Focused acoustic vortex-mediated sonochemotherapy for the amplification of immunogenic cell death combined with checkpoint blockade to potentiate cancer immunotherapy

Activatable Sulfur Dioxide Nanosonosensitizer Enables Precisely Controllable Sono-Gaseous Checkpoint Trimodal Therapy for Orthotopic Hepatocellular Carcinoma

Immune checkpoint blockade (ICB) is combined with sonodynamic therapy (SDT) to increase response rates and enhance anticancer efficacy. However, the "always on" property of most sonosensitizers in reducing tumor microenvironment (TME) compromises the therapeutic outcome of sonoimmunotherapy and exacerbates adverse side effects. Precisely controllable strategies combining sulfur dioxide (SO2) gas therapy with cancer immunotherapy can address these issues but remain lacking. Herein an "activatable SO2 nanosonosensitizer" for precise sono-gaseous checkpoint trimodal therapy of orthotopic hepatocellular carcinoma (HCC) is reported, whose full activity is initiated by ultrasound (US) irradiation in the reducing TME. This "activatable SO2 nanosonosensitizer," Aza-DNBS nanoparticles (NPs), are established by self-assembling Aza-boron-dipyrromethene based sonosensitizer molecules and 2,4-dinitrobenzenesulfonate (DNBS)-caged SO2 prodrug. The activity of Aza-DNBS NPs is initially silenced, and the sonodynamic, gaseous, and immunosuppressive TME reprogramming activities are precisely awakened under US irradiation. Due to the glutathione-responsiveness of Aza-DNBS NPs, Aza-DNBS NPs can generate large amounts of SO2 for gas therapy-enhanced SDT, which triggers robust immunogenic cell death activation and reprogramming of the immunosuppressive TME, thereby significantly suppressing orthotopic tumor growth and delaying lung metastasis. Thus, this study represents a strategy for designing a generic nanoplatform for precisely combined immunotherapy of orthotopic HCC.

Advances in tumor immunotherapy targeting macrophages

INTRODUCTION

In recent years, immunotherapy has shown significant therapeutic potential in patients with advanced tumors. However, only a small number of individuals benefit, mainly due to the tumor microenvironment (TME), which provides conditions for the development of tumors. Macrophages in TME, known as tumor-associated macrophages (TAM), are mainly divided into M1 anti-tumor and M2 pro-tumor phenotypes, which play a regulatory role in various stages of tumorigenesis, promote tumorigenesis and metastasis, and cause immunotherapy resistance.

AREAS COVERED

This review focuses on research strategies and preclinical/clinical research progress in translating TAM into antitumor phenotype by referring to the PubMed database for five years. These include small molecule chemotherapy drug development, metabolic regulation, gene editing, physical stimulation, nanotechnology-mediated combination therapy strategies, and chimeric antigen receptor-based immunotherapy.

EXPERT OPINION

It is necessary to explore the surface-specific receptors and cell signaling pathways of TAM further to improve the specificity and targeting of drugs and to strengthen research in the field of probes that can monitor changes in TAM in real time. In addition, the physical stimulation polarization strategy has the advantages of being noninvasive, economical, and stable and will have excellent clinical transformation value in the future.

Synergistic anticancer immunity in metastatic triple-negative breast cancer through an in situ amplifying Peptide-Drug Conjugate

Despite significant progress in combining cancer immunotherapy with chemotherapy to treat triple negative breast cancer (TNBC), challenges persist due to target depletion and tumor heterogeneity, especially in metastasis. Chemotherapy lacks precise targeting abilities, and targeted therapy is inadequate in addressing the diverse heterogeneity of tumors. To address these challenges, we introduce RGDEVD-DOX as a tumor-specific immunogenic agent, namely TPD1, which targets integrin αvβ3 and gets continuously activated by apoptosis. TPD1 facilitates the caspase-3-mediated in situ amplification that results in tumor-specific accumulation of doxorubicin. This local concentration of doxorubicin induces immunogenic cell death and promotes the recruitment of immune cells to the tumor site. Notably, the tumor-targeting capabilities of TPD1 help bypass the systemic immunotoxicity of doxorubicin. Consequently, this alters the tumor microenvironment, converting it into a 'hot' tumor that is more susceptible to immune checkpoint inhibition. We demonstrated the anti-metastatic and anti-cancer efficacy of this treatment using various xenograft and metastatic models. This study underscores the high potential of caspase-3 cleavable peptide-drug conjugates to be used in conjunction with anti-cancer immunotherapies.

Endoplasmic reticulum-targeted delivery of celastrol and PD-L1 siRNA for reinforcing immunogenic cell death and potentiating cancer immunotherapy

The prospect of employing chemoimmunotherapy targeted towards the endoplasmic reticulum (ER) presents an opportunity to amplify the synergistic effects of chemotherapy and immunotherapy. In this study, we initially validated celastrol (CEL) as an inducer of immunogenic cell death (ICD) by promoting ER stress and autophagy in colorectal cancer (CRC) cells. Subsequently, an ER-targeted strategy was posited, involving the codelivery of CEL with PD-L1 small interfering RNAs (siRNA) using KDEL peptide-modified exosomes derived from milk (KME), to enhance chemoimmunotherapy outcomes. Our findings demonstrate the efficient transportation of KME to the ER via the Golgi-to-ER pathway. Compared to their non-targeting counterparts, KME exhibited a significant augmentation of the CEL-induced ICD effect. Additionally, it facilitated the release of danger signaling molecules (DAMPs), thereby stimulating the antigen-presenting function of dendritic cells and promoting the infiltration of T cells into the tumor. Concurrently, the ER-targeted delivery of PD-L1 siRNA resulted in the downregulation of both intracellular and membrane PD-L1 protein expression, consequently fostering the proliferation and activity of CD8+ T cells. Ultimately, the ER-targeted formulation exhibited enhanced anti-tumor efficacy and provoked anti-tumor immune responses against orthotopic colorectal tumors in vivo. Collectively, a robust ER-targeted delivery strategy provides an encouraging approach for achieving potent cancer chemoimmunotherapy.

The emergence of cancer sono-immunotherapy

Owing to its remarkable ease of use, ultrasound has recently been explored for stimulating or amplifying immune responses during cancer therapy, termed 'sono-immunotherapy'. Ultrasound can cause immunogenic cell death in cancer cells via thermal and nonthermal effects to regulate the tumor microenvironment, thereby priming anticancer immunity; by integrating well-designed biomaterials, novel sono-immunotherapy approaches with augmented efficacy can also be developed. Here, we review the advances in sono-immunotherapy for cancer treatment and summarize existing limitations along with potential trends. We offer emerging insights into this realm, which might prompt breakthroughs and expand its potential applications to other diseases.

Versatile chondroitin sulfate-based nanoplatform for chemo-photodynamic therapy against triple-negative breast cancer

Versatile nanoplatform equipped with chemo-photodynamic therapeutic attributes play an important role in improving the effectiveness of tumor treatments. Herein, we developed multifunctional nanoparticles based on chondroitin sulfate A (CSA) for the targeted delivery of chlorin e6 (Ce6) and doxorubicin (DOX), in a combined chemo-photodynamic therapy against triple-negative breast cancer. CSA was chosen for its hydrophilic properties and its affinity to CD44 receptor-overexpressed tumor cells. The CSA-ss-Ce6 (CSSC) conjugate was synthesized utilizing a disulfide linker. Subsequently, DOX-loaded CSSC (CSSC-D) nanoparticles were fabricated, showcasing a nearly spherical shape with an average particle size of 267 nm. In the CSSC-D nanoparticles, the chemically attached Ce6 constituted 1.53 %, while the physically encapsulated DOX accounted for 8.11 %. Both CSSC-D and CSSC nanoparticles demonstrated a reduction-sensitive release of DOX or Ce6 in vitro. Under near-infrared (NIR) laser irradiation, CSSC-D showed the enhanced generation of reactive oxygen species (ROS), improving cytotoxic effects against triple-negative breast cancer 4T1 and MDA-MB-231 cells. Remarkably, the CSSC-D with NIR exhibited the most potent tumor growth inhibition in comparison to other groups in the 4T1-bearing Balb/c mice model. Overall, this CSSC-D nanoplatform shows significant promise as a powerful tool for a synergetic approach in chemo-photodynamic therapy in triple-negative breast cancer.

Immunogenic cell stress and death in the treatment of cancer

The successful treatment of oncological malignancies which results in long-term disease control or the complete eradication of cancerous cells necessitates the onset of adaptive immune responses targeting tumor-specific antigens. Such desirable anticancer immunity can be triggered via the induction of immunogenic cell death (ICD) of cancer cells, thus converting malignant cells into an in situ vaccine that elicits T cell mediated adaptive immune responses and establishes durable immunological memory. The exploration of ICD for cancer treatment has been subject to extensive research. However, functional heterogeneity among ICD activating therapies in many cases requires specific co-medications to achieve full-blown efficacy. Here, we described the hallmarks of ICD and classify ICD activators into three distinct functional categories namely, according to their mode of action: (i) ICD inducers, which increase the immunogenicity of malignant cells, (ii) ICD sensitizers, which prime cellular circuitries for ICD induction by conventional cytotoxic agents, and (iii) ICD enhancers, which improve the perception of ICD signals by antigen presenting dendritic cells. Altogether, ICD induction, sensitization and enhancement offer the possibility to convert well-established conventional anticancer therapies into immunotherapeutic approaches that activate T cell-mediated anticancer immunity.