Assessment of the immune landscapes of advanced ovarian cancer in an optimized in vivo model

Cisplatin resistance alters ovarian cancer spheroid formation and impacts peritoneal invasion

Epithelial ovarian cancer (EOC) is an aggressive and lethal gynaecologic malignancy due to late diagnosis and acquired resistance to chemotherapeutic drugs, such as cisplatin. EOC metastasis commonly occurs through the extensive dissemination of multicellular aggregates, formed of cells originally shed from the primary ovarian tumour, within the peritoneal cavity. However, little is known about how cisplatin resistance (CR) alters the biophysical properties of EOC multicellular aggregates and how this impacts metastasis. In this interdisciplinary study, light and atomic force microscopy was used, alongside quantitative gene and protein expression analysis, to reveal distinct differences in the biophysical properties of CR spheroids, which correlated with altered protein expression of plasminogen activator inhibitor-1 (PAI-1) and Tenascin-C. CR SKOV3 spheroids (IC50: 25.5 µM) had a significantly greater area and perimeter and were less spherical, with a reduced Young's modulus, (p < 0.01) compared to parental (P) SKOV3 spheroids (IC50: 5.4 µM). Gene expression arrays revealed upregulation of genes associated with cell adhesion, extracellular matrix (ECM) and epithelial-to-mesenchymal transition (EMT) in CR spheroids, while immunofluorescence assays demonstrated increased protein expression of PAI-1 (p < 0.05; implicated in cell adhesion) and reduced protein expression of Tenascin-C (p < 0.01; implicated in elasticity) in CR spheroids compared to P spheroids. Furthermore, the CR spheroids demonstrated altered interactions with a surface that mimics the peritoneal lining post mesothelial clearance (Matrigel). CR spheroids were significantly less adhesive with reduced disaggregation on Matrigel surfaces, compared to P spheroids (p < 0.05), while CR cells were more invasive compared to P cells. The combined characterisation of the biophysical and biological roles of EOC multicellular aggregates in drug resistance and metastasis highlight key proteins which could be responsible for altered metastatic progression that may occur in patients that present with cisplatin resistance.

Egfl6 promotes ovarian cancer progression by enhancing the immunosuppressive functions of tumor-associated myeloid cells

Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) play a critical role in resistance to immunotherapy. In this study, we identified epidermal growth factor-like 6 (Egfl6) as a regulator of myeloid cell functions. Our analyses indicated that Egfl6, via binding with β3 integrins and activation of p38 and SYK signaling, acts as a chemotactic factor for myeloid cell migration and promotes their differentiation toward an immunosuppressive state. In syngeneic mouse models of ovarian cancer (OvCa), tumor expression of Egfl6 increased the intratumoral accumulation of polymorphonuclear (PMN) MDSCs and TAMs and their expression of immunosuppressive factors, including CXCL2, IL-10, and PD-L1. Consistent with this, in an immune 'hot' tumor model, Egfl6 expression eliminated response to anti-PD-L1 therapy, while Egfl6 neutralizing antibody decreased the accumulation of tumor-infiltrating CD206+ TAMs and PMN-MDSCs and restored the efficacy of anti-PD-L1 therapy. Supporting a role in human tumors, in human OvCa tissue samples, areas of high EGFL6 expression colocalized with myeloid cell infiltration. scRNA-Seq analyses revealed a correlation between EGFL6 and immune cell expression of immunosuppressive factors. Our data provide mechanistic insights into the oncoimmunologic functions of EGFL6 in mediating tumor immune suppression and identified EGFL6 as a potential therapeutic target to enhance immunotherapy in patients with OvCa.

Paracrine Ovarian Cancer Cell-Derived CSF1 Signaling Regulates Macrophage Migration Dynamics in a 3D Microfluidic Model that Recapitulates In Vivo Infiltration Patterns in Patient-Derived Xenografts

A high density of macrophages in the ovarian cancer microenvironment is associated with disease progression and poor outcomes. Understanding cancer-macrophage interaction mechanisms that establish this pro-tumorigenic microenvironment is critical for developing macrophage-targeted therapies. Here, 3D microfluidic assays and patient-derived xenografts are utilized to define the role of cancer-derived colony stimulating factor 1 (CSF1) on macrophage infiltration dynamics toward ovarian cancer cells. It is demonstrated that multiple ovarian cancer models promote the infiltration of macrophages into a 3D extracellular matrix in vitro in a cell density-dependent manner. Macrophages exhibit directional migration and increased migration speed under both direct interactions with cancer cells embedded within the matrix and paracrine crosstalk with cancer cells seeded in an independent microchannel. It is also found that platinum-based chemotherapy increases macrophage recruitment and the levels of cancer cell-derived CSF1. Targeting CSF1 signaling under baseline or chemotherapy-treatment conditions reduces the number of infiltrated macrophages. It is further shown that results obtained with the 3D microfluidic model reflect the recruitment profiles of macrophages in patient-derived xenografts in vivo. These findings highlight the role of CSF1 signaling in establishing macrophage-rich ovarian cancer microenvironments, as well as the utility of microfluidic models in recapitulating 3D tumor ecosystems and dissecting cancer-macrophage signaling.

Injectable Nanocomposite Hydrogels Improve Intraperitoneal Co-delivery of Chemotherapeutics and Immune Checkpoint Inhibitors for Enhanced Peritoneal Metastasis Therapy

Intraperitoneal co-delivery of chemotherapeutic drugs (CDs) and immune checkpoint inhibitors (ICIs) brings hope to improve treatment outcomes in patients with peritoneal metastasis from ovarian cancer (OC). However, current intraperitoneal drug delivery systems face issues such as rapid drug clearance from lymphatic drainage, heterogeneous drug distribution, and uncontrolled release of therapeutic agents into the peritoneal cavity. Herein, we developed an injectable nanohydrogel by combining carboxymethyl chitosan (CMCS) with bioadhesive nanoparticles (BNPs) based on polylactic acid-hyperbranched polyglycerol. This system enables the codelivery of CD and ICI into the intraperitoneal space to extend drug retention. The nanohydrogel is formed by cross-linking of aldehyde groups on BNPs with amine groups on CMCS via reversible Schiff base bonds, with CD and ICI loaded separately into BNPs and CMCS network. BNP/CMCS nanohydrogel maintained the activity of the biomolecules and released drugs in a sustained manner over a 7 day period. The adhesive property, through the formation of Schiff bases with peritoneal tissues, confers BNPs with an extended residence time in the peritoneal cavity after being released from the nanohydrogel. In a mouse model, BNP/CMCS nanohydrogel loaded with paclitaxel (PTX) and anti-PD-1 antibodies (αPD-1) significantly suppressed peritoneal metastasis of OC compared to all other tested groups. In addition, no systemic toxicity of nanohydrogel-loaded PTX and αPD-1 was observed during the treatment, which supports potential translational applications of this delivery system.

Establishment of highly metastatic ovarian cancer model with omental tropism via in vivo selection

Epithelial ovarian cancer (OC) is often diagnosed at an advanced stage with peritoneal metastasis, and preclinical models mimicking the natural course of OC peritoneal metastasis are essential to improve treatment. We implanted ES2 and ID8 cells in the ovaries of mice and obtained highly metastatic (HM) sublines from their omental metastases after three cycles in vivo selection. Orthotopic xenografts derived from the HM sublines showed enhanced omental tropism and more extensive metastasis with earlier onset. The HM cells exhibited increased in vitro migration and invasion properties, and RNA sequencing revealed that the genes related to epithelial-mesenchymal transition and extracellular matrix regulation were significantly altered in the HM cells. Among them, the upregulated genes were significantly associated with poorer survival in OC patients. In conclusion, these HM sublines can be leveraged to establish spontaneous metastatic OC mouse models, which may serve as ideal preclinical models for anti-metastasis therapy for OC patients.

Nanomedicine Strategies for Heating "Cold" Ovarian Cancer (OC): Next Evolution in Immunotherapy of OC

Immunotherapy has revolutionized cancer treatment, dramatically improving survival rates of melanoma and lung cancer patients. Nevertheless, immunotherapy is almost ineffective against ovarian cancer (OC) due to its cold tumor immune microenvironment (TIM). Many traditional medications aimed at remodeling TIM are often associated with severe systemic toxicity, require frequent dosing, and show only modest clinical efficacy. In recent years, emerging nanomedicines have demonstrated extraordinary immunotherapeutic effects for OC by reversing the TIM because the physical and biochemical features of nanomedicines can all be harnessed to obtain optimal and expected tissue distribution and cellular uptake. However, nanomedicines are far from being widely explored in the field of OC immunotherapy due to the lack of appreciation for the professional barriers of nanomedicine and pathology, limiting the horizons of biomedical researchers and materials scientists. Herein, a typical cold tumor-OC is adopted as a paradigm to introduce the classification of TIM, the TIM characteristics of OC, and the advantages of nanomedicines for immunotherapy. Subsequently, current nanomedicines are comprehensively summarized through five general strategies to substantially enhance the efficacy of immunotherapy by heating the cold OC. Finally, the challenges and perspectives of this expanding field for improved development of clinical applications are also discussed.