Enhancement of glioma-specific immunity in mice by "NOBEL", an insulin-like growth factor 1 receptor antisense oligodeoxynucleotide

Autologous cell immunotherapy (IGV-001) with IGF-1R antisense oligonucleotide in newly diagnosed glioblastoma patients

Standard-of-care first-line therapy for patients with newly diagnosed glioblastoma (ndGBM) is maximal safe surgical resection, then concurrent radiotherapy and temozolomide, followed by maintenance temozolomide. IGV-001, the first product of the Goldspire™ platform, is a first-in-class autologous immunotherapeutic product that combines personalized whole tumor-derived cells with an antisense oligonucleotide (IMV-001) in implantable biodiffusion chambers, with the intent to induce a tumor-specific immune response in patients with ndGBM. Here, we describe the design and rationale of a randomized, double-blind, phase IIb trial evaluating IGV-001 compared with placebo, both followed by standard-of-care treatment in patients with ndGBM. The primary end point is progression-free survival, and key secondary end points include overall survival and safety.

Manipulating the tumor immune microenvironment to improve cancer immunotherapy: IGF1R, a promising target

Cancer immunotherapy has made impressive advances in improving the outcome of patients affected by malignant diseases. Nonetheless, some limitations still need to be tackled to more efficiently and safely treat patients, in particular for those affected by solid tumors. One of the limitations is related to the immunosuppressive tumor microenvironment (TME), which impairs anti-tumor immunity. Efforts to identify targets able to turn the TME into a milieu more auspicious to current immuno-oncotherapy is a real challenge due to the high redundancy of the mechanisms involved. However, the insulin-like growth factor 1 receptor (IGF1R), an attractive drug target for cancer therapy, is emerging as an important immunomodulator and regulator of key immune cell functions. Here, after briefly summarizing the IGF1R signaling pathway in cancer, we review its role in regulating immune cells function and activity, and discuss IGF1R as a promising target to improve anti-cancer immunotherapy.

Drugging IGF-1R in cancer: New insights and emerging opportunities

The insulin-like growth factor (IGF) axis plays important roles in cancer development and metastasis. The type 1 IGF receptor (IGF-1R) is a key member in the IGF axis and has long been recognized for its oncogenic role in multiple cancer lineages. Here we review the occurrence of IGF-1R aberrations and activation mechanisms in cancers, which justify the development of anti-IGF-1R therapies. We describe the therapeutic agents available for IGF-1R inhibition, with focuses on the recent or ongoing pre-clinical and clinical studies. These include antisense oligonucleotide, tyrosine kinase inhibitors and monoclonal antibodies which may be conjugated with cytotoxic drug. Remarkably, simultaneous targeting of IGF-1R and several other oncogenic vulnerabilities has shown early promise, highlighting the potential benefits of combination therapy. Further, we discuss the challenges in targeting IGF-1R so far and new concepts to improve therapeutic efficacy such as blockage of the nuclear translocation of IGF-1R.

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.

Phase Ib Clinical Trial of IGV-001 for Patients with Newly Diagnosed Glioblastoma

PURPOSE

Despite standard of care (SOC) established by Stupp, glioblastoma remains a uniformly poor prognosis. We evaluated IGV-001, which combines autologous glioblastoma tumor cells and an antisense oligonucleotide against IGF type 1 receptor (IMV-001), in newly diagnosed glioblastoma.

PATIENTS AND METHODS

This open-label protocol was approved by the Institutional Review Board at Thomas Jefferson University. Tumor cells collected during resection were treated ex vivo with IMV-001, encapsulated in biodiffusion chambers with additional IMV-001, irradiated, then implanted in abdominal acceptor sites. Patients were randomized to four exposure levels, and SOC was initiated 4-6 weeks later. On the basis of clinical improvements, randomization was halted after patient 23, and subsequent patients received only the highest exposure. Safety and tumor progression were primary and secondary objectives, respectively. Time-to-event outcomes were compared with the SOC arms of published studies.

RESULTS

Thirty-three patients were enrolled, and median follow-up was 3.1 years. Six patients had adverse events (grade ≤3) possibly related to IGV-001. Median progression-free survival (PFS) was 9.8 months in the intent-to-treat population (vs. SOC, 6.5 months; P = 0.0003). In IGV-001-treated patients who met Stupp-eligible criteria, PFS was 11.6 months overall (n = 22; P = 0.001) and 17.1 months at the highest exposure (n = 10; P = 0.0025). The greatest overall survival was observed in Stupp-eligible patients receiving the highest exposure (median, 38.2 months; P = 0.044). Stupp-eligible patients with methylated O⁶-methylguanine-DNA methyltransferase promoter (n = 10) demonstrated median PFS of 38.4 months (P = 0.0008). Evidence of immune activation was noted.

CONCLUSIONS

IGV-001 was well tolerated, PFS compared favorably with SOC, and evidence suggested an immune-mediated mechanism (ClinicalTrials.gov: NCT02507583).

Intratumor injection of CCL21-coupled vault nanoparticles is associated with reduction in tumor volume in an in vivo model of glioma

PURPOSE

Glioblastoma (GBM) is the most common and malignant primary adult brain tumor. Current care includes surgical resection, radiation, and chemotherapy. Recent clinical trials for GBM have demonstrated extended survival using interventions such as tumor vaccines or tumor-treating fields. However, prognosis generally remains poor, with expected survival of 20 months after randomization. Chemokine-based immunotherapy utilizing CCL21 locally recruits lymphocytes and dendritic cells to enhance host antitumor response. Here, we report a preliminary study utilizing CPZ-vault nanoparticles as a vehicle to package, protect, and steadily deliver therapy to optimize CCL21 therapy in a murine flank model of GBM.

METHODS

GL261 cells were subcutaneously injected into the left flank of eight-week-old female C57BL/6 mice. Mice were treated with intratumoral injections of either: (1) CCL21-packaged vault nanoparticles (CPZ-CCL21), (2) free recombinant CCL21 chemokine empty vault nanoparticles, (3) empty vault nanoparticles, or 4) PBS.

RESULTS

The results of this study showed that CCL21-packaged vault nanoparticle injections can decrease the tumor volume in vivo. Additionally, this study showed mice injected with CCL21-packaged vault nanoparticle had the smallest average tumor volume and remained the only treatment group with a negative percent change in tumor volume.

CONCLUSIONS

This preliminary study establishes vault nanoparticles as a feasible vehicle to increase drug delivery and immune response in a flank murine model of GBM. Future animal studies involving an intracranial orthotopic tumor model are required to fully evaluate the potential for CCL21-packaged vault nanoparticles as a strategy to bypass the blood brain barrier, enhance intracranial immune activity, and improve intracranial tumor control and survival.

Exosomal αvβ6 integrin is required for monocyte M2 polarization in prostate cancer

Therapeutic approaches aimed at curing prostate cancer are only partially successful given the occurrence of highly metastatic resistant phenotypes that frequently develop in response to therapies. Recently, we have described αvβ6, a surface receptor of the integrin family as a novel therapeutic target for prostate cancer; this epithelial-specific molecule is an ideal target since, unlike other integrins, it is found in different types of cancer but not in normal tissues. We describe a novel αvβ6-mediated signaling pathway that has profound effects on the microenvironment. We show that αvβ6 is transferred from cancer cells to monocytes, including β6-null monocytes, by exosomes and that monocytes from prostate cancer patients, but not from healthy volunteers, express αvβ6. Cancer cell exosomes, purified via density gradients, promote M2 polarization, whereas αvβ6 down-regulation in exosomes inhibits M2 polarization in recipient monocytes. Also, as evaluated by our proteomic analysis, αvβ6 down-regulation causes a significant increase in donor cancer cells, and their exosomes, of two molecules that have a tumor suppressive role, STAT1 and MX1/2. Finally, using the Pten^pc-/- prostate cancer mouse model, which carries a prostate epithelial-specific Pten deletion, we demonstrate that αvβ6 inhibition in vivo causes up-regulation of STAT1 in cancer cells. Our results provide evidence of a novel mechanism that regulates M2 polarization and prostate cancer progression through transfer of αvβ6 from cancer cells to monocytes through exosomes.

MicroRNA-17-5p regulated apoptosis-related protein expression and radiosensitivity in oral squamous cell carcinoma caused by betel nut chewing

Betel nut chewing is associated with oral cavity cancer. Radiotherapy is one of the therapeutic approaches. Here, we used miR-17-5p antisense oligonucleotides (AS-ODNs) and human apoptosis protein array to clarify which apoptosis-related proteins are increased or decreased by miR-17-5p in betel nut chewing- oral squamous cell carcinoma OC3 cells. Furthermore, miR-17-5p AS-ODN was used to evaluate the radio-sensitization effects both in vitro and in vivo. An OC3 xenograft tumor model in severe combined immunodeficiency mice was used to determine the effect of miR-17-5p AS ODN on tumor irradiation. We simultaneously detected the relative expressions of 35 apoptosis-related proteins in irradiated OC3 cells that were treated with miR-17-5p AS-ODN or a control ODN. Several proteins, including p21, p53, TNF RI, FADD, cIAP-1, HIF-1α, and TRAIL R1, were found to be up- or downregulated by miR-17-5p in OC3 cells; their expression patterns were also confirmed by Western blotting. We further clarified the role of p53 in irradiated OC3 cells, using a p53 overexpression strategy. The results revealed that the enhancement of p53 expression significantly enhanced radiation-induced G2/M arrest of the OC3 cells. In the in vivo study, treatment of miR-17-5p AS-ODN before irradiation significantly enhanced p53 expression and reduced tumor growth. These results suggest that miR-17-5p increases or decreases apoptosis-related proteins in irradiated OC3 cells; its effect on p53 protein expression contributes to the modulation of the radiosensitivity of the OC3 cells.

Type 1 Immune Mechanisms Driven by the Response to Infection with Attenuated Rabies Virus Result in Changes in the Immune Bias of the Tumor Microenvironment and Necrosis of Mouse GL261 Brain Tumors

Immunotherapeutic strategies for malignant glioma have to overcome the immunomodulatory activities of M2 monocytes that appear in the circulation and as tumor-associated macrophages (TAMs). M2 cell products contribute to the growth-promoting attributes of the tumor microenvironment (TME) and bias immunity toward type 2, away from the type 1 mechanisms with antitumor properties. To drive type 1 immunity in CNS tissues, we infected GL261 tumor-bearing mice with attenuated rabies virus (RABV). These neurotropic viruses spread to CNS tissues trans-axonally, where they induce a strong type 1 immune response that involves Th1, CD8, and B cell entry across the blood-brain barrier and virus clearance in the absence of overt sequelae. Intranasal infection with attenuated RABV prolonged the survival of mice bearing established GL261 brain tumors. Despite the failure of virus spread to the tumor, infection resulted in significantly enhanced tumor necrosis, extensive CD4 T cell accumulation, and high levels of the proinflammatory factors IFN-γ, TNF-α, and inducible NO synthase in the TME merely 4 d postinfection, before significant virus spread or the appearance of RABV-specific immune mechanisms in CNS tissues. Although the majority of infiltrating CD4 cells appeared functionally inactive, the proinflammatory changes in the TME later resulted in the loss of accumulating M2 and increased M1 TAMs. Mice deficient in the Th1 transcription factor T-bet did not gain any survival advantage from RABV infection, exhibiting only limited tumor necrosis and no change in TME cytokines or TAM phenotype and highlighting the importance of type 1 mechanisms in this process.

Focus on Extracellular Vesicles: Development of Extracellular Vesicle-Based Therapeutic Systems

Many types of cells release phospholipid membrane vesicles thought to play key roles in cell-cell communication, antigen presentation, and the spread of infectious agents. Extracellular vesicles (EVs) carry various proteins, messenger RNAs (mRNAs), and microRNAs (miRNAs), like a “message in a bottle” to cells in remote locations. The encapsulated molecules are protected from multiple types of degradative enzymes in body fluids, making EVs ideal for delivering drugs. This review presents an overview of the potential roles of EVs as natural drugs and novel drug-delivery systems.