Response In Tumor Microenvironment Research Articles

Mammary tumour microenvironment response to vitamin D and exercise in aged mice fed by high fat diet

Mammary tumour microenvironment response to vitamin D and exercise in aged mice fed by high fat diet

Single-cell transcriptomics reveals ferrimagnetic vortex iron oxide nanoring-mediated mild magnetic hyperthermia exerts antitumor effects by alleviating macrophage suppression in breast cancer

The potential of Ferrimagnetic vortex iron oxide nanoring-mediated mild magnetic hyperthermia (FVIO-MHT) in solid tumor therapy has been demonstrated. However, the impact of FVIO-MHT on the tumor microenvironment (TME) remains unclear. This study utilized single-cell transcriptome sequencing to examine the alterations in the TME in response to FVIO-MHT in breast cancer. The results revealed the cellular composition within the tumor microenvironment (TME) was primarily modified due to a decrease in tumor cells and an increased infiltration of myeloid cells. Subsequently, an enhancement in active oxygen (ROS) metabolism was observed, indicating oxidative damage to tumor cells. Interestingly, FVIO-MHT reprogrammed the macrophages’ phenotypes, as evidenced by alterations in the transcriptome characteristics associated with both classic and alternative activated phenotypes. And an elevated level of ROS generation and oxidative phosphorylation suggested that activated phagocytosis and inflammation occurred in macrophages. Additionally, cell–cell communication analysis revealed that FVIO-MHT attenuated the suppression between tumor cells and macrophages by inhibiting phagocytic checkpoint and macrophage migration inhibitory factor signaling pathways. Inhibition of B2m, an anti-phagocytosis checkpoint, could promote macrophage-mediated phagocytosis and significantly inhibit tumor growth. These data emphasize FVIO-MHT may promote the antitumor capabilities of macrophages by alleviating the suppression between tumor cells and macrophages.

Supramolecular nanoparticles based on elastin-like peptides modified capsid protein as drug delivery platform with enhanced cancer chemotherapy efficacy

Cancer, a prevalent disease posing significant threats to human health and longevity, necessitates effective therapeutic interventions. Chemotherapy has emerged as a primary strategy following surgical procedures for combating most malignancies. Despite the considerable efficacy of conventional chemotherapeutic agents against cancer cells, their utility is hindered by profound challenges such as multidrug resistance and deleterious toxic side effects, thereby limiting their systemic application. To tackle these challenges, we have devised a promising nanomedicine platform based on a plant virus. Specifically, we have selected the cowpea melanoma mottled virus (CCMV) as our nano-delivery system owing to its monodisperse and homogeneous size, as well as its intrinsic ability for controlled self-assembly. Leveraging the potential of this platform, we have engineered CCMV-based nanoparticles functionalized with elastin-like peptides (ELPs) at their N-terminal region. The target protein, CP-ELP, was expressed via E.coli, enabling encapsulation of the model drug DOX upon structural domain modification of the protein. The resulting nanoparticles exhibit uniform size distribution, facilitating efficient internalization by tumor cells and subsequent intracellular drug release, leading to enhanced antitumor efficacy. In addition, EVLP@DOX nanoparticles were found to activate immune response of tumor microenvironment in vivo, which further inhibiting tumor growth. Our designed nanoparticles have also demonstrated remarkable therapeutic effectiveness and favorable biological safety profiles in both murine melanoma and colorectal cancer models.

Metastatic castration-resistant prostate cancer-emerging trends in therapy

An increasing understanding of the cellular processes involved in growth, metastasis and development of resistance enable the development of new treatment strategies for advanced prostate cancer. Using selected examples, the aim of this report is to present current developments to the reader and to give an outlook on possible upcoming changes in the treatment of advanced prostate cancer. Narrative report based on expert consensus, supported by aliterature search in PubMed (MEDLINE) and the abstract databases of the American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO). Examples were selected to illustrate current developments without claiming completeness. The androgen receptor (AR) signal transduction pathway remains afocus of scientific interest. Androgen synthesis inhibitors and AR degraders are promising new approaches to overcome resistance mediated by AR mutations or splice variants. Inhibition of key switch sites of alternative signaling pathways such as AKT or CDK4/6 provide additional treatment options, including combinational strategies through atight linkage with the AR signaling pathway. Abetter understanding of tumor microenvironment and immune response is required for novel immunotherapeutic strategies using bispecific T‑cell engagers (BiTEs) and chimeric antigen receptor (CAR) Tcells. New treatment strategies give hope that we will be able to intervene even more effectively in the course of disease of advanced prostate cancer in the future. However, amajor challenge, especially for the implementation of targeted treatment approaches, is likely to be the heterogeneity of tumor progression not only inter- but also intrapersonally.

TMIC-69. TARGETING TUMOR-ASSOCIATED MACROPHAGES IN THE IMMUNE-MICROENVIRONMENT OF MENINGIOMAS

Abstract Meningiomas represent the most common primary brain malignancies in adults with a subset of tumors exhibiting aggressive clinical behavior. Immunotherapy might present a new treatment strategy but is highly dependent on the immunological composition of the tumor microenvironment. Our previous data have shown that tumor-associated macrophages (TAMs) make up the main immune cell population in meningiomas with a significant negative impact on patient outcome. In this study, we investigated whether TAMs from meningioma tissue could be reprogrammed to an immunologically active and tumoricidal phenotype. For this purpose, CD11b+ sorted macrophages derived from > 40 patients were treated with small molecule inhibitors targeting the colony-stimulating factor-1 receptor (CSF-1R). In a first analysis, the direct treatment response of CD11b+ patient-derived macrophages was investigated by various techniques including flow cytometry and bulk RNA-sequencing of treated TAMs and further analysis of the macrophage-conditioned media after treatment. In addition, we studied the influence of CSF-1R-targeted macrophage treatment on the phenotype and functional activity of T cells to assess a potential indirect treatment response in the tumor microenvironment. Our data revealed that CSF-1R-targeted treatment of CD11b+ TAMs induced significant changes in the protein and gene expression of macrophage polarization markers towards a more immunologically active state and a significantly higher metabolic nitric oxide production as another sign of immunological activation. Subsequent analysis of indirect effects on T cells showed not only a significantly increased expression of the T cell activation marker CD69+, but also a significantly increased tumor cell killing by autologous T cells after macrophage-targeted treatment. Together these data suggest both a direct and indirect CSF-1R-targeted macrophage treatment response in the local tumor microenvironment and give first promising results on the efficacy of macrophage-targeted immunotherapy in human meningiomas.

EXTH-16. DEVELOPMENT OF INTRATHECAL (IT) DRUG DELIVERY PLATFORM TO CURE BREAST CANCER (BC) LEPTOMENINGEAL DISEASE (LMD) BY PEPTIDE-PULSED TYPE 1 CONVENTIONAL DENDRITIC CELL (CDC1) VACCINE IN PRECLINICAL MODEL

Abstract BACKGROUND LMD is a rare form of metastasis in the meninges. Approximately 5% of advanced stage BC will develop LMD and currently there is no cure. One of the major hurdles is drug penetration due to the blood brain barrier (BBB) and blood-cerebral spinal fluid (CSF)-barrier. While the Ommaya reservoir is used clinically to overcome this challenge, there has not been an optimized preclinical model that allows researchers to adequately test novel therapies in the CSF space. METHODS The Forsyth lab have recently developed an MRI-compatible device called the “murine Ommaya” which mimics the Ommaya reservoir and allows repeated IT administration of drugs in minute 3-7 μL directly into CSF, bypassing BBB. In a joint effort with Dr. Czerniecki, whose lab have developed a pipeline for screening immunogenic MHC class II peptides from tumor-associated oncodrivers and subsequently generating tumor-targeting cDC1s, we have created a platform to IT deliver peptide-pulsed cDC1 immunotherapy directly targeting BC-LMD. RESULTS Currently, we have tested the efficacy of treatment in HER2+ LMD and triple negative breast cancer (TNBC) LMD models and found a very favorable response; LMD mice that received IT cDC1 therapy showed tumor regression and their survival were significantly prolonged. About 70% of mice from HER2+ LMD and 30% from TNBC LMD were eventually disease-free. Cured mice also exhibited resistance against LMD recurrence. CONCLUSIONS Our preliminary data suggest IT cDC1 vaccine is effective against the incurable BC-LMD. We are currently investigating the mechanism(s) by which IT cDC1-initiated CD4 Th1 adaptive immune response against LMD. By using single-cell RNA-sequencing technique, we are analyzing the immune landscape in CSF tumor microenvironment in response to IT cDC1. FDA-approved phase 1 clinical trial has been funded by the DOD. Future approach includes employing our IT cDC1 immunotherapy platform in other cancer types, such as LMD from melanoma.

Predicting PD-L1 Status in Solid Tumors Using Transcriptomic Data and Artificial Intelligence Algorithms

Programmed death ligand-1 (PD-L1) immunohistochemistry (IHC) is routinely used to predict the clinical response to immune checkpoint inhibitors (ICIs); however, multiple assays and antibodies have been used. This study aimed to evaluate the potential of targeted transcriptome and artificial intelligence (AI) to determine PD-L1 RNA expression levels and predict the ICI response compared with traditional IHC. RNA from 396 solid tumors samples was sequenced using next-generation sequencing (NGS) with a targeted 1408-gene panel. RNA expression and PD-L1 IHC were assessed across a broad range of PD-L1 expression levels. AI was used to predict the PD-L1 status. PD-L1 RNA levels assessed by NGS demonstrated robust linearity across high and low expression ranges, and those assessed using NGS and IHC (tumor proportion score and tumor-infiltrating immune cells) had a similar pattern. RNA sequencing provided in-depth information on the tumor microenvironment and immune response, including CD19, CD22, CD8A, CTLA4, and PD-L2 expression status. Subanalyses showed a sustained correlation of mRNA expression with IHC (tumor proportion score and immune cells) across different solid tumor types. Machine learning showed high accuracy in predicting PD-L1 status, with the area under the curve varying between 0.83 and 0.91. Targeted transcriptome sequencing combined with AI is highly useful for predicting PD-L1 status. Measuring PD-L1 mRNA expression by NGS is comparable to measuring PD-L1 expression by IHC for predicting ICI response. RNA expression has the added advantages of being amenable to standardization and avoiding interpretation bias, along with an in-depth evaluation of the tumor microenvironment.

Single-cell morphological and topological atlas reveals the ecosystem diversity of human breast cancer

Digital pathology allows computerized analysis of tumor ecosystem using whole slide images (WSIs). Here, we present single-cell morphological and topological profiling (sc-MTOP) to characterize tumor ecosystem by extracting the features of nuclear morphology and intercellular spatial relationship for individual cells. We construct a single-cell atlas comprising 410 million cells from 637 breast cancer WSIs and dissect the phenotypic diversity within tumor, inflammatory and stroma cells respectively. Spatially-resolved analysis identifies recurrent micro-ecological modules representing locoregional multicellular structures and reveals four breast cancer ecotypes correlating with distinct molecular features and patient prognosis. Further analysis with multiomics data uncovers clinically relevant ecosystem features. High abundance of locally-aggregated inflammatory cells indicates immune-activated tumor microenvironment and favorable immunotherapy response in triple-negative breast cancers. Morphological intratumor heterogeneity of tumor nuclei correlates with cell cycle pathway activation and CDK inhibitors responsiveness in hormone receptor-positive cases. sc-MTOP enables using WSIs to characterize tumor ecosystems at the single-cell level.

Mitochondria-related lncRNAs: predicting prognosis, tumor microenvironment and treatment response in lung adenocarcinoma

Lung cancer is the most common type of malignant tumor that affects people in China and even across the globe, as it exhibits the highest rates of morbidity and mortality. Lung adenocarcinoma (LUAD) is a type of lung cancer with a very high incidence. The purpose of this study was to identify potential biomarkers that could be used to forecast the prognosis and improve the existing therapy options for treating LUAD. Clinical and RNA sequencing data of LUAD patients were retrieved from the TCGA database, while the mitochondria-associated gene sets were acquired from the MITOMAP database. Thereafter, Pearson correlation analysis was carried out to screen mitochondria-associated lncRNAs. Furthermore, univariate Cox and Lasso regression analyses were used for the initial screening of the target lncRNAs for prognostic lncRNAs before they could be incorporated into a multivariate Cox Hazard ratio model. Then, the clinical data, concordance index, Kaplan–Meier (K-M) curves, and the clinically-relevant subjects that were approved by the Characteristic Curves (ROC) were employed for assessing the model's predictive value. Additionally, the differences in immune-related functions and biological pathway enrichment between high- and low-risk LUAD groups were examined. Nomograms were developed to anticipate the OS rates of the patients within 1-, 3-, and 5 years, and the differences in drug sensitivity and immunological checkpoints were compared. In this study, 2175 mitochondria-associated lncRNAs were screened. Univariate, multivariate, and Lasso Cox regression analyses were carried out to select 13 lncRNAs with an independent prognostic significance, and a prognostic model was developed. The OS analysis of the established prognostic prediction model revealed significant variations between the high- and low-risk patients. The AUC-ROC values after 1, 3, and 5 years were seen to be 0.746, 0.692, and 0.726, respectively. The results suggested that the prognostic model riskscore could be used as an independent prognostic factor that differed from the other clinical characteristics. After analyzing the findings of the study, it was noted that both the risk groups showed significant differences in their immune functioning, immunological checkpoint genes, and drug sensitivity. The prognosis of patients with LUAD could be accurately and independently predicted using a risk prediction model that included 13 mitochondria-associated lncRNAs.

An and Logic Gate for Magnetic Resonance Imaging-Guided Ferroptosis Therapy of Tumors.

To improve the magnetic resonance imaging (MRI) efficiency and ferroptosis therapy efficacy of exceedingly small magnetic iron oxide nanoparticles (IO, < 5nm) for tumors via enhancing the sensitivity of tumor microenvironment (TME) responsiveness, inspired by molecular logic gates, we designed and constructed a self-assembled IO with a AND logic gate function. Typically, cystamine (CA) was conjugated onto the end of poly(2-methylthio-ethanol methacrylate) (PMEMA) to generate PMEMA-CA. The PMEMA-CA was grafted onto the surface of brequinar (BQR)-loaded IO to form IO-BQR@PMEMA. The self-assembled IO-BQR@PMEMA (SA-IO-BQR@PMEMA) was obtained due to the hydrophobicity of PMEMA. The carbon-sulfur single bond of PMEMA-CA can be oxidized by the reactive oxygen species (ROS) in TME to thio-oxygen double bond, resulting in the conversion from being hydrophobic to hydrophilic. The disulfide bond of PMEMA-CA can be broken by the glutathione (GSH) in TME, leading to the shedding of PMEMA from the IO surface. Under the dual actions of ROS and GSH in TME (i.e., AND logic gate), SA-IO-BQR@PMEMA can be disassembled to release IO, Fe2+/3+ , and BQR. In vitro and in vivo results demonstrate the AND logic gate function and mechanism, the high T1 MRI performance and exceptional ferroptosis therapy efficacy for tumors, and the excellent biosafety of SA-IO-BQR@PMEMA. This article is protected by copyright. All rights reserved.

A macrophage related signature for predicting prognosis and drug sensitivity in ovarian cancer based on integrative machine learning

BackgroundOvarian cancer ranks the leading cause of gynecologic cancer-related death in the United States and the fifth most common cause of cancer-related mortality among American women. Increasing evidences have highlighted the vital role of macrophages M2/M1 proportion in tumor progression, prognosis and immunotherapy.MethodsWeighted gene co-expression network analysis (WGCNA) was performed to identify macrophages related markers. Integrative procedure including 10 machine learning algorithms were performed to develop a prognostic macrophage related signature (MRS) with TCGA, GSE14764, GSE140082 datasets. The role of MRS in tumor microenvironment (TME) and therapy response was evaluated with the data of CIBERSORT, MCPcounter, QUANTISEQ, XCELL, CIBERSORT-ABS, TIMER and EPIC, GSE91061 and IMvigor210 dataset.ResultsThe optimal MRS developed by the combination of CoxBoost and StepCox[forward] algorithm served as an independent risk factor in ovarian cancer. Compared with stage, grade and other established prognostic signatures, the current MRS had a better performance in predicting the overall survival rate of ovarian cancer patients. Low risk score indicated a higher TME score, higher level of immune cells, higher immunophenoscore, higher tumor mutational burden, lower TIDE score and lower IC50 value in ovarian cancer. The survival prediction nomogram had a good potential for clinical application in predicting the 1-, 3-, and 5-year overall survival rate of ovarian cancer patients.ConclusionAll in all, the current study constructed a powerful prognostic MRS for ovarian cancer patients using 10 machine learning algorithms. This MRS could predict the prognosis and drug sensitivity in ovarian cancer.

Vaccination with post-translational modified, homocitrullinated peptides induces CD8 T-cell responses that mediate antitumor immunity

BackgroundPost-translational modification of proteins has the potential to alter the ability of T cells to recognize major histocompatibility complex (MHC) class -I and class-II restricted antigens, thereby resulting in altered...

Redox-active polyphenol nanoparticles deprive endogenous glutathione of electrons for ROS generation and tumor chemodynamic therapy

Chemodynamic therapy (CDT) based on generating reactive oxygen species (ROS) is promising for cancer treatment. However, the intrinsic H2O2 is deficient for CDT, and glutathione (GSH) eliminates ROS to protect tumor cells from ROS cytotoxicity. Herein, we propose a strategy to switch the electron flow direction of GSH for O2 reduction and ROS generation rather than ROS clearance by using P(DA-Fc) nanoparticles, which are polymerized from ferrocenecarboxylic acid (Fc) coupled dopamine. P(DA-Fc) NPs with phenol-quinone conversion ability mimic NOX enzyme to deprive electrons from GSH to reduce O2 for H2O2 generation; the following •OH release can be triggered by Fc. Semiquinone radicals in P(DA-Fc) are significantly enhanced after GSH treatment, further demonstrated with strong single-electron reduction ability by calculation. In vitro and in vivo experiments indicate that P(DA-Fc) can consume intrinsic GSH to produce endogenous ROS; ROS generation strongly depends on GSH/pH level and eventually causes tumor cell death. Our work makes the first attempt to reverse the function of GSH from ROS scavenger to ROS producer, explores new roles of PDA-based nanomaterials in CDT beyond photothermal reagents and drug carriers, and provides a new strategy to improve the efficiency of CDT. Statement of SignificanceP(DA-Fc) nanoparticles performing tumor microenvironment response capacity and tumor reductive power utilize ability were fabricated for CDT tumor suppression. After endocytosis by tumor cells, P(DA-Fc) deprived GSH of electrons for H2O2 and •OH release, mimicking the intrinsic ROS production conducted by NADPH, further inducing tumor cell necrosis and apoptosis. Our work makes the first attempt to reverse the function of GSH from ROS scavenger to producer, explores new functions of PDA-based nanomaterials in CDT beyond photothermal reagents and drug carriers, and provides a new strategy to improve CDT efficiency.

Crosstalk of RNA methylation writers defines tumor microenvironment and alisertib resistance in breast cancer.

The five major RNA methylation modifications (m6A, m1A, m6Am, m5C, and m7G) exert biological roles in tumorigenicity and immune response, mediated mainly by "writer" enzymes. Here, the prognostic values of the "writer" enzymes and the TCP1 role in drug resistance in breast cancer (BC) were explored for further therapeutic strategies. We comprehensively characterized clinical, molecular, and genetic features of subtypes by consensus clustering. RNA methylation modification "Writers" and related genes_risk (RMW_risk) model for BC was constructed via a machine learning approach. Moreover, we performed a systematical analysis for characteristics of the tumor microenvironment (TME), alisertib sensitivity, and immunotherapy response. A series of experiments in vitro were carried out to assess the association of TCP1 with drug resistance. One "writer" (RBM15B) and two related genes (TCP1 and ANKRD36) were identified for prognostic model construction, validated by GSE1456, GSE7390, and GSE20685 cohorts and our follow-up data. Based on the patterns of the genes related to prognosis, patients were classified into RMW_risk-high and RMW_risk-low subtypes. Lower RMW_Score was associated with better overall survival and the infiltration of immune cells such as memory B cells. Further analysis revealed that RMW_Score presented potential values in predicting drug sensitivity and response for chemo- and immunotherapy. In addition, TCP1 was confirmed to promote BC alisertib-resistant cell proliferation and migration in vitro. RMW_Score could function as a robust biomarker for predicting BC patient survival and therapeutic benefits. This research revealed a potential TCP1 role regarding alisertib resistance in BC, providing new sights into more effective therapeutic plans.

Luminescence-activated Pt(IV) prodrug for in situ triggerable cancer therapy

Anticancer platinum prodrugs that can be controllably activated are highly desired for personalized precision medicine and patient compliance in cancer therapy. However, the clinical application of platinum(IV) prodrugs (Pt(IV)) is restricted by tissue penetration of external irradiation. Here, we report a novel Pt(IV) activation strategy based on endogenous luminescence of tumor microenvironment responsiveness, which completely circumvents the limitation of external irradiation. The designed Pt(IV)Lu, a mixture of trans, trans, trans-[Pt(N3)2(OH)2(py)2] and luminol (Lu), has controllable activation property: it remains inert in reductant environment and normal tissues, but under tumor microenvironment, Lu will be oxidized to produce blue luminescence, which rapidly reduce Pt(IV) to Pt(II) without the need of any external activator. Pt(IV)Lu shows excellent responsive antitumor ability both in vitro and in vivo. Compared to cisplatin, the median lethal dose in BALB/c mice increased by an order of magnitude. Our results suggest that Pt(IV)Lu exhibits highly controllable activation property, superior antitumor activity, and good biosafety, which may provide a novel strategy for the design of platinum prodrugs.

Identification of disulfidptosis-related subgroups and prognostic signatures in lung adenocarcinoma using machine learning and experimental validation.

Disulfidptosis is a newly identified variant of cell death characterized by disulfide accumulation, which is independent of ATP depletion. Accordingly, the latent influence of disulfidptosis on the prognosis of lung adenocarcinoma (LUAD) patients and the progression of tumors remains poorly understood. We conducted a multifaceted analysis of the transcriptional and genetic modifications in disulfidptosis regulators (DRs) specific to LUAD, followed by an evaluation of their expression configurations to define DR clusters. Harnessing the differentially expressed genes (DEGs) identified from these clusters, we formulated an optimal predictive model by amalgamating 10 distinct machine learning algorithms across 101 unique combinations to compute the disulfidptosis score (DS). Patients were subsequently stratified into high and low DS cohorts based on median DS values. We then performed an exhaustive comparison between these cohorts, focusing on somatic mutations, clinical attributes, tumor microenvironment, and treatment responsiveness. Finally, we empirically validated the biological implications of a critical gene, KYNU, through assays in LUAD cell lines. We identified two DR clusters and there were great differences in overall survival (OS) and tumor microenvironment. We selected the "Least Absolute Shrinkage and Selection Operator (LASSO) + Random Survival Forest (RFS)" algorithm to develop a DS based on the average C-index across different cohorts. Our model effectively stratified LUAD patients into high- and low-DS subgroups, with this latter demonstrating superior OS, a reduced mutational landscape, enhanced immune status, and increased sensitivity to immunotherapy. Notably, the predictive accuracy of DS outperformed the published LUAD signature and clinical features. Finally, we validated the DS expression using clinical samples and found that inhibiting KYNU suppressed LUAD cells proliferation, invasiveness, and migration in vitro. The DR-based scoring system that we developed enabled accurate prognostic stratification of LUAD patients and provides important insights into the molecular mechanisms and treatment strategies for LUAD.

Reovirus infection of tumor cells reduces the expression of NKG2D ligands, leading to impaired NK-cell cytotoxicity and functionality.

In recent years, reoviruses have been of major interest in immunotherapy because of their oncolytic properties. Preclinical and clinical trials, in which reovirus was used for the treatment of melanoma and glioblastoma, have paved the way for future clinical use of reovirus. However, little is known about how reovirus infection affects the tumor microenvironment and immune response towards infected tumor cells. Studies have shown that reovirus can directly stimulate natural killer (NK) cells, but how reovirus affects cellular ligands on tumor cells, which are ultimately key to tumor recognition and elimination by NK cells, has not been investigated. We tested how reovirus infection affects the binding of the NK Group-2 member D (NKG2D) receptor, which is a dominant mediator of NK cell anti-tumor activity. Using models of human-derived melanoma and glioblastoma tumors, we demonstrated that NKG2D ligands are downregulated in tumor cells post-reovirus-infection due to the impaired translation of these ligands in reovirus-infected cells. Moreover, we showed that downregulation of NKG2D ligands significantly impaired the binding of NKG2D to infected tumor cells. We further demonstrated that reduced recognition of NKG2D ligands significantly alters NK cell anti-tumor cytotoxicity in human primary NK cells and in the NK cell line NK-92. Thus, this study provides novel insights into reovirus-host interactions and could lead to the development of novel reovirus-based therapeutics that enhance the anti-tumor immune response.

P16.03.A DEVELOPMENT OF INTRATHECAL DRUG DELIVERY PLATFORM TO CURE BREAST CANCER LEPTOMENINGEAL DISEASE BY DENDRITIC CELL VACCINE IN PRECLINICAL MODEL

Abstract BACKGROUND Leptomeningeal disease (LMD) is a rare form of metastasis in the meninges, a membrane surrounding the brain and spinal cord. Approximately 5% of advanced stage breast cancer (BC) will develop LMD and currently there is no cure. One reason for poor prognosis is the issue of drug accessibility to tumor sites due to the blood brain barrier (BBB) and blood-cerebral spinal fluid (CSF)-barrier. While the Ommaya reservoir is used clinically to overcome this challenge, there has not been an optimized preclinical model that allows researchers to adequately test novel therapies in the CSF space. MATERIAL AND METHODS The Forsyth lab have recently developed an MRI-compatible device called the “murine Ommaya” which mimics the Ommaya reservoir and allows repeated intrathecal (IT) administration of drugs in 3-7μl volume directly into CSF, bypassing BBB. In a joint effort with Dr. Czerniecki, whose lab have developed a pipeline for screening immunogenic MHC class II peptides from tumor-associated oncodrivers and subsequently generating tumor-targeting dendritic cells (DC), we have created a platform to IT deliver peptide-pulsed DCs directly targeting BC-LMD. RESULTS Currently, we have tested the efficacy of treatment in HER2+ LMD and triple negative breast cancer (TNBC) LMD models and found a very favorable response; LMD mice that received IT DC therapy exhibited reduced tumor burden and prolonged survival, and is more superior than systemic therapy. About 70% of mice from HER2+ LMD and 30% from TNBC LMD were cured of disease. Cured mice also exhibited resistance against LMD recurrence. CONCLUSION Our preliminary data suggest IT DC immunotherapy is effective against the incurable BC-LMD. We are currently investigating the mechanism(s) by which IT DC-initiated CD4 Th1 adaptive immune response against LMD. By using single-cell RNA-sequencing technique, we are analyzing the immune landscape in CSF tumor microenvironment in response to IT DC. FDA-approved phase I clinical trial has been funded by the US Department Of Defense. Future approach includes employing our IT DC vaccine platform in other cancer types, such as LMD from melanoma.

Associations of Multiparametric Breast MRI Features, Tumor-Infiltrating Lymphocytes, and Immune Gene Signature Scores Following a Single Dose of Trastuzumab in HER2-Positive Early-Stage Breast Cancer.

Dynamic biomarkers that permit the real-time monitoring of the tumor microenvironment response to therapy are an unmet need in breast cancer. Breast magnetic resonance imaging (MRI) has demonstrated value as a predictor of pathologic complete response and may reflect immune cell changes in the tumor microenvironment. The purpose of this pilot study was to investigate the value of breast MRI features as early markers of treatment-induced immune response. Fourteen patients with early HER2+ breast cancer were enrolled in a window-of-opportunity study where a single dose of trastuzumab was administered and both tissue and MRIs were obtained at the pre- and post-treatment stages. Functional diffusion-weighted and dynamic contrast-enhanced MRI tumor measures were compared with tumor-infiltrating lymphocytes (TILs) and RNA immune signature scores. Both the pre-treatment apparent diffusion coefficient (ADC) and the change in peak percent enhancement (DPE) were associated with increased tumor-infiltrating lymphocytes with trastuzumab therapy (r = -0.67 and -0.69, p < 0.01 and p < 0.01, respectively). Low pre-treatment ADC and a greater decrease in PE in response to treatment were also associated with immune-activated tumor microenvironments as defined by RNA immune signatures. Breast MRI features hold promise as biomarkers of early immune response to treatment in HER2+ breast cancer.

A Trojan Horse Delivery Vehicle Carrying Sirna Nanotherapeutics with Multiple Tumor Microenvironment Responsiveness Elicits Robust Antitumor Immune Responses in Situ via A "self-synergistic" Approach.

The potential of small interfering RNAs (siRNAs) in the treatment of malignant tumors has attracted increasing attention due to their inherent advantages. However, their therapeutic performance strongly depends on the efficiency of their cytoplasmic delivery in vivo by the delivery vehicle with good cellular permeability and histocompatibility. Herein, a polycationic carrier camouflaged with macrophage membrane was constructed biomimetically, which was condensed from endogenous spermine monomers through diselenide bonds. The developed Trojan horse delivery vehicle has desirable compression efficacy for siPDL1 as well as intracytoplasmic release properties derived from its sequential degradation triggered by redox microenvironment in tumor cells. Further, the co-loading of photosensitizer could mediate PDT accompanied by the generation of reactive oxygen species (ROS) upon light irradiation applied, which accelerated the degradation of the carrier as well as the release of cargoes while enhancing the PDL1 blockage-mediated immunotherapy by inducing in situ immunogenic cell death. Moreover, the synchronously delivered siPDL1 attenuated the ROS-induced increase in immunosuppressive PDL1 expression, thereby effectively eliciting a robust antitumor immune response with a "self-synergistic" manner in the xenograft breast cancer mouse model. This article is protected by copyright. All rights reserved.