Localization, tissue biology and T cell state - implications for cancer immunotherapy

CAR-T therapy and targeted treatments: Emerging combination strategies in solid tumors

CAR-T cell therapies hold great potential in achieving long-term remission in patients suffering from malignancies. However, their efficacy in treating solid tumors is impeded by challenges such as limited infiltration, compromised cancer recognition, decreased cytotoxicity, heightened exhaustion, absence of memory phenotypes, and inevitable toxicity. To surmount these obstacles, researchers are exploring innovative strategies, including the integration of CAR-T cells with targeted inhibitors. The combination of CAR-T therapies with specific targeted drugs has shown promise in enhancing CAR-T cell infiltration into tumor sites, boosting their tumor recognition capabilities, strengthening their cytotoxicity, alleviating exhaustion, promoting the development of a memory phenotype, and reducing toxicity. By harnessing the synergistic potential, a wider range of patients with solid tumors may potentially experience favorable outcomes. To summarize the current combined strategies of CAR-T therapies and targeted therapies, outline the potential mechanisms, and provide insights for future studies, we conducted this review by collecting existing experimental and clinical evidence.

Leveraging Long-Distance Singlet-Oxygen Transfer for Bienzyme-Locked Afterglow Imaging of Intratumoral Granule Enzymes

Dual-locked activatable optical probes, leveraging the orthogonal effects of two biomarkers, hold great promise for the specific imaging of biological processes. However, their design approaches are limited to a short-distance energy or charge transfer mechanism, while the signal readout relies on fluorescence, which inevitably suffers from tissue autofluorescence. Herein, we report a long-distance singlet oxygen transfer approach to develop a bienzyme-locked activatable afterglow probe (BAAP) that emits long-lasting self-luminescence without real-time light excitation for the dynamic imaging of an intratumoral granule enzyme. Composed of an immuno-biomarker-activatable singlet oxygen (1O2) donor and a cancer-biomarker-activatable 1O2 acceptor, BAAP is initially nonafterglow. Only in the presence of both immune and cancer biomarkers can 1O2 be generated by the activated donor and subsequently diffuse toward the activated acceptor, resulting in bright near-infrared afterglow with a high signal-to-background ratio and specificity toward an intratumoral granule enzyme. Thus, BAAP allows for real-time tracking of tumor-infiltrating cytotoxic T lymphocytes, enabling the evaluation of cancer immunotherapy and the differentiation of tumor from local inflammation with superb sensitivity and specificity, which are unachievable by single-locked probes. Thus, this study not only presents the first dual-locked afterglow probe but also proposes a new design way toward dual-locked probes via reactive oxygen species transfer processes.

The neoantigens derived from transposable elements - A hidden treasure for cancer immunotherapy

Neoantigen-based therapy is a promising approach that selectively activates the immune system of the host to recognize and eradicate cancer cells. Preliminary clinical trials have validated the feasibility, safety, and immunogenicity of personalized neoantigen-directed vaccines, enhancing their effectiveness and broad applicability in immunotherapy. While many ongoing oncological trials concentrate on neoantigens derived from mutations, these targets do not consistently provoke an immune response in all patients harboring the mutations. Additionally, tumors like ovarian cancer, which have a low tumor mutational burden (TMB), may be less amenable to mutation-based neoantigen therapies. Recent advancements in next-generation sequencing and bioinformatics have uncovered a rich source of neoantigens from non-canonical RNAs associated with transposable elements (TEs). Considering the substantial presence of TEs in the human genome and the proven immunogenicity of TE-derived neoantigens in various tumor types, this review investigates the latest findings on TE-derived neoantigens, examining their clinical implications, challenges, and unique advantages in enhancing tumor immunotherapy.

Antitumor activity of dictamnine against colorectal cancer through induction of ferroptosis and inhibition of M2 macrophage polarization via the MAPK signaling

Colorectal cancer (CRC) is an aggressive cancer type globally. Surgery and chemotherapy are often ineffective at curing CRC. Dictamnine is a natural product derived from Dictamnus dasycarpus Turcz. root bark and possesses multi-pharmacological properties, including anticancer effects. Nevertheless, the biological roles and the possible mechanism of dictamnine in CRC are still unclear. Here, we demonstrated that dictamnine blocked cell viability and proliferation in DLD-1 human colorectal adenocarcinoma cells and LoVo human colon cancer cells. Dictamnine triggered CRC cell ferroptosis, as evidenced by enhanced levels of reactive oxygen species, malondialdehyde, and Fe2+ levels, alongside downregulation of glutathione peroxidase 4 protein expression. In addition, CD163 (HPA ID: HPA046404) was highly expressed and CD68 (HPA ID: CAB000051) was lowly expressed in CRC tissues and CRC cell culture medium-cultured THP-1 monocytes-derived macrophages. The patients with CD163 low-expression lived much longer than those with CD163 high-expression, indicating that M2 polarization of macrophages was related to poor prognosis of CRC. Dictamnine markedly inhibited CD163 protein expression, transforming growth factor-β and arginase 1 mRNA expressions and IL-10 production in macrophages with CRC cell co-culture, suggesting that dictamnine impeded M2 polarization of macrophages. Mechanistically, dictamnine repressed ERK phosphorylation in CRC cells. The treatment with the ERK activator tBHQ counteracted the effects of dictamnine on CRC cell proliferation and ferroptosis, as well as its inhibitory effect on M2 polarization of macrophages. Results of a xenograft model showed that dictamnine effectively hindered CRC tumor growth in vivo. Collectively, these data provide evidence for the clinical trials of dictamnine as a novel drug for CRC therapy.

Role of Exosomes in Cancer and Aptamer-Modified Exosomes as a Promising Platform for Cancer Targeted Therapy

Exosomes are increasingly recognized as important mediators of intercellular communication in cancer biology. Exosomes can be derived from cancer cells as well as cellular components in tumor microenvironment. After secretion, the exosomes carrying a wide range of bioactive cargos can be ingested by local or distant recipient cells. The released cargos act through a variety of mechanisms to elicit multiple biological effects and impact most if not all hallmarks of cancer. Moreover, owing to their excellent biocompatibility and capability of being easily engineered or modified, exosomes are currently exploited as a promising platform for cancer targeted therapy. In this review, we first summarize the current knowledge of roles of exosomes in risk and etiology, initiation and progression of cancer, as well as their underlying molecular mechanisms. The aptamer-modified exosome as a promising platform for cancer targeted therapy is then briefly introduced. We also discuss the future directions for emerging roles of exosome in tumor biology and perspective of aptamer-modified exosomes in cancer therapy.

Preliminary evidence of localizing CD8+ T-cell responses in COVID-19 patients with PET imaging

The upper respiratory tract (URT) is the entry site for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), from where it further disseminates. Early and effective adaptive immune responses are crucial to restrict viral replication and limit symptom development and transmission. Current vaccines increasingly incorporate strategies to boost mucosal immunity in the respiratory tract. Positron emission tomography (PET) is a non-invasive technology that measures cellular responses at a whole-body level. In this case series, we explored the feasibility of [89Zr]Zr-crefmirlimab berdoxam PET to assess CD8+ T-cell localization during active COVID-19. Our results suggest that CD8+ T-cell distributions assessed by PET imaging reflect their differentiation and functional state in blood. Therefore, PET imaging may represent a novel tool to visualize and quantify cellular immune responses during infections at a whole-body level.

SFXN1-mediated immune cell infiltration and tumorigenesis in lung adenocarcinoma: A potential therapeutic target

BACKGROUND

Sideroflexin 1 (SFXN1), a mitochondrial serine transporter implicated in one-carbon metabolism, is a prognostic biomarker in lung adenocarcinoma (LUAD). However, its role in LUAD progression remains elusive. This study aimed to investigate the functional significance of SFXN1 in LUAD and evaluate its potential as a therapeutic target.

METHODS

We analyzed SFXN1 expression and its diagnostic and prognostic value in LUAD using the Pan-cancer TCGA dataset. In vitro assays (CCK-8, cell cycle, EDU, wound-healing, and transwell) were employed to assess the role of SFXN1, complemented by in vivo experiments. RNA sequencing elucidated SFXN1-mediated cellular functions and potential mechanisms. Bulk RNA-seq and scRNA-seq data from TCGA and GEO were used to investigate the correlation between SFXN1 and the tumor immune microenvironment. RT-qPCR, Western blot, and IHC assays validated SFXN1 expression and its impact on the immune microenvironment in LUAD.

RESULTS

SFXN1 was upregulated in LUAD tissues and associated with poor prognosis. RNA-seq and scRNA-seq analyses revealed increased SFXN1 expression in tumor cells, accompanied by decreased infiltration of NK and cytotoxic T cells. SFXN1 knockdown significantly reduced cell proliferation and migration, and the inhibition of ERK phosphorylation and CCL20 expression may be the molecular mechanism involved. In vivo, targeting SFXN1 decreased Tregs infiltration and inhibited tumor growth.

CONCLUSIONS

Our findings suggest that SFXN1 may be a potential therapeutic target for LUAD treatment.

Function of alveolar macrophages in lung cancer microenvironment

BACKGROUND

Cancer tissues contain a wide variety of immune cells that play critical roles in suppressing or promoting tumor progression. Macrophages are one of the most predominant populations in the tumor microenvironment and are composed of two classes: infiltrating macrophages from the bone marrow and tissue-resident macrophages (TRMs). This review aimed to outline the function of TRMs in the tumor microenvironment, focusing on lung cancer.

REVIEW

Although the functions of infiltrating macrophages and tumor-associated macrophages have been intensively analyzed, a comprehensive understanding of TRM function in cancer is relatively insufficient because it differs depending on the tissue and organ. Alveolar macrophages (AMs), one of the most important TRMs in the lungs, are replenished in situ, independent of hematopoietic stem cells in the bone marrow, and are abundant in lung cancer tissue. Recently, we reported that AMs support cancer cell proliferation and contribute to unfavorable outcomes.

CONCLUSION

In this review, we introduce the functions of AMs in lung cancer and their underlying molecular mechanisms. A thorough understanding of the functions of AMs in lung cancer will lead to improved treatment outcomes.

Helicobacter pylori and immunotherapy for gastrointestinal cancer

Helicobacter pylori infection is associated with the risk of gastrointestinal (GI) cancers; however, its impact on immunotherapy for GI cancers remains uncertain. In this study, we included 10,122 patients who underwent 13C-urea breath tests. Among 636 patients with Epstein-Barr virus-negative microsatellite-stable gastric cancer (GC) who were treated with anti-PD-1/PD-L1 therapy, H. pylori-positive patients exhibited significantly longer immune-related progression-free survival (irPFS) compared with H. pylori-negative patients (6.97 months versus 5.03 months, p < 0.001, hazard ratio [HR] 0.76, 95% confidence interval [CI] 0.62-0.95, p = 0.015). Moreover, the H. pylori-positive group demonstrated a trend of 4 months longer median immune-related overall survival (irOS) than the H. pylori-negative group. H. pylori-positive GC displayed higher densities of PD-L1+ cells and nonexhausted CD8+ T cells, indicative of a "hot" tumor microenvironment. Transcriptomic analysis revealed that H. pylori-positive GC shared molecular characteristics similar to those of immunotherapy-sensitive GC. However, H. pylori-positive patients with DNA mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal adenocarcinoma and esophageal squamous cell carcinoma (ESCC) had shorter irPFS compared with H. pylori-negative patients (16.13 months versus not reached, p = 0.042, HR 2.26, 95% CI 1.13-4.50, p = 0.021 and 5.57 months versus 6.97 months, p = 0.029, HR 1.59, 95% CI 1.14-2.23, p = 0.006, respectively). The difference in irOS between H. pylori-positive and -negative patients had the same trend as that between dMMR/MSI-H colorectal adenocarcinoma and ESCC patients. We also identified a trend of shorter irPFS and irOS in H. pylori-positive liver cancer and pancreatic cancer patients. In summary, our findings supported that H. pylori infection is a beneficial factor for GC immunotherapy by shaping hot tumor microenvironments. However, in dMMR/MSI-H colorectal adenocarcinoma and ESCC patients, H. pylori adversely affects the efficacy of immunotherapy.

Ceramide metabolism-related prognostic signature and immunosuppressive function of ST3GAL1 in osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor with elevated disability and mortality rates in children and adolescents and the therapeutic effect for osteosarcoma has remained stagnant in the past 30 years. Emerging evidence has shown ceramide metabolism plays a vital role in tumor progression, but its mechanisms in osteosarcoma progression remain unknown. Through consensus clustering and LASSO regression analysis based on the osteosarcoma cohorts from TARGET database, we constructed a ceramide metabolism-related prognostic signature including ten genes for osteosarcoma, with ST3GAL1 exhibiting the highest hazard ratio. Biological signatures analysis demonstrated that ceramide metabolism was associated with immune-related pathways, immune cell infiltration and the expression of immune checkpoint genes. Single-cell profiling revealed that ceramide metabolism was enriched in myeloid, osteoblast and mesenchymal cells. The interaction between TAMs and CD8+ T cells played an essential role in osteosarcoma. ST3GAL1 regulated the SPP1-CD44 interaction between TAMs and CD8+ T cells and IL-10 secretion in TAMs through α2,3 sialic acid receptors, which inhibited CD8+ T cell function. IHC analysis showed that ST3GAL1 expression correlated with the prognosis of osteosarcoma patients. Co-culture assay revealed that upregulation of ST3GAL1 in tumor cells regulated the differentiation of TAMs and cytokine secretion. Collectively, our findings demonstrated that ceramide metabolism was associated with clinical outcome in osteosarcoma. ST3GAL1 facilitated tumor progression through regulating tumor immune microenvironment, providing a feasible therapeutic approach for patients with osteosarcoma.

CD69 is a Promising Immunotherapy and Prognosis Prediction Target in Cancer

Immunotherapy utilizing T cells that attack tumors is a promising strategy for treatment, but immune suppressive T cell subsets, such as regulatory T cell (Treg), and immune checkpoint molecules, including programmed death-1 (PD-1), can suppress the intensity of a T cell immune reaction and thereby impair tumor clearance. Cluster of differentiation 69 (CD69), known as an early leukocyte activation marker, can be used as a measure or early marker of T cell activation. In recent years, the functions of CD69 in the regulation of Treg/Th17 (T helper cell 17) differentiation and in the tissue retention of T cells have attracted considerable interest. These functions are related to the role of CD69 in immune suppression in tumor environments (TME). In this review, we first summarized current perspectives in the biological function of CD69 and demonstrated that CD69 acts as a regulator of T cell activation, differentiation, retention, and exhaustion. Then, we discussed recent advances in understanding of CD69 deficiency and anti-CD69 antibody administration and shed light on the value of targeting on CD69 for cancer immunotherapy and prognosis prediction.

Distinct regulatory machineries underlying divergent chromatin landscapes distinguish innate lymphoid cells from T helper cells

Innate lymphoid cells (ILCs), as the innate counterpart of CD4+ T helper (Th) cells, play crucial roles in maintaining tissue homeostasis. While the ILC subsets and their corresponding Th subsets demonstrate significant similarities in core programming related to effector function and regulatory mechanisms, their principal distinctions, given their innate and adaptive lymphocyte nature, remain largely unknown. In this study, we have employed an integrative analysis of 294 bulk RNA-sequencing results across all ILC and Th subsets, using scRNA-seq algorithms. Consequently, we identify two genesets that predominantly differentiate ILCs from Th cells, as well as three genesets that distinguish various immune responses. Furthermore, through chromatin accessibility analysis, we find that the ILC geneset tends to rely on specific transcriptional regulation at promoter regions compared with the Th geneset. Additionally, we observe that ILCs and Th cells are under differential transcriptional regulation. For example, ILCs are under stronger regulation by multiple transcription factors, including RORα, GATA3, and NF-κB. Otherwise, Th cells are under stronger regulation by AP-1. Thus, our findings suggest that, despite the acknowledged similarities in effector functions between ILC subsets and corresponding Th subsets, the underlying regulatory machineries still exhibit substantial distinctions. These insights provide a comprehensive understanding of the unique roles played by each cell type during immune responses.

Pathogenic CD8 T cell responses are driven by neutrophil-mediated hypoxia in cutaneous leishmaniasis

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8 T cell responses mediate disease. While these responses originate in the lymph node, we find that expression of the cytolytic effector molecule granzyme B is restricted to lesional CD8 T cells in Leishmania - infected mice, suggesting that local cues within inflamed skin induce cytolytic function. Expression of Blimp-1 ( Prdm1 ), a transcription factor necessary for cytolytic CD8 T cell differentiation, is driven by hypoxia within the inflamed skin. Hypoxia is further enhanced by the recruitment of neutrophils that consume oxygen to produce reactive oxygen species, ultimately increasing granzyme B expression in CD8 T cells. Importantly, lesions from cutaneous leishmaniasis patients exhibit hypoxia transcription signatures that correlate with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8 T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as other inflammatory skin diseases where cytolytic CD8 T cells contribute to pathogenesis.

CD8+ T cells in the cancer-immunity cycle

CD8+ T cells are end effectors of cancer immunity. Most forms of effective cancer immunotherapy involve CD8+ T cell effector function. Here, we review the current understanding of T cell function in cancer, focusing on key CD8+ T cell subtypes and states. We discuss factors that influence CD8+ T cell differentiation and function in cancer through a framework that incorporates the classic three-signal model and a fourth signal-metabolism-and also consider the impact of the tumor microenvironment from a T cell perspective. We argue for the notion of immunotherapies as "pro-drugs" that act to augment or modulate T cells, which ultimately serve as the drug in vivo, and for the importance of overall immune health in cancer treatment and prevention. The progress in understanding T cell function in cancer has and will continue to improve harnessing of the immune system across broader tumor types to benefit more patients.

T Cells in Colorectal Cancer: Unravelling the Function of Different T Cell Subsets in the Tumor Microenvironment

Therapeutic options for metastatic colorectal cancer (mCRC) are very limited, and the prognosis using combination therapy with a chemotherapeutic drug and a targeted agent, e.g., epidermal growth factor receptor or tyrosine kinase, remains poor. Therefore, mCRC is associated with a poor median overall survival (mOS) of only 25-30 months. Current immunotherapies with checkpoint inhibitor blockade (ICB) have led to a substantial change in the treatment of several cancers, such as melanoma and non-small cell lung cancer. In CRC, ICB has only limited effects, except in patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) tumors, which comprise about 15% of sporadic CRC patients and about 4% of patients with metastatic CRC. The vast majority of sporadic CRCs are microsatellite-stable (MSS) tumors with low levels of infiltrating immune cells, in which immunotherapy has no clinical benefit so far. Immunotherapy with checkpoint inhibitors requires the presence of infiltrating T cells into the tumor microenvironment (TME). This makes T cells the most important effector cells in the TME, as evidenced by the establishment of the immunoscore-a method to estimate the prognosis of CRC patients. The microenvironment of a tumor contains several types of T cells that are anti-tumorigenic, such as CD8⁺ T cells or pro-tumorigenic, such as regulatory T cells (Tregs) or T helper 17 (Th17) cells. However, even CD8⁺ T cells show marked heterogeneity, e.g., they can become exhausted, enter a state of hyporesponsiveness or become dysfunctional and express high levels of checkpoint molecules, the targets for ICB. To kill cancer cells, CD8⁺ T cells need the recognition of the MHC class I, which is often downregulated on colorectal cancer cells. In this case, a population of unconventional T cells with a γδ T cell receptor can overcome the limitations of the conventional CD8⁺ T cells with an αβT cell receptor. γδ T cells recognize antigens in an MHC-independent manner, thus acting as a bridge between innate and adaptive immunity. Here, we discuss the effects of different T cell subsets in colorectal cancer with a special emphasis on γδ T cells and the possibility of using them in CAR-T cell therapy. We explain T cell exclusion in microsatellite-stable colorectal cancer and the possibilities to overcome this exclusion to enable immunotherapy even in these "cold" tumors.