Modulating the wayward T cell: New horizons with immune checkpoint inhibitor treatments in autoimmunity, transplant, and cancer

The role of tumor-associated macrophages in tumor immune evasion

BACKGROUND

Tumor growth is closely linked to the activities of various cells in the tumor microenvironment (TME), particularly immune cells. During tumor progression, circulating monocytes and macrophages are recruited, altering the TME and accelerating growth. These macrophages adjust their functions in response to signals from tumor and stromal cells. Tumor-associated macrophages (TAMs), similar to M2 macrophages, are key regulators in the TME.

METHODS

We review the origins, characteristics, and functions of TAMs within the TME. This analysis includes the mechanisms through which TAMs facilitate immune evasion and promote tumor metastasis. Additionally, we explore potential therapeutic strategies that target TAMs.

RESULTS

TAMs are instrumental in mediating tumor immune evasion and malignant behaviors. They release cytokines that inhibit effector immune cells and attract additional immunosuppressive cells to the TME. TAMs primarily target effector T cells, inducing exhaustion directly, influencing activity indirectly through cellular interactions, or suppressing through immune checkpoints. Additionally, TAMs are directly involved in tumor proliferation, angiogenesis, invasion, and metastasis. Developing innovative tumor-targeted therapies and immunotherapeutic strategies is currently a promising focus in oncology. Given the pivotal role of TAMs in immune evasion, several therapeutic approaches have been devised to target them. These include leveraging epigenetics, metabolic reprogramming, and cellular engineering to repolarize TAMs, inhibiting their recruitment and activity, and using TAMs as drug delivery vehicles. Although some of these strategies remain distant from clinical application, we believe that future therapies targeting TAMs will offer significant benefits to cancer patients.

Features of the immunosuppressive tumor microenvironment in endometrial cancer based on molecular subtype

Endometrial cancer (EC) is one of the three most prevalent gynecological tumors affecting women and is the most prevalent gynecological malignancy in the developed world. Its incidence is rapidly increasing worldwide, mostly affecting postmenopausal women, whereas recently its prevalence has increased in younger people. EC is an immune gene disease and many studies have shown that the tumor-immunosuppressive microenvironment plays an important role in cancer progression. In recent years, findings regarding the immunosuppressive tumor microenvironment (ITME) of EC have included immune evasion mechanisms and immunotherapy, which are mostly immune checkpoint inhibitors (ICI) for EC. Recently studies on the ITME of different molecular types of EC have found that different molecular types may have different ITME. With the research on the immune microenvironment of EC, a new immunophenotype classification based on the immune microenvironment has been carried out in recent years. However, the impact of the ITME on EC remains unclear, and the immunophenotype of EC remains limited to the research stage. Our review describes recent findings regarding the ITME features of different EC molecular types. The advent of immunotherapy has brought hope for improved efficacy and prognosis in patients with advanced or recurrent EC. The efficacy and safety of ICIs combination therapy remains the focus of future research.

Immune-checkpoint expression in antigen-presenting cells (APCs) of cytomegaloviruses infection after transplantation: as a diagnostic biomarker

Cytomegalovirus (CMV), a member of the Herpesviridae family, mostly causes only slight feverish symptoms or can be asymptomatic in immunocompetent individuals. However, it is known to be particularly a significant cause of morbidity in immunocompromised patients, including transplant recipients, whose immune system has been weakened due to the consumption of immunosuppressor drugs. Therefore, the diagnosis of CMV infection after transplantation is crucial. New diagnostic methods for the quick detection of CMV have been developed as a result of understanding the clinical importance of invasive CMV. Antigen-presenting cells (APCs) and T cells are important components of the immune system and it may be possible to diagnose viral infections using immunological markers, such as lymphocytosis, cytotoxic T lymphocytes (CTL), and serum cytokine levels. Moreover, PD-1, CTLA 4, and TIGIT, which are expressed on certain T cells and antigen-presenting cells, are over-expressed during the infection. The assessment of CMV infection based on T cell and APC activity, and the expression of immunological checkpoints, can be helpful for the diagnosis of transplant patients at risk for CMV infection. In this review, we will investigate how immune checkpoints affect immune cells and how they impair organ transplantation after CMV infection.

Contribution of adaptive immunity to human COPD and experimental models of emphysema

The pathophysiology of chronic obstructive pulmonary disease (COPD) and the undisputed role of innate immune cells in this condition have dominated the field in the basic research arena for many years. Recently, however, compelling data suggesting that adaptive immune cells may also contribute to the progressive nature of lung destruction associated with COPD in smokers have gained considerable attention. The histopathological changes in the lungs of smokers can be limited to the large or small airways, but alveolar loss leading to emphysema, which occurs in some individuals, remains its most significant and irreversible outcome. Critically, however, the question of why emphysema progresses in a subset of former smokers remained a mystery for many years. The recognition of activated and organized tertiary T- and B-lymphoid aggregates in emphysematous lungs provided the first clue that adaptive immune cells may play a crucial role in COPD pathophysiology. Based on these findings from human translational studies, experimental animal models of emphysema were used to determine the mechanisms through which smoke exposure initiates and orchestrates adaptive autoreactive inflammation in the lungs. These models have revealed that T helper (Th)1 and Th17 subsets promote a positive feedback loop that activates innate immune cells, confirming their role in emphysema pathogenesis. Results from genetic studies and immune-based discoveries have further provided strong evidence for autoimmunity induction in smokers with emphysema. These new findings offer a novel opportunity to explore the mechanisms underlying the inflammatory landscape in the COPD lung and offer insights for development of precision-based treatment to halt lung destruction.

Risk stratification and molecular heterogeneity of endometrial cancer and expression profile of TIM-3: A retrospective cohort study

OBJECTIVE

The present study aimed to implement ProMisE classification and risk grouping on a retrospective cohort of 628 patients with endometrial cancer (EC) and determine the molecular heterogeneity across subtypes and subgroups, as well as to investigate the potential beneficiary for TIM-3 checkpoint inhibition in ECs.

METHODS

Protein expressions of p53, MMR, TIM-3 and CD8 were measured by immunohistochemistry, and massively parallel sequencing was conducted for 128 cancer-related genes. Patients were categorized into four ProMisE subtypes: MMR-deficient (MMRd), POLE-ultramutated (POLEmut), p53-wild type (p53wt), and p53-abnormal (p53abn), and were subjected to risk classification.

RESULTS

43 (6.9%) patients belonged to POLEmut, 118 (18.8%) to MMRd, 69 (11%) to p53abn, and 398 (63.3%) to p53wt. Compared to the 2016 stratification system, the 2021 ESGO/ESTRO/ESP risk stratification integrated with molecular classification revealed that 11 patients (11/628, 1.8%) were upgraded due to the p53abn signature, whereas 23 patients (23/628, 3.7%) were downgraded due to the POLEmut signature. JAK1 and RAD50 mutations showed higher frequencies in patients with aggressive phenotypes. RAD51B mutation was significantly related to poor RFS of the p53wt subtype but not of the other three molecular subgroups. TIM-3 expression was detected in 30.9% immune cells (ICs) and 29.0% tumor cells (TCs) in ECs, respectively. It was frequently expressed in POLEmut and MMRd ECs as compared to that in the other two molecular subtypes in TCs and ICs.

CONCLUSIONS

Our study revealed the molecular heterogeneity across subtypes and subgroups. The new risk stratification system changed the risk grouping of some patients due to the integration of molecular features. RAD51B mutation can further stratify the recurrence risk in the p53wt subtype. Patients with MMRd or POLEmut may benefit most from immunotherapy against TIM-3.

Musculoskeletal immune-related adverse events in 927 patients treated with immune checkpoint inhibitors for solid cancer

OBJECTIVE

The prevalence of the musculoskeletal immune-related adverse events (irAEs) is probably underestimated, as most studies report only severe side effects. Our aim was to describe and characterize all musculoskeletal irAEs in a large cohort of patients treated with immune checkpoint inhibitors (ICI).

METHODS

We conducted a retrospective study among patients who received ICI from 07/27/2014 to 05/08/2020 at the medical oncology department of the Institut Paoli-Calmettes, Marseille, France. All medical files were systemically reviewed by a rheumatologist who collected clinical features, time of occurrence, treatment regimen, irAEs management, course and outcomes. We also assessed tumor response 3 months after introduction of ICI, according to severity and treatments used to manage musculoskeletal irAEs.

RESULTS

Among 927 patients treated with ICI for a solid tumor, 118 patients (12.7%) presented a musculoskeletal irAE. Their median age was 66.5, 61% were male, and they mainly had a lung (57.6%) or urological cancer (27.1%). The most frequently involved ICI was an anti PD-1. Arthralgias and myalgias were the most frequent musculoskeletal irAEs (9.8%) and inflammatory rheumatic features were reported in 36 patients (3.9%) with elevated acute phase reactants and negative immunological markers. The median time of onset was 2 months (IC 95% 1.8; 2.7). Tumor response at 3 months did not differ according to musculoskeletal irAE severity, type of manifestation (arthralgias/myalgias versus inflammatory rheumatic features), pain patterns (mechanical versus inflammatory) or irAE treatments.

CONCLUSION

Musculoskeletal irAEs in this large cohort of patients treated with ICI were frequent (12.7%), mostly mild and well tolerated.

Preservation of antigen-specific responses in cryopreserved CD4+ and CD8+ T cells expanded with IL-2 and IL-7

Objectives

We sought to develop medium throughput standard operating procedures for screening cryopreserved human peripheral blood mononuclear cells (PBMCs) for CD4⁺ and CD8⁺ T cell responses to potential autoantigens.

Methods

Dendritic cells were loaded with a peptide cocktail from ubiquitous viruses or full-length viral protein antigens and cocultured with autologous T cells. We measured expression of surface activation markers on T cells by flow cytometry and cytometry by time of flight 24-72 h later. We tested responses among T cells freshly isolated from healthy control PBMCs, cryopreserved T cells, and T cells derived from a variety of T cell expansion protocols. We also compared the transcriptional profile of CD8⁺ T cells rested with interleukin (IL)7 for 48 h after 1) initial thawing, 2) expansion, and 3) secondary cryopreservation/thawing of expanded cells. To generate competent antigen presenting cells from PBMCs, we promoted differentiation of PBMCs into dendritic cells with granulocyte macrophage colony stimulating factor and IL-4.

Results

We observed robust dendritic cell differentiation from human PBMCs treated with 50 ng/mL GM-CSF and 20 ng/mL IL-4 in as little as 3 days. Dendritic cell purity was substantially increased by magnetically enriching for CD14⁺ monocytes prior to differentiation. We also measured antigen-dependent T cell activation in DC-T cell cocultures. However, polyclonal expansion of T cells with anti-CD3/antiCD28 abolished antigen-dependent upregulation of CD69 in our assay despite minimal transcriptional differences between rested CD8⁺ T cells before and after expansion. Furthermore, resting these expanded T cells in IL-2, IL-7 or IL-15 did not restore the antigen dependent responses. In contrast, T cells that were initially expanded with IL-2 + IL-7 rather than plate bound anti-CD3 + anti-CD28 retained responsiveness to antigen stimulation and these responses strongly correlated with responses measured at initial thawing.

Significance

While screening techniques for potential pathological autoantibodies have come a long way, comparable full-length protein target assays for screening patient T cells at medium throughput are noticeably lacking due to technical hurdles. Here we advance techniques that should have broad applicability to translational studies investigating cell mediated immunity in infectious or autoimmune diseases. Future studies are aimed at investigating possible CD8⁺ T cell autoantigens in MS and other CNS autoimmune diseases.

Analysis of the immune checkpoint lymphocyte activation gene-3 (LAG-3) in endometrial cancer: An emerging target for immunotherapy

BACKGROUND

Lymphocyte activation gene-3 (LAG-3) is a novel molecule that participates in the immune escape of tumor cells and is a target for immunotherapy. However, the expression of LAG-3 in patients with endometrial cancer (EC) has not been comprehensively characterized.

OBJECTIVES

We elucidated the expression of LAG-3 and investigated its correlation with clinicopathological parameters, ProMisE subtypes, CD8⁺ T-cell infiltration and relapse-free survival (RFS) in a retrospective cohort of 421 patients with endometrial cancer.

METHODS

Next-generation sequencing of the polymerase epsilon (POLE) and immunohistochemistry of mismatch repair (MMR)-related protein (MLH1, PMS2, MSH2, and MSH6), p53, CD8 and LAG-3 protein in whole sections were performed.

RESULTS

Positive LAG-3 was detected in tumor cells (TCs) and immune cells (ICs) in 31.6% (133/421) and 24.0% (101/421) of the patients, respectively. LAG-3 positivity in ICs was more common in high-grade, high-intermediate risk, high-risk, and advanced/metastatic subgroups and was relevant to lymphovascular space invasion, while that in TCs was more common in older individuals (≥54 years). LAG-3 expression was more prevalent in POLE ultramutated (POLEmut) and MMR-deficient (MMRd) EC than in p53-abnormal (p53abn) and p53-wild (p53wt) EC in TCs (34.4 % and 66.3% in POLEmut and MMRd versus 28.6% and 19.5% in p53abn and p53wt, P < 0.001) and ICs (78.1 % and 65.1% in POLEmut and MMRd versus 2.9% and 5.2% in p53abn and p53wt, P < 0.001). Positive expression of LAG-3 in TCs and ICs was associated with high levels of tumor-associated CD8⁺ T-cell immune infiltration. Additionally, LAG-3 positivity in TCs was related to improved RFS.

CONCLUSIONS

This study suggests that immunotherapy targeting LAG-3 may play a role in EC patients with POLEmut or MMRd molecular markers. Positive LAG-3 expression in TCs may be a predictor of improved RFS.

Non-small cell lung cancer in the era of immunotherapy

Immunotherapy for non-small cell lung cancer (NSCLC) has revolutionized treatment for those with advanced disease, and recent data have emerged providing evidence for its benefits in earlier stages of the disease. Several pivotal clinical trials provide compelling data that adaptive immune cells may be highly effective and possibly even curative for NSCLC. Immune checkpoint inhibitors (ICIs) can unleash highly reactive memory immune responses to tumor antigens with durable effects against advanced or recurrent disease. Despite these encouraging results, many critical questions remain in the field including, for example, how to identify the subsets of NSCLC patients who most benefit from ICI treatment, and how ICI efficacy might be enhanced by utilizing combinations or sequencing of agents. A deeper understanding of biological mechanisms involved in lung cancer offers a unique opportunity to further explore the interaction between the adaptive immune landscape and NSCLC. Given the high incidence of lung cancer in Veterans and many Veterans being treated with immunotherapy for this disease, it is timely to have their adequate representation in future clinical trials. New clinical trials focused on Veterans can assist in exploring ways to mitigate resistant mechanisms as well as to investigate predictive and prognostic biomarkers for response to ICIs and other treatments. This paper will review current data and indications for immunotherapy in NSCLC, introduce new areas of research within immunotherapy, and discuss its applicability to the Veteran population.

The Role of Immune Checkpoint Molecules on Macrophages in Cancer, Infection, and Autoimmune Pathologies

Immune checkpoint inhibitors have revolutionized immunotherapy against various cancers over the last decade. The use of checkpoint inhibitors results in remarkable re-activation of patients’ immune system, but is also associated with significant adverse events. In this review, we emphasize the importance of cell-type specificity in the context of immune checkpoint-based interventions and particularly focus on the relevance of macrophages. Immune checkpoint blockade alters the dynamic macrophage phenotypes and thereby substantially manipulates therapeutical outcome. Considering the macrophage-specific immune checkpoint biology, it seems feasible to ameliorate the situation of patients with severe side effects and even increase the probability of survival for non-responders to checkpoint inhibition. Apart from malignancies, investigating immune checkpoint molecules on macrophages has stimulated their fundamental characterization and use in other diseases as well, such as acute and chronic infections and autoimmune pathologies. Although the macrophage-specific effect of checkpoint molecules has been less studied so far, the current literature shows that a macrophage-centered blockade of immune checkpoints as well as a stimulation of their expression represents promising therapeutic avenues. Ultimately, the therapeutic potential of a macrophage-focused checkpoint therapy might be maximized by diagnostically assessing individual checkpoint expression levels on macrophages, thereby personalizing an effective treatment approach for each patient having cancer, infection, or autoimmune diseases.

B7 immune checkpoint family members as putative therapeutics in autoimmune disease: An updated overview

Autoimmune diseases, especially among young people in the US, are one of the leading causes of morbidity and death. The immune responses are the fundamental pathogenicity of autoimmune disorders. The equilibrium between stimulatory and inhibitory signals is critical for the stimulation, migration, survival, and T cell-related immune responses. The B7 family can substantially regulate T cell-mediated immune responses. Nevertheless, recent breakthroughs in immune checkpoint blockade in cancer immunotherapy have facilitated autoimmune diseases, especially among the prone populations. In the current study, we tried to concisely review the role of the B7 family in regulating immune reactions and the influence of immune checkpoint inhibitors on autoimmunity development.

NKG2A is a late immune checkpoint on CD8 T cells and marks repeated stimulation and cell division

The surface inhibitory receptor NKG2A forms heterodimers with the invariant CD94 chain and is expressed on a subset of activated CD8 T cells. As antibodies to block NKG2A are currently tested in several efficacy trials for different tumor indications, it is important to characterize the NKG2A⁺ CD8 T cell population in the context of other inhibitory receptors. Here we used a well‐controlled culture system to study the kinetics of inhibitory receptor expression. Naïve mouse CD8 T cells were synchronously and repeatedly activated by artificial antigen presenting cells in the presence of the homeostatic cytokine IL‐7. The results revealed NKG2A as a late inhibitory receptor, expressed after repeated cognate antigen stimulations. In contrast, the expression of PD‐1, TIGIT and LAG‐3 was rapidly induced, hours after first contact and subsequently down regulated during each resting phase. This late, but stable expression kinetics of NKG2A was most similar to that of TIM‐3 and CD39. Importantly, single‐cell transcriptomics of human tumor‐infiltrating lymphocytes (TILs) showed indeed that these receptors were often coexpressed by the same CD8 T cell cluster. Furthermore, NKG2A expression was associated with cell division and was promoted by TGF‐β in vitro, although TGF‐β signaling was not necessary in a mouse tumor model in vivo. In summary, our data show that PD‐1 reflects recent TCR triggering, but that NKG2A is induced after repeated antigen stimulations and represents a late inhibitory receptor. Together with TIM‐3 and CD39, NKG2A might thus mark actively dividing tumor‐specific TILs.