CD8+ T cell activation in cancer comprises an initial activation phase in lymph nodes followed by effector differentiation within the tumor

Dynamic evolution and antitumor mechanisms of CXCR6+CD8+ T cells in small cell lung cancer treated with low-dose radiotherapy and immunotherapy

BACKGROUND

Patients with small-cell lung cancer (SCLC) have the poor prognosis. Current research suggested that low-dose radiotherapy (LDRT) combined with immunotherapy can enhance the immunogenicity of tumor cells, thereby improving antigen presentation and promoting the intratumoral infiltration of CD8+ T cells, which significantly extends the survival of patients. However, the change trajectory of T cells, and the mechanisms underlying the promotion of intratumoral infiltration of CD8+ T cells, and the enhancement of their cytotoxic functions remain to be elucidated.

METHODS

To delineate the dynamic changes of T cells, we collected tumors from Kaede tumor-bearing mice that had undergone radioimmunotherapy. Using flow cytometry, we sorted intratumoral-infiltrating immune cells, which were required for single-cell RNA sequencing, at various time points (Kaede Red: derived from tumor-draining lymph node [TDLN]). The results obtained from the sequencing analysis were further validated through experiments, such as flow cytometry, immunofluorescence, and analysis of clinical cohort data.

RESULTS

Here, we observed stem-like T cells migrating from the TDLN to the tumor site and differentiating into effector phenotypes within the tumor. Dendritic cells (DCs) are the key cluster that induces the differentiation of stem-like T cell into effector phenotypes. Moreover, SCLC patients with a high infiltration of tumor-specific CXCR6+CD8+ T cells exhibited a supportive TME and longer survival time (P < 0.001).

CONCLUSIONS

This study delineates the change trajectory of CD8+ T cells, identifies the crucial role of DCs in T cell differentiation, and highlights the significance of tumor-specific CXCR6+CD8+ T cells in anti-tumor immunity. Future therapeutic strategies for SCLC could focus on enhancing the infiltration of activated DCs and CXCR6+CD8+ T cells within the tumor microenvironment to improve treatment efficacy.

TIMEPOINT, a phase 1 study combining MTL-CEBPA with pembrolizumab, supports the immunomodulatory effect of MTL-CEBPA in solid tumors

Many patients with cancer do not benefit from currently approved immune checkpoint inhibitors (ICIs), suggesting that additional immunomodulation of the immunosuppressive tumor microenvironment (TME) is required. MTL-CCAAT enhancer-binding protein alpha (CEBPA) specifically upregulates the expression of the master myeloid transcription factor, CEBPA, relieving myeloid-driven immunosuppression. Here, we report the safety, tolerability, pharmacokinetics, and efficacy of MTL-CEBPA in combination with pembrolizumab in patients with advanced solid tumors that typically show ICI resistance. Multimodal exploratory analyses of paired patient biopsies demonstrate biological changes associated with the combination treatment of MTL-CEBPA and pembrolizumab, including increased infiltration of T cell and antigen-presenting cells supporting conversion from an immune-desert toward a more immune-inflamed TME. Patients with disease stabilization demonstrate reductions in immunosuppressive myeloid cells post treatment. Collectively, these data support a role for MTL-CEBPA in reducing immunosuppression in the TME. This study was registered at ClinicalTrials.gov (NCT04105335).

Combination radiation and αPD-L1 enhance tumor control by stimulating CD8+ PD-1+ TCF-1+ T cells in the tumor-draining lymph node

Combination radiotherapy (RT) and αPD-L1 therapy has potential to enhance local and distant (abscopal) tumor control, however, clinical results in humans have been variable. Using murine melanoma models, we found RT + αPD-L1 increases intra-tumor progenitor CD8+ PD-1+ TCF-1+ T cells. This increase depends on trafficking of the PD-1+ TCF-1+ cells from the tumor-draining lymph node (TdLN) to the tumor. RT alone promotes the expansion and differentiation of the TdLN derived PD-1+ TCF-1+ cells into TIM-3+ GZMB+ TCF-1- effector-like cells in the tumor with further enhancement after the addition of αPD-L1. In the TdLN, combination therapy enriches for a novel PD-1+ TCF-1+ TOX- LY6A+ subset with expression of a type I interferon and migratory signature. This subset is able to traffic to the tumor and differentiate into TIM-3+ TCF-1- cells. Finally, we found that ablation of the PD-1+ TCF-1+ T cell population attenuates the enhanced tumor control observed with combination RT + αPD-L1. These results suggest that abscopal response failures may be secondary to impaired stimulation of TdLN CD8+ PD-1 + TCF-1+ T cells or an inability of PD-1+ TCF-1+ cells in the TdLN to traffic to the tumor.

Acasunlimab, an Fc-inert PD-L1×4-1BB bispecific antibody, combined with PD-1 blockade potentiates antitumor immunity via complementary immune modulatory effects

BACKGROUND

Next-generation cancer immunotherapies aim to improve patient outcomes by combining inhibitory signal blockade with targeted T-cell costimulation in tumor and lymphoid tissues. Acasunlimab (DuoBody-PD-L1×4-1BB) is an investigational, bispecific antibody designed to elicit an antitumor immune response via conditional 4-1BB activation strictly dependent on simultaneous programmed death-ligand 1 (PD-L1) binding. Since 4-1BB is coexpressed with programmed cell death protein-1 (PD-1) on CD8+ T cells, PD-1 blockade and simultaneous costimulation through 4-1BB may synergistically enhance T-cell effector functions. We hypothesized that combining acasunlimab with PD-1 blockade to fully disrupt PD-1 interactions with both PD-L1 and PD-L2 would amplify the depth and duration of antitumor immunity.

METHODS

The effect of acasunlimab and pembrolizumab combination was analyzed in vitro using functional immune cell assays, including mixed-lymphocyte reactions and antigen-specific T-cell proliferation and cytotoxicity assays. The antitumor activity of the combination was tested in vivo in (1) MC38, MB49, Pan02, and B16F10 syngeneic tumor models using acasunlimab and anti-PD-1 mouse-surrogate antibodies; and (2) triple knock-in mice expressing the human targets using an acasunlimab chimeric antibody (chi-acasunlimab) and pembrolizumab. The mechanism of action of the combination was investigated in the MC38 syngeneic model through immunohistochemistry, flow cytometry, and bulk RNA sequencing.

RESULTS

The combination reinvigorated dysfunctional T cells in vitro, while also potentiating T-cell expansion, interleukin (IL)-4 and interferon gamma secretion and cytotoxic activity. In vivo, the combination of chi-acasunlimab and pembrolizumab or mouse-surrogate antibodies potentiated antitumor activity and survival in the humanized knock-in and multiple syngeneic mouse models, leading to durable complete tumor regressions in the MC38 model consistent with therapeutic synergy. Mechanistically, the combination enhanced clonal expansion of tumor-specific CD8+ T cells in tumor-draining lymph nodes and increased the density of proliferating and cytotoxic CD8+ T cells in the tumor microenvironment. It also potentiated the IL-2 signaling pathway, increasing the proportion of granzyme B (GZMB+) stem-like CD8+ T cells thought to have superior effector function.

CONCLUSION

These preclinical results demonstrate that conditional 4-1BB stimulation combined with complete PD-1 blockade enhances antitumor immunity through complementary mechanisms. The acasunlimab and pembrolizumab combination is being evaluated in Phase 2 (NCT05117242) and pivotal Phase 3 (NCT06635824) trials in patients with metastatic non-small cell lung cancer after checkpoint inhibitor therapy failure.

Potency-optimized CD28-activating bispecific antibody for the targeted treatment of Nectin-4 positive cancers

BACKGROUND

T-cell costimulation is crucial for an effective and sustained antitumor immune response, and inadequate expression of costimulatory ligands within tumors can impair T-cell function. Bispecific antibodies (bsAbs) targeting a tumor-associated antigen and the T-cell costimulatory receptor CD28 represent a novel class of immune-stimulatory therapeutics designed to enhance antitumor immune responses by selectively delivering T-cell costimulation directly to the tumor microenvironment. This approach holds the potential to improve the survival, proliferation, and cytotoxic function of antitumor T cells while minimizing the risk of systemic immune activation. Urothelial cancer (UC) is associated with significant morbidity and mortality worldwide, particularly in advanced disease settings. Nectin-4, a membrane protein highly expressed in UC with limited expression in healthy tissues, presents a compelling target for therapeutic intervention.

METHODS

Using our proprietary high-throughput antibody discovery pipeline, we identified a panel of novel antibodies with a range of affinities for CD28 and Nectin-4 and successfully engineered them as bsAbs. We tested the T-cell costimulatory function of these molecules in vitro using primary human T cells and human cancer cell lines. Based on these results, we selected a clinical candidate which we assessed in a syngeneic mouse tumor model system and investigated tolerability and pharmacokinetics (PK) in non-human primates (NHP).

RESULTS

Our in vitro studies demonstrated that these bsAbs effectively enhance T-cell activation and cytotoxicity against Nectin-4 positive tumor cells in the presence of T-cell receptor engagement. The bsAb panel exhibited a range of potencies, enabling the selection of a clinical candidate, termed RNDO-564, that maximized antitumor efficacy as well as the likelihood of a broad therapeutic window. Tumor-bearing syngeneic mouse models confirmed the in vivo efficacy of RNDO-564, demonstrating significant tumor regression both as a single agent and in combination with an immune checkpoint inhibitor. We observed favorable PK and tolerability profiles in NHP assessments.

CONCLUSIONS

Our study reports the first CD28 bsAb targeting Nectin-4 and highlights the potential of CD28 × Nectin-4 bsAbs as a new immunotherapeutic modality. The findings support the clinical development of RNDO-564 in patients with locally advanced and metastatic UC and other Nectin-4 positive malignancies.

IL-12-producing cytokine factories induce precursor exhausted T cells and elimination of primary and metastatic tumors

BACKGROUND

Curative responses to immunotherapy require the generation of robust systemic immunity with limited toxicity. Recruitment of T cell populations such as precursor exhausted T cells (Tpex) from lymphoid tissues to tumors is a hallmark of effective treatment. However, the ability to efficiently induce this recruitment is lacking in current immunotherapy approaches. Furthermore, systemic administration of immunotherapies frequently results in dose-limiting toxicities, yielding an inadequate therapeutic window for eliciting durable responses.

METHODS

In this investigation, we evaluated the safety and antitumor efficacy of locally administered interleukin 12 (IL-12) using a clinically translatable cytokine delivery platform (NCT05538624) to identify Tpex recruitment capabilities at tolerable cytokine doses.

RESULTS

We show IL-12 cytokine factories can effectively treat a broad spectrum of cancer types. Single-cell RNA sequencing data suggests that the antitumor efficacy seen in our studies was due to retinal pigmented epithelial cells-mIL12 treatment inducing differentiation of Tpex cells within the tumor microenvironment. When administered in combination with checkpoint therapy, IL-12 cytokine factory treatment generated systemic abscopal immunity, preventing subcutaneous tumor outgrowth in 8/9 mice with colorectal cancer and lung metastasis in mice with melanoma. Furthermore, this platform was well tolerated in a non-human primate without signs of toxicity.

CONCLUSIONS

Our new immunotherapy approach provides a robust strategy for inducing Tpex recruitment and systemic immunity against a range of solid peritoneal malignancies, many incurable with current immunotherapy strategies. Notably, these features were achieved using IL-12, and by leveraging our technology, we avoided the toxicities that have prevented the translation of IL-12 to the clinic. Our findings provide a strong rationale for the clinical development of IL-12 cytokine factories.

CD8+ T cell-based immunotherapy: Promising frontier in human diseases

The abundant cell components of the adaptive immune system called T lymphocytes (T cells) play important roles in mediating immune responses to eliminate the invaders and create the memory of the germs to form a new immunity for the next encounter. Among them, cytotoxic T cells expressing cell-surface CD8 are the most critical effector cells that directly eradicate the target infected cells by recognizing antigens presented by major histocompatibility complex class I molecules to protect our body from pathological threats. In the continuous evolution of immunotherapy, various CD8+ T cell-based therapeutic strategies have been developed based on the role and molecular concept of CD8+ T cells. The emergence of such remarkable therapies provides promising hope for multiple human disease treatments such as autoimmunity, infectious disease, cancer, and other non-infectious diseases. In this review, we aim to discuss the current knowledge on the utilization of CD8+ T cell-based immunotherapy for the treatment of various diseases, the molecular basis involved, and its limitations. Additionally, we summarize the recent advances in the use of CD8+ T cell-based immunotherapy and provide a comprehensive overview of CD8+ T cells, including their structure, underlying mechanism of function, and markers associated with CD8+ T cell exhaustion. Building upon these foundations, we delineate the advancement of CD8+ T cell-based immunotherapies with fundamental operating principles followed by research studies, and challenges, as well as illustrate human diseases involved in this development.

Engineering cytokines for tumor-targeting and selective T cell activation

Cytokines are promising therapeutic agents for cancer due to their immune-stimulating properties. However, their clinical application is limited by a narrow therapeutic window and dose-limiting on-target, off-tumor toxicity. Advances in protein engineering enable the selective delivery of cytokines to the tumor microenvironment (TME) and antigen-specific T cells, enhancing antitumor efficacy while reducing systemic side effects. This review focuses on selected cytokines and outlines their developmental trajectory for treating solid tumors. We highlight strategies for constructing cis-signaling immunocytokines and procytokines for precise delivery to tumor sites and discuss the biological mechanisms through which these cytokines reactivate antitumor immunity. We also discuss the challenges and future directions for creating more effective cytokine-based therapeutics.

Lymphatic collection and cell isolation from mouse models for multiomic profiling

Premetastatic cancer cells often spread from the primary lesion through the lymphatic vasculature and, clinically, the presence or absence of lymph node metastases impacts treatment decisions. However, little is known about cancer progression via the lymphatic system or of the effect that the lymphatic environment has on cancer progression. This is due, in part, to the technical challenge of studying lymphatic vessels and collecting lymph fluid. Here we provide a step-by-step procedure to collect both lymph and tumor-draining lymph in mouse models of cancer metastasis. This protocol has been adapted from established methods of lymph collection and was developed specifically for the collection of lymph from tumors. The approach involves the use of mice bearing melanoma or breast cancer orthotopic tumors. After euthanasia, the cisterna chyli and the tumor are exposed and viewed using a stereo microscope. Then, a glass cannula connected to a 1 mL syringe is inserted directly into the cisterna chyli or the tumor-draining lymphatics for collection of pure lymph. These lymph samples can be used to analyze the lymph-derived cancer cells using highly sensitive multiomics approaches to investigate the impact of the lymph environment during cancer metastasis. The procedure requires 2 h per mouse to complete and is suitable for users with minimal expertise in small animal handling and use of microsurgical tools under a stereo microscope.

An early precursor CD8+ T cell that adapts to acute or chronic viral infection

This study examines the origin and differentiation of stem-like CD8+ T cells that are essential for sustained T cell immunity in chronic viral infections and cancer and also have a key role in PD-1 directed immunotherapy1-10. These PD-1+TCF-1+TOX+ stem-like CD8+ T cells (also known as precursors of exhausted T cells8,9) have a distinct program that enables them to adapt to chronic antigen stimulation. Here, using the mouse model of chronic lymphocytic choriomeningitis virus (LCMV) infection, we find that virus-specific stem-like CD8+ T cells are generated early (day 5) during chronic infection, suggesting that this crucial fate commitment occurs irrespective of the infection outcome. Indeed, we find that nearly identical populations of stem-like CD8+ T cells were generated early during acute or chronic LCMV infection, and that antigen was essential for maintaining the stem-like phenotype. We performed reciprocal adoptive transfer experiments to determine the fate of these early stem-like CD8+ T cells after viral clearance versus persistence. After transfer of day 5 stem-like CD8+ T cells from chronically infected mice into acutely infected mice, these cells downregulated canonical markers of the chronic stem-like CD8+ T cells and expressed markers (CD127 and CD62L) associated with central memory CD8+ T cells. Reciprocally, when day 5 stem-like cells from acutely infected mice were transferred into chronically infected mice, these CD8+ T cells functioned like chronic resource cells and responded effectively to PD-1 therapy. These findings highlight the ability of these early PD-1+TCF-1+TOX+ stem-like CD8+ T cells to adapt their differentiation trajectory to either an acute or a chronic viral infection. Importantly, our study shows that the host is prepared a priori to deal with a potential chronic infection.

Neck Dissection and Survival Among Head and Neck Cancer Patients Undergoing Adjuvant Immunotherapy

Background

Some studies suggest that neck dissection (ND) should be avoided in candidates for immunotherapy because lymph nodes are primary sites for immunotherapy activation. Our study investigates ND utilization and associated differences in overall survival (OS) among patients with head and neck cancer (HNC) undergoing adjuvant immunotherapy.

Methods

The 2013-2018 National Cancer Database was retrospectively reviewed for patients with HNC undergoing surgery with curative intent, and adjuvant immunotherapy. Multivariable binary logistic and Cox regression models adjusted for patient demographics, clinicopathologic features, and treatment.

Results

Of 1335 patients satisfying inclusion criteria, 679 (50.9%) patients underwent ND: 94 (13.8%) had pN0, 109 (16.1%) had pN1, 411 (60.5%) had pN2, 60 (8.8%) had pN3, and 5 (0.7%) had pNx classification. On multivariable binary logistic regression, academic treatment facility, cT4, and cN1-3 classification were associated with higher odds of undergoing ND (p < 0.05); salivary, sinonasal, oropharyngeal, hypopharyngeal, and laryngeal primary sites were associated with decreased odds (p < 0.05). Compared with those undergoing neck observation, patients undergoing ND had worse OS (49.4% vs. 61.5%, p < 0.001) on Kaplan-Meier but not multivariable Cox (adjusted hazard ratio [aHR] 1.00, 95% confidence interval [CI] 0.82-1.24, p = 0.968) regression. Compared with adjuvant immunotherapy alone, the addition of radiotherapy (aHR 0.64, 95% CI 0.44-0.93) and chemoradiotherapy (aHR 0.56, 95% CI 0.37-0.86) were associated with higher OS (p < 0.025).

Conclusion

ND was utilized in approximately 51% of patients with HNC undergoing adjuvant immunotherapy. ND was not associated with worse OS, possibly related to the high rate of pN1-3 classification.

Level of Evidence

4.

Dendritic cell maturation in cancer

Dendritic cells (DCs) are specialized antigen-presenting cells that are present at low abundance in the circulation and tissues; they serve as crucial immune sentinels by continually sampling their environment, migrating to secondary lymphoid organs and shaping adaptive immune responses through antigen presentation. Owing to their ability to orchestrate tolerogenic or immunogenic responses to a specific antigen, DCs have a pivotal role in antitumour immunity and the response to immune checkpoint blockade and other immunotherapeutic approaches. The multifaceted functions of DCs are acquired through a complex, multistage process called maturation. Although the role of inflammatory triggers in driving DC maturation was established decades ago, less is known about DC maturation in non-inflammatory contexts, such as during homeostasis and in cancer. The advent of single-cell technologies has enabled an unbiased, high-dimensional characterization of various DC states, including mature DCs. This approach has clarified the molecular programmes associated with DC maturation and also revealed how cancers exploit these pathways to subvert immune surveillance. In this Review, we discuss the mechanisms by which cancer disrupts DC maturation and highlight emerging therapeutic opportunities to modulate DC states. These insights could inform the development of DC-centric immunotherapies, expanding the arsenal of strategies to enhance antitumour immunity.

ERCC3 serves as a prognostic biomarker for hepatocellular carcinoma and positively regulates cell proliferation and migration

BACKGROUND

ERCC3, a crucial component of the nucleotide excision repair pathway, is implicated in the development and progression of various cancers and is a potential indicator of poor prognosis. However, the expression and function of ERCC3 in hepatocellular carcinoma (HCC) remain unclear. This study aimed to investigate the expression of ERCC3 in HCC tissues and its clinical significance, focusing on elucidating its potential mechanisms and therapeutic value in immunotherapy.

METHODS

The differential expression and genetic variation characteristics of ERCC3 across various cancers were evaluated using the TCGA database. The expression and prognostic value of ERCC3 in HCC were analyzed by integrating TCGA, GEO, and ICGC datasets. Independent prognostic value of ERCC3 expression levels in HCC was assessed using Cox regression analysis, Kaplan-Meier survival analysis, receiver operating characteristic curves, and nomograms. Pathway association scores were determined using ssGSEA to reveal the biological functions of ERCC3 in HCC and its potential clinical efficacy in immunotherapy. Stable transient cell lines were established by infecting HepG2 cells with lentivirus overexpressing ERCC3. The effects of ERCC3 on HCC cell biological phenotypes were evaluated using RTCA, wound healing, and Transwell assays. Cell cycle distribution and apoptosis were detected by flow cytometry. Transcriptome sequencing was performed to explore the impact of ERCC3 overexpression on the expression of signaling pathway-related genes in HCC.

RESULTS

The study revealed that ERCC3 is aberrantly expressed in various tumors, with significantly higher mRNA and protein levels in HCC tissues compared to normal tissues. High ERCC3 expression was significantly correlated with poor survival outcomes in HCC patients. Multivariate Cox regression analysis revealed that ERCC3 expression level is an independent prognostic factor for overall survival (P = 0.014). Gene sets associated with the high ERCC3 group were significantly involved in multiple immune pathways and tumor progression-related pathways, and ERCC3 expression was significantly correlated with immune checkpoints in HCC. Overexpression of ERCC3 promoted the proliferation and migration of HCC cells and influenced cell cycle progression. Transcriptome sequencing analysis indicated that ERCC3 overexpression regulated the proliferation of HCC cells, participated in multiple pro-inflammatory pathways, induced the formation of an inflammatory tumor microenvironment, and promoted HCC progression.

CONCLUSION

This study is the first to reveal the association between high ERCC3 expression and poor prognosis in HCC and to elucidate its immunomodulatory role in HCC. Unlike previous studies, we found that ERCC3 promotes HCC progression by regulating the inflammatory microenvironment and immune checkpoints. These findings establish a novel theoretical foundation for the development of targeted immunotherapies for HCC and provide new insights into the molecular mechanisms underlying ERCC3's role in HCC.

Microwave ablation combined with immune checkpoint inhibitor enhanced the antitumor immune activation and memory in rechallenged tumor mouse model

Microwave ablation (MWA) is a super minimally invasive therapeutic approach that has been widely applied in the treatment of non-small cell lung cancer (NSCLC). Although MWA can elicit antitumor immune responses, these immune responses are not relatively steady and insufficient to completely clear recurrence tumor cells within the body. Immunotherapy monotherapy has shown low clinical efficacy in the treatment of advanced NSCLC. MWA combined with immune checkpoint inhibitors (ICIs) is a promising therapeutic approach. However, the mechanism of synergic effect remains elusive. In this study, we have conducted a retrospective analysis of the clinical outcomes of MWA combined with ICIs, finding that the combinational therapy yielded superior Objective Response Rate and longer Progression-Free Survival. In preclinical models, we established a tumor rechallenged model to address post-MWA recurrence and to delve into the underlying mechanisms of the combined therapy. We observed that the combined treatment (MWA + PD-L1 blockade therapy) effectively addressed the issue of tumor recurrence in tumor rechallenged model. The combinational therapy increased the function and percentage of CD8+ tumor-infiltrating lymphocytes, enhanced the functionality of CD8+ T cells within tumor-draining lymph nodes (TdLNs), and elevated the proportion of T central memory cells. Additionally, the combined treatments promoted the proportion of Migration Dendritic Cells type 1 (Mig DC1) within TdLNs, thereby enhancing their activation potential. Notably, FTY720-mediated blockade of lymphocyte egress abolished the therapeutic benefits, confirming TdLNs-dependent systemic immunity. Moreover, the efficacy of the combinational therapy depended on the migration of T cells from TdLNs to tumor site. In summary, we proposed a potentially effective combined treatment regimen and have elucidated the underlying cellular mechanisms that underpin its efficacy.

A comprehensive review on targeting diverse immune cells for anticancer therapy: Beyond immune checkpoint inhibitors

Although immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, primary resistance and acquired resistance continue to limit their efficacy for many patients. To address resistance and enhance the anti-tumor activity within the tumor immune microenvironment (TIME), numerous therapeutic strategies targeting both innate and adaptive immune cells have emerged. These include combination therapies with ICIs, chimeric antigen receptor T-cell (CAR-T), chimeric antigen receptor macrophages (CAR-Ms) or chimeric antigen receptor natural killer cell (CAR-NK) therapy, colony stimulating factor 1 receptor (CSF1R) inhibitors, dendritic cell (DC) vaccines, toll-like receptor (TLR) agonists, cytokine therapies, and chemokine inhibition. These approaches underscore the significant potential of the TIME in cancer treatment. This article provides a comprehensive and up-to-date review of the mechanisms of action of various innate and adaptive immune cells within the TIME, as well as the therapeutic strategies targeting each immune cell type, aiming to deepen the understanding of their therapeutic potential.

Humanizing a CD28 signaling domain affects CD8 activation, exhaustion and stem-like precursors

CD28 ligation provides critical signals that modulate activated T cell fate. In a human to mouse reverse-engineering approach, a single amino acid substitution adjacent to the C-terminal proline-rich domain created CD28 A210P mice with enhanced signaling. CD28 A210P mice experienced pro-inflammatory responses to CD28 superagonist antibody, analogous to severe cytokine storm induced in a human clinical trial, with a striking increase of activated CD8 T cells. In acute and chronic viral infections, early activation and expansion of CD28 A210P CD8 effector T cells increased, with accelerated exhaustion in chronic infection. Mechanistically, CD28 A210P enhanced JunB, IL-2, and inhibitory receptors driven by MEK1/2. Generation of CD28 A210P stem-like progenitor (Tpex) cells was enhanced in acute and chronic infections, and further expanded by PD-L1 blockade in chronically-infected mice. Thus, 'humanized' PYAP mice reveal key roles for CD28 signaling strength in CD8 activation, accelerating exhaustion during antigen persistence, while promoting and sustaining Tpex during acute and chronic viral infection.

One sentence Summary

A single amino acid substitution adjacent to PYAP to 'humanize' CD28 signaling enhances superagonist response, early CD8 activation and Tpex generation during viral infection while accelerating exhaustion and sustaining Tpex during chronic infection.

Neoadjuvant cabozantinib for locally advanced nonmetastatic clear cell renal cell carcinoma: a phase 2 trial

Cabozantinib is an oral multikinase inhibitor approved for treatment in metastatic renal cell carcinoma (RCC). We conducted a phase 2, nonrandomized, single-arm clinical trial (NCT04022343) of cabozantinib treatment for 12 weeks in 17 patients with locally advanced, biopsy-proven, nonmetastatic clear cell RCC before surgical resection. The primary end point was the objective response rate (complete and partial responses) at week 12 and secondary end points included safety, tolerability, clinical and surgical outcomes, and quality of life. Six patients (35%) experienced a partial response and 11 patients (65%) had stable disease. The most common adverse events were diarrhea (n = 12, 70.6%), anorexia, fatigue and hypertension (n = 10, 58.8%), nausea and palmar-plantar erythrodysesthesia syndrome (n = 9, 52.9%). No treatment grade 4 or 5 adverse events related to cabozantinib or surgery occurred. The 1-year disease-free survival and overall survival were 82.4% (95% CI 54.7-93.9%) and 94.1% (95% CI 65-99.1%), respectively. Cabozantinib treatment activated CD8+ T cells in the blood, depleted myeloid populations and induced immune niches for TCF1+ stem-like CD8+ T cells. Cabozantinib was clinically active and safe in the neoadjuvant setting in patients with locally advanced nonmetastatic clear cell RCC.

A microRNA-regulated transcriptional state defines intratumoral CD8+ T cells that respond to immunotherapy

The rising incidence of advanced-stage colorectal cancer (CRC) and poor survival outcomes necessitate new and effective therapies. Immune checkpoint inhibitors (ICIs), specifically anti-PD-1 therapy, show promise, yet clinical determinants of a positive response are suboptimal. Here, we identify microRNA-155 (miR-155) as necessary for CD8+ T cell-infiltrated tumors through an unbiased in vivo CRISPR-Cas9 screen identifying functional tumor antigen-specific CD8+ T cell-expressed microRNAs. T cell miR-155 is required for anti-PD-1 responses and for a vital intratumor CD8+ T cell differentiation cascade by repressing Ship-1, inhibiting Tcf-1 and stemness, and subsequently enhancing Cxcr6 expression, anti-tumor immunity, and effector functions. Based on an underlying miR-155-dependent CD8+ T cell transcriptional profile, we identify a gene signature that predicts ICI responses across 12 diverse cancers. Together, our findings support a model whereby miR-155 serves as a central regulator of CD8+ T cell-dependent cancer immunity and ICI responses that may be leveraged for future therapeutics.

Lymph nodes link sex-biased immune aging to compromised antigen recognition

A diverse naive CD8 T cell repertoire is essential to provide broad protection against infection and cancer. Aging diminishes naive T cells, reducing potential diversity and leading to lymph node contraction. Here, we revealed that this decline occurs earlier in males, resulting in significant sex differences in immunity during middle age. Earlier in life, naive CD8 T cells in males become virtual memory cells prone to premature senescence. Due to androgen-driven thymic atrophy in males, naïve CD8 T cells are insufficiently replenished. Therapeutic thymus rejuvenation via testosterone ablation restored naive CD8 T cells in lymph nodes of middle-aged male mice, leading to enhanced tumor recognition. These findings show the crucial role of sex and age on lymph node T cell repertoires and suggest potential strategies to restore immune function in males during aging.

Functional memory T cells are derived from exhausted clones and expanded by checkpoint blockade

Immune checkpoint blockade can facilitate tumor clearance by T cells, resulting in long term patient survival. However, the capacity of exhausted CD8+ T cells (Tex), present during chronic antigen exposure, to form memory after antigen clearance remains unclear. Here, we performed longitudinal single cell RNA/T cell receptor sequencing and ATAC-sequencing on antigen-specific T cells after the clearance of chronic lymphocytic choriomeningitis virus (LCMV) infection. These data revealed the formation of a robust population of memory CD8+ T cells that transcriptionally, epigenetically, and functionally resemble central memory T cells (Tcm) that form after clearance of acute infection. To lineage trace the origin and memory recall response of Tex-derived memory clones, we utilized T cell receptor sequencing over the course of primary infection and rechallenge. We show that chronic Tcm are a clonally distinct lineage of Tex derived from progenitor exhausted cells, persist long-term in the absence of antigen, and undergo rapid clonal expansion during rechallenge. Finally, we demonstrate that αPD-L1 immune checkpoint blockade after chronic LCMV infection preferentially expands clones which form Tcm after clearance. Together, these data support the concept that chronically stimulated T cells form bona fide functional memory T cells through an analogous differentiation pathway to acutely stimulated T cells, which may have significant implications for enhancing immune memory to cancer through checkpoint blockade and vaccination.

Improving CD3 bispecific antibody therapy in solid tumors using combination strategies

CD3 bispecific antibodies (bsAbs) are emerging as an important treatment option in the arsenal of oncologists. There are numerous FDA-approved CD3 bsAbs for both hematological and solid tumors. Despite these recent advances, the success of CD3 bsAbs in solid cancer has been hampered by hurdles like limited intratumoral T cell numbers, immunosuppressive tumor microenvironments (TME), and poor memory T-cell induction. Furthermore, tumor surface antigen selection for an optimal therapeutic window and acceptable collateral damage to normal tissues is challenging. In this review, we discuss recent research investigating combination approaches aimed at improving CD3 bsAb efficacy in solid cancer.

Targeting P4HA1 promotes CD8+ T cell progenitor expansion toward immune memory and systemic anti-tumor immunity

Successful immunotherapy relies on both intratumoral and systemic immunity, which is yet to be achieved for most patients with cancer. Here, we identify P4HA1, encoding prolyl 4-hydroxylase 1, as a crucial regulator of CD8+ T cell differentiation strongly upregulated in tumor-draining lymph nodes (TDLNs) and hypoxic tumor microenvironment. P4HA1 accumulates in mitochondria, disrupting the tricarboxylic acid (TCA) cycle through aberrant α-ketoglutarate and succinate metabolism, promoting mitochondria unfitness and exhaustion while suppressing progenitor expansion. Targeting P4HA1 enhances both adoptive and endogenous TCF1+ CD8+ T progenitor expansion while mitigating the development of exhaustion in the tumor, TDLN, and blood, enabling a notable and durable systemic anti-cancer immunity. We propose that P4HA1 induction in CD8+ T cells in cancer orchestrates an immune-escape program, offering a T cell-directed target for system immunotherapy in solid tumors.

Intratumoral gene delivery of 4-1BBL boosts IL-12-triggered anti-glioblastoma immunity

The standard of care in high-grade gliomas has remained unchanged in the past 20 years. Efforts to replicate effective immunotherapies in non-cranial tumors have led to only modest therapeutical improvements in glioblastoma (GB). Here, we demonstrate that intratumoral administration of recombinant interleukin-12 (rIL-12) promotes local cytotoxic CD8 POS T cell accumulation and conversion into an effector-like state, resulting in a dose-dependent survival benefit in preclinical GB mouse models. This tumor-reactive CD8 T cell response is further supported by intratumoral rIL-12-sensing dendritic cells (DCs) and is accompanied by the co-stimulatory receptor 4-1BB expression on both cell types. Given that DCs and CD8 POS T cells are functionally suppressed in the tumor microenvironments of de novo and recurrent glioma patients, we tested whether anti-tumor response at the rIL-12-inflamed tumor site could be enhanced with 4-1BBL, the ligand of 4-1BB. 4-1BBL was delivered using an adeno-associated virus (AAV) vector targeting GFAP-expressing cells and resulted in prolonged survival of rIL-12 treated GB-bearing mice. This study establishes that tumor antigen-specific CD8 T cell activity can be directed using an AAV-vector-mediated gene therapy approach, effectively enhancing anti-GB immunity.

Neoadjuvant anti-4-1BB confers protection against spontaneous metastasis through low-affinity intratumor CD8 + T cells in triple-negative breast cancer

Neoadjuvant immunotherapy seeks to harness the primary tumor as a source of relevant tumor antigens to enhance systemic anti-tumor immunity through improved immunological surveillance. Despite having revolutionized the treatment of patients with high-risk early-stage triple-negative breast cancer (TNBC), a significant portion of patients remain unresponsive and succumb to metastatic recurrence post-treatment. Here, we found that optimally scheduled neoadjuvant administration of anti-4-1BB monotherapy was able to counteract metastases and prolong survival following surgical resection. Phenotypic and transcriptional profiling revealed enhanced 4-1BB expression on tumor-infiltrating intermediate (T int ), relative to progenitor (T prog ) and terminally exhausted (T term ) T cells. Furthermore, T int was enriched in low-affinity T cells. Treatment with anti-4-1BB drove clonal expansion of T int , with reduced expression of tissue-retention marker CD103 in T prog . This was accompanied by increased TCR clonotype sharing between paired tumors and pre-metastatic lungs. Further interrogation of sorted intratumor T cells confirmed enhanced T cell egress into circulation following anti-4-1BB treatment. In addition, gene signature extracted from anti-4-1BB treated T int was consistently associated with improved clinical outcomes in BRCA patients. Combinatorial neoadjuvant anti-4-1BB and ablation of tumor-derived CXCL16 resulted in enhanced therapeutic effect. These findings illustrate the intratumor changes underpinning the efficacy of neoadjuvant anti-4-1BB, highlighting the reciprocity between local tissue-retention and distant immunologic fortification, suggesting treatment can reverse the siphoning of intratumor T cells to primary tumor, enabling redistribution to distant tissues and subsequent protection against metastases.

Chemokines that govern T cell activity in tumors

Local regulation of T cell-mediated immunity to solid tumors occurs at multiple levels, including their recruitment from the bloodstream to the tumor microenvironment (TME), coordinated crosstalk with different subsets of antigen-presenting cells (APCs) controlling their local survival, proliferation, and effector differentiation, as well as their egress from tumors via lymphatics. At each level, chemokines play essential roles, for instance, by guiding directional T cell migration across blood and lymphatic endothelial barriers or by promoting their spatial proximity and direct physical interactions with APCs to enable functional crosstalk. In this article, we will review recent mechanistic insights into the chemokine axes that guide T cell functions in TMEs in light of the emerging functional state heterogeneity of CD8+ effector T cells and our growing understanding of how regulatory T cells restrain antitumor activity.

Functional subsets of tumor-specific CD8+ T cells in draining lymph nodes and tumor microenvironment

Accumulating evidence demonstrates that tumor-specific CD8+ T cells in tumor-draining lymph nodes (TdLNs) act as an upstream reservoir of exhausted subsets within tumor microenvironment (TME). This reservoir primarily consists of progenitor exhausted CD8+ T (TPEX) cells and newly defined tumor-specific memory subsets (TTSM). We propose that these two subsets work together to mediate the antitumor effects of PD-1/PD-L1 immune checkpoint blockade (ICB) in a spatiotemporal manner. Although PD-1/PD-L1 ICB monotherapy drives the proliferation and further differentiation of these subsets, it does not alter the programmed differentiation trajectory from TTSM cells to TPEX cells, ultimately leading to the development of terminally exhausted CD8+ T cells. This phenomenon may partly explaining the frequent relapse in patients following initial ICB therapy. In this review, we focus on the phenotypic and functional heterogeneity of tumor-specific CD8+ T cells in both TdLNs and the TME and discuss the implications of these studies for ICB. Our insights aim to illuminate new strategies for advancing tumor immunotherapies.

Fibroblastic reticular cells generate protective intratumoral T cell environments in lung cancer

Stringent control of T cell activity in the tumor microenvironment is essential for the generation of protective antitumor immunity. However, the identity, differentiation, and functions of the cells that create critical fibroblastic niches promoting tumor-infiltrating T cells remain elusive. Here, we show that CCL19-expressing fibroblastic reticular cells (FRCs) generate interconnected T cell environments (TEs) in human non-small cell lung cancer, including tertiary lymphoid structures and T cell tracks. Analysis of the FRC-T cell interactome in TEs indicated molecular networks regulating niche-specific differentiation of CCL19-expressing fibroblasts and T cell activation pathways. Single-cell transcriptomics and cell fate-mapping analyses in mice confirmed that FRCs in TEs originate from mural and adventitial progenitors. Ablation of intratumoral FRC precursors decreased antitumor T cell activity, resulting in reduced tumor control during coronavirus vector-based immunotherapy. In summary, specialized FRC niches in the tumor microenvironment govern the quality and extent of antitumor T cell immunity.

Syngeneic natural killer cell therapy activates dendritic and T cells in metastatic lungs and effectively treats low-burden metastases

Natural killer (NK) cells can control metastasis through cytotoxicity and IFN-γ production independently of T cells in experimental metastasis mouse models. The inverse correlation between NK activity and metastasis incidence supports a critical role for NK cells in human metastatic surveillance. However, autologous NK cell therapy has shown limited benefit in treating patients with metastatic solid tumors. Using a spontaneous metastasis mouse model of MHC-I+ breast cancer, we found that transfer of IL-15/IL-12-conditioned syngeneic NK cells after primary tumor resection promoted long-term survival of mice with low metastatic burden and induced a tumor-specific protective T cell response that is essential for the therapeutic effect. Furthermore, NK cell transfer augments activation of conventional dendritic cells (cDCs), Foxp3-CD4+ T cells and stem cell-like CD8+ T cells in metastatic lungs, to which IFN-γ of the transferred NK cells contributes significantly. These results imply direct interactions between transferred NK cells and endogenous cDCs to enhance T cell activation. We conducted an investigator-initiated clinical trial of autologous NK cell therapy in six patients with advanced cancer and observed that the NK cell therapy was safe and showed signs of effectiveness. These findings indicate that autologous NK cell therapy is effective in treating established low burden metastases of MHC-I+ tumor cells by activating the cDC-T cell axis at metastatic sites.

Weakly Supervised Nuclei Segmentation with Point-Guided Attention and Self-Supervised Pseudo-Labeling

Due to the labor-intensive manual annotations for nuclei segmentation, point-supervised segmentation based on nuclei coordinate supervision has gained recognition in recent years. Despite great progress, two challenges hinder the performance of weakly supervised nuclei segmentation methods: (1) The stable and effective segmentation of adjacent cell nuclei remains an unresolved challenge. (2) Existing approaches rely solely on initial pseudo-labels generated from point annotations for training, and inaccurate labels may lead the model to assimilate a considerable amount of noise information, thereby diminishing performance. To address these issues, we propose a method based on center-point prediction and pseudo-label updating for precise nuclei segmentation. First, we devise a Gaussian kernel mechanism that employs multi-scale Gaussian masks for multi-branch center-point prediction. The generated center points are utilized by the segmentation module to facilitate the effective separation of adjacent nuclei. Next, we introduce a point-guided attention mechanism that concentrates the segmentation module's attention around authentic point labels, reducing the noise impact caused by pseudo-labels. Finally, a label updating mechanism based on the exponential moving average (EMA) and k-means clustering is introduced to enhance the quality of pseudo-labels. The experimental results on three public datasets demonstrate that our approach has achieved state-of-the-art performance across multiple metrics. This method can significantly reduce annotation costs and reliance on clinical experts, facilitating large-scale dataset training and promoting the adoption of automated analysis in clinical applications.

Architects of immunity: How dendritic cells shape CD8+ T cell fate in cancer

Immune responses against cancer are dominated by T cell exhaustion and dysfunction. Recent advances have underscored the critical role of early priming interactions in establishing T cell fates. In this review, we explore the importance of dendritic cell (DC) signals in specifying CD8+ T cell fates in cancer, drawing on insights from acute and chronic viral infection models. We highlight the role of DCs in lymph nodes and tumors in maintaining stem-like CD8+ T cells, which are critical for durable antitumor immune responses. Understanding how CD8+ T cell fates are determined will enable the rational design of immunotherapies, particularly therapeutic cancer vaccines, that can modulate DC-T cell interactions to generate beneficial CD8+ T cell fates.

Antigen presentation by tumor-associated macrophages drives T cells from a progenitor exhaustion state to terminal exhaustion

Whereas terminally exhausted T (Tex_term) cells retain anti-tumor cytotoxic functions, the frequencies of stem-like progenitor-exhausted T (Tex_prog) cells better reflect immunotherapeutic responsivity. Here, we examined the intratumoral cellular interactions that govern the transition to terminal T cell exhaustion. We defined a metric reflecting the intratumoral progenitor exhaustion-to-terminal exhaustion ratio (PETER), which decreased with tumor progression in solid cancers. Single-cell analyses of Tex_prog cells and Tex_term cells in glioblastoma (GBM), a setting of severe T cell exhaustion, revealed disproportionate loss of Tex_prog cells over time. Exhaustion concentrated within tumor-specific T cell subsets, with cognate antigen exposure requisite for acquisition of the Tex_term phenotype. Tumor-associated macrophages (TAMs)-not tumor cells-were the primary source of antigenic exposure governing the Tex_prog to Tex_term transition. TAM depletion increased frequencies of Tex_prog cells in multiple tumor models, increased PETER, and promoted responsiveness to αPD1 immunotherapy. Thus, targeting TAM-T cell interactions may further license checkpoint blockade responses.

Immunogenic clearance combined with PD-1 blockade elicits antitumor effect by promoting the recruitment and expansion of the effector memory-like CD8+T cell

Immune checkpoint inhibition shows promise for cancer treatment, but only a minority of patients respond. Combination strategies have been explored to overcome this resistance. Combining immunogenic clearance using immunogenic cell death inducers with a rho kinase inhibitor enhances phagocytosis of immunogenically dying cancer cells by antigen-presenting cells, stimulating tumor-specific immune responses by activating CD8+T cells via dendritic cell-mediated priming. This approach increases the responsiveness of immune checkpoint blockade (ICB)-resistant cancer to ICB. However, the precise mechanisms remain unclear. This study elucidates cellular mechanisms of immunogenic clearance enhancing ICB response. Using single-cell RNA sequencing, we observed an increase in effector memory-like CD8+T cells within the tumor microenvironment with combined treatment. We propose this cell cluster may originate from proliferating CD8+T cells elevated by immunogenic clearance. Notably, abundant effector memory-like CD8+T cells in ICB-responsive patients suggest their antitumor effect. Thus, increasing this cell population through enhanced T cell priming may improve the response of ICB-resistant tumors.

Cancer cells impair monocyte-mediated T cell stimulation to evade immunity

The tumour microenvironment is programmed by cancer cells and substantially influences anti-tumour immune responses1,2. Within the tumour microenvironment, CD8+ T cells undergo full effector differentiation and acquire cytotoxic anti-tumour functions in specialized niches3-7. Although interactions with type 1 conventional dendritic cells have been implicated in this process3-5,8-10, the underlying cellular players and molecular mechanisms remain incompletely understood. Here we show that inflammatory monocytes can adopt a pivotal role in intratumoral T cell stimulation. These cells express Cxcl9, Cxcl10 and Il15, but in contrast to type 1 conventional dendritic cells, which cross-present antigens, inflammatory monocytes obtain and present peptide-major histocompatibility complex class I complexes from tumour cells through 'cross-dressing'. Hyperactivation of MAPK signalling in cancer cells hampers this process by coordinately blunting the production of type I interferon (IFN-I) cytokines and inducing the secretion of prostaglandin E2 (PGE2), which impairs the inflammatory monocyte state and intratumoral T cell stimulation. Enhancing IFN-I cytokine production and blocking PGE2 secretion restores this process and re-sensitizes tumours to T cell-mediated immunity. Together, our work uncovers a central role of inflammatory monocytes in intratumoral T cell stimulation, elucidates how oncogenic signalling disrupts T cell responses through counter-regulation of PGE2 and IFN-I, and proposes rational combination therapies to enhance immunotherapies.

Metabolic immunoengineering approaches to enhance CD8+ T cell-based cancer immunotherapy

Many cancer immunotherapies rely on robust CD8+ T cells capable of eliminating cancer cells and establishing long-term tumor control. Recent insights into immunometabolism highlight the importance of nutrients and metabolites in T cell activation and differentiation. Within the tumor microenvironment (TME), CD8+ tumor-infiltrating lymphocytes (TILs) undergo metabolic adaptations to survive but compromise their effector function and differentiation. Targeting metabolism holds promise for enhancing CD8+ T cell-mediated antitumor immunity. Here, we overview the metabolic features of CD8+ TILs and their impact on T cell effector function and differentiation. We also highlight immunoengineering strategies by leveraging the Yin-Yang of metabolic modulation for improving cancer immunotherapy.

Intratumoral delivery of lipid nanoparticle-formulated mRNA encoding IL-21, IL-7, and 4-1BBL induces systemic anti-tumor immunity

Local delivery of mRNA-based immunotherapy offers a promising avenue as it enables the production of specific immunomodulatory proteins that can stimulate the immune system to recognize and eliminate cancer cells while limiting systemic exposure and toxicities. Here, we develop and employ lipid-based nanoparticles (LNPs) to intratumorally deliver an mRNA mixture encoding the cytokines interleukin (IL)-21 and IL-7 and the immunostimulatory molecule 4-1BB ligand (Triplet LNP). IL-21 synergy with IL-7 and 4-1BBL leads to a profound increase in the frequency of tumor-infiltrating CD8+ T cells and their capacity to produce granzyme B and IFN-γ, leading to tumor eradication and the development of long-term immunological memory. Mechanistically, the efficacy of the Triplet LNP depends on tumor-draining lymph nodes to tumor CD8+ T-cell trafficking. Moreover, we highlight the therapeutic potential of the Triplet LNP in multiple tumor models in female mice and its superior therapeutic efficacy to immune checkpoint blockade. Ultimately, the expression of these immunomodulators is associated with better overall survival in patients with cancer.

Therapeutic Immunomodulation of Tumor-Lymphatic Crosstalk via Intratumoral Immunotherapy

Intra- and peritumoral lymphatics and tumor-draining lymph nodes play major roles in mediating the adaptive immune response to cancer immunotherapy. Despite this, current paradigms of clinical cancer management seldom seek to therapeutically modulate tumor-lymphatic immune crosstalk. This review explores recent developments that set the stage for how this regulatory axis can be therapeutically manipulated, with a particular emphasis on tumor-localized immunomodulation. Building on this idea, the nature of tumor-lymphatic immune crosstalk and relevant immunotherapeutic targets and pathways are reviewed, with a focus on their translational potential. Engineered drug delivery systems that enhance intratumoral immunotherapy by improving drug delivery to both the tumor and lymph nodes are also highlighted.

The importance of type I interferon in orchestrating the cytotoxic T-cell response to cancer

Both type I interferon (IFN-I) and CD4+ T-cell help are required to generate effective CD8+ T-cell responses to cancer. We here outline based on existing literature how IFN-I signaling and CD4+ T-cell help are connected. Both impact on the functional state of dendritic cells (DCs), particularly conventional (c)DC1. The cDC1s are critical for crosspresentation of cell-associated antigens and for delivery of CD4+ T-cell help for cytotoxic T-lymphocyte (CTL) effector and memory differentiation. In infection, production of IFN-I is prompted by pathogen-associated molecular patterns (PAMPs), while in cancer it relies on danger-associated molecular patterns (DAMPs). IFN-I production by tumor cells and pDCs in the tumor micro-environment (TME) is often limited. IFN-I signals increase the ability of migratory cDC1s and cDC2s to transport tumor antigens to tumor-draining lymph nodes (tdLNs). IFN-I also enables cDC1s to form and sustain the platform for help delivery by stimulating the production of chemokines that attract CD4+ and CD8+ T cells. IFN-I promotes delivery of help in concert with CD40 signals by additive and synergistic impact on cross-presentation and provision of critical costimulatory and cytokine signals for CTL effector and memory differentiation. The scenario of CD4+ T-cell help therefore depends on IFN-I signaling. This scenario can play out in tdLNs as well as in the TME, thereby contributing to the cancer immunity cycle. The collective observations may explain why both IFN-I and CD4+ T-cell help signatures in the TME correlate with good prognosis and response to PD-1 targeting immunotherapy in human cancer. They also may explain why a variety of tumor types in which IFN-I signaling is attenuated, remain devoid of functional CTLs.

Differentiation fate of a stem-like CD4 T cell controls immunity to cancer

The T cell response to cancer controls disease progression and response to immunotherapy1-3. Despite extensive knowledge regarding CD8 T cells, how CD4 T cells contribute to this process is less well understood. Here we identified a population of PD1+TCF1+ CD4 T cells with stem-like properties that are capable of self-renewal and differentiation into canonical CD4 effector cells. Primarily residing in tumour-draining lymph nodes (TDLNs), these tumour-specific CD4 T cells are restricted by T regulatory (Treg) cells to a stem-like fate that predominantly generated induced Treg (iTreg) cells, limiting effector CD8 T cell responses to the tumour. By contrast, upon Treg depletion, stem-like CD4 T cells differentiated into T helper 1 (TH1) cells, and via IFNγ production induced robust effector differentiation from TCF1+ CD8 T cells in TDLNs, a state we defined as 'active'. Notably, enforcing TBET expression in transferred stem-like CD4 T cells was sufficient to overcome the established restricted T cell state. Despite the presence of Treg cells, endogenous stem-like CD4 T cells actively generated TH1 cells, which were required to restore TDLN effector CD8 T cell differentiation, enhance tumour control and rescue response to immunotherapy. In agreement, TH1 differentiation in patients with kidney cancer predicted successful immunotherapy responses and improved progression-free survival. Together, these findings identify a stem-like CD4 T cell population that through alternative differentiation fates controls the switch between restricted and active T cell states with implications for cancer immunotherapies.

Tumor-infiltrating lymphocytes and immune-related adverse events in advanced melanoma

Background

The predictive value of tumor-infiltrating lymphocytes (TILs) in immune-related adverse event (irAE) development remains unknown, although an association between tumor immunogenicity and irAEs has been suggested. We investigated the association between TIL abundance in pretreatment primary and metastasis specimens and the subsequent development of severe irAEs.

Patients and methods

We retrospectively identified patients with advanced cutaneous melanoma who received first-line anti-programmed cell death protein 1 (PD-1) with or without anti-cytotoxic T-lymphocyte associated protein 4 (anti-CTLA-4) from 10 hospitals in the Netherlands. TILs were scored on representative hematoxylin and eosin (H&E) stains of the primary melanoma and pretreatment melanoma metastasis as 'absent', 'nonbrisk', or 'brisk'. A univariable logistic regression analysis was carried out to assess the association between the TIL scores and the development of severe irAEs. Fine and Gray subdistribution hazard models were used to estimate the cumulative incidence of severe irAEs.

Results

Of the 1346 eligible patients, 536 patients had primary melanoma specimens available, and 613 patients had metastasis specimens available. Severe irAEs occurred in 15% of anti-PD-1-treated patients and 49% of anti-PD-1 + anti-CTLA-4-treated patients. The presence of TILs was not associated with the occurrence of grade ≥3 irAEs in primary melanoma specimens (P = 0.70) nor pretreatment metastasis specimens (P = 0.91). In the univariable analysis, patients with brisk TILs did not have a higher chance of developing severe irAEs compared with patients with absent TILs, for both primary specimen (odds ratio 1.15, 95% confidence interval 0.60-2.18) and metastasis specimen (odds ratio 0.77, 95% confidence interval 0.37-1.59). There was also no significant difference in the lifetime risk or timing of the development of severe irAEs in patients with TILs present compared with patients with TILs absent.

Conclusion

There was no association between the TIL scores on H&E-stained slides from the primary melanoma or pretreatment metastasis and the development of grade 3 or higher irAEs. Additionally, no correlation was found between the presence of TILs and the timing of irAEs.

CD28 co-stimulation: novel insights and applications in cancer immunotherapy

Substantial progress in understanding T cell signalling, particularly with respect to T cell co-receptors such as the co-stimulatory receptor CD28, has been made in recent years. This knowledge has been instrumental in the development of innovative immunotherapies for patients with cancer, including immune checkpoint blockade antibodies, adoptive cell therapies, tumour-targeted immunostimulatory antibodies, and immunostimulatory small-molecule drugs that regulate T cell activation. Following the failed clinical trial of a CD28 superagonist antibody in 2006, targeted CD28 agonism has re-emerged as a technologically viable and clinically promising strategy for cancer immunotherapy. In this Review, we explore recent insights into the molecular functions and regulation of CD28. We describe how CD28 is central to the success of current cancer immunotherapies and examine how new questions arising from studies of CD28 as a clinical target have enhanced our understanding of its biological role and may guide the development of future therapeutic strategies in oncology.

IL-2/anti-IL-2 antibody complexes augment immune responses to therapeutic cancer vaccines

One driver of the high failure rates of clinical trials for therapeutic cancer vaccines is likely the inability to sufficiently engage conventional dendritic cells (cDCs), the antigen-presenting cell (APC) subset that is specialized in priming antitumor T cells. Here, we demonstrate that, relative to vaccination with an injectable mesoporous silica rod (MPS) vaccine alone (Vax), combining MPS vaccines with CD122-biased IL-2/anti-IL-2 antibody complexes (IL-2cx) drives ~3-fold expansion of cDCs at the vaccination sites, vaccine-draining lymph nodes, and spleens of treated mice. Furthermore, relative to Vax alone, Vax+IL-2cx led to a ~3-fold increase in the numbers of CD8+ T cells and ~15-fold increase in the numbers of NK cells at the vaccination site. Notably, with both the model protein antigen OVA as well as various peptide neoantigens, Vax+IL-2cx induced ~5 to 30-fold greater numbers of circulating antigen-specific CD8+ T cells relative to Vax alone. We further demonstrate that Vax+IL-2cx leads to significantly improved efficacy in the MC38 colon carcinoma model relative to either monotherapy alone, driving complete regressions in 50% of mice in a cDC-dependent manner. Relative to vaccine alone, Vax+IL-2cx led to comparable numbers of CD8+ T cells, but markedly greater numbers of NK cells and activated cDCs in the B16F10 melanoma tumor microenvironment post-therapy. Taken together, these findings suggest that the administration of factors that engage both the cDC-CD8+ T cell and cDC-NK cell axes can boost the potency of therapeutic cancer vaccines.

Dual CD47 and PD-L1 blockade elicits anti-tumor immunity by intratumoral CD8+ T cells

Objectives

Bispecific antibodies targeting CD47 and PD-L1 (CD47 × PD-L1 BisAb) demonstrate efficacy against a range of solid cancers. While dual blockade negates anti-CD47-mediated toxicity, the effect of combined innate and adaptive immune activation on protective tumor-resident CD8+ T cells has yet to be fully elucidated.

Methods

CD8+ T cell populations were tracked upon CD47 × PD-L1 BisAb treatment in an orthotopic model of murine breast cancer where anti-tumor immunity is mediated by CD8+ T cells. Immune responses were also compared with anti-PD-L1 monotherapy to assess the advantage of dual checkpoint targeting.

Results

We found that CD47 × PD-L1 BisAb treatment augmented CD8+ T cell responses in tumors, which resulted in enhanced tumor control. Compared with anti-PD-L1 treatment, dual CD47 and PD-L1 blockade promoted greater numbers of antigen-specific tumor-resident CD8+ T cells that exhibited increased cytokine production.

Conclusions

Engagement of innate and adaptive immune checkpoint molecules via CD47 × PD-L1 BisAb treatment resulted in robust CD8+ T cell responses, including the induction of tumor-resident CD8+ T cells that exhibited functionally superior anti-tumor immunity. These results demonstrate that innate immune activation potentiates anti-tumor adaptive responses, highlighting the use of dual checkpoint blockade as an optimal strategy for promoting CD8+ T cell-mediated protection.

An early, novel arginine methylation of KCa3.1 attenuates subsequent T cell exhaustion

T cell receptor (TCR) engagement initiates the activation process, and this signaling event is regulated in multifaceted ways. Nutrient availability in the immediate niche is one such mode of regulation 1-3 . Here, we investigated how the availability of an essential amino acid methionine (Met) and TCR signaling might interplay in the earliest events of T cell activation to affect subsequent T cell fate and function. We found that limiting Met during only the initial 30 minutes of CD8 + T cell activation increased Ca 2+ influx, Ca 2+ -mediated NFAT1 ( Nfatc2 ) activation, NFAT1 promoter occupancy, and T cell exhaustion. We identified changes in the protein arginine methylome during the initial 30 min of TCR engagement and discovered a novel arginine methylation of a Ca 2+ -activated potassium transporter, KCa3.1, which regulates Ca 2+ -mediated NFAT1 signaling to ensure optimal activation. Ablation of arginine methylation in KCa3.1 led to increased NFAT1 activation, rendering T cells dysfunctional in murine tumour and infection models. Furthermore, acute Met supplementation at early stages reduced nuclear NFAT1 in tumour-infiltrating T cells and augmented their anti-tumour activity. Our findings identify a metabolic event occurring early after T cell activation that influences the subsequent fate of the cell.

New opportunities to overcome T cell dysfunction: the role of transcription factors and how to target them

Immune checkpoint blockade (ICB) therapies, which block inhibitory receptors on T cells, can be efficacious in reinvigorating dysfunctional T cell responses. However, most cancers do not respond to these therapies and even in those that respond, tumors can acquire resistance. New strategies are needed to rescue and recruit T cell responses across patient populations and disease states. In this review, we define mechanisms of T cell dysfunction, focusing on key transcription factor (TF) networks. We discuss the complex and sometimes contradictory roles of core TFs in both T cell function and dysfunction. Finally, we review strategies to target TFs using small molecule modulators, which represent a challenging but highly promising opportunity to tune the T cell response toward sustained immunity.

Pre-operative stereotactic radiosurgery and peri-operative dexamethasone for resectable brain metastases: a two-arm pilot study evaluating clinical outcomes and immunological correlates

Enhancing the efficacy of immunotherapy in brain metastases (BrM) requires an improved understanding of the immune composition of BrM and how this is affected by radiation and dexamethasone. Our two-arm pilot study (NCT04895592) allocated 26 patients with BrM to either low (Arm A) or high (Arm B) dose peri-operative dexamethasone followed by pre-operative stereotactic radiosurgery (pSRS) and resection (n= 13 per arm). The primary endpoint, a safety analysis at 4 months, was met. The secondary clinical endpoints of overall survival, distant brain failure, leptomeningeal disease and local recurrence at 12-months were 66%, 37.3%, 6%, and 0% respectively and were not significantly different between arms (p= 0.7739, p= 0.3884, p= 0.3469). Immunological data from two large retrospective BrM datasets and confirmed by correlates from both arms of this pSRS prospective trial revealed that BrM CD8 T cells were composed of predominantly PD1+ TCF1+ stem-like and PD1+ TCF1-TIM3+ effector-like cells. Clustering of TCF1+ CD8 T cells with antigen presenting cells in immune niches was prognostic for local control, even without pSRS. Following pSRS, CD8 T cell and immune niche density were transiently reduced compared to untreated BrM, followed by a rebound 6+ days post pSRS with an increased frequency of TCF1- effector-like cells. In sum, pSRS is safe and therapeutically beneficial, and these data provide a framework for how pSRS may be leveraged to maximize intracranial CD8 T cell responses.

Preclinical study and phase II trial of adapting low-dose radiotherapy to immunotherapy in small cell lung cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs) provide modest but unsatisfactory benefits for extensive-stage small cell lung cancer (ES-SCLC). Developing strategies for treating ES-SCLC is critical.

METHODS

We preliminarily explored the outcomes of salvage low-dose radiotherapy (LDRT) plus ICI on refractory SCLC patients. Next, we evaluated the combinational efficacy in murine SCLC. The tumor immune microenvironment (TIME) was analyzed for mechanistic study. Subsequently, we conducted a multicenter, prospective phase II trial that administered concurrent thoracic LDRT plus chemoimmunotherapy to treatment-naive ES-SCLC patients (MATCH trial, NCT04622228). The primary endpoint was confirmed objective response rate (ORR), and the key secondary endpoints included progression-free survival (PFS) and safety.

FINDINGS

Fifteen refractory SCLC patients treated with LDRT plus ICI were retrospectively reviewed. The ORR was 73.3% (95% confidence interval [CI], 44.9-92.2). We identified a specific dose of LDRT (15 Gy/5 fractions) that exhibited growth retardation and improved survival in murine SCLC when combined with ICIs. This combination recruited a special T cell population, TCF1+ PD-1+ CD8+ stem-like T cells, from tumor-draining lymph nodes into the TIME. The MATCH trial showed a confirmed ORR of 87.5% (95% CI, 75.9-94.8). The median PFS was 6.9 months (95% CI, 5.4-9.3).

CONCLUSIONS

These findings verified that LDRT plus chemoimmunotherapy was safe, feasible, and effective for ES-SCLC, warranting further investigation.

FUNDING

This research was funded by West China Hospital (no. ZYJC21003), the National Natural Science Foundation of China (no. 82073336), and the MATCH trial was fully funded by Roche (China) Holding Ltd. (RCHL) and Shanghai Roche Pharmaceuticals Ltd. (SRPL).

Unwrapping stemness to revive T cells

Targeting epigenetic regulators prevents T cell exhaustion.

Epigenetic regulators of clonal hematopoiesis control CD8 T cell stemness during immunotherapy

Epigenetic reinforcement of T cell exhaustion is known to be a major barrier limiting T cell responses during immunotherapy. However, the core epigenetic regulators restricting antitumor immunity during prolonged antigen exposure are not clear. We investigated three commonly mutated epigenetic regulators that promote clonal hematopoiesis to determine whether they affect T cell stemness and response to checkpoint blockade immunotherapy. CD8 T cells lacking Dnmt3a, Tet2, or Asxl1 preserved a progenitor-exhausted (Tpex) population for more than 1 year during chronic antigen exposure without undergoing malignant transformation. Asxl1 controlled the self-renewal capacity of T cells and reduced CD8 T cell differentiation through H2AK119 ubiquitination and epigenetic modification of the polycomb group-repressive deubiquitinase pathway. Asxl1-deficient T cells synergized with anti-PD-L1 immunotherapy to improve tumor control in experimental models and conferred a survival advantage to mutated T cells from treated patients.

Tumor cell-intrinsic Piezo2 drives radioresistance by impairing CD8+ T cell stemness maintenance

Changes in mechanosensitive ion channels following radiation have seldom been linked to therapeutic sensitivity or specific factors involved in antitumor immunity. Here, in this study, we found that the mechanical force sensor, Piezo2, was significantly upregulated in tumor cells after radiation, and Piezo2 knockout in tumor cells enhanced tumor growth suppression by radiotherapy. Specifically, loss of Piezo2 in tumor cells induced their IL-15 expression via unleashing JAK2/STAT1/IRF-1 axis after radiation. This increase in IL-15 activates IL-15Rα on tumor-infiltrating CD8+ T cells, thereby leading to their augmented effector and stem cell-like properties, along with reduced terminal exhausted feature. Importantly, Piezo2 expression was negatively correlated with CD8 infiltration, as well as with radiosensitivity of patients with rectum adenocarcinoma receiving radiotherapy treatment. Together, our findings reveal that tumor cell-intrinsic Piezo2 induces radioresistance by dampening the IRF-1/IL-15 axis, thus leading to impaired CD8+ T cell-dependent antitumor responses, providing insights into the further development of combination strategies to treat radioresistant cancers.

Local delivery of cell surface-targeted immunocytokines programs systemic antitumor immunity

Systemically administered cytokines are potent immunotherapeutics but can cause severe dose-limiting toxicities. To overcome this challenge, cytokines have been engineered for intratumoral retention after local delivery. However, despite inducing regression of treated lesions, tumor-localized cytokines often elicit only modest responses at distal untreated tumors. In the present study, we report a localized cytokine therapy that safely elicits systemic antitumor immunity by targeting the ubiquitous leukocyte receptor CD45. CD45-targeted immunocytokines have lower internalization rates relative to wild-type counterparts, leading to sustained downstream cis and trans signaling between lymphocytes. A single intratumoral dose of αCD45-interleukin (IL)-12 followed by a single dose of αCD45-IL-15 eradicated treated tumors and untreated distal lesions in multiple syngeneic mouse tumor models without toxicity. Mechanistically, CD45-targeted cytokines reprogrammed tumor-specific CD8+ T cells in the tumor-draining lymph nodes to have an antiviral transcriptional signature. CD45 anchoring represents a broad platform for protein retention by host immune cells for use in immunotherapy.