Antitumor therapy for breast cancer: Focus on tumor-associated macrophages and nanosized drug delivery systems

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Repolarizing Tumor-Associated Macrophages and inducing immunogenic cell Death: A targeted liposomal strategy to boost cancer immunotherapy

Cancer immunotherapy has shown promise in treating various malignancies. However, the presence of an immunosuppressive tumor microenvironment (TME) triggered by M2 tumor-associated macrophages (TAMs) and the limited tumor cell antigenicity have hindered its broader application. To address these challenges, we developed DOX/R837@ManL, a liposome loaded with imiquimod (R837) and doxorubicin (DOX), modified with mannose-polyethylene glycol (Man-PEG). DOX/R837@ManL employed a mannose receptor (MRC1)-mediated targeting strategy, allowing it to accumulate selectively at M2 Tumor associated macrophages (TAMs) and tumor sites. R837, an immune adjuvant, promoted the conversion of immunosuppressive M2 TAMs into immunostimulatory M1 TAMs, and reshaped the immunosuppressive TME. Simultaneously, DOX release induced immunogenic cell death (ICD) in tumor cells and enhanced tumor cell antigenicity by promoting dendritic cells (DCs) maturation. Through targeted delivery, the synergistic action of R837 and DOX activated innate immunity and coordinated adaptive immunity, enhancing immunotherapy efficacy. In vivo experiments have demonstrated that DOX/R837@ManL effectively eliminated primary tumors and lung metastases, while also preventing tumor recurrence post-surgery. These findings highlighted the potential of DOX/R837@ManL as a promising strategy for cancer immunotherapy.

Targeting and repolarizing M2-like tumor-associated macrophage-mediated MR imaging and tumor immunotherapy by biomimetic nanoparticles

Anti-tumor M1-like and pro-tumor M2-like tumor-associated macrophages (TAMs) coexist in tumor microenvironments (TME). The adverse effects of these M1/M2 subsets on tumors directly affect the current strategies to improve anti-tumor immune response. Therefore, it has attracted great attention to change the tumor immunosuppressive microenvironment by reprogramming TAMs. In this paper, we constructed biomimetic nanoparticles (HMMDN-Met@PM) targeting M2-like TAMs for macrophage re-polarization. In detail, the core of the biomimetic nanoparticles is metformin-loaded hollow mesoporous manganese dioxide nanoparticles (HMMDN-Met). Benefited from the hollow and porous structure of HMMDN, metformin, the regulator of M1/M2 adopted in this work, can be easily and widely loaded into HMMDN. Moreover, macrophage membranes were utilized for HMMDN-Met coating (HMMDN-Met@MM) to prevent the premature drug leakage and provide specific molecular recognition/TME targeting. In addition, M2 macrophage targeting peptide (M2pep) was modified on the surface of macrophage membrane to specifically deliver the drug to M2-like TAMs to promote the polarization of M2 to M1 macrophages. Through in vitro and in vivo studies, we found that the expression of surface markers and inflammatory factors CD206, Arg-1 and IL-10 of type M2 macrophages decreased, while the surface markers of type M1 macrophages and the expression of inflammatory factors CD80, TNF-α and iNOS increased, indicating the successful re-polarization of M2 macrophages and finally realizing the inhibition of tumor growth. At the same time, under the acidic and GSH conditions of tumor, HMMDN was decomposed into Mn2+, which is a contrast agent for magnetic resonance imaging, thus realizing the tracking of tumor. This work practices biomimetic nanosystem in targeted imaging and immunotherapy, paving the way for strategy designing for tumor inhibition.

Unveiling the Immune Microenvironment's Role in Breast Cancer: A Glimpse into Promising Frontiers

Breast cancer (BC), one of the most widespread and devastating diseases affecting women worldwide, presents a significant public health challenge. This review explores the emerging frontiers of research focused on deciphering the intricate interplay between BC cells and the immune microenvironment. Understanding the role of the immune system in BC is critical as it holds promise for novel therapeutic approaches and precision medicine strategies. This review delves into the current literature regarding the immune microenvironment's contribution to BC initiation, progression, and metastasis. It examines the complex mechanisms by which BC cells interact with various immune cell populations, including tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs). Furthermore, this review highlights the impact of immune-related factors, such as cytokines and immune checkpoint molecules. Additionally, this comprehensive analysis sheds light on the potential biomarkers associated with the immune response in BC, enabling early diagnosis and prognostic assessment. The therapeutic implications of targeting the immune microenvironment are also explored, encompassing immunotherapeutic strategies and combination therapies to enhance treatment efficacy. The significance of this review lies in its potential to pave the way for novel therapeutic interventions, providing clinicians and researchers with essential knowledge to design targeted and personalized treatment regimens for BC patients.