an augmented IL-12/IL-10 ratio as compared to untreated controls. Both alterations seemed to be induced by interferon-γ (IFN-γ), which is upregulated in T cells and natural killer cells upon ICB. Furthermore, the enhanced IL-12/IL-10 ratio, which favors Th1-prone antitumor T-cell responses, was a consequence of direct interaction of ICB antibodies with DCs. Importantly, the capability of tumor-infiltrating DCs of stimulating peptide-specific or allogeneic T-cell responses in vitro was improved when DCs were derived from ICB-treated mice. The data indicate that ICB therapy is not only effective by directly activating T cells, but also by triggering a complex network, in which DCs play a pivotal role at the interface between innate and adaptive antitumor responses.

Response and outcomes after anti-CTLA4 versus anti-PD1 combined with stereotactic body radiation therapy for metastatic non-small cell lung cancer: retrospective analysis of two single-institution prospective trials

BACKGROUND

This study compared response rates and outcomes of combined radiotherapy and immunotherapy (iRT) based on the type of checkpoint inhibitor (anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) vs antiprogrammed death-1 (PD1)) for metastatic non-small cell lung cancer (mNSCLC).

METHODS

We retrospectively reviewed two prospective trials of radiation combined with anti-CTLA4 or anti-PD1 for patients with mNSCLC. Patients undergoing non-salvage stereotactic body radiation therapy (SBRT) to lung sites were selected from both trials and grouped by the immunotherapeutic compound received. Endpoints included in-field and out-of-field response rates, and overall response rate (complete or partial response) (all by response evaluation criteria in solid tumors). Progression-free survival (PFS) and overall survival (OS) were estimated with the Kaplan-Meier method.

RESULTS

Median follow-up times for the 33 patients (n=17 SBRT+anti-CTLA4, n=16 SBRT+anti-PD1) were 19.6 and 19.9 months. Response rates for out-of-field lesions were similar between anti-PD1 (37%) and anti-CTLA4 (24%) (p=0.054). However, global response rates for all lesions were 24% anti-CTLA4 vs 56% anti-PD1 (p=0.194). The PFS was 76% for anti-CTLA4 vs 94% anti-PD1 at 3 months, 52% vs 87% at 6 months, 31% vs 80% at 12 months, and 23% vs 63% at 18 months (p=0.02). Respective OS values were 76% vs 87% at 6 months, 47% vs 80% at 12 months, and 39% vs 66% at 18 months (p=0.08).

CONCLUSIONS

Both anti-CTLA4 and anti-PD1 agents prompt a similar degree of in-field and out-of-field responses after iRT, although the global response rate and PFS were statistically higher in the anti-PD1 cohort. Further dedicated study and biological mechanistic assessment is required.

TRIAL REGISTRATION NUMBERS

NCT02239900 and NCT02444741.

Targeting the epigenetic regulation of antitumour immunity

Dysregulation of the epigenome drives aberrant transcriptional programmes that promote cancer onset and progression. Although defective gene regulation often affects oncogenic and tumour-suppressor networks, tumour immunogenicity and immune cells involved in antitumour responses may also be affected by epigenomic alterations. This could have important implications for the development and application of both epigenetic therapies and cancer immunotherapies, and combinations thereof. Here, we review the role of key aberrant epigenetic processes - DNA methylation and post-translational modification of histones - in tumour immunogenicity, as well as the effects of epigenetic modulation on antitumour immune cell function. We emphasize opportunities for small-molecule inhibitors of epigenetic regulators to enhance antitumour immune responses, and discuss the challenges of exploiting the complex interplay between cancer epigenetics and cancer immunology to develop treatment regimens combining epigenetic therapies with immunotherapies.

Re-education of the Tumor Microenvironment With Targeted Therapies and Immunotherapies

The clinical success of cancer immunotherapies targeting PD-1 and CTLA-4 has ignited a substantial research effort to improve our understanding of tumor immunity. Recent studies have revealed that the immune contexture of a tumor influences therapeutic response and survival benefit for cancer patients. Identifying treatment modalities that limit immunosuppression, relieve T cell exhaustion, and potentiate effector functions in the tumor microenvironment (TME) is of much interest. In particular, combinatorial therapeutic approaches that re-educate the TME by limiting the accumulation of immunosuppressive immune cells, such as Foxp3 regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), while promoting CD8+ and CD4+ effector T cell activity is critical. Here, we review key approaches to target these immunosuppressive immune cell subsets and signaling molecules and define the impact of these changes to the tumor milieu. We will highlight the preclinical and clinical evidence for their ability to improve anti-tumor immune responses as well as strategies and challenges for their implementation. Together, this review will provide understanding of therapeutic approaches to efficiently shape the TME and reinvigorate the immune response against cancer.

Engineering CD4+ T Cells to Enhance Cancer Immunity

This review presents key advances in combining T cell receptor (TCR) gene transfer to redirect T-cell specificity with gene engineering in order to enhance cancer-protective immune function. We discuss how emerging insights might be applied to CD4+ T cells. Although much attention has been paid to the role of CD8+ cytotoxic T cells in tumour protection, we provide convincing evidence that CD4+ helper T cells play a critical role in cancer immune responses in animal models and also in patients. We demonstrate that genetic engineering technologies provide exciting opportunities to extend the specificity range of CD4+ T cells from MHC class-II-presented epitopes to include peptides presented by MHC class I molecules. Functional enhancement of tumour immunity can improve the sensitivity of T cells to cancer antigens, promote survival in a hostile tumour microenvironment, boost cancer-protective effector mechanisms and enable the formation of T-cell memory. Engineered cancer-specific CD4+ T cells may contribute to protective immunity by a direct pathway involving cancer cell killing, and by an indirect pathway that boosts the function, persistence and memory formation of CD8+ T cells.

Analysis of single-cell RNAseq identifies transitional states of T cells associated with hepatocellular carcinoma

BACKGROUND

Exhausted T cells and regulatory T cells (Tregs) comprise diverse subsets of tumor immunosuppressive microenvironment that play key roles in tumor progress. Understanding subset diversity in T cells is a critical question for developing cancer immunotherapy.

METHODS

A total of 235 specimens from surgical resections of hepatocellular carcinoma (HCC) patients were examined for infiltration of exhausted T cell (Tex) in tumor and adjacent tissue. We conducted deep single-cell targeted immune profiling on CD3⁺ cells collected from tumor tissues, adjacent normal tissues (ANTs) and peripheral blood of HCC patients. Total 10 cell clusters were identified with distinct distributions and characteristics.

RESULTS

We observed transitional differentiation of exhausted CD8⁺ T cells and Tregs increasingly enriched in tumor tissue. The accumulation and location of Tex were related to the differences in the long-term clinical outcome of HCC. Furthermore, data of single-cell RNA-seq showed that (1) cells transforming from effector CD8⁺ T cells to exhausted CD8⁺ T cells simultaneously expressed upregulated effector molecules and inhibitory receptors, (2) indicated alteration of gene expression related to stress response and cell cycle at early exhaustion stage, and (3) immunosuppressive Treg had profound activation in comparison to resting Tregs.

CONCLUSIONS

T cell exhaustion is a progressive process, and the gene-expression profiling displayed T cell exhaustion and anergy are different. Accordingly, it is possible that functional exhaustion is caused by the combination effects of passive defects and overactivation in stress response. The results help to understand the dynamic framework of T cells function in cancer which is important for designing rational cancer immunotherapies.

Adoptive cellular therapy with T cells expressing the dendritic cell growth factor Flt3L drives epitope spreading and antitumor immunity

Adoptive cell therapies using genetically engineered T cell receptor or chimeric antigen receptor T cells are emerging forms of immunotherapy that redirect T cells to specifically target cancer. However, tumor antigen heterogeneity remains a key challenge limiting their efficacy against solid cancers. Here, we engineered T cells to secrete the dendritic cell (DC) growth factor Fms-like tyrosine kinase 3 ligand (Flt3L). Flt3L-secreting T cells expanded intratumoral conventional type 1 DCs and substantially increased host DC and T cell activation when combined with immune agonists poly (I:C) and anti-4-1BB. Importantly, combination therapy led to enhanced inhibition of tumor growth and the induction of epitope spreading towards antigens beyond those recognized by adoptively transferred T cells in solid tumor models of T cell receptor and chimeric antigen receptor T cell therapy. Our data suggest that augmenting endogenous DCs is a promising strategy to overcome the clinical problem of antigen-negative tumor escape following adoptive cell therapy.

Harnessing neoantigen specific CD4 T cells for cancer immunotherapy

The goal of precision immunotherapy is to direct a patient's T cell response against the immunogenic mutations expressed on their tumors. Most immunotherapy approaches to-date have focused on MHC class I-restricted peptide epitopes by which cytotoxic CD8+ T lymphocytes (CTL) can directly recognize tumor cells. This strategy largely overlooks the critical role of MHC class II-restricted CD4+ T cells as both positive regulators of CTL and other effector cell types, and as direct effectors of antitumor immunity. In this review, we will discuss the role of neoantigen specific CD4+ T cells in cancer immunotherapy and how existing treatment modalities may be leveraged to engage this important T cell subset.

Comparative Efficacy and Safety of Nivolumab and Nivolumab Plus Ipilimumab in Advanced Cancer: A Systematic Review and Meta-Analysis

Background

Combination therapy with immune checkpoint inhibitors (ICIs) has been applied in the clinic to achieve synergistic effects and to improve clinical efficacy. Compared with monotherapy, combination therapy has promising efficacy against various advanced cancers. To further verify the effectiveness of combination therapy, we conducted a meta-analysis of the efficacy and safety of nivolumab (NIVO) and NIVO plus ipilimumab (IPI) in advanced cancer.

Methods

Electronic databases (PubMed, EMbase, and The Cochrane Library) were systematically searched for applicable studies published in English between January 1990 and June 2019. Relevant outcomes included objective response rate (ORR), disease control rate (DCR), median progression-free survival (mPFS), median overall survival (mOS), and grade 3–4 adverse events (AEs).

Results

A total of 1,297 patients from six studies were included. Compared with NIVO alone, NIVO + IPI was more efficacious for advanced tumors. Pooled outcome values were: ORR, 1.73 (95% CI: 1.34–2.23); DCR, 1.80 (95% CI: 1.21–2.69); mPFS, 0.22 (95% CI: 0.03–0.41); mOS, 0.03 (95% CI: −0.20–0.26); and grade 3–4 AEs, 3.64 (95% CI: 2.86–4.62).

Conclusion

NIVO + IPI is more effective than NIVO alone for the treatment of advanced cancer and can significantly improve ORR and DCR and prolong mPFS. Due to the limited quality and quantity of the included studies, more high-quality studies are needed to validate the above conclusions.

Resistance Mechanism of PD-1/PD-L1 Blockade in the Cancer-Immunity Cycle

In recent years, the PD-1/PD-L1 axis blockade has become a very promising therapy with significant clinical benefits for multiple tumor types. However, some patients still do not respond sufficiently to PD-1/PD-L1 targeted monotherapy. Therefore, investigating the mechanism of PD-1 blockade resistance will assist in exploring new immunotherapy strategies, controlling the progress of the disease, and thus bringing more sustainable survival benefits to patients. The tumor-immune cycle is divided into the following seven steps: the release of cancer antigens, cancer antigen presentation, priming and activation, trafficking of T cells to tumors, infiltration of T cells into tumors, recognition of cancer cells by T cells, and killing of cancer cells. Given that PD-1/PD-L1 blockade is primarily involved in step 7, any abnormalities in the previous steps may affect the efficacy of PD-1/PD-L1 inhibitors and lead to drug resistance. This review discussed the resistance mechanisms of PD-1/PD-L1 blockade in each cancer-immunity step to finding a more suitable treatment population and an optimized combination therapy to exert immunotherapy in tumor treatment to a greater extent.

Tissue-specific tumor microenvironments influence responses to immunotherapies

Objectives

Investigation of variable response rates to cancer immunotherapies has exposed the immunosuppressive tumor microenvironment (TME) as a limiting factor of therapeutic efficacy. A determinant of TME composition is the tumor location, and clinical data have revealed associations between certain metastatic sites and reduced responses. Preclinical models to study tissue‐specific TMEs have eliminated genetic heterogeneity, but have investigated models with limited clinical relevance.

Methods

We investigated the TMEs of tumors at clinically relevant sites of metastasis (liver and lungs) and their impact on αPD‐1/αCTLA4 and trimAb (αDR5, α4‐1BB, αCD40) therapy responses in the 67NR mouse breast cancer and Renca mouse kidney cancer models.

Results

Tumors grown in the lungs were resistant to both therapies whereas the same tumor lines growing in the mammary fat pad (MFP), liver or subcutaneously could be completely eradicated, despite greater tumor burden. Assessment of tumor cells and drug delivery in 67NR lung or MFP tumors revealed no differences and prompted investigation into the immune TME. Lung tumors had a more immunosuppressive TME with increased myeloid‐derived suppressor cell infiltration, decreased T cell infiltration and activation, and decreased NK cell activation. Depletion of various immune cell subsets indicated an equivalent role for NK cells and CD8⁺ T cells in lung tumour control. Thus, targeting T cells with αPD‐1/αCTLA4 or trimAb was not sufficient to elicit a robust antitumor response in lung tumors.

Conclusion

Taken together, these data demonstrate that tissue‐specific TMEs influence immunotherapy responses and highlight the importance in defining tissue‐specific response patterns in patients.

Macrophage-Derived CXCL9 and CXCL10 Are Required for Antitumor Immune Responses Following Immune Checkpoint Blockade

PURPOSE

Response rates to immune checkpoint blockade (ICB; anti-PD-1/anti-CTLA-4) correlate with the extent of tumor immune infiltrate, but the mechanisms underlying the recruitment of T cells following therapy are poorly characterized. A greater understanding of these processes may see the development of therapeutic interventions that enhance T-cell recruitment and, consequently, improved patient outcomes. We therefore investigated the chemokines essential for immune cell recruitment and subsequent therapeutic efficacy of these immunotherapies.

EXPERIMENTAL DESIGN

The chemokines upregulated by dual PD-1/CTLA-4 blockade were assessed using NanoString-based analysis with results confirmed at the protein level by flow cytometry and cytometric bead array. Blocking/neutralizing antibodies confirmed the requirement for key chemokines/cytokines and immune effector cells. Results were confirmed in patients treated with immune checkpoint inhibitors using single-cell RNA-sequencing (RNA-seq) and paired survival analyses.

RESULTS

The CXCR3 ligands, CXCL9 and CXCL10, were significantly upregulated following dual PD-1/CTLA-4 blockade and both CD8⁺ T-cell infiltration and therapeutic efficacy were CXCR3 dependent. In both murine models and patients undergoing immunotherapy, macrophages were the predominant source of CXCL9 and their depletion abrogated CD8⁺ T-cell infiltration and the therapeutic efficacy of dual ICB. Single-cell RNA-seq analysis of patient tumor-infiltrating lymphocytes (TIL) revealed that CXCL9/10/11 was predominantly expressed by macrophages following ICB and we identified a distinct macrophage signature that was associated with positive responses to ICB.

CONCLUSIONS

These data underline the fundamental importance of macrophage-derived CXCR3 ligands for the therapeutic efficacy of ICB and highlight the potential of manipulating this axis to enhance patient responses.

Combination anti-CTLA-4 plus anti-PD-1 checkpoint blockade utilizes cellular mechanisms partially distinct from monotherapies

Immune checkpoint blockade therapy has become a critical pillar of cancer therapy. Here, we characterize the cellular mechanisms of monotherapy and combination anti–cytotoxic T lymphocyte antigen-4 plus anti–programmed cell death-1 therapy. Using high-dimensional single-cell profiling, we determine that combination therapy elicits cellular responses that are partially distinct from those induced by either monotherapy. In particular, combination therapy mediates a switch from expansion of phenotypically exhausted cluster of differentiation 8 (CD8) T cells to expansion of activated effector CD8 T cells. In addition, we systematically compare T cell subsets present in matched peripheral blood and tumor tissues to define what aspects of antitumor responses can be observed peripherally. These findings have significant implications for both the cellular mechanisms of action and biomarkers of response to monotherapies and combination therapy.

Immune checkpoint blockade therapy targets T cell-negative costimulatory molecules such as cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 (PD-1). Combination anti–CTLA-4 and anti–PD-1 blockade therapy has enhanced efficacy, but it remains unclear through what mechanisms such effects are mediated. A critical question is whether combination therapy targets and modulates the same T cell populations as monotherapies. Using a mass cytometry-based systems approach, we comprehensively profiled the response of T cell populations to monotherapy and combination anti–CTLA-4 plus anti–PD-1 therapy in syngeneic murine tumors and clinical samples. Most effects of monotherapies were additive in the context of combination therapy; however, multiple combination therapy-specific effects were observed. Highly phenotypically exhausted cluster of differentiation 8 (CD8) T cells expand in frequency following anti–PD-1 monotherapy but not combination therapy, while activated terminally differentiated effector CD8 T cells expand only following combination therapy. Combination therapy also led to further increased frequency of T helper type 1 (Th1)-like CD4 effector T cells even though anti–PD-1 monotherapy is not sufficient to do so. Mass cytometry analyses of peripheral blood from melanoma patients treated with immune checkpoint blockade therapies similarly revealed mostly additive effects on the frequencies of T cell subsets along with unique modulation of terminally differentiated effector CD8 T cells by combination ipilimumab plus nivolumab therapy. Together, these findings indicate that dual blockade of CTLA-4 and PD-1 therapy is sufficient to induce unique cellular responses compared with either monotherapy.

Organotypic tumor slice cultures provide a versatile platform for immuno-oncology and drug discovery

Organotypic tumor slices represent a physiologically-relevant culture system for studying the tumor microenvironment. Systematic characterization of the tumor slice culture system will enable its effective application for translational research. Here, using flow cytometry-based immunophenotyping, we performed a comprehensive characterization of the immune cell composition in organotypic tumor slices prepared from four syngeneic mouse tumor models and a human liver tumor. We found that the immune cell compositions of organotypic tumor slices prepared on the same day as the tumor cores were harvested are similar. Differences were primarily observed in the lymphocyte population of a clinical hepatocellular carcinoma case. Viable populations of immune cells persisted in the tumor slices for 7 days. Despite some changes in the immune cell populations, we showed the utility of mouse tumor slices for assessing responses to immune-modulatory agents. Further, we demonstrated the ability to use patient-derived xenograft tumor slices for assessing responses to targeted and cytotoxic drugs. Overall, tumor slices provide a broadly useful platform for studying the tumor microenvironment and evaluating the preclinical efficacy of cancer therapeutics.

Autologous Hematopoietic Stem Cells Are a Preferred Source to Generate Dendritic Cells for Immunotherapy in Multiple Myeloma Patients

In multiple myeloma (MM), dendritic cells (DCs), and their precursors are prone to malignant cell-mediated regulation of function leading to low efficacy of DC vaccine. DCs taken directly from MM patient's body or derived from monocytes are fewer in numbers and are also dysfunctional. Here, we investigated the functionality of Hematopoietic stem cell-derived DCs (SC-DCs) from MM patients. Mature-MM-SC-DCs showed all essential functions like antigen uptake, allogenic T cells simulation and migration comparable to those derived from healthy donor (HD) samples. A comparison of Mo-DCs and SC-DCs obtained from the same MM patients' samples revealed that the expression of IL-6 was higher in the precursors of Mo-DCs leading to their impaired migration. In addition, expression of CCR7 which is responsible for DCs migration was found to be lower in MM-Mo-DCs. The chromatin permissiveness as observed by H3K4me³ histone modification at the Ccr7 promoter in MM-Mo-DCs was significantly lower than those in MM-SC-DCs. Levels of Zbtb46- a hall mark DC transcription factor mRNA was also found to be reduced in MM-Mo-DCs. Cytotoxic T cells generated from MM-SC-DCs from autologous naïve T cells exhibited reduced antitumor activity because the T cells were exhausted. Blocking of CTLA-4 on autologous T cells could partially restore T cell proliferation and activation. Thus, a combination of MM-SC-DC vaccine and anti-CTLA-4 antibody may serve as a better candidate for immunotherapy of MM. This study has implications in increasing the efficacy of cancer immunotherapy in MM.

Clinical significance of CD8+ T cell immunoreceptor with Ig and ITIM domains+ in locally advanced gastric cancer treated with SOX regimen after D2 gastrectomy

Gastric cancer (GC) development and progression is significantly associated with tumour immune escape. T cell immunoreceptor with Ig and ITIM domains (TIGIT) inhibits T-cell responses and is associated with human cancers and T cell exhaustion phenotypes, but its role in cancers remains unclear. TIGIT and programmed cell death protein (PD)-1 levels were detected in 441 human GC specimens using histochemistry. We used flow cytometry to evaluate percentage of TIGIT⁺ constituting CD8⁺ T cells of 23 patients with GC who underwent D2 gastrectomy and the S-1 plus oxaliplatin (SOX) regimen. We investigated the influence of SOX regimen and TIGIT functional antibody on CD8 tumour-infiltrating lymphocytes (TILs). Results showed that PD-1 and TIGIT were significantly over expressed in GC and predicted poorer outcome, agreeing with bioinformatics analysis. Significantly reduced percentages of CD8⁺ TIGIT⁺ cells were observed in patients after D2 gastrectomy (pre- vs post-surgery, 38 ± 8.7% vs. 26.7% ± 5.2%, p < 0.0001). TIGIT expression on CD8⁺T cells was modulated by chemotherapeutics (pre- and post-chemotherapy, 31.3 ± 9% vs. 25.1 ± 4.5%, respectively, p = 0.0047) and higher TIGIT expression in post-chemotherapy group was associated with relapsed GC (p = 0.036). In vitro experiments revealed increased CD8⁺ TIL proliferation and interferon (IFN)-γ production following SOX regimen and TIGIT functional antibody treatments. In conclusion, TIGIT contributes to CD8⁺ TILs immune dysfunction in patients with GC. Combination of anti-TIGIT therapy and chemotherapy could be considered a therapy for GC.

Targeting the tumor microenvironment to overcome immune checkpoint blockade therapy resistance

The ability of immune checkpoint inhibitors (ICIs) to reactivate the killing function of the immune system to tumor cells has led to long lasting immune response presenting highly promising clinical advances. Recently, immune checkpoint inhibitors related resistance due to the specialized tumor microenvironment has also drawn a widely attention. To overcome resistance to immune checkpoint blockade therapy, understanding the relationship of this type of therapy and tumor microenvironment is necessary and critical. This review will focus on how the tumor environment influences the effectiveness of the immunotherapeutic check inhibitors. Finally, we provide a briefly succinct glimpse into the most exciting pre-clinical discoveries and ongoing clinical trials to overcome the resistance of ICIs.

Recent therapeutic trends and promising targets in triple negative breast cancer

Breast cancer accounts for 25% of all types of cancer in women, and triple negative breast cancer (TNBC) comprises around 15~20% of breast cancers. Conventional chemotherapy and radiation are the primary systemic therapeutic strategies; no other FDA-approved targeted therapies are yet available as for TNBC. TNBC is generally characterized by a poor prognosis and high rates of proliferation and metastases. Due to these aggressive features and lack of targeted therapies, numerous attempts have been made to discover viable molecular targets for TNBC. Massive cohort studies, clinical trials, and in-depth analyses have revealed diverse molecular alterations in TNBC; however, controversy exists as to whether many of these changes are beneficial or detrimental in caner progression. Here we review the complicated tumorigenic processes and discuss critical findings and therapeutic trends in TNBC with a focus on promising therapeutic approaches, the clinical trials currently underway, and potent experimental compounds under preclinical and evaluation.

Are Conventional Type 1 Dendritic Cells Critical for Protective Antitumor Immunity and How?

Dendritic cells (DCs) are endowed with a unique potency to prime T cells, as well as to orchestrate their expansion, functional polarization and effector activity in non-lymphoid tissues or in their draining lymph nodes. The concept of harnessing DC immunogenicity to induce protective responses in cancer patients was put forward about 25 years ago and has led to a multitude of DC-based vaccine trials. However, until very recently, objective clinical responses were below expectations. Conventional type 1 DCs (cDC1) excel in the activation of cytotoxic lymphocytes including CD8⁺ T cells (CTLs), natural killer (NK) cells, and NKT cells, which are all critical effector cell types in antitumor immunity. Efforts to investigate whether cDC1 might orchestrate immune defenses against cancer are ongoing, thanks to the recent blossoming of tools allowing their manipulation in vivo. Here we are reporting on these studies. We discuss the mouse models used to genetically deplete or manipulate cDC1, and their main caveats. We present current knowledge on the role of cDC1 in the spontaneous immune rejection of tumors engrafted in syngeneic mouse recipients, as a surrogate model to cancer immunosurveillance, and how this process is promoted by type I interferon (IFN-I) effects on cDC1. We also discuss cDC1 implication in promoting the protective effects of immunotherapies in mouse preclinical models, especially for adoptive cell transfer (ACT) and immune checkpoint blockers (ICB). We elaborate on how to improve this process by in vivo reprogramming of certain cDC1 functions with off-the-shelf compounds. We also summarize and discuss basic research and clinical data supporting the hypothesis that the protective antitumor functions of cDC1 inferred from mouse preclinical models are conserved in humans. This analysis supports potential applicability to cancer patients of the cDC1-targeting adjuvant immunotherapies showing promising results in mouse models. Nonetheless, further investigations on cDC1 and their implications in anti-cancer mechanisms are needed to determine whether they are the missing key that will ultimately help switching cold tumors into therapeutically responsive hot tumors, and how precisely they mediate their protective effects.