Mutual regulation of PD-L1 immunosuppression between tumor-associated macrophages and tumor cells: a critical role for exosomes

Efficacy and safety of PD-1 and PD-L1 inhibitors in advanced colorectal cancer: a meta-analysis of randomized controlled trials

BACKGROUND

PD-1 and PD-L1 inhibitors have emerged as promising therapies for advanced colorectal cancer (CRC), but their efficacy and safety profiles require further evaluation. This meta-analysis aims to assess the efficacy and safety of PD-1/PD-L1 inhibitors in this patient population.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines, with data sourced from PubMed, Embase, CENTRAL, Web of Science, and CNKI up to August 3, 2024. Nine randomized controlled trials (RCTs) involving 1680 patients were included. The primary outcomes were overall survival (OS), progression-free survival (PFS) and objective response rate (ORR), while safety was assessed through adverse events (AEs) and grade ≥ 3 AEs. Effect sizes were calculated using mean differences (MD) and risk ratios (RR) with 95% confidence intervals (CIs).

RESULTS

Overall, the meta-analysis showed that PD-1/PD-L1 inhibitors did not significantly extend OS (MD = 0.86, 95% CI: -0.55, 2.27), but they significantly improved PFS (MD = 2.53, 95% CI: 0.92, 4.15). Additionally, PD-1/PD-L1 inhibitors did not significantly increase the ORR compared to controls (RR = 1.19, 95% CI: 0.99, 1.44). In terms of safety, PD-1/PD-L1 inhibitors did not significantly increase the incidence of overall AEs. Subgroup analysis further indicated that PD-1 inhibitors significantly improved OS (MD = 1.24, 95% CI: 0.20, 2.29) and PFS (MD = 6.27, 95% CI: 0.56, 11.97), while PD-L1 inhibitors did not have a significant impact on these outcomes. Additionally, PD-L1 inhibitors were associated with a higher risk of grade ≥ 3 AEs (RR = 1.29, 95% CI: 1.07, 1.57), a risk not observed with PD-1 inhibitors.

CONCLUSION

PD-1 inhibitors significantly improve PFS and OS in advanced CRC, making them a preferable option over PD-L1 inhibitors, which show limited efficacy and a higher risk of severe AEs. These findings support prioritizing PD-1 inhibitors in clinical practice for this patient group, while caution is warranted with PD-L1 inhibitors due to their safety concerns.

TRIAL REGISTRATION

PROSPERO (CRD42024611696).

Exosomes in cancer diagnosis based on the Latest Evidence: Where are We?

Exosomes are small extracellular vesicles (EVs) derived from various cellular sources and have emerged as favorable biomarkers for cancer diagnosis and prognosis. These vesicles contain a variety of molecular components, including nucleic acids, proteins, and lipids, which can provide valuable information for cancer detection, classification, and monitoring. However, the clinical application of exosomes faces significant challenges, primarily related to the standardization and scalability of their use. In order to overcome these challenges, sophisticated methods such as liquid biopsy and imaging are being combined to augment the diagnostic capabilities of exosomes. Additionally, a deeper understanding of the interaction between exosomes and immune system components within the tumor microenvironment (TME) is essential. This review discusses the biogenesis and composition of exosomes, addresses the current challenges in their clinical translation, and highlights recent technological advancements and integrative approaches that support the role of exosomes in cancer diagnosis and prognosis.

Influencing immunity: role of extracellular vesicles in tumor immune checkpoint dynamics

Immune checkpoint proteins (ICPs) serve as critical regulators of the immune system, ensuring protection against damage due to overly activated immune responses. However, within the tumor environment, excessive ICP activation weakens antitumor immunity. Despite the development of numerous immune checkpoint blockade (ICB) drugs in recent years, their broad application has been inhibited by uncertainties about their clinical efficacy. A thorough understanding of ICP regulation in the tumor microenvironment is essential for advancing the development of more effective and safer ICB therapies. Extracellular vesicles (EVs), which are pivotal mediators of cell-cell communication, have been extensively studied and found to play key roles in the functionality of ICPs. Nonetheless, a comprehensive review summarizing the current knowledge about the crosstalk between EVs and ICPs in the tumor environment is lacking. In this review, we summarize the interactions between EVs and several widely studied ICPs as well as their potential clinical implications, providing a theoretical basis for further investigation of EV-related ICB therapeutic approaches.

Roles of lncRNAs in NF-κB-Mediated Macrophage Inflammation and Their Implications in the Pathogenesis of Human Diseases

Over the past century, molecular biology's focus has transitioned from proteins to DNA, and now to RNA. Once considered merely a genetic information carrier, RNA is now recognized as both a vital element in early cellular life and a regulator in complex organisms. Long noncoding RNAs (lncRNAs), which are over 200 bases long but do not code for proteins, play roles in gene expression regulation and signal transduction by inducing epigenetic changes or interacting with various proteins and RNAs. These interactions exhibit a range of functions in various cell types, including macrophages. Notably, some macrophage lncRNAs influence the activation of NF-κB, a crucial transcription factor governing immune and inflammatory responses. Macrophage NF-κB is instrumental in the progression of various pathological conditions including sepsis, atherosclerosis, cancer, autoimmune disorders, and hypersensitivity. It orchestrates gene expression related to immune responses, inflammation, cell survival, and proliferation. Consequently, its malfunction is a key contributor to the onset and development of these diseases. This review aims to summarize the function of lncRNAs in regulating NF-κB activity in macrophage activation and inflammation, with a particular emphasis on their relevance to human diseases and their potential as therapeutic targets. The insights gained from studies on macrophage lncRNAs, as discussed in this review, could provide valuable knowledge for the development of treatments for various pathological conditions involving macrophages.