Role of myeloid-derived suppressor cells in immune checkpoint inhibitor therapy in cancer

Rapamycin Induces Phenotypic Alterations in Oral Cancer Cells That May Facilitate Antitumor T Cell Responses

OBJECTIVES

In this study, we investigated the antitumor immunomodulatory effects of rapamycin in oral cancer.

STUDY DESIGN

We examined the proliferation, apoptosis, and migration of cancer cells and investigated the cell surface expression levels of immune accessory molecules and T cell immune responses in vitro. We investigated the effect of in vivo administration of rapamycin on immune cell distribution and T cell immune responses in oral tumor-bearing mice.

RESULTS

Rapamycin treatment significantly inhibited OSCC cell proliferation and migration, increased apoptotic cell death, and upregulated cell surface expression of several immune accessory and adhesion molecules, including CD40, CD83, PD-L1, PD-L2, MHC class I, P-selectin, and VCAM-1. These cancer cells augmented T cell proliferation. In vivo rapamycin administration significantly attenuated mouse tumor growth with an increased proportion of immune cells, including CD4+ T cells, CD8+ T cells, and dendritic cells (DCs); decreased the proportion of immune suppressive cells, such as myeloid-derived suppressor cells and regulatory T cells; enhanced DC maturation and upregulated the surface expression of CD40, CD86, and ICAM-1.

CONCLUSIONS

Our results suggest that the therapeutic effect of mTOR inhibition in oral cancer can cause direct antitumor and immunomodulatory effects.

Immune checkpoint inhibition: a future guided by radiology

The limitation of the function of antitumour immune cells is a common hallmark of cancers that enables their survival. As such, the potential of immune checkpoint inhibition (ICI) acts as a paradigm shift in the treatment of a range of cancers but has not yet been fully capitalised. Combining minimally and non-invasive locoregional therapies offered by radiologists with ICI is now an active field of research with the aim of furthering therapeutic capabilities in medical oncology. In parallel to this impending advancement, the "imaging toolbox" available to radiologists is also growing, enabling more refined tumour characterisation as well as greater accuracy in evaluating responses to therapy. Options range from metabolite labelling to cellular localisation to immune checkpoint screening. It is foreseeable that these novel imaging techniques will be integrated into personalised treatment algorithms. This growth in the field must include updating the current standardised imaging criteria to ensure they are fit for purpose. Such criteria is crucial to both appropriately guide clinical decision-making regarding next steps of treatment, but also provide reliable prognosis. Quantitative approaches to these novel imaging techniques are also already being investigated to further optimise personalised therapeutic decision-making. The therapeutic potential of specific ICIs and locoregional therapies could be determined before administration thus limiting unnecessary side-effects whilst maintaining efficacy. Several radiological aspects of oncological care are advancing simultaneously. Therefore, it is essential that each development is assessed for clinical use and optimised to ensure the best treatment decisions are being offered to the patient. In this review, we discuss state of the art advances in novel functional imaging techniques in the field of immuno-oncology both pre-clinically and clinically.

Mobilization of monocytic myeloid-derived suppressor cells is regulated by PTH1R activation in bone marrow stromal cells

Myeloid-derived suppressor cells (MDSCs) are bone marrow (BM)-derived immunosuppressive cells in the tumor microenvironment, but the mechanism of MDSC mobilization from the BM remains unclear. We investigated how BM stromal cell activation by PTH1R contributes to MDSC mobilization. PTH1R activation by parathyroid hormone (PTH) or PTH-related peptide (PTHrP), a tumor-derived counterpart, mobilized monocytic (M-) MDSCs from murine BM without increasing immunosuppressive activity. In vitro cell-binding assays demonstrated that α4β1 integrin and vascular cell adhesion molecule (VCAM)-1, expressed on M-MDSCs and osteoblasts, respectively, are key to M-MDSC binding to osteoblasts. Upon PTH1R activation, osteoblasts express VEGF-A and IL6, leading to Src family kinase phosphorylation in M-MDSCs. Src inhibitors suppressed PTHrP-induced MDSC mobilization, and Src activation in M-MDSCs upregulated two proteases, ADAM-17 and MMP7, leading to VCAM1 shedding and subsequent disruption of M-MDSC tethering to osteoblasts. Collectively, our data provide the molecular mechanism of M-MDSC mobilization in the bones of tumor hosts.

Myeloid-Derived Suppressor Cells in Cancer and COVID-19 as Associated with Oxidative Stress

Myeloid-derived suppressor cells MDSCs are a heterogeneous population of cells that expand beyond their physiological regulation during pathologies such as cancer, inflammation, bacterial, and viral infections. Their key feature is their remarkable ability to suppress T cell and natural killer NK cell responses. Certain risk factors for severe COVID-19 disease, such as obesity and diabetes, are associated with oxidative stress. The resulting inflammation and oxidative stress can negatively impact the host. Similarly, cancer cells exhibit a sustained increase in intrinsic ROS generation that maintains the oncogenic phenotype and drives tumor progression. By disrupting endoplasmic reticulum calcium channels, intracellular ROS accumulation can disrupt protein folding and ultimately lead to proteostasis failure. In cancer and COVID-19, MDSCs consist of the same two subtypes (PMN-MSDC and M-MDSC). While the main role of polymorphonuclear MDSCs is to dampen the response of T cells and NK killer cells, they also produce reactive oxygen species ROS and reactive nitrogen species RNS. We here review the origin of MDSCs, their expansion mechanisms, and their suppressive functions in the context of cancer and COVID-19 associated with the presence of superoxide anion •O2- and reactive oxygen species ROS.

Deletion of PD-1 destabilizes the lineage identity and metabolic fitness of tumor-infiltrating regulatory T cells

Regulatory T (T_reg) cells have an immunosuppressive function and highly express the immune checkpoint receptor PD-1 in the tumor microenvironment; however, the function of PD-1 in tumor-infiltrating (TI) T_reg cells remains controversial. Here, we showed that conditional deletion of PD-1 in T_reg cells delayed tumor progression. In Pdcd1^fl/flFoxp3^{eGFP-Cre-ERT2(+/-)} mice, in which both PD-1-expressing and PD-1-deficient T_reg cells coexisted in the same tissue environment, conditional deletion of PD-1 in T_reg cells resulted in impairment of the proliferative and suppressive capacity of TI T_reg cells. PD-1 antibody therapy reduced the TI T_reg cell numbers, but did not directly restore the cytokine production of TI CD8⁺ T cells in TC-1 lung cancer. Single-cell analysis indicated that PD-1 signaling promoted lipid metabolism, proliferation and suppressive pathways in TI T_reg cells. These results suggest that PD-1 ablation or inhibition can enhance antitumor immunity by weakening T_reg cell lineage stability and metabolic fitness in the tumor microenvironment.

S-1 eliminates MDSCs and enhances the efficacy of PD-1 blockade via regulation of tumor-derived Bv8 and S100A8 in thoracic tumor

Myeloid-derived suppressor cells (MDSCs) have been known to play a pivotal role in the induction of immune tolerance, which limits the benefits of immune checkpoint inhibitors (ICIs). Recent studies revealed that several chemotherapeutic agents decreased tumor-infiltrating MDSCs. Therefore, combination therapy with cytotoxic chemotherapeutic agents and ICIs was approved for first-line treatment for lung cancer. However, the impact of chemotherapeutic agents on MDSCs and an optimal partner of ICIs has not been fully investigated in thoracic tumors, including lung cancer and malignant pleural mesothelioma. In the present study, we found that treatment with 5-FU and its oral formulation, S-1, suppressed tumor progression and inhibited the accumulation of MDSCs in thoracic tumor-bearing mice. Tumor-infiltrating T cells and dendritic cells were significantly expanded in S-1-treated mice. 5-FU suppressed the ability of tumor cells to recruit MDSCs, while it did not suppress the survival and differentiation of mouse MDSCs in vitro. We also revealed that 5-FU or S-1 significantly downregulated the expression of tumor-derived Bv8 and S100A8. The knockdown of Bv8 or S100A8 in tumor cells suppressed tumor growth and MDSC recruitment in vivo. Furthermore, in comparison with pemetrexed, administration of S-1 improved the synergistic therapeutic efficacy of anti-PD-1 antibodies with or without carboplatin. Our findings revealed a novel mechanism wherein S-1 primed a favorable tumor microenvironment to provide the rationale for combination therapy with S-1 and ICIs as the optimal therapy for thoracic cancer.

Key Candidate Prognostic Biomarkers Correlated with Immune Infiltration in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common subtype of primary liver cancer, which causes ~800,000 deaths annually world-wide. Immune checkpoint inhibitor (ICI) has reformed cancer therapy and achieved unprecedented results in various malignancies, including HCC. However, the response rate of immunotherapy is very low in HCC. Considereing the complicated and unique immune status in liver, we hypothesize that critical molecules will affect prognosis and correlate with immune context in the tumor microenvironment of HCC.

Methods

Using Kaplan–Meier plotter, GEPIA2 and Integrative Molecular Database of Hepatocellular Carcinoma (HCCDB), survival genes and their prognostic value were estimated in HCC. Based on Tumor Immune Estimation Resource (TIMER), association between survival genes and immune infiltration was examined in HCC. FunRich and STRING were used to analyze gene ontology and protein–protein interaction (PPI) Network, qRT-PCR was used to measure mRNA level of candidates; and a Cell Counting Kit-8 was used to measure proliferation of HCC cell line.

Results

Using multiple databases, we identified 36 key prognostic genes highly expressed in HCC and associated with poor survival of patients. Meanwhile, the 36 gene signatures correlated with immune infiltration in HCC. Moreover, these genes were significantly associated with exhausted T cells and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in HCC. Among the 36 key genes, SKA3, SGOL2, SPINDOC, TEDC2, TMCO3 and NUP205 were highly expressed in tumor samples compared with adjacent normal tissues in our HCC cohort (n=22). Additionally, proliferation of SMMC7721 cell line was inhibited when it interfered with SiRNA of each gene.

Conclusion

The 36 genes may serve as potential prognostic biomarkers and molecular targets to ameliorate tumor immune microenvironment (TIME) in HCC and therefore represent a novel avenue for individualized immunotherapy in HCC.

Single-cell analysis reveals EP4 as a target for restoring T cell infiltration and sensitizing prostate cancer to immunotherapy

PURPOSE

Immunotherapies targeting immune checkpoint molecules have shown promising treatment for a subset of cancers; however, many "cold" tumors, such as prostate cancer, remain unresponsive. We aimed to identify a potential targetable marker relevant to prostate cancer and develop novel immunotherapy.

EXPERIMENTAL DESIGN

Analysis of transcriptomic profiles at single-cell resolution was performed in clinical patients' samples, along with integrated analysis of multiple RNA-seq datasets. The antitumor activity of YY001, a novel EP4 antagonist, combined with anti-programmed cell death protein 1 (PD-1) antibody was evaluated both in vitro and in vivo Results: We identified EP4 (PTGER4) as expressed in epithelial cells and various immune cells and involved in modulating the prostate cancer immune microenvironment. YY001, a novel EP4 antagonist, inhibited the differentiation, maturation, and immunosuppressive function of myeloid-derived suppressor cells (MDSCs) while enhancing the proliferation and anticancer functions of T cells. Furthermore, it reversed the infiltration levels of MDSCs and T cells in the tumor microenvironment by overturning the chemokine profile of tumor cells in vitro and in vivo The combined immunotherapy demonstrated a robust antitumor immune response as indicated by the robust accumulation and activation of CD8⁺ cytotoxic T cells, with a significantly decreased MDSC ratio and reduced MDSC immunosuppression function.

CONCLUSIONS

Our study identified EP4 as a specific target for prostate cancer immunotherapy and demonstrated that YY001 inhibited the growth of prostate tumors by regulating the immune microenvironment and strongly synergized with anti-PD-1 antibodies to convert completely unresponsive prostate cancers into responsive cancers, resulting in marked tumor regression, long-term survival, and lasting immunologic memory.

Resistance to Immune Checkpoint Inhibitors Secondary to Myeloid-Derived Suppressor Cells: A New Therapeutic Targeting of Haematological Malignancies

Myeloid-derived suppressor cells (MDSCs) are a set of immature myeloid lineage cells that include macrophages, granulocytes, and dendritic cell precursors. This subpopulation has been described in relation to the tumour processes at different levels, including resistance to immunotherapy, such as immune checkpoint inhibitors (ICIs). Currently, multiple studies at the preclinical and clinical levels seek to use this cell population for the treatment of different haematological neoplasms, together with ICIs. This review addresses the different points in ongoing studies of MDSCs and ICIs in haematological malignancies and their future significance in routine clinical practice.

Myeloid-Derived Suppressor Cells: Facilitators of Cancer and Obesity-Induced Cancer

Immature myeloid cells at varied stages of differentiation, known as myeloid-derived suppressor cells (MDSC), are present in virtually all cancer patients. MDSC are profoundly immune-suppressive cells that impair adaptive and innate antitumor immunity and promote tumor progression through nonimmune mechanisms. Their widespread presence combined with their multitude of protumor activities makes MDSC a major obstacle to cancer immunotherapies. MDSC are derived from progenitor cells in the bone marrow and traffic through the blood to infiltrate solid tumors. Their accumulation and suppressive potency are driven by multiple tumor- and host-secreted proinflammatory factors and adrenergic signals that act via diverse but sometimes overlapping transcriptional pathways. MDSC also accumulate in response to the chronic inflammation and lipid deposition characteristic of obesity and contribute to the more rapid progression of cancers in obese individuals. This article summarizes the key aspects of tumor-induced MDSC with a focus on recent progress in the MDSC field.

Clinical correlates for immune checkpoint therapy: significance for CNS malignancies

Immune checkpoint inhibitors (ICIs) have revolutionized the field of cancer immunotherapy. Most commonly, inhibitors of PD-1 and CTLA4 are used having received approval for the treatment of many cancers like melanoma, non-small-cell lung carcinoma, and leukemia. In contrast, to date, clinical studies conducted in patients with CNS malignancies have not demonstrated promising results. However, patients with CNS malignancies have several underlying factors such as treatment with supportive medications like corticosteroids and cancer therapies including radiation and chemotherapy that may negatively impact response to ICIs. Although many clinical trials have been conducted with ICIs, measures that reproducibly and reliably indicate that treatment has evoked an effective immune response have not been fully developed. In this article, we will review the history of ICI therapy and the correlative biology that has been performed in the clinical trials testing these therapies in different cancers. It is our aim to help provide an overview of the assays that may be used to gauge immunologic response. This may be particularly germane for CNS tumors, where there is currently a great need for predictive biomarkers that will allow for the selection of patients with the highest likelihood of responding.

The role of myeloid-derived suppressor cells in hematologic malignancies

PURPOSE OF REVIEW

This article focuses on the immunosuppressive impact of myeloid-derived suppressor cells (MDSCs) and the potential clinical implications in hematological malignancies.

RECENT FINDINGS

MDSCs play a critical role in the regulation of the immune response in cancer. They inhibit activation of adaptive immune response and as a result foster the growth of the malignancy. Recent studies have shown that MDSCs serve as prognostic biomarkers and as targets for cancer immunotherapy. Preclinical and clinical studies have identified new approaches to deplete MDSC populations and inhibit MDSC function with combination immunomodulatory therapies including chemotherapeutic agents with immune checkpoint-directed treatment.

SUMMARY

A broad spectrum of publications indicate that direct targeting of MDSCs may abrogate their protumorigenic impact within the tumor microenvironment through activation of the adaptive immune response.

Biomarkers for precision immunotherapy in the metastatic setting: hope or reality?

Precision immunotherapy is a crucial approach to improve the efficacy of anti-cancer treatments, particularly in the metastatic setting. In this respect, accurate patient selection takes advantage of the multidimensional integration of patients' clinical information and tumour-specific biomarkers status. Among these biomarkers, programmed death-ligand 1, tumour-infiltrating lymphocytes, microsatellite instability, mismatch repair and tumour mutational burden have been widely investigated. However, novel tumour-specific biomarkers and testing methods will further improve patients' outcomes. Here, we discuss the currently available strategies for the implementation of a precision immunotherapy approach in the clinical management of metastatic solid tumours and highlight future perspectives.

Targeting Myeloid-Derived Suppressor Cells in Cancer Immunotherapy

Simple Summary

Myeloid-Derived Suppressor Cells (MDSCs) have been regarded as the main promoters of cancer development in recent years. They can protect tumor cells from being eliminated by neutralizing the anti-tumor response mediated by T cells, macrophages and dendritic cells (DCs). Therefore, different treatment methods targeting MDSCs, including chemotherapy, radiotherapy and immunotherapy, have been developed and proven to effectively inhibit tumor expansion. Herein, we summarize the immunosuppressive role of MDSCs in the tumor microenvironment and some effective treatments targeting MDSCs, and discuss the differences between different therapies.

Abstract

Myeloid-derived suppressor cells (MDSCs), which are activated under pathological conditions, are a group of heterogeneous immature myeloid cells. MDSCs have potent capacities to support tumor growth via inhibition of the antitumoral immune response and/or the induction of immunosuppressive cells. In addition, multiple studies have demonstrated that MDSCs provide potential therapeutic targets for the elimination of immunosuppressive functions and the inhibition of tumor growth. The combination of targeting MDSCs and other therapeutic approaches has also demonstrated powerful antitumor effects. In this review, we summarize the characteristics of MDSCs in the tumor microenvironment (TME) and current strategies of cancer treatment by targeting MDSCs.

Application of Anti-Inflammatory Agents in Prostate Cancer

Chronic inflammation is a major cause of human cancers. The environmental factors, such as microbiome, dietary components, and obesity, provoke chronic inflammation in the prostate, which promotes cancer development and progression. Crosstalk between immune cells and cancer cells enhances the secretion of intercellular signaling molecules, such as cytokines and chemokines, thereby orchestrating the generation of inflammatory microenvironment. Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) play pivotal roles in inflammation-associated cancer by inhibiting effective anti-tumor immunity. Anti-inflammatory agents, such as aspirin, metformin, and statins, have potential application in chemoprevention of prostate cancer. Furthermore, pro-inflammatory immunity-targeted therapies may provide novel strategies to treat patients with cancer. Thus, anti-inflammatory agents are expected to suppress the “vicious cycle” created by immune and cancer cells and inhibit cancer progression. This review has explored the immune cells that facilitate prostate cancer development and progression, with particular focus on the application of anti-inflammatory agents for both chemoprevention and therapeutic approach in prostate cancer.

Myeloid Cells as Clinical Biomarkers for Immune Checkpoint Blockade

Immune checkpoint inhibitors are becoming standard treatments in several cancer types, profoundly changing the prognosis of a fraction of patients. Currently, many efforts are being made to predict responders and to understand how to overcome resistance in non-responders. Given the crucial role of myeloid cells as modulators of T effector cell function in tumors, it is essential to understand their impact on the clinical outcome of immune checkpoint blockade and on the mechanisms of immune evasion. In this review we focus on the existing clinical evidence of the relation between the presence of myeloid cell subsets and the response to anti-PD(L)1 and anti-CTLA-4 treatment. We highlight how circulating and tumor-infiltrating myeloid populations can be used as predictive biomarkers for immune checkpoint inhibitors in different human cancers, both at baseline and on treatment. Moreover, we propose to follow the dynamics of myeloid cells during immunotherapy as pharmacodynamic biomarkers. Finally, we provide an overview of the current strategies tested in the clinic that use myeloid cell targeting together with immune checkpoint blockade with the aim of uncovering the most promising approaches for effective combinations.

Metabolic Regulation of Myeloid-Derived Suppressor Cell Function in Cancer

Myeloid-derived suppressor cells (MDSCs) are a group of immunosuppressive cells that play crucial roles in promoting tumor growth and protecting tumors from immune recognition in tumor-bearing mice and cancer patients. Recently, it has been shown that the metabolic activity of MDSCs plays an important role in the regulation of their inhibitory function, especially in the processes of tumor occurrence and development. The MDSC metabolism, such as glycolysis, fatty acid oxidation and amino acid metabolism, is rewired in the tumor microenvironment (TME), which enhances the immunosuppressive activity, resulting in effector T cell apoptosis and suppressive cell proliferation. Herein, we summarized the recent progress in the metabolic reprogramming and immunosuppressive function of MDSCs during tumorigenesis.

Jianpi Huayu Decoction Attenuates the Immunosuppressive Status of H22 Hepatocellular Carcinoma-Bearing Mice: By Targeting Myeloid-Derived Suppressor Cells

Tumor-induced immunosuppressive microenvironment in which myeloid-derived suppressor cells (MDSCs) plays an important role, remains an obstacle for effective oncotherapy currently. Inducing MDSCs into maturation was confirmed as an effective method to reduce the tumor-bearing host's immunosuppression. Traditional Chinese medicines (TCM) possess characteristics of alleviating immunosuppression of cancer patients and low toxicity. Jianpi Huayu Decoction (JHD) was an experienced formula of TCM for oncotherapy based on TCM theory and clinical practice. We previously observed that JHD attenuated the expression of interleukin-10 (IL-10) and transforming growth factor beta (TGF-β) in tumor. IL-10 and TGF-β were found to be cytokines positively related to immunosuppression induced by MDSCs. Here, our study was designed to further investigate the regulation of JHD on the immune system in the H₂₂ liver-cancer mouse model. Mainly, flow cytometry was used to detect the proportion of immune cells, to analyze the apoptosis, differentiation and reactive oxygen species of MDSCs. We found that JHD significantly reduced the destruction of spleen structure, reduced the proportion of regulatory T cells (Treg) and T helper 17 cells (Th17), and increased the proportion of cytotoxic T lymphotes (CTL), Dendritic cells (DC) and CD11b⁺Gr-1⁺cells in spleen, but with no significant change of T helper 1 cells (Th1), T helper 2 cells (Th2) and macrophages. In vitro experiments showed that apoptosis of MDSCs was decreased as the time of JHD stimulation increased, which partly explained the increase of CD11b⁺Gr-1⁺cells in the spleen. Meanwhile, JHD could promote the differentiation of MDSCs into macrophages and dendritic cells, attenuate expression of ROS in MDSCs and reduce its inhibition on the proliferation of CD4⁺ T cells, in vitro. Therefore, that the proportion of CD11b⁺Gr-1⁺ cells increased in the spleen of tumor-bearing hosts may not be villainy after treatment, when these drugs suppress the immunosuppressive ability of CD11b⁺Gr-1⁺ cells and promote it mature to replenish dendritic cell, at the same time. Generally, JHD may be a complementary and alternative drug for attenuating the immunosuppressive status induced by hepatocellular carcinoma, possibly by promoting differentiation and inhibiting the immunosuppressive activity of MDSCs.

Multimodal Molecular Imaging of the Tumour Microenvironment

The tumour microenvironment (TME) surrounding tumour cells is a highly dynamic and heterogeneous composition of immune cells, fibroblasts, precursor cells, endothelial cells, signalling molecules and extracellular matrix (ECM) components. Due to the heterogeneity and the constant crosstalk between the TME and the tumour cells, the components of the TME are important prognostic parameters in cancer and determine the response to novel immunotherapies. To improve the characterization of the TME, novel non-invasive imaging paradigms targeting the complexity of the TME are urgently needed.The characterization of the TME by molecular imaging will (1) support early diagnosis and disease follow-up, (2) guide (stereotactic) biopsy sampling, (3) highlight the dynamic changes during disease pathogenesis in a non-invasive manner, (4) help monitor existing therapies, (5) support the development of novel TME-targeting therapies and (6) aid stratification of patients, according to the cellular composition of their tumours in correlation to their therapy response.This chapter will summarize the most recent developments and applications of molecular imaging paradigms beyond FDG for the characterization of the dynamic molecular and cellular changes in the TME.

Doxorubicin-polyglycerol-nanodiamond conjugate is a cytostatic agent that evades chemoresistance and reverses cancer-induced immunosuppression in triple-negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) has the poorest prognosis of all breast cancer subtypes and is one of the most fatal diseases for women. Combining cytotoxic chemotherapy with immunotherapy has shown great promise for TNBC treatment. However, chemotherapy often leads to the development of chemoresistance and severe systemic toxicity compromising the immune functions that are crucial to anti-TNBC immune therapy. Tumor-induced immunosuppression also poses a great hindrance to efficacious anti-TNBC immunotherapy. Nanomedicine holds great promise to overcome these hurdles.

RESULTS

Doxorubicin-polyglycerol-nanodiamond conjugate (Nano-DOX) was firstly found to be a cytostatic agent to the 4T1 cells and displayed a lower apparent therapeutic potency than DOX. However, the tumor-bearing animals, particularly some key immune cells thereof, showed good tolerance of Nano-DOX as opposed to the severe toxicity of DOX. Next, Nano-DOX did not induce significant upregulation of P-gp and IL-6, which were demonstrated to be key mediators of chemoresistance to DOX in the 4T1 cells. Then, Nano-DOX was shown to downregulate tumor-derived granulocyte-colony stimulating factor (G-CSF) and suppresses the induction and tissue filtration of myeloid-derived suppressor cells (MDSCs) that are the principal effectors of cancer-associated systemic immunosuppression. Nano-DOX also alleviated the phenotype of MDSCs induced by 4T1 cells. Finally, Nano-DOX induced the 4T1 cells to emit damage associated molecular patterns (DAMPs) that stimulated the tumor immune microenvironment through activating key immune effector cells involved in anti-tumor immunity, such as macrophages, dendritic cells and lymphocytes in the tumor tissue.

CONCLUSIONS

Nano-DOX is a cytostatic agent with good host tolerance which is capable of evading chemoresistance and reversing cancer-induced immunosuppression both at the systemic level and in the tumor microenvironment in TNBC. Our work presents Nano-DOX as an interesting example that a chemotherapeutic agent in nano-form may possess distinct biochemical properties from its free form, which can be exploited to join chemotherapy with immunotherapy for better treatment of cancer.

Gr-MDSC-linked asset as a potential immune biomarker in pretreated NSCLC receiving nivolumab as second-line therapy

PURPOSE

Immunotherapy is a new standard first-line treatment for non-small cell lung cancers (NSCLC) with high programmed cell death-ligand 1 (PD-L1) expression (≥ 50%) and second-line treatment regardless of PD-L1 status, though not all patients benefit from this approach. Much effort is ongoing to identify robust prognostic and predictive biomarkers of response to immune checkpoint inhibitors, overcoming PD-L1 that appears limited in its ability to discriminate patient candidates to this new class of anticancer agents. The purpose of this research study is to identify potential new biomarkers for immunotherapy in lung cancer.

METHODS

Fifty-three consecutive patients with advanced NSCLC treated with nivolumab were enrolled in the study. All the patients received a blood analysis looking for the relationship between different populations of baseline white blood cells and granulocytic myeloid-derived suppressor cells (Gr-MDSC) detected by flow cytometry, to identify and characterize patients with poor likelihood of benefit from nivolumab in NSCLC second-line setting, regardless of clinical feature and PDL1 expression.

RESULTS

Univariate analysis showed that high baseline levels of Gr-MDSC and low baseline CD8/Gr-MDSC ratio are associated with significantly better (P = 0.02) response to immunotherapy treatment. Log-rank tests suggested a significant improvement in OS and PFS with high baseline levels of Gr-MDSC levels (≥ 6 cell/μl), low absolute neutrophil count (< 5840/μl), high eosinophil count (> 90 /μl), and NLR < 3. The multivariate analysis showed a statistically significant improvement for PFS (P = 0.003) and OS (P = 0.05) in favour of the identified good prognostic Gr-MDSC-linked asset group, compared with the poor prognosis group.

CONCLUSION

The role of Gr-MDSC appears interesting as a potential biomarker in NSCLC patients receiving immune-checkpoint inhibitors. Further analyses are needed to confirmed and study in deep the role of these particular cells and their role in cancer response and progression during ICI therapy.