Cancer cell-intrinsic PD-1: Its role in malignant progression and immunotherapy

Exploring immune checkpoint inhibitors: Focus on PD-1/PD-L1 axis and beyond

Immunotherapy emerges as a promising approach, marked by recent substantial progress in elucidating how the host immune response impacts tumor development and its sensitivity to various treatments. Immune checkpoint inhibitors have revolutionized cancer therapy by unleashing the power of the immune system to recognize and eradicate tumor cells. Among these, inhibitors targeting the programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have garnered significant attention due to their remarkable clinical efficacy across various malignancies. This review delves into the mechanisms of action, clinical applications, and emerging therapeutic strategies surrounding PD-1/PD-L1 blockade. We explore the intricate interactions between PD-1/PD-L1 and other immune checkpoints, shedding light on combinatorial approaches to enhance treatment outcomes and overcome resistance mechanisms. Furthermore, we discuss the expanding landscape of immune checkpoint inhibitors beyond PD-1/PD-L1, including novel targets such as CTLA-4, LAG-3, TIM-3, and TIGIT. Through a comprehensive analysis of preclinical and clinical studies, we highlight the promise and challenges of immune checkpoint blockade in cancer immunotherapy, paving the way for future advancements in the field.

Programmed cell death protein 1 in cancer cells

Programmed cell death protein 1 (PD-1) is frequently detected in certain subsets of tumor cells, and our understanding of PD-1 signaling consequences has expanded to include control of tumor growth, stemness and drug resistance. Nonetheless, tumor cell-intrinsic PD-1 has been comparatively underexplored in relation to PD-1 expressed on the surface of immune cells as an immune checkpoint, despite the imperative need to comprehensively elucidate the underlying mechanisms of action for achieving optimal responses in tumor immunotherapy. Here, we review the roles of the regulation and function of tumor-intrinsic PD-1 from its expression to degradation processes. Our primary focus is on unraveling its enigmatic influence on tumorigenesis and progression as proposed by recent findings, while navigating the labyrinthine network of regulatory mechanisms governing its expression and intricate functional interplay. We also discuss how the elucidation of the mechanistic underpinnings of tumor-intrinsic PD-1 expression holds the potential to explain the divergent therapeutic outcomes observed with anti-PD-1-based combination therapies, thereby furnishing indispensable insights crucial for synergistic anti-tumor strategies.

Comprehensive immunophenotyping reveals distinct tumor microenvironment alterations in anti-PD-1 sensitive and resistant syngeneic mouse model

The advent of immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway has revolutionized cancer treatment, resulting in improved clinical outcomes. However, resistance remains a critical challenge. This study aimed to comparatively elucidate immunophenotypic changes in syngeneic mouse models sensitive (MC-38) or resistant (LLC1) to anti-PD-1 monoclonal antibody (mAb) treatment. In the sensitive MC-38 model, anti-PD-1 therapy increased dendritic cells (DCs) and macrophages, while decreasing myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment. Enhanced expression of antigen presentation molecules (MHC I/II) and costimulatory molecules (CD80/CD86) was observed on tumor-associated DCs and macrophages. Tumor-infiltrating CD4+T, CD8+T, regulatory T, NK, and NKT cells also significantly increased. Importantly, treatment boosted lymphocyte cytotoxic potential, with perforin identified as a key marker of efficacy. Notably, perforin expression in CD4+T and NKT cells strongly negatively correlated with tumor volume. In contrast, the resistant LLC1 model exhibited minimal immunophenotypic changes upon treatment. These findings highlight critical immune modifications induced by anti-PD-1 therapy, particularly the role of perforin, and the DC/MDSC ratio in predicting therapeutic outcomes. This research offers valuable insights into potential predictive biomarkers and informs strategies to overcome resistance, emphasizing the complex interplay between anti-PD-1 treatment and the tumor microenvironment, ultimately aiming to improve immunotherapy response rates.

Tumor-derived extracellular vesicle PD-1 promotes tumor immune evasion via disruption of peripheral T cell homeostasis

The programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) axis mediates immune evasion of tumor, and targeting this axis has achieved some clinical benefits. The regulation of PD-1 expression in immune cells has been well studied. However, whether any other potential source of immune cell-expressed PD-1 exists remains unknown. Here, we report that tumor cells express PD-1 and release PD-1 in the form of extracellular vesicles, which enters T cells and suppresses T cell function via PD-L1 in vitro. In vivo, tumor cell-derived extracellular vesicle PD-1 promotes tumor growth via disrupting peripheral T cell homeostasis, showing by decreased number of T cells and impaired function of CD8+ T cells in spleens, draining lymph nodes and tumor infiltrating lymphocytes, which is restored by PD-1-targeted antibodies. Our study provides a unique and novel perspective for immune evasion of tumor, and expands a source of PD-1 in immune cells.

Targeting novel regulated cell death: disulfidptosis in cancer immunotherapy with immune checkpoint inhibitors

The battle against cancer has evolved over centuries, from the early stages of surgical resection to contemporary treatments including chemotherapy, radiation, targeted therapies, and immunotherapies. Despite significant advances in cancer treatment over recent decades, these therapies remain limited by various challenges. Immune checkpoint inhibitors (ICIs), a cornerstone of tumor immunotherapy, have emerged as one of the most promising advancements in cancer treatment. Although ICIs, such as CTLA-4 and PD-1/PD-L1 inhibitors, have demonstrated clinical efficacy, their therapeutic impact remains suboptimal due to patient-specific variability and tumor immune resistance. Cell death is a fundamental process for maintaining tissue homeostasis and function. Recent research highlights that the combination of induced regulatory cell death (RCD) and ICIs can substantially enhance anti-tumor responses across multiple cancer types. In cells exhibiting high levels of recombinant solute carrier family 7 member 11 (SLC7A11) protein, glucose deprivation triggers a programmed cell death (PCD) pathway characterized by disulfide bond formation and REDOX (reduction-oxidation) reactions, termed "disulfidptosis." Studies suggest that disulfidptosis plays a critical role in the therapeutic efficacy of SLC7A11high cancers. Therefore, to investigate the potential synergy between disulfidptosis and ICIs, this study will explore the mechanisms of both processes in tumor progression, with the goal of enhancing the anti-tumor immune response of ICIs by targeting the intracellular disulfidptosis pathway.

Colony-stimulating factor 3 and its receptor promote leukocyte immunoglobulin-like receptor B2 expression and ligands in gastric cancer

BACKGROUND

Colony-stimulating factor 3 (CSF3) and its receptor (CSF3R) are known to promote gastric cancer (GC) growth and metastasis. However, their effects on the immune microenvironment remain unclear. Our analysis indicated a potential link between CSF3R expression and the immunosuppressive receptor leukocyte immunoglobulin-like receptor B2 (LILRB2) in GC. We hypothesized that CSF3/CSF3R may regulate LILRB2 and its ligands, angiopoietin-like protein 2 (ANGPTL2) and human leukocyte antigen-G (HLA-G), contributing to immunosuppression.

AIM

To investigate the relationship between CSF3/CSF3R and LILRB2, as well as its ligands ANGPTL2 and HLA-G, in GC.

METHODS

Transcriptome sequencing data from The Cancer Genome Atlas were analyzed, stratifying patients by CSF3R expression. Differentially expressed genes and immune checkpoints were evaluated. Immunohistochemistry (IHC) was performed on GC tissues. Correlation analyses of CSF3R, LILRB2, ANGPTL2, and HLA-G were conducted using The Cancer Genome Atlas data and IHC results. GC cells were treated with CSF3, and expression levels of LILRB2, ANGPTL2, and HLA-G were measured by quantitative reverse transcriptase-polymerase chain reaction and western blotting.

RESULTS

Among 122 upregulated genes in high CSF3R expression groups, LILRB2 showed the most significant increase. IHC results indicated high expression of LILRB2 (63.0%), ANGPTL2 (56.5%), and HLA-G (73.9%) in GC tissues. Strong positive correlations existed between CSF3R and LILRB2, ANGPTL2, and HLA-G mRNA levels (P < 0.001). IHC confirmed positive correlations between CSF3R and LILRB2 (P < 0.001), and HLA-G (P = 0.010), but not ANGPTL2 (P > 0.05). CSF3 increased LILRB2, ANGPTL2, and HLA-G expression in GC cells. Heterogeneous nuclear ribonucleoprotein H1 modulation significantly altered their expression, impacting CSF3's regulatory effects.

CONCLUSION

The CSF3/CSF3R pathway may contribute to immunosuppression in GC by upregulating LILRB2 and its ligands, with heterogeneous nuclear ribonucleoprotein H1 playing a regulatory role.

Targeted delivery of Saikosaponin A and doxorubicin via hyaluronic acid-modified ZIF-8 nanoparticles for TNBC treatment: Inhibiting metastasis and reducing cardiotoxicity

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of estrogen receptors, progesterone receptors, and HER2 expression, making traditional hormone and targeted therapies ineffective. Chemotherapy remains the primary treatment for TNBC; however, it has failed to adequately address the high rates of recurrence and metastasis, underscoring the urgent need for new therapeutic strategies. This study investigates Saikosaponin A (SSA), a compound extracted from traditional Chinese medicine, for its potential to enhance the efficacy of doxorubicin (DOX) chemotherapy while reducing TNBC metastasis and mitigating DOX-induced cardiotoxicity. We first confirmed SSA's cardioprotective effects against DOX-induced cardiotoxicity, highlighting its potential as an adjunctive therapy for TNBC chemotherapy. Subsequently, through network pharmacology analysis, we identified that SSA may inhibit TNBC progression and metastasis by downregulating integrin β3, a key regulatory factor in tumor development. This was further validated through both in vivo and in vitro experiments. To address the poor bioavailability of SSA, we developed a novel drug delivery system utilizing hyaluronic acid (HA)-modified zeolitic imidazolate framework-8 (ZIF-8) nanoparticles for the co-delivery of SSA and DOX. This nano-drug system exhibited excellent stability and high drug-loading capacity, with loading efficiencies of 40.07 % for SSA and 43.07 % for DOX. After 24 h of nano-drug administration, the DOX concentration in the group using the nano-delivery system was 5.01 times higher than control group, demonstrated enhanced tumor-targeting capability. Furthermore, after 14 days of treatment, the tumor volume was reduced by 80.8 % compared to the control group, indicating significantly improved therapeutic efficacy (all P < 0.05). This study systematically evaluates the potential of this dual drug-loaded nanocarrier in improving TNBC treatment, reducing DOX-induced cardiotoxicity, and inhibiting metastasis, offering a novel therapeutic approach that integrates traditional medicine with advanced nanotechnology.

Updated Bayesian network meta-analysis on the efficacy and safety of PD-1 versus PD-L1 inhibitors in first-line treatment with chemotherapy for extensive-stage small-cell lung cancer

Objective

To compare the efficacy and safety of programmed cell death 1 inhibitors plus chemotherapy (PD-1 + Chemo) and programmed cell death ligand 1 inhibitors plus chemotherapy (PD-L1 + Chemo) for the treatment of extensive-stage small-cell lung cancer (ES-SCLC).

Methods

We performed a meta-analysis of relevant data using R software, considering overall survival (OS), progression-free survival (PFS), and grade ≥ 3 treatment-related adverse events (TRAES).

Results

PD-1 + Chemo (OS: hazard ratio [HR] 0.71; PFS: HR 0.59) and PD-L1 + Chemo (OS: HR 0.72; PFS: HR 0.73) significantly prolonged survival and did not increase the incidence of grade ≥3 TRAEs compared with chemotherapy. Indirect comparisons showed no significant difference in clinical efficacy (OS: HR 0.99, 95% CI: 0.86-1.1; PFS: HR 0.80, 95% CI: 0.61-1.0) or safety (HR 1.0, 95% CI: 0.93-1.1) between PD-1 + Chemo and PD-L1 + Chemo. Non-cumulative probability ranking plot ranking results showed that PD-1 + Chemo ranked first in OS and PFS. Patients with PD-L1 expression levels < 1%, PD-1 + Chemo showed a trend of disadvantage (OS: HR 1.3; PFS: HR 1.2), whereas for patients with PD-L1 expression levels ≥ 1%, PD-1 + Chemo showed a trend of advantage (OS: HR 0.85; PFS: HR 0.85).

Conclusions

PD-1 + Chemo and PD-L1 + Chemo significantly prolonged OS and PFS in patients with ES-SCLC and did not significantly increase the incidence of grade ≥ 3 TRAES. The efficacy and safety profiles of PD-1 + Chemo and PD-L1 + Chemo appear to be similar.

PD1-Targeted Transgene Delivery to Treg Cells

Achieving the precise targeting of lentiviral vectors (LVs) to specific cell populations is crucial for effective gene therapy, particularly in cancer treatment where the modulation of the tumor microenvironment can enhance anti-tumor immunity. Programmed cell death protein 1 (PD-1) is overexpressed on activated tumor-infiltrating T lymphocytes, including regulatory T cells that suppress immune responses via FOXP3 expression. We developed PD1-targeted LVs by incorporating the anti-PD1 nanobody nb102c3 into receptor-blinded measles virus H and VSV-Gmut glycoproteins. We assessed the retargeting potential of nb102c3 and evaluated transduction efficiency in activated T lymphocytes. FOXP3 expression was suppressed using shRNA delivered by these LVs. Our results demonstrate that PD1-targeted LVs exerted pronounced tropism towards PD1+ cells, enabling the selective transduction of activated T lymphocytes while sparing naive T cells. The suppression of FOXP3 in Tregs reduced their suppressive activity. PD1-targeted glycoprotein H provided greater specificity, whereas the VSV-Gmut, together with the anti-PD1 pseudoreceptor, achieved higher viral titers but was less selective. Our study demonstrates that PD1-targeted LVs may offer a novel strategy to modulate immune responses within the tumor microenvironment with the potential for developing new therapeutic strategies aimed at enhancing anti-tumor immunity.

Notch Signaling and PD-1/PD-L1 Interaction in Hepatocellular Carcinoma: Potentialities of Combined Therapies

Immunotherapy has shown significant improvement in the survival of patients with hepatocellular carcinoma (HCC) compared to TKIs as first-line treatment. Unfortunately, approximately 30% of HCC exhibits intrinsic resistance to ICIs, making new therapeutic combinations urgently needed. The dysregulation of the Notch signaling pathway observed in HCC can affect immune cell response, reducing the efficacy of cancer immunotherapy. Here, we provide an overview of how Notch signaling regulates immune responses and present the therapeutic rationale for combining Notch signaling inhibition with ICIs to improve HCC treatment. Moreover, we propose using exosomes as non-invasive tools to assess Notch signaling activation in hepatic cancer cells, enabling accurate stratification of patients who can benefit from combined strategies.

PD-L1: From cancer immunotherapy to therapeutic implications in multiple disorders

The PD-L1/PD-1 signaling pathway is the gold standard for cancer immunotherapy. Therapeutic antibodies targeting PD-1, such as nivolumab (Opdivo) and pembrolizumab (Keytruda), and PD-L1, including atezolizumab (Tecentriq), durvalumab (Imfinzi), and avelumab (Bavencio) have received Food and Drug Administration approval and are currently being used to treat various cancers. Traditionally, PD-L1 is known as an immune checkpoint protein that binds to the PD-1 receptor on its surface to inhibit the activity of T cells, which are the primary effector cells in antitumor immunity. However, it also plays a role in cancer progression, which goes beyond traditional understanding. Here, we highlight the multifaceted mechanisms of action of PD-L1 in cancer cell proliferation, transcriptional regulation, and systemic immune suppression. Moreover, we consider the potential role of PD-L1 in the development and pathogenesis of diseases other than cancer, explore PD-L1-focused therapeutic approaches for these diseases, and assess their clinical relevance. Through this review, we hope to provide deeper insights into the PD-L1/PD-1 signaling pathway and present a broad perspective on potential therapeutic approaches for cancer and other diseases.

Dynamics of tumor in situ fluid circulating tumor DNA in recurrent glioblastomas forecasts treatment efficacy of immune checkpoint blockade coupled with low-dose bevacizumab

PURPOSE

Immune checkpoint blockade (ICB) therapies have shown efficacy in various tumors, but long-term responses in glioblastoma are less than 10%. Quantifying tumor in situ fluid circulating tumor DNA (TISF-ctDNA) and therapeutic dynamics may enable real-time GBM disease burden evaluation. This study explores the potential of tumor in situ fluid circulating tumor DNA (TISF-ctDNA) dynamics in predicting treatment efficacy.

METHODS

TISF and peripheral blood samples were collected from patients with recurrent glioblastoma (rGBM) undergoing tislelizumab (a programmed death 1 inhibitor) combined with low-dose bevacizumab (an anti-vascular endothelial growth factor antibody) treatment before and during each immunotherapy cycle. Biomarkers evaluated included TISF-ctDNA, measured using Next Generation Sequencing (NGS), and host inflammation markers such as the platelet-to-lymphocyte ratio (PLR).

RESULTS

All 32 patients received tislelizumab plus low-dose bevacizumab regularly. The median progression-free survival (PFS) was 4.0 months, and overall survival (OS) was 22.3 months. An analysis of 19 patients with continuous evaluable TISF showed baseline TISF-ctDNA abundance did not correlate with OS (p = 0.23) or PFS (p = 0.23). However, a change in TISF-ctDNA maximal Somatic Variant Allelic Frequency (MVAF) after six treatment cycles predicted both PFS (p = 0.02) and OS (p < 0.0001). Lower baseline PLR also correlated with better survival outcomes.

CONCLUSION

The combination of tislelizumab and low-dose bevacizumab therapy appears to be effective in extending both OS and PFS in rGBM patients. Continuous TISF-ctDNA testing shows potential utility in complementing radiological monitoring. The temporal change pattern of TISF MVAF is more predictive of immunotherapy response than imaging. PLR before immunotherapy can screen patients likely to benefit from tislelizumab plus low-dose bevacizumab therapy.

TRIAL REGISTRATION

The trial registration number: NCT05502991; Date of registration: 2022-08-14.

Role of PD-1 in Skin Cancer: Molecular Mechanism, Clinical Applications, and Resistance

Skin cancer is a widespread worldwide health concern, manifesting in many subtypes such as squamous cell carcinoma, basal cell carcinoma, and melanoma. Although all these types occur frequently, they generally lack the possibility of being cured, emphasizing the importance of early discovery and treatment. This comprehensive study explores the role of programmed cell death protein 1 (PD-1) in skin cancer, focusing on its molecular mechanisms in immune regulation and its critical role in tumor immune evasion, while also clarifying the complexities of immune checkpoints in cancer pathogenesis. It critically evaluates the clinical applications of PD-1 inhibitors, spotlighting their therapeutic potential in treating skin cancer, while also addressing the significant challenge of resistance. This work further discusses the evolution of resistance mechanisms against PD-1 inhibitors and suggests potential approaches to mitigate these issues, thereby enhancing the effectiveness of these therapies. The study further highlights the current state of PD-1 targeted therapies and sets the stage for future research aimed at optimizing these treatments for better clinical outcomes in skin cancer.

Assessment of the Circulating PD-1 and PD-L1 Levels and P53 Expression as a Predictor of Relapse in Pediatric Patients with Wilms Tumor and Hypernephroma

Background/Objectives: Wilms tumor (WT) is the most common form of pediatric renal tumor, accounting for over 90% of cases followed by hypernephroma. Some pediatric patients with WT (10%) experience relapse or metastasis and have poor survival rates. PD-L1 assists cancer cells in escaping damage from the immune system. P53 mutations are found in relapsed WT tumor samples. We hypothesized that testing circulating PD-1 and PD-L1 and P53 expression levels could offer a simple method to predict patient relapse and explore novel treatments for pediatric WTs and hypernephroma. Methods: Flow cytometric detection of cPD-1, cPD-L1, and P53 expression in relapsed and in-remission WT and hypernephroma before and after one year of chemotherapy was performed. Results: Our data shows increased levels of cPD-L1 in relapsed pediatric patients with WT or hypernephroma before and after chemotherapy. There were also slight and significant increases in cPD-1 levels in relapsed groups before chemotherapy. Additionally, we observed significant decreases in P53 expression after one year of chemotherapy in relapsed pediatric patients. Conclusions: Our study found that circulating PD-L1 can be used as a predictor marker for WT and hypernephroma relapse. In conclusion, these circulating markers can assist in monitoring relapse in WT and hypernephroma patients without the need for several biopsies.

Immunotherapy revolutionizing brain metastatic cancer treatment: personalized strategies for transformative outcomes

Brain metastatic cancer poses a significant clinical challenge, with limited treatment options and poor prognosis for patients. In recent years, immunotherapy has emerged as a promising strategy for addressing brain metastases, offering distinct advantages over conventional treatments. This review explores the evolving landscape of tumor immunotherapy in the context of brain metastatic cancer, focusing on the intricate interplay between the tumor microenvironment (TME) and immunotherapeutic approaches. By elucidating the complex interactions within the TME, including the role of immune cells, cytokines, and extracellular matrix components, this review highlights the potential of immunotherapy to reshape the treatment paradigm for brain metastases. Leveraging immune checkpoint inhibitors, cellular immunotherapies, and personalized treatment strategies, immunotherapy holds promise in overcoming the challenges posed by the blood-brain barrier and immunosuppressive microenvironment of brain metastases. Through a comprehensive analysis of current research findings and future directions, this review underscores the transformative impact of immunotherapy on the management of brain metastatic cancer, offering new insights and opportunities for personalized and precise therapeutic interventions.

Doxorubicin induces deglycosylation of cancer cell-intrinsic PD-1 by NGLY1

Tumor cells can express the immune checkpoint protein programmed death-1 (PD-1), but how cancer cell-intrinsic PD-1 is regulated in response to cellular stresses remains largely unknown. Here, we uncover a unique mechanism by which the chemotherapy drug doxorubicin (Dox) regulates cancer cell-intrinsic PD-1. Dox upregulates PD-1 mRNA while reducing PD-1 protein levels in tumor cells. Although Dox shortens the PD-1 half-life, it fails to directly induce PD-1 degradation. Instead, we observe that Dox promotes the interaction between peptide-N(4)-(N-acetyl-beta-glucosaminyl)asparagine amidase (NGLY1) and PD-1, facilitating NGLY1-mediated PD-1 deglycosylation and destabilization. The maintenance of PD-1 sensitizes tumor cells to Dox-mediated antiproliferative effects. Our study unveils a regulatory mechanism of PD-1 in response to Dox and highlights a potential role of cancer cell-intrinsic PD-1 in Dox-mediated antitumor effects.

Immunological signatures and predictive biomarkers for first-generation somatostatin receptor ligand resistance in Acromegaly

PURPOSE

Predicting resistance to first-generation Somatostatin Receptor Ligands (fg-SRL) in Acromegaly patients remains an ongong challenge. Tumor-associated immune components participate in various pathological processes, including drug-resistance. We aimed to identify the immune components involved in resistance of fg-SRL, and to investigate biomarkers that can be targeted to treat those drug-resistant Acromegaly.

METHODS

We conducted a retrospective study involving 35 Acromegaly patients with somatotropinomas treated postoperatively with fg-SRL. Gathering clinicopathological data, SSTR2 expression, and immunological profiles, we utilized univariate, binary logistic regression, and ROC analyses to assess their predictive roles in fg-SRL resistance. Spearman correlation analysis further examined interactions among interested characteristics.

RESULTS

19 patients (54.29%) exhibited resistance to postoperative fg-SRL. GH level at diagnosis, preoperative tumor volume, T2WI-MRI intensity, granularity, PD-L1, SSTR2, and CD8 + T cell infiltration showed association with clinical outcomes of fg-SRL. Notably, T2WI-MRI hyperintensity, PD-L1-IRS > 7, CD8 + T cell infiltration < 14.8/HPF, and SSTR2-IRS < 5.4 emerged as reliable predictors for fg-SRL resistance. Correlation analysis highlighted a negative relationship between PD-L1 expression and CD8 + T cell infiltration, while showcasing a positive correlation with preoperative tumor volume of somatotropinomas. Additionally, 5 patients with fg-SRL resistance underwent re-operation were involved. Following fg-SRL treatment, significant increases in PD-L1 and SSTR5 expression were observed, while SSTR2 expression decreased in somatotropinoma.

CONCLUSION

PD-L1 expression and CD8 + T cell infiltration, either independently or combined with SSTR2 expression and T2WI-MRI intensity, could form a predictive model guiding clinical decisions on fg-SRL employment. Furthermore, targeting PD-L1 through immunotherapy and embracing second-generations of SRL with higher affinity to SSTR5 represent promising strategies to tackle fg-SRL resistance in somatotropinomas.

PTMs of PD-1/PD-L1 and PROTACs application for improving cancer immunotherapy

Immunotherapy has been developed, which harnesses and enhances the innate powers of the immune system to fight disease, particularly cancer. PD-1 (programmed death-1) and PD-L1 (programmed death ligand-1) are key components in the regulation of the immune system, particularly in the context of cancer immunotherapy. PD-1 and PD-L1 are regulated by PTMs, including phosphorylation, ubiquitination, deubiquitination, acetylation, palmitoylation and glycosylation. PROTACs (Proteolysis Targeting Chimeras) are a type of new drug design technology. They are specifically engineered molecules that target specific proteins within a cell for degradation. PROTACs have been designed and demonstrated their inhibitory activity against the PD-1/PD-L1 pathway, and showed their ability to degrade PD-1/PD-L1 proteins. In this review, we describe how PROTACs target PD-1 and PD-L1 proteins to improve the efficacy of immunotherapy. PROTACs could be a novel strategy to combine with radiotherapy, chemotherapy and immunotherapy for cancer patients.

Small molecule agents for triple negative breast cancer: Current status and future prospects

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor prognosis. The number of cases increased by 2.26 million in 2020, making it the most commonly diagnosed cancer type in the world. TNBCs lack hormone receptor (HR) and human epidermal growth factor 2 (HER2), which limits treatment options. Currently, paclitaxel-based drugs combined with other chemotherapeutics remain the main treatment for TNBC. There is currently no consensus on the best therapeutic regimen for TNBC. However, there have been successful clinical trials exploring large-molecule monoclonal antibodies, small-molecule targeted drugs, and novel antibody-drug conjugate (ADC). Although monoclonal antibodies have produced clinical success, their large molecular weight can limit therapeutic benefits. It is worth noting that in the past 30 years, the FDA has approved small molecule drugs for HER2-positive breast cancers. The lack of effective targets and the occurrence of drug resistance pose significant challenges in the treatment of TNBC. To improve the prognosis of TNBC, it is crucial to search for effective targets and to overcome drug resistance. This review examines the clinical efficacy, adverse effects, resistance mechanisms, and potential solutions of targeted small molecule drugs in both monotherapies and combination therapies. New therapeutic targets, including nuclear export protein 1 (XPO1) and hedgehog (Hh), are emerging as potential options for researchers and become integrated into clinical trials for TNBC. Additionally, there is growing interest in the potential of targeted protein degradation chimeras (PROTACs), degraders of rogue proteins, as a future therapy direction. This review provides potentially valuable insights with clinical implications.

Exosome-mediated communication between gastric cancer cells and macrophages: implications for tumor microenvironment

Gastric cancer (GC) is a malignant neoplasm originating from the epithelial cells of the gastric mucosa. The pathogenesis of GC is intricately linked to the tumor microenvironment within which the cancer cells reside. Tumor-associated macrophages (TAMs) primarily differentiate from peripheral blood monocytes and can be broadly categorized into M1 and M2 subtypes. M2-type TAMs have been shown to promote tumor growth, tissue remodeling, and angiogenesis. Furthermore, they can actively suppress acquired immunity, leading to a poorer prognosis and reduced tolerance to chemotherapy. Exosomes, which contain a myriad of biologically active molecules including lipids, proteins, mRNA, and noncoding RNAs, have emerged as key mediators of communication between tumor cells and TAMs. The exchange of these molecules via exosomes can markedly influence the tumor microenvironment and consequently impact tumor progression. Recent studies have elucidated a correlation between TAMs and various clinicopathological parameters of GC, such as tumor size, differentiation, infiltration depth, lymph node metastasis, and TNM staging, highlighting the pivotal role of TAMs in GC development and metastasis. In this review, we aim to comprehensively examine the bidirectional communication between GC cells and TAMs, the implications of alterations in the tumor microenvironment on immune escape, invasion, and metastasis in GC, targeted therapeutic approaches for GC, and the efficacy of potential GC drug resistance strategies.

Statin therapy: a potential adjuvant to immunotherapies in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide and accounts for more than 90% of primary liver cancer. The advent of immune checkpoint inhibitor (ICI)-related therapies combined with angiogenesis inhibition has revolutionized the treatment of HCC in late-stage and unresectable HCC, as ICIs alone were disappointing in treating HCC. In addition to the altered immune microenvironment, abnormal lipid metabolism in the liver has been extensively characterized in various types of HCC. Stains are known for their cholesterol-lowering properties and their long history of treating hypercholesterolemia and reducing cardiovascular disease risk. Apart from ICI and other conventional therapies, statins are frequently used by advanced HCC patients with dyslipidemia, which is often marked by the abnormal accumulation of cholesterol and fatty acids in the liver. Supported by a body of preclinical and clinical studies, statins may unexpectedly enhance the efficacy of ICI therapy in HCC patients through the regulation of inflammatory responses and the immune microenvironment. This review discusses the abnormal changes in lipid metabolism in HCC, summarizes the clinical evidence and benefits of stain use in HCC, and prospects the possible mechanistic actions of statins in transforming the immune microenvironment in HCC when combined with immunotherapies. Consequently, the use of statin therapy may emerge as a novel and valuable adjuvant for immunotherapies in HCC.

Prognostic biomarker DARS2 correlated with immune infiltrates in bladder tumor

Background

DARS2 is a pivotal member of the Aminoacyl-tRNA synthetases family that is critical for regulating protein translation. However, the biological role of DARS2 in bladder cancer remains elusive.

Methods

We analyzed the correlation between DARS2 expression and prognosis, tumor stage, and immune infiltration in bladder cancer using The Cancer Genome Atlas (TCGA) database. We validated findings in clinical samples from The First Affiliated Hospital of Nanchang University and explored the biological functions of DARS2 using cell and animal models.

Results

We found DARS2 to be upregulated in bladder cancer, associated with tumor progression and poor prognosis. Immune infiltration analysis suggested that DARS2 may facilitate immune evasion by modulating PD-L1. Cell and animal experiments validated that DARS2 knockdown and overexpress can inhibit or increase cancer cell proliferation, metastasis, tumorigenesis, immune escape, and PD-L1 levels.

Conclusions

Our study reveals DARS2 as a potential prognostic biomarker and immunotherapy target in BLCA.