Microenvironment Of Solid Tumors Research Articles

Light‐Controlled Bioorthogonal Chemistry Altered Natural Killer Cell Activity for Boosted Adoptive Immunotherapy

AbstractNatural killer (NK) cell‐based immunotherapy has received much attention in recent years. However, its practical application is still suffering from the decreased function and inadequate infiltration of NK cells in the immunosuppressive microenvironment of solid tumors. Herein, we construct light‐responsive porphyrin Fe array‐armed NK cells (denoted as NK@p‐Fe) for cell behavior modulation via bioorthogonal catalysis. By installing cholesterol‐modified porphyrin Fe molecules on the NK cell surface, a catalytic array with light‐harvesting capabilities is formed. This functionality transforms NK cells into cellular factories capable of catalyzing the production of active agents in a light‐controlled manner. NK@p‐Fe can generate the active antineoplastic drug doxorubicin through bioorthogonal reactions to enhance the cytotoxic function of NK cells. Beyond drug synthesis, NK@p‐Fe can also bioorthogonally catalyze the production of the FDA‐approved immune agonist imiquimod (IMQ). The activated immune agonist plays a dual role, inducing dendritic cell maturation for NK cell activation and reshaping the tumor immunosuppressive microenvironment for NK cell infiltration. This work represents a paradigm for the modulation of adoptive cell behaviors to boost cancer immunotherapy by bioorthogonal catalysis.

NK1 receptor blockade disrupts microtumor growth and aggregation in a three-dimensional syngeneic breast cancer model

Several data indicate that Substance P (SP) neurokinin type 1 receptor (NK1R) is at the center of the interaction between cancer cells and peripheral sensory neurons. Selecting the appropriate cancer cell line and its susceptibility to being modulated by NK1 antagonists are critical to studying this complex interaction. In the current study, we have focused on this selection by comparing several aspects of the allogeneic triple-negative breast cancer (TNBC) cell line (MDA-MB-231LUC+) with a modified syngeneic cell line (E0771LUC+), both expressing luciferase. This comparison was made using several methods, SP stimulation and 3D cell culture models, to better reproduce the heterogenous microenvironment of solid tumors observed in vivo. Furthermore, the susceptibility of the syngeneic cell line (E0771LUC+) to NK1R antagonist (Aprepitant) was tested. Our results indicate that E0771LUC+ recapitulates several essential aspects of the allogenic cell line, rendering this syngeneic line ideal to be used on immune-competent animals during in vivo studies. We have also found that both cell lines are susceptible to SP stimulation, and their proliferation is disrupted by NK1R antagonists (Aprepitant). Follow-up in vivo studies are required to verify and refine these findings.

Combinatorial leaky probiotic for anticancer immunopotentiation and tumor eradication.

Combination therapies present a compelling therapeutic regimen against the immunosuppressive and heterogeneous microenvironment of solid tumors. However, incorporating separate therapeutic modalities in regimen designs can be encumbered by complex logistical, manufacturing, and pharmacokinetic considerations. Herein, we demonstrate a single-vector combinational anticancer therapy using an lpp gene knockout leaky probiotic for simultaneous secretion of immunotherapeutic and oncolytic effector molecules. Through fusion protein design and vector optimization, a Nissle1917 (EcN) bacteria vector is engineered to secrete Neoleukin-2/15 (Neo-2/15) cytokine-functionalized anti-PDL1 nanobody (aPDL1-Neo2/15) and anti-mesothelin-functionalized hemolysin E (HlyE-aMSLN). The multifunctional leaky probiotic enables synchronous immune activation and tumor-targeted cytolytic activity for effective tumor suppression, elevation of tumor immune cell infiltration, and establishment of anticancer immunological memory. lpp gene knockout is further shown to improve probiotic tolerability and intravenous applicability, offering a therapeutically viable approach for combination regimen development.

Abstract C105: Novel cancer-specific hypoxia signature predicts poor prognosis and highlights racial disparities in breast cancer

Abstract Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. TNBC displays exceptional transcriptional heterogeneity, both between patients and intratumorally, and disproportionately affects underserved women. Hypoxia, a state of low oxygen levels, is often present in the solid tumor microenvironment. In TNBC, hypoxia is a key driver of aggressiveness and therapeutic resistance. Past bulk RNA sequencing (RNAseq) studies in cancer research have lacked spatial resolution, failing to uncover precise transcriptional differences within tumor regions. This spatial limitation has been especially problematic for studying transcriptional heterogeneity of the cellular hypoxia response within tumors. By integrating single-cell RNA sequencing and spatial transcriptomic analyses in a TNBC xenograft tumor model, our research has uncovered a novel hypoxia gene signature, specific to cancer cells. Elevated expression of this hypoxia signature predicts poorer prognosis in breast cancer patients, especially within TNBC patients and those of African ancestry. This suggests that hypoxia may play a role in the racial disparities observed in TNBC prognosis, potentially informing treatment strategies. This workflow introduces a novel framework for translating general spatial transcriptomics data into clinically relevant and accurate gene signatures. Citation Format: Kent Schechter, Long C. Nguyen, Geetha P. Yerradoddi, Rania Bassiouni, John D. Carpten, Marsha R. Rosner. Novel cancer-specific hypoxia signature predicts poor prognosis and highlights racial disparities in breast cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C105.

Microbial metabolite-guided CAR T cell engineering enhances anti-tumor immunity via epigenetic-metabolic crosstalk.

Emerging data have highlighted a correlation between microbiome composition and cancer immunotherapy outcome. While commensal bacteria and their metabolites are known to modulate the host environment, contradictory effects and a lack of mechanistic understanding impede the translation of microbiome-based therapies into the clinic. In this study, we demonstrate that abundance of the commensal metabolite pentanoate is predictive for survival of chimeric antigen receptor (CAR) T cell patients in two independent cohorts. Its implementation in the CAR T cell manufacturing workflow overcomes solid tumor microenvironments in immunocompetent cancer models by hijacking the epigenetic-metabolic crosstalk, reducing exhaustion and promoting naive-like differentiation. While synergy of clinically relevant drugs mimicked the phenotype of pentanoate-engineered CAR T cells in vitro, in vivo challenge showed inferior tumor control. Metabolic tracing of 13C-pentanoate revealed citrate generation in the TCA cycle via the acetyl- and succinyl-CoA entry points as a unique feature of the C5 aliphatic chain. Inhibition of the ATP-citrate lyase, which links metabolic output and histone acetylation, led to accumulation of pentanoate-derived citrate from the succinyl-CoA route and decreased functionality of SCFA-engineered CAR T cells. Our data demonstrate that microbial metabolites are incorporated as epigenetic imprints and implementation into CAR T cell production might serve as embodiment of the microbiome-host axis benefits for clinical applications.

A CD25×TIGIT bispecific antibody induces anti-tumor activity through selective intratumoral Treg cell depletion

Intratumoral regulatory T cells (Tregs) express high levels of CD25 and TIGIT, which are also recognized as markers of effector T cell (Teff) activation. Targeting these molecules each alone with monoclonal antibodies (mAbs) poses a risk of concurrently depleting both Teffs and peripheral Tregs, thereby compromising the effectiveness and selectivity of intratumoral Treg depletion. Here, leveraging the increased abundance of CD25+ TIGIT+ double positive Tregs in the solid tumor microenvironment (but not in peripheral tissues), we explored the feasibility of using a CD25×TIGIT bispecific antibody (bsAb) to selectively deplete intratumoral Tregs. We initially constructed a bsAb co-targeting mouse CD25 and TIGIT, NSWm7210, and found that NSWm7210 conferred enhanced intratumoral Treg depletion, Teff activation, and tumor suppression as compared to the parental monotherapies in mouse models. We subsequently constructed a bsAb co-targeting human CD25 and TIGIT (NSWh7216), which preferentially eliminated CD25+ TIGIT+ double positive cells over single positive cells in vitro. NSWh7216 exhibited enhanced anti-tumor activity without toxicity of peripheral Tregs in CD25 humanized mice compared to the parental monotherapies. Our study illustrates the use of CD25×TIGIT bsAbs as effective agents against solid tumors based on selective depletion of intratumoral Tregs.

Exploring tumor microenvironment in molecular subtyping and prognostic signatures in ovarian cancer and identification of SH2D1A as a key regulator of ovarian cancer carcinogenesis

IntroductionA deadly gynecological cancer, ovarian cancer (OV), has a poor prognosis because of late-stage diagnosis and few targeted therapies. Addressing the tumor microenvironment (TME) in solid tumors has shown promise since it is crucial in promoting cancer progression. MethodsWe obtained bulk RNA-seq data from TCGA-OV, GSE26712, GSE102073, and ICGC cohorts, as well as scRNA-seq data from EMTAB8107, GSE118828, GSE130000, and GSE154600 cohorts using the TISCH2 database. The ConsensusClusterPlus package was used to cluster the OV tumor tissues hierarchically to determine two molecularly different groups (C1 and C2). A total of ten different types of machine learning techniques with 101 combinations were used for prognostic model construction. Using eight TME algorithms integrated into the IOBR R package, the bulk RNA-seq dataset was analyzed. For in vitro experiments, OVCAR3 and SKOV3, two OV cell lines, were used. The migratory potential of the ovarian cancer cells was assessed using Transwell assay, while proliferation was assessed using CCK8 assay. ResultsBased on TME-related gene set expression, two distinct molecular subgroups (C1 and C2) were identified through consensus clustering, with C1 showing higher TME activity. Further analysis indicated that C1 had increased cancer-associated fibroblasts (CAFs), M1 macrophages, and CD8+ T cells, suggesting a more activated and pro-inflammatory TME. Drug sensitivity analysis revealed that 5-Fluorouracil might be beneficial to C1 patients. Functional differences between C1 and C2 were identified, including cell adhesion, mononuclear cell differentiation, and leukocyte migration. A machine learning model was developed to create a TME-related prognostic signature, demonstrating strong prognostic capabilities across multiple datasets. High-risk patients showed a more immune-suppressive TME and higher tumor stemness. ScRNA-seq disclosed a highly activated TME-related signature in OV. Cancer cell lines had significantly higher SH2D1A mRNA expression than normal ovarian epithelial cells. We observed that SH2D1A knockdown in 2 ovarian cancer cell lines (OVCAR3 and SKOV3) reduced migration and proliferation through a series of in-vitro experiments. ConclusionTME-associated genes were efficient in ovarian cancer molecular subtyping. A TME-based prognosis model was constructed for vigorous prognostic stratification efficacy across multiple datasets. Moreover, we identified a pivotal role of SH2D1A in promoting proliferation and migration in ovarian cancer.

Multiomics and machine learning-based analysis of pancancer pseudouridine modifications

Pseudouridine widely affects the stability and function of RNA. However, our knowledge of pseudouridine properties in tumors is incomplete. We systematically analyzed pseudouridine synthases (PUSs) expression, genomic aberrations, and prognostic features in 10907 samples from 33 tumors. We found that the pseudouridine-associated pathway was abnormal in tumors and affected patient prognosis. Dysregulation of the PUSs expression pattern may arise from copy number variation (CNV) mutations and aberrant DNA methylation. Functional enrichment analyses determined that the PUSs expression was closely associated with the MYC, E2F, and MTORC1 signaling pathways. In addition, PUSs are involved in the remodeling of the tumor microenvironment (TME) in solid tumors, such as kidney and lung cancers. Particularly in lung cancer, increased expression of PUSs is accompanied by increased immune checkpoint expression and Treg infiltration. The best signature model based on more than 112 machine learning combinations had good prognostic ability in ACC, DLBC, GBM, KICH, MESO, THYM, TGCT, and PRAD tumors, and is expected to guide immunotherapy for 19 tumor types. The model was also effective in identifying patients with tumors amenable to etoposide, camptothecin, cisplatin, or bexarotene treatment. In conclusion, our work highlights the dysregulated features of PUSs and their role in the TME and patient prognosis, providing an initial molecular basis for future exploration of pseudouridine. Studies targeting pseudouridine are expected to lead to the development of potential diagnostic strategies and the evaluation and improvement of antitumor therapies.

Hypoxia Reversion and STING Pathway Activation through Large Mesoporous Nanozyme for Near-Infrared-II Light Amplified Tumor Polymetallic-Immunotherapy.

cGAS/STING pathway, which is highly related to tumor hypoxia, is considered as a potential target for remodeling the immunosuppressive microenvironment of solid tumors. Metal ions, such as Mn2+, activate the cGAS/STING pathway, but their efficacy in cancer therapy is limited by insufficient effect on immunogenic tumor cell death of a single ion. Here, we evaluate the association between tumor hypoxia and cGAS/STING inhibition and report a polymetallic-immunotherapy strategy based on large mesoporous trimetal-based nanozyme (AuPdRh) coordinated with Mn2+ (Mn2+@AuPdRh) to activate cGAS/STING signaling for robust adaptive antitumor immunity. Specifically, the inherent CAT-like activity of this polymetallic Mn2+@AuPdRh nanozyme decomposes the endogenous H2O2 into O2 to relieve tumor hypoxia induced suppression of cGAS/STING signaling. Moreover, the Mn2+@AuPdRh nanozyme displays a potent near-infrared-II photothermal effect and strong POD-mimic activity; and the generated hyperthermia and •OH radicals synergistically trigger immunogenic cell death in tumors, releasing abundant dsDNA, while the delivered Mn2+ augments the sensitivity of cGAS to dsDNA and activates the cGAS-STING pathway, thereby triggering downstream immunostimulatory signals to kill primary and distant metastatic tumors. Our study demonstrates the potential of metal-based nanozyme for STING-mediated tumor polymetallic-immunotherapy and may inspire the development of more effective strategies for cancer immunotherapy.

Confocal microscopic oxygen imaging of xenograft tumors using Ir(III) complexes as in vivo intravascular and intracellular probes

Hypoxia is an important feature of the tumor microenvironment (TME) of most solid tumors, and it is closely linked to cancer cell proliferation, therapy resistance, and the tumor immune response. Herein, we describe a method for hypoxia-induced heterogeneous oxygen distribution in xenograft tumors based on phosphorescence imaging microscopy (PLIM) using intravascular and intracellular oxygen probes. We synthesized Ir(III) complexes with polyethylene glycol (PEG) units of different molecular weights into the ligand as intravascular oxygen probes, BTP-PEGm (m = 2000, 5000, 10000, 20000). BTP-PEGm showed red emission with relatively high emission quantum yield and high oxygen sensitivity in saline. Cellular and in vivo experiments using these complexes revealed that BTP-PEG10000 was the most suitable probe in terms of blood retention and ease of intravenous administration in mice. PLIM measurements of xenograft tumors in mice treated with BTP-PEG10000 allowed simultaneous imaging of the tumor microvasculature and quantification of oxygen partial pressures. From lifetime images using the red-emitting intracellular oxygen probe BTPDM1 and the green-emitting intravascular fluorescent probe FITC-dextran, we demonstrated hypoxic heterogeneity in the TME with a sparse vascular network and showed that the oxygen levels of tumor cells gradually decreased with vascular distance.

The Microenvironment of Solid Tumors: Components and Current Challenges of Tumor-on-a-Chip Models.

Solid tumors represent the most common type of cancer in humans and are classified into sarcomas, lymphomas, and carcinomas based on the originating cells. Among these, carcinomas, which arise from epithelial and glandular cells lining the body's tissues, are the most prevalent. Around the world, a significant increase in the incidence of solid tumors is observed during recent years. In this context, efforts to discover more effective cancer treatments have led to a deeper understanding of the tumor microenvironment (TME) and its components. Currently, the interactions between cancer cells and elements of the TME are being intensely investigated. Remarkable progress in research is noted, largely owing to the development of advanced in vitro models, such as tumor-on-a-chip models that assist in understanding and ultimately discovering new effective treatments for a specific type of cancer. The purpose of this article is to provide a review of the TME and cancer cell components, along with the advances on tumor-on-a-chip models designed to mimic tumors, offering a perspective on the current state of the art. Recent studies using this kind of microdevices that reproduce the TME have allowed a better understanding of the cancer and its treatments. Nevertheless, current applications of this technology present some limitations that must be overcome to achieve a broad application by researchers looking for a deeper knowledge of cancer and new strategies to improve current therapies.

Biologically based strategies for overcoming in vivo barriers with functional nano-delivery systems.

Nanomedicine has been developed to reduce or eliminate the side effects and toxicity upon systemic therapy of chemotherapeutic agents and to improve their therapeutic efficacy. However, the translation of non-sized or nano-encapsulated drugs is hampered by the low penetration and accumulation of engineered nanoparticles (NPs) in sites of tumors as well as their poor pharmacokinetics. This may be due to the synthetic structure of NPs and also complicated and unknown characteristics of the solid tumor microenvironment (TME). As a result, the TME is being better identified, and the interactions between NPs and the TME or human body are being discovered or predicted. These findings have led to the development of more biocompatible, intelligent, and controllable bio-based nanoformulations that could overcome current barriers and provide sufficient drug delivery to the TME, as discussed in this paper. These formulations are designed to (i) modify the surface of NPs to improve blood circulation while reducing their off-target accumulation and side effects in vivo, (ii) pass through the tumor vasculature by modulating or targeting angiogenesis, (iii) promote NPs distribution in solid tumor regions by applying biological/physical stimuli or extracellular matrix remodeling, and (iv) overcome the cell membrane barrier and other compartments of the cell by specific cell targeting to release the payload drug into the cytoplasm or nucleoplasm.

Reshaping tumor microenvironment by regulating local cytokines expression with a portable smart blue-light controlled device

Cytokines have attracted sustained attention due to their multi-functional cellular response in immunotherapy. However, their application was limited to their short half-time, narrow therapeutic window, and undesired side effects. To address this issue, we developed a portable smart blue-light controlled (PSLC) device based on optogenetic technology. By combining this PSLC device with blue-light controlled gene modules, we successfully achieved the targeted regulation of cytokine expression within the tumor microenvironment. To alter the tumor microenvironment of solid tumors, pro-inflammatory cytokines were selected as blue-light controlled molecules. The results show that blue-light effectively regulates the expression of pro-inflammatory cytokines both in vitro and in vivo. This strategy leads to enhanced and activated tumor-infiltrating immune cells, which facilitated to overcome the immunosuppressive microenvironment, resulting in significant tumor shrinkage in tumor-bearing mice. Hence, our study offers a unique strategy for cytokine therapy and a convenient device for animal studies in optogenetic immunotherapy.

CAR T cell infiltration and cytotoxic killing within the core of 3D breast cancer spheroids under the control of antigen sensing in microwell arrays.

The success of chimeric antigen receptor (CAR) T cells in blood cancers has intensified efforts to develop CAR T therapies for solid cancers. In the solid tumor microenvironment, CAR T cell trafficking and suppression of cytotoxic killing represent limiting factors for therapeutic efficacy. Here, we present a microwell platform to study CAR T cell interactions with 3D breast tumor spheroids and determine predictors of anti-tumor CAR T cell function. To precisely control antigen sensing, we utilized a switchable adaptor CAR system that covalently attaches to co-administered antibody adaptors and mediates antigen recognition. Following the addition of an anti-HER2 adaptor antibody, primary human CAR T cells exhibited higher infiltration, clustering, and secretion of effector cytokines. By tracking CAR T cell killing in individual spheroids, we showed the suppressive effects of spheroid size and identified the initial CAR T cell to spheroid area ratio as a predictor of cytotoxicity. We demonstrate that larger spheroids exhibit higher hypoxia levels and are infiltrated by CAR T cells with a suppressed activation state, characterized by reduced expression of IFN-γ, TNF-α, and granzyme B. Spatiotemporal analysis revealed lower CAR T cell numbers and cytotoxicity in the spheroid core compared to the periphery. Finally, increasing CAR T cell seeding density resulted in higher CAR T cell infiltration and cancer cell elimination in the spheroid core. Our findings provide new quantitative insight into CAR T cell function within 3D cancer spheroids. Given its miniaturized nature and live imaging capabilities, our microfabricated system holds promise for screening cellular immunotherapies.

Adaptive Immune Receptor Distinctions Along the Colorectal Polyp-Tumor Timelapse

Colorectal cancer (CRC) is the third-most common cancer diagnosed worldwide, with 1.85 million new cases per year. While mortality has significantly decreased due to preventive colonoscopy, only 5% of polyps identified progress to cancer. Studies have found that immunological alterations in other solid tumor microenvironments are associated with worse prognoses. Thus, we applied an immunogenomics approach to assess adaptive immune receptor gene expression changes that were associated with development of adenocarcinoma, utilizing 79 samples that represented normal, tubular, villous, and tumor colorectal tissue for 32 patients. Results indicated that the number of productive TRD and TRG recombination reads, representing gamma-delta (γδ) T-cells, significantly decreased with progression from normal to tumor tissue. A further assessment of 2 independent CRC datasets was consistent with a decrease in TRD recombination reads with progression to CRC. Further, we identified 3 physicochemical parameters for immunoglobulin, complementarity determining region-3 (CDR3) amino acids associated with progression from normal to tumor tissue. Overall, this study points towards a need for further investigation of γδ T-cells in relation to CRC development; and indicates immunoglobulin CDR3 physicochemical features as potential CRC biomarkers.

Carrageenan-ferrocene-eicosapentaenoic acid composite hydrogel induce ferroptosis and apoptosis for anti-tumor recurrence and metastasis

The immune-suppressive microenvironment of solid tumors is a key factor limiting the effectiveness of immunotherapy, which seriously threatens human life and health. Ferroptosis and apoptosis are key cell-death pathways implicated in cancers, which can synergistically activate tumor immune responses. Here, we developed a multifunctional composite hydrogel (CE-Fc-Gel) based on the self-assembly of poloxamer 407, cystamine-linked ιota-carrageenan (CA)-eicosapentaenoic acid (EPA), and ferrocene (Fc). CE-Fc-Gel improved targeting in tumor microenvironment due to its disulfide bonds. Moreover, CE-Fc-Gel promoted lipid peroxidation, enhanced reactive oxygen species (ROS) production, and decreased glutathione peroxidase 4 (GPX4), inducing ferroptosis by the synergistic effect of Fc and EPA. CE-Fc-Gel induced apoptosis and immunogenic cell death (ICD), thereby promoting dendritic cells (DCs) maturation and T cell infiltration. As a result, CE-Fc-Gel significantly inhibited primary and metastatic tumors in vivo. Our findings provide a novel strategy for enhancing tumor immunotherapy by combining apoptosis, ferroptosis, and ICD.

3D stem-like spheroids-on-a-chip for personalized combinatorial drug testing in oral cancer

BackgroundFunctional drug testing (FDT) with patient-derived tumor cells in microfluidic devices is gaining popularity. However, the majority of previously reported microfluidic devices for FDT were limited by at least one of these factors: lengthy fabrication procedures, absence of tumor progenitor cells, lack of clinical correlation, and mono-drug therapy testing. Furthermore, personalized microfluidic models based on spheroids derived from oral cancer patients remain to be thoroughly validated. Overcoming the limitations, we develop 3D printed mold-based, dynamic, and personalized oral stem-like spheroids-on-a-chip, featuring unique serpentine loops and flat-bottom microwells arrangement.ResultsThis unique arrangement enables the screening of seven combinations of three drugs on chemoresistive cancer stem-like cells. Oral cancer patients-derived stem-like spheroids (CD 44+) remains highly viable (> 90%) for 5 days. Treatment with a well-known oral cancer chemotherapy regimen (paclitaxel, 5 fluorouracil, and cisplatin) at clinically relevant dosages results in heterogeneous drug responses in spheroids. These spheroids are derived from three oral cancer patients, each diagnosed with either well-differentiated or moderately-differentiated squamous cell carcinoma. Oral spheroids exhibit dissimilar morphology, size, and oral tumor-relevant oxygen levels (< 5% O2). These features correlate with the drug responses and clinical diagnosis from each patient’s histopathological report.ConclusionsOverall, we demonstrate the influence of tumor differentiation status on treatment responses, which has been rarely carried out in the previous reports. To the best of our knowledge, this is the first report demonstrating extensive work on development of microfluidic based oral cancer spheroid model for personalized combinatorial drug screening. Furthermore, the obtained clinical correlation of drug screening data represents a significant advancement over previously reported personalized spheroid-based microfluidic devices. Finally, the maintenance of patient-derived spheroids with high viability under oral cancer relevant oxygen levels of less than 5% O2 is a more realistic representation of solid tumor microenvironment in our developed device.Graphical

Advances in 2,3-Dimethylmaleic Anhydride (DMMA)-Modified Nanocarriers in Drug Delivery Systems.

Cancer represents a significant threat to human health. The cells and tissues within the microenvironment of solid tumors exhibit complex and abnormal properties in comparison to healthy tissues. The efficacy of nanomedicines is inhibited by the presence of substantial and complex physical barriers in the tumor tissue. The latest generation of intelligent drug delivery systems, particularly nanomedicines capable of charge reversal, have shown promise in addressing this issue. These systems can transform their charge from negative to positive upon reaching the tumor site, thereby enhancing tumor penetration via transcytosis and promoting cell internalization by interacting with the negatively charged cell membranes. The modification of nanocarriers with 2,3-dimethylmaleic anhydride (DMMA) and its derivatives, which are responsive to weak acid stimulation, represents a significant advance in the field of charge-reversal nanomedicines. This review provides a comprehensive examination of the recent insights into DMMA-modified nanocarriers in drug delivery systems, with a particular focus on their potential in targeted therapeutics. It also discusses the synthesis of DMMA derivatives and their role in charge reversal, shell detachment, size shift, and ligand reactivation mechanisms, offering the prospect of a tailored, next-generation therapeutic approach to overcome the diverse challenges associated with cancer therapy.

Immune Microenvironment in Childhood Cancers: Characteristics and Therapeutic Challenges.

The tumor immune microenvironment is pivotal in cancer initiation, advancement, and regulation. Its molecular and cellular composition is critical throughout the disease, as it can influence the balance between suppressive and cytotoxic immune responses within the tumor's vicinity. Studies on the tumor immune microenvironment have enriched our understanding of the intricate interplay between tumors and their immunological surroundings in various human cancers. These studies illuminate the role of significant components of the immune microenvironment, which have not been extensively explored in pediatric tumors before and may influence the responsiveness or resistance to therapeutic agents. Our deepening understanding of the pediatric tumor immune microenvironment is helping to overcome challenges related to the effectiveness of existing therapeutic strategies, including immunotherapies. Although in the early stages, targeted therapies that modulate the tumor immune microenvironment of pediatric solid tumors hold promise for improved outcomes. Focusing on various aspects of tumor immune biology in pediatric patients presents a therapeutic opportunity that could improve treatment outcomes. This review offers a comprehensive examination of recent literature concerning profiling the immune microenvironment in various pediatric tumors. It seeks to condense research findings on characterizing the immune microenvironment in pediatric tumors and its impact on tumor development, metastasis, and response to therapeutic modalities. It covers the immune microenvironment's role in tumor development, interactions with tumor cells, and its impact on the tumor's response to immunotherapy. The review also discusses challenges targeting the immune microenvironment for pediatric cancer therapies.

Programmable melanoma-targeted radio-immunotherapy via fusogenic liposomes functionalized with multivariate-gated aptamer assemblies

Radio-immunotherapy exploits the immunostimulatory features of ionizing radiation (IR) to enhance antitumor effects and offers emerging opportunities for treating invasive tumor indications such as melanoma. However, insufficient dose deposition and immunosuppressive microenvironment (TME) of solid tumors limit its efficacy. Here we report a programmable sequential therapeutic strategy based on multifunctional fusogenic liposomes (Lip@AUR-ACP-aptPD-L1) to overcome the intrinsic radio-immunotherapeutic resistance of solid tumors. Specifically, fusogenic liposomes are loaded with gold-containing Auranofin (AUR) and inserted with multivariate-gated aptamer assemblies (ACP) and PD-L1 aptamers in the lipid membrane, potentiating melanoma-targeted AUR delivery while transferring ACP onto cell surface through selective membrane fusion. AUR amplifies IR-induced immunogenic death of melanoma cells to release antigens and damage-associated molecular patterns such as adenosine triphosphate (ATP) for triggering adaptive antitumor immunity. AUR-sensitized radiotherapy also upregulates matrix metalloproteinase-2 (MMP-2) expression that combined with released ATP to activate ACP through an “and” logic operation-like process (AND-gate), thus triggering the in-situ release of engineered cytosine-phosphate-guanine aptamer-based immunoadjuvants (eCpG) for stimulating dendritic cell-mediated T cell priming. Furthermore, AUR inhibits tumor-intrinsic vascular endothelial growth factor signaling to suppress infiltration of immunosuppressive cells for fostering an anti-tumorigenic TME. This study offers an approach for solid tumor treatment in the clinics.