A biologic-device combination product delivering tumor-derived antigens elicits immunogenic cell death-associated immune responses against glioblastoma.

BACKGROUND: IGV-001 is a personalized, autologous cancer cell-based immunotherapy conceived to deliver a tumor-derived antigenic payload in the context of immunostimulatory signals to patients with glioblastoma (GBM). IGV-001 consists of patient-derived GBM cells treated with an antisense oligodeoxynucleotide against insulin-like growth factor 1 receptor (IGF1R) and placed in proprietary biodiffusion chambers (BDCs). The BDCs are then exposed to 5-6 Gy radiation and implanted at abdominal sites for ~48 hours. IGV-001 has previously been shown to be generally safe with promising clinical activity in newly diagnosed GBM patients. METHODS: Mouse (m) or human (h) variants of IGV-001 were prepared using GL261 mouse GBM cells or human GBM cells, respectively. BDCs containing vehicle or mIGV-001 were implanted in the flanks of C57BL/6 albino female mice in preventative and therapeutic experiments, optionally in combination with a programmed cell death 1 (PD-1) blocker. Bioactivity of the general approach was also measured against hepatocellular carcinoma Hepa 1-6 cells. Mice were followed for the growth of subsequently implanted or pre-existing tumors and survival. Draining lymph nodes from mice receiving mIGV-001 were immunophenotyped. mIGV-001 and hIGV-001 were analyzed for extracellular ATP and high mobility group box 1 (HMGB1) as indicators of immunogenic cell death (ICD), along with flow cytometric analysis of viability, surface calreticulin, and reactive oxygen species. Stress and cell death-related pathways were analyzed by immunoblotting. RESULTS: IGV-001 causes oxidative and endoplasmic reticulum stress in GL261 cells, resulting in a cytotoxic response that enables the release of antigenic material and immunostimulatory, ICD-associated molecules including ATP and HMGB1 from BDCs. Immunophenotyping confirmed that IGV-001 increases the percentage of dendritic cells, as well as effector, and effector memory T cells in BDC-draining lymph nodes. Consistent with these observations, preventative IGV-001 limited tumor progression and extended overall survival in mice intracranially challenged with GL261 cells, a benefit that was associated with an increase in tumor-specific T cells with effector features. Similar findings were obtained in the Hepa 1-6 model. Moreover, therapeutically administered IGV-001 combined with PD-1 delayed progression in GBM-bearing mice. CONCLUSIONS: These results support treatment with IGV-001 to induce clinically relevant ICD-driven anticancer immune responses in patients with GBM.

Challenges and Opportunities for Immunotherapeutic Intervention against Myeloid Immunosuppression in Glioblastoma.

Glioblastoma multiforme (GBM), the most common and deadly brain cancer, exemplifies the paradigm that cancers grow with help from an immunosuppressive tumor microenvironment (TME). In general, TME includes a large contribution from various myeloid lineage-derived cell types, including (in the brain) altered pathogenic microglia as well as monocyte-macrophages (Macs), myeloid-derived suppressor cells (MDSC) and dendritic cell (DC) populations. Each can have protective roles, but has, by definition, been coopted by the tumor in patients with progressive disease. However, evidence demonstrates that myeloid immunosuppressive activities can be reversed in different ways, leading to enthusiasm for this therapeutic approach, both alone and in combination with potentially synergistic immunotherapeutic and other strategies. Here, we review the current understanding of myeloid cell immunosuppression of anti-tumor responses as well as potential targets, challenges, and developing means to reverse immunosuppression with various therapeutics and their status. Targets include myeloid cell colony stimulating factors (CSFs), insulin-like growth factor 1 (IGF1), several cytokines and chemokines, as well as CD40 activation and COX2 inhibition. Approaches in clinical development include antibodies, antisense RNA-based drugs, cell-based combinations, polarizing cytokines, and utilizing Macs as a platform for Chimeric Antigen Receptors (CAR)-based tumor targeting, like with CAR-T cells. To date, promising clinical results have been reported with several of these approaches.

Characterization of pore structure in biologically functional poly(2-hydroxyethyl methacrylate)-poly(ethylene glycol) diacrylate (PHEMA-PEGDA).

A copolymer composed of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(ethylene glycol) diacrylate (PEGDA) (PHEMA-PEGDA) is structurally versatile. Its structure can be adjusted using the following porogens: water, sucrose, and benzyl alcohol. Using phase separation technique, a variety of surface architectures and pore morphologies were developed by adjusting porogen volume and type. The water and sucrose porogens were effective in creating porous and cytocompatible PHEMA-PEGDA scaffolds. When coated with collagen, the PHEMA-PEGDA scaffolds accommodated cell migration. The PHEMA-PEGDA scaffolds are easy to produce, non-toxic, and mechanically stable enough to resist fracture during routine handling. The PHEMA-PEGDA structures presented in this study may expedite the current research effort to engineer tissue scaffolds that provide both structural stability and biological activity.

Engineering copolymeric artificial cornea with salt porogen.

Artificial corneas or keratoprostheses (KPros) are designed to replace diseased or damaged cornea. Although many synthetic KPros have been developed, current products are often inappropriate or inadequate for long term use due to ineffective host integration. This study presents an alternative approach of engineering a KPro that comprises a combination of poly (2-hydroxyethyl methacrylate) (PHEMA), poly (methyl methacrylate) (PMMA), and sodium chloride (NaCl) as porogen. Based on the core-skirt model for KPro, the porous outer portion of artificial cornea (skirt) was engineered by combining NaCl with HEMA and MMA monomers to promote tissue ingrowth from the host. The central optic (core) was designed to provide >85% light transmission in the visible wavelength range and securely attached to the skirt. Mechanical tensile data indicated that our KPro (referred to as salt porogen KPro) is mechanically stable to maintain its structure in the ocular environment and during implantation. Using human corneal fibroblasts (HCFs), we demonstrate that the cells grew into the pores of the skirt and proliferated, suggesting biointegration is adequately achieved. This novel PHEMA-PMMA copolymeric salt porogen KPro may offer a cornea replacement option that leads to minimal risk of corneal melting by permitting sufficient tissue ingrowth and mass transport.

Designing a gas foamed scaffold for keratoprosthesis.

Artificial corneas or keratoprostheses are intended to replace diseased or damaged cornea in the event that vision cannot be restored using donor cornea tissue. A new class of artificial cornea comprising a combination of poly (2-hydroxyethyl methacrylate) and poly (methyl methacrylate) was developed which was fabricated using a gas foaming technique. Referred to as the gas-foamed KPro, it was designed to permit clear vision and secure host biointegration to facilitate long-term stability of the device. In vitro assessments show cell growth into the body of the porous edge or skirt of the gas-foamed KPro. The optically transparent center (i.e., core) of the device demonstrates 85 - 90% of light transmittance in the 500 - 700 nm wavelength range. Mechanical tensile data indicates that the gas-foamed KPro is mechanically stable enough to maintain its structure in the ocular environment and also during implantation. The gas-foamed KPro may provide an alternate option for cornea replacement that minimizes post implantation tissue melting, thereby achieving long-term stability in the ocular environment.