DTX@VTX NPs synergy PD-L1 immune checkpoint nanoinhibitor to reshape immunosuppressive tumor microenvironment for enhancing chemo-immunotherapy

Nanomedicine Targeting Myeloid-Derived Suppressor Cells Enhances Anti-Tumor Immunity

Cancer immunotherapy, a field within immunology that aims to enhance the host's anti-cancer immune response, frequently encounters challenges associated with suboptimal response rates. The presence of myeloid-derived suppressor cells (MDSCs), crucial constituents of the tumor microenvironment (TME), exacerbates this issue by fostering immunosuppression and impeding T cell differentiation and maturation. Consequently, targeting MDSCs has emerged as crucial for immunotherapy aimed at enhancing anti-tumor responses. The development of nanomedicines specifically designed to target MDSCs aims to improve the effectiveness of immunotherapy by transforming immunosuppressive tumors into ones more responsive to immune intervention. This review provides a detailed overview of MDSCs in the TME and current strategies targeting these cells. Also the benefits of nanoparticle-assisted drug delivery systems, including design flexibility, efficient drug loading, and protection against enzymatic degradation, are highlighted. It summarizes advances in nanomedicine targeting MDSCs, covering enhanced treatment efficacy, safety, and modulation of the TME, laying the groundwork for more potent cancer immunotherapy.

MDSCs in breast cancer: an important enabler of tumor progression and an emerging therapeutic target

Women worldwide are more likely to develop breast cancer (BC) than any other type of cancer. The treatment of BC depends on the subtype and stage of the cancer, such as surgery, radiotherapy, chemotherapy, and immunotherapy. Although significant progress has been made in recent years, advanced or metastatic BC presents a poor prognosis, due to drug resistance and recurrences. During embryonic development, myeloid-derived suppressor cells (MDSCs) develop that suppress the immune system. By inhibiting anti-immune effects and promoting non-immune mechanisms such as tumor cell stemness, epithelial-mesenchymal transformation (EMT) and angiogenesis, MDSCs effectively promote tumor growth and metastasis. In various BC models, peripheral tissues, and tumor microenvironments (TME), MDSCs have been found to amplification. Clinical progression or poor prognosis are strongly associated with increased MDSCs. In this review, we describe the activation, recruitment, and differentiation of MDSCs production in BC, the involvement of MDSCs in BC progression, and the clinical characteristics of MDSCs as a potential BC therapy target.

GE11-modified carboxymethyl chitosan micelles to deliver DOX·PD-L1 siRNA complex for combination of ICD and immune escape inhibition against tumor

Programmed cell death-ligand 1 (PD-L1) small interfering RNA (siRNA) achieves tumor immunotherapy by restoring the immune response of T cells, but the efficacy of PD-1/PD-L1 monotherapy is relatively low. While immunogenic cell death (ICD) can improve the response of most tumors to anti-PD-L1 and enhance tumor immunotherapy. Herein, a targeting peptide GE11-functionalized dual-responsive carboxymethyl chitosan (CMCS) micelle (G-CMssOA) is developed for simultaneous delivery of PD-L1 siRNA and doxorubicin (DOX) in a complex form of DOX·PD-L1 siRNA (D&P). The complex-loaded micelles (G-CMssOA/D&P) have good physiological stability and pH/reduction responsiveness, and improve the intratumoral infiltration of CD4⁺ and CD8⁺ T cells, reduce Tregs (TGF-β), and increase the secretion of immune-stimulatory cytokine (TNF-α). The combination of DOX-induced ICD and PD-L1 siRNA-mediated immune escape inhibition significantly improves anti-tumor immune response and inhibits tumor growth. This complex delivery strategy provides a new approach for effectively delivering siRNA and enhancing anti-tumor immunotherapy.

Improvement strategy for immune checkpoint blockade: A focus on the combination with immunogenic cell death inducers

Cancer immunotherapies have yielded promising outcomes in various malignant tumors by blocking specific immune checkpoint molecules, such as programmed cell death 1 and cytotoxic T lymphocyte antigen 4. However, only a few patients respond to immune checkpoint blockade therapy because of the poor immunogenicity of tumor cells and immune-suppressive tumor microenvironment. Accumulating evidence suggests that chemotherapeutic agents, including oxaliplatin and doxorubicin, not only mediate direct cytotoxicity in tumor cells but also induce immunogenic cancer cell death to stimulate a powerful anti-cancer immune response in the tumor microenvironment. In this review, we summarize the recent advances in cancer combination therapy based on immune checkpoint inhibitors plus immunogenic cell death inducers. Despite some clinical failures and challenges, immunogenic cell death inducers have displayed great potential when combined with immune checkpoint inhibitors for anti-cancer treatment in both preclinical studies and clinical trials.

Comparison of tumor-derived total RNA and cell lysate on antitumor immune activity

Tumor-derived total RNA (TdRNA) and cell lysate (TCL), with almost all the relevant tumor antigens, represent attractive alternative sources of antigens in antitumor immunotherapy. However, the comparison of their capacity to elicit immune responses against breast cancer is still lacking. In this study, the antitumor immune effects of TdRNA and TCL were systematically compared. We isolated TdRNA and TCL from 4T1 mouse breast cancer cells, and found that both sources of antigens could stimulate the maturation of dendritic cells (DCs) at the cellular and in vivo levels, and induce robust cellular immune responses, as evidenced by the increased percentages of both CD4⁺ and CD8⁺ T cells in the inguinal lymph nodes and spleen. But TdRNA performed stronger immunoactivities than TCL on the increase of T cell population through DCs activation. Additionally, the synergistic antitumor efficacy of paclitaxel (PTX) with TdRNA and TCL respectively was further evaluated in the murine 4T1 tumor model. Compared with TCL, TdRNA could inhibit tumor growth more effectively with low systemic toxicity when combined with PTX, which was, at least in part, attributable to the improvement of systemic immune function and tumor immune infiltration. Overall, TdRNA outperforms TCL in antitumor immunity, and is expected to be a promising candidate for application as the source of tumor antigens.

Breaking the niche: multidimensional nanotherapeutics for tumor microenvironment modulation

Most of the current antitumor therapeutics were developed targeting the cancer cells only. Unfortunately, in the majority of tumors, this single-dimensional therapy is found to be ineffective. Advanced research has shown that cancer is a multicellular disorder. The tumor microenvironment (TME), which is made by a complex network of the bulk tumor cells and other supporting cells, plays a crucial role in tumor progression. Understanding the importance of the TME in tumor growth, different treatment modalities have been developed targeting these supporting cells. Recent clinical results suggest that simultaneously targeting multiple components of the tumor ecosystem with drug combinations can be highly effective. This type of "multidimensional" therapy has a high potential for cancer treatment. However, tumor-specific delivery of such multi-drug combinations remains a challenge. Nanomedicine could be utilized for the tumor-targeted delivery of such multidimensional therapeutics. In this review, we first give a brief overview of the major components of TME. We then highlight the latest developments in nanoparticle-based combination therapies, where one drug targets cancer cells and other drug targets tumor-supporting components in the TME for a synergistic effect. We include the latest preclinical and clinical studies and discuss innovative nanoparticle-mediated targeting strategies.

Genome editing of PD-L1 mediated by nucleobase-modified polyamidoamine for cancer immunotherapy

Immune checkpoint blockade therapy against programmed death protein-1 and its ligand (PD-1/PD-L1) has been accepted as a promising approach to activate the immune system's anti-tumor response. Although small interfering RNA...