Enhanced anti-metastatic bioactivity of an IGF-TRAP re-engineered to improve physicochemical properties

Transcranial Magnetic Stimulation Enhances the Therapeutic Effect of IGF-Trap in Intracerebral Glioma Models

Background: Glioblastoma multiforme is an aggressive malignancy with a dismal 5-year survival rate of 5-10%. Current therapeutic options are limited, due in part to drug exclusion by the blood-brain barrier (BBB). We have previously shown that high-amplitude repetitive transcranial magnetic stimulation (rTMS) in rats allowed the delivery across the BBB of an IGF signaling inhibitor-IGF-Trap. The objective of this study was to assess the therapeutic effect of IGF-Trap when delivered in conjunction with rTMS on the intracerebral growth of glioma. Results: We found that systemic administration of IGF-Trap without rTMS had a minimal effect on the growth of orthotopically injected glioma cells in rats and mice, compared to control animals injected with vehicle only or treated with sham rTMS. In rats treated with a combination of rTMS and IGF-Trap, we observed a growth retardation of C6 tumors for up to 14 days post-tumor cell injection, although tumors eventually progressed. In mice, tumors were detectable in all control groups by 14-17 days post-injection of glioma GL261 cells and progressed rapidly thereafter. In mice treated with rTMS prior to IGF-Trap administration, tumor growth was inhibited or delayed, although the tumors also eventually progressed. Conclusion: The results showed that rTMS could increase the anti-tumor effect of IGF-Trap during the early phases of tumor growth. Further optimization of the rTMS protocol is required to improve survival outcomes.

Extracellular Interactors of the IGF System: Impact on Cancer Hallmarks and Therapeutic Approaches

Dysregulation of the insulin-like growth factor (IGF) system determines the onset of various pathological conditions, including cancer. Accordingly, therapeutic strategies have been developed to block this system in tumor cells, but the results of clinical trials have been disappointing. After decades of research in the field, it is safe to say that one of the major reasons underlying the poor efficacy of anti-IGF-targeting agents is derived from an underestimation of the molecular complexity of this axis. Genetic, transcriptional, post-transcriptional and functional interactors interfere with the activity of canonical components of this axis, supporting the need for combinatorial approaches to effectively block this system. In addition, cancer cells interface with a multiplicity of factors from the extracellular compartment, which strongly affect cell destiny. In this review, we will cover novel extracellular mechanisms contributing to IGF system dysregulation and the implications of such dangerous liaisons for cancer hallmarks and responses to known and new anti-IGF drugs. A deeper understanding of both the intracellular and extracellular microenvironments might provide new impetus to better decipher the complexity of the IGF axis in cancer and provide new clues for designing novel therapeutic approaches.

Complementary Cell Lines for Protease Gene-Deleted Single-Cycle Adenovirus Vectors

To increase the safety of adenovirus vector (AdV)-based therapy without reducing its efficacy, a single-cycle adenovirus vector (SC-AdV) with a deletion in the protease gene (PS) was developed in order to be used as a substitute for the replication-competent adenovirus (RC-AdV). Since no infectious viral particles are assembled, there is no risk of viral shedding. The complementary cell lines for this developed AdV proved to be suboptimal for the production of viral particles and require the presence of fetal bovine serum (FBS) to grow. In the current study, we produced both stable pools and clones using adherent and suspension cells expressing the PS gene. The best adherent cell pool can be used in the early stages for the generation of protease-deleted adenovirus, plaque purification, and titration. Using this, we produced over 3400 infectious viral particles per cell. Additionally, the best suspension subclone that was cultured in the absence of FBS yielded over 4000 infectious viral particles per cell. Harvesting time, culture media, and concentration of the inducer for the best suspension subclone were further characterized. With these two types of stable cells (pool and subclone), we successfully improved the titer of protease-deleted adenovirus in adherent and suspension cultures and eliminated the need for FBS during the scale-up production. Eight lots of SC-AdV were produced in the best suspension subclone at a scale of 2 to 8.2 L. The viral and infectious particle titers were influenced by the virus backbone and expressed transgene.

Insulin‑like growth factor axis: A potential nanotherapy target for resistant cervical cancer tumors (Review)

Cervical cancer is among the most frequently occurring neoplasms worldwide, and it particularly affects individuals in developing countries. Factors such as the low quality of screening tests, the high incidence of locally advanced cancer stages and the intrinsic resistance of certain tumors are the main causes of failure in the treatment of this neoplasm. Due to advances in the understanding of carcinogenic mechanisms and bioengineering research, advanced biological nanomaterials have been manufactured. The insulin-like growth factor (IGF) system comprises multiple growth factor receptors, including IGF receptor 1. These receptors are activated by binding to their respective growth factor ligands, IGF-1 and IGF-2, and insulin, and play an important role in the development, maintenance, progression, survival and treatment resistance of cervical cancer. In the present review, the role of the IGF system in cervical cancer and three nanotechnological applications that use elements of this system are described, namely Trap decoys, magnetic iron oxide nanoparticles and protein nanotubes. Their use in the treatment of resistant cervical cancer tumors is also discussed.

Targeting the IGF-Axis Potentiates Immunotherapy for Pancreatic Ductal Adenocarcinoma Liver Metastases by Altering the Immunosuppressive Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy, resistant to chemotherapy and associated with high incidence of liver metastases and poor prognosis. Using murine models of aggressive PDAC, we show here that in mice bearing hepatic metastases, treatment with the IGF-Trap, an inhibitor of type I insulin-like growth factor receptor (IGF-IR) signaling, profoundly altered the local, immunosuppressive tumor microenvironment in the liver, curtailing the recruitment of myeloid-derived suppressor cells, reversing innate immune cell polarization and inhibiting metastatic expansion. Significantly, we found that immunotherapy with anti-PD-1 antibodies also reduced the growth of experimental PDAC liver metastases, and this effect was enhanced when combined with IGF-Trap treatment, resulting in further potentiation of a T-cell response. Our results show that a combinatorial immunotherapy based on dual targeting of the prometastatic immune microenvironment of the liver via IGF blockade, on one hand, and reversing T-cell exhaustion on the other, can provide a significant therapeutic benefit in the management of PDAC metastases.

Purification of Modified Therapeutic Proteins Available on the Market: An Analysis of Chromatography-Based Strategies

Proteins, which have inherent biorecognition properties, have long been used as therapeutic agents for the treatment of a wide variety of clinical indications. Protein modification through covalent attachment to different moieties improves the therapeutic's pharmacokinetic properties, affinity, stability, confers protection against proteolytic degradation, and increases circulation half-life. Nowadays, several modified therapeutic proteins, including PEGylated, Fc-fused, lipidated, albumin-fused, and glycosylated proteins have obtained regulatory approval for commercialization. During its manufacturing, the purification steps of the therapeutic agent are decisive to ensure the quality, effectiveness, potency, and safety of the final product. Due to the robustness, selectivity, and high resolution of chromatographic methods, these are recognized as the gold standard in the downstream processing of therapeutic proteins. Moreover, depending on the modification strategy, the protein will suffer different physicochemical changes, which must be considered to define a purification approach. This review aims to deeply analyze the purification methods employed for modified therapeutic proteins that are currently available on the market, to understand why the selected strategies were successful. Emphasis is placed on chromatographic methods since they govern the purification processes within the pharmaceutical industry. Furthermore, to discuss how the modification type strongly influences the purification strategy, the purification processes of three different modified versions of coagulation factor IX are contrasted.

Unraveling the IGF System Interactome in Sarcomas Exploits Novel Therapeutic Options

Aberrant bioactivity of the insulin-like growth factor (IGF) system results in the development and progression of several pathologic conditions including cancer. Preclinical studies have shown promising anti-cancer therapeutic potentials for anti-IGF targeted therapies. However, a clear but limited clinical benefit was observed only in a minority of patients with sarcomas. The molecular complexity of the IGF system, which comprises multiple regulators and interactions with other cancer-related pathways, poses a major limitation in the use of anti-IGF agents and supports the need of combinatorial therapeutic strategies to better tackle this axis. In this review, we will initially highlight multiple mechanisms underlying IGF dysregulation in cancer and then focus on the impact of the IGF system and its complexity in sarcoma development and progression as well as response to anti-IGF therapies. We will also discuss the role of Ephrin receptors, Hippo pathway, BET proteins and CXCR4 signaling, as mediators of sarcoma malignancy and relevant interactors with the IGF system in tumor cells. A deeper understanding of these molecular interactions might provide the rationale for novel and more effective therapeutic combinations to treat sarcomas.

IGF2 Mediates Resistance to Isoform-Selective-Inhibitors of the PI3K in HPV Positive Head and Neck Cancer

Simple Summary

In the current study, we delineate the molecular mechanisms of acquisition of resistance to two isoform-selective inhibitors of PI3K (isiPI3K), alpelisib and taselisib, in human papillomavirus positive head and neck cell lines. By comparing RNA sequencing of isiPI3K-sensitive tumor cells and their corresponding isiPI3K-acquired-resistant tumor cells, we found that overexpression of insulin growth factor 2 (IGF2) is associated with the resistance phenotype. We further demonstrated by gain and loss of function studies that IGF2 plays a causative role in limiting the sensitivity of human papillomavirus-positive head and neck cell lines. Moreover, we show that blocking IGF2 stimulation activity, using an inhibitor of the IGF1 receptor (IGF1R), enhances isiPI3K efficacy and displays a synergistic anti-tumor effect in vitro and superior anti-tumor activity ex vivo and in vivo.

Abstract

Over 50% of human papilloma positive head-and-neck cancer (HNC^HPV+) patients harbor genomic-alterations in PIK3CA, leading to hyperactivation of the phosphatidylinositol-4, 5-bisphosphate 3-kinase (PI3K) pathway. Nevertheless, despite PI3K pathway activation in HNC^HPV+ tumors, the anti-tumor activities of PI3K pathway inhibitors are moderate, mostly due to the emergence of resistance. Thus, for potent and long-term tumor management, drugs blocking resistance mechanisms should be combined with PI3K inhibitors. Here, we delineate the molecular mechanisms of the acquisition of resistance to two isoform-selective inhibitors of PI3K (isiPI3K), alpelisib (BYL719) and taselisib (GDC0032), in HNC^HPV+ cell lines. By comparing the transcriptional landscape of isiPI3K-sensitive tumor cells with that of their corresponding isiPI3K-acquired-resistant tumor cells, we found upregulation of insulin growth factor 2 (IGF2) in the resistant cells. Mechanistically, we show that upon isiPI3K treatment, isiPI3K-sensitive tumor cells upregulate the expression of IGF2 to induce cell proliferation via the activation of the IGF1 receptor (IGF1R). Stimulating tumor cells with recombinant IGF2 limited isiPI3K efficacy and released treated cells from S phase arrest. Knocking-down IGF2 with siRNA, or blocking IGF1R with AEW541, resulted in superior anti-tumor activity of isiPI3K in vitro and ex vivo. In vivo, the combination of isiPI3K and IGF1R inhibitor induced stable disease in mice bearing either tumors generated by the HNC^HPV+ UM-SCC47 cell line or HPV+ patient-derived xenografts. These findings indicate that IGF2 and the IGF2/IGF1R pathway may constitute new targets for combination therapies to enhance the efficacy of PI3K inhibitors for the treatment of HNC^HPV+.

Identification of a Resistance Mechanism to IGF-IR Targeting in Human Triple Negative MDA-MB-231 Breast Cancer Cells

Triple negative breast cancer (TNBC) is associated with unfavorable prognosis and high relapse rates following chemotherapy. There is an urgent need to develop effective targeted therapy for this BC subtype. The type I insulin-like growth factor receptor (IGF-IR) was identified as a potential target for BC management. We previously reported on the production of the IGF-Trap, a soluble IGF-1R fusion protein that reduces the bioavailability of circulating IGF-1 and IGF-2 to the cognate receptor, impeding signaling. In nude mice xenotransplanted with the human TNBC MDA-MB-231 cells, we found variable responses to this inhibitor. We used this model to investigate potential resistance mechanisms to IGF-targeted therapy. We show here that prolonged exposure of MDA-MB-231 cells to the IGF-Trap in vitro selected a resistant subpopulation that proliferated unhindered in the presence of the IGF-Trap. We identified in these cells increased fibroblast growth factor receptor 1 (FGFR1) activation levels that sensitized them to the FGFR1-specific tyrosine kinase inhibitor PD166866. Treatment with this inhibitor caused cell cycle arrest in both the parental and resistant cells, markedly increasing cell death in the latter. When combined with the IGF-Trap, an increase in cell cycle arrest was observed in the resistant cells. Moreover, FGFR1 silencing increased the sensitivity of these cells to IGF-Trap treatment in vivo. Our data identify increased FGFR1 signaling as a resistance mechanism to targeted inhibition of the IGF-IR and suggest that dual IGF-1R/FGFR1 blockade may be required to overcome TNBC cell resistance to IGF-axis inhibitors.

Microenvironmental Determinants of Breast Cancer Metastasis: Focus on the Crucial Interplay Between Estrogen and Insulin/Insulin-Like Growth Factor Signaling

The development and progression of the great majority of breast cancers (BCs) are mainly dependent on the biological action elicited by estrogens through the classical estrogen receptor (ER), as well as the alternate receptor named G-protein–coupled estrogen receptor (GPER). In addition to estrogens, other hormones and growth factors, including the insulin and insulin-like growth factor system (IIGFs), play a role in BC. IIGFs cooperates with estrogen signaling to generate a multilevel cross-communication that ultimately facilitates the transition toward aggressive and life-threatening BC phenotypes. In this regard, the majority of BC deaths are correlated with the formation of metastatic lesions at distant sites. A thorough scrutiny of the biological and biochemical events orchestrating metastasis formation and dissemination has shown that virtually all cell types within the tumor microenvironment work closely with BC cells to seed cancerous units at distant sites. By establishing an intricate scheme of paracrine interactions that lead to the expression of genes involved in metastasis initiation, progression, and virulence, the cross-talk between BC cells and the surrounding microenvironmental components does dictate tumor fate and patients’ prognosis. Following (i) a description of the main microenvironmental events prompting BC metastases and (ii) a concise overview of estrogen and the IIGFs signaling and their major regulatory functions in BC, here we provide a comprehensive analysis of the most recent findings on the role of these transduction pathways toward metastatic dissemination. In particular, we focused our attention on the main microenvironmental targets of the estrogen-IIGFs interplay, and we recapitulated relevant molecular nodes that orientate shared biological responses fostering the metastatic program. On the basis of available studies, we propose that a functional cross-talk between estrogens and IIGFs, by affecting the BC microenvironment, may contribute to the metastatic process and may be regarded as a novel target for combination therapies aimed at preventing the metastatic evolution.

TMS-Induced Controlled BBB Opening: Preclinical Characterization and Implications for Treatment of Brain Cancer

Proper neuronal function requires strict maintenance of the brain's extracellular environment. Therefore, passage of molecules between the circulation and brain neuropil is tightly regulated by the blood-brain barrier (BBB). While the BBB is vital for normal brain function, it also restricts the passage of drugs, potentially effective in treating brain diseases, into the brain. Despite previous attempts, there is still an unmet need to develop novel approaches that will allow safe opening of the BBB for drug delivery. We have recently shown in experimental rodents and in a pilot human trial that low-frequency, high-amplitude repetitive transcranial magnetic stimulation (rTMS) allows the delivery of peripherally injected fluorescent and Gd-based tracers into the brain. The goals of this study were to characterize the duration and safety level of rTMS-induced BBB opening and test its capacity to enhance the delivery of the antitumor growth agent, insulin-like growth factor trap, across the BBB. We employed direct vascular and magnetic resonance imaging, as well as electrocorticography recordings, to assess the impact of rTMS on brain vascular permeability and electrical activity, respectively. Our findings indicate that rTMS induces a transient and safe BBB opening with a potential to facilitate drug delivery into the brain.

Targeting the IGF-Axis for Cancer Therapy: Development and Validation of an IGF-Trap as a Potential Drug

The insulin-like growth factor (IGF)-axis was implicated in cancer progression and identified as a clinically important therapeutic target. Several IGF-I receptor (IGF-IR) targeting drugs including humanized monoclonal antibodies have advanced to phase II/III clinical trials, but to date, have not progressed to clinical use, due, at least in part, to interference with insulin receptor signaling and compensatory signaling by the insulin receptor (IR) isoform A that can bind IGF-II and initiate mitogenic signaling. Here we briefly review the current state of IGF-targeting biologicals, discuss some factors that may be responsible for their poor performance in the clinic and outline the stepwise bioengineering and validation of an IGF-Trap—a novel anti-cancer therapeutic that could bypass these limitations. The IGF-Trap is a heterotetramer, consisting of the entire extracellular domain of the IGF-IR fused to the Fc portion of human IgG₁. It binds human IGF-I and IGF-II with a three-log higher affinity than insulin and could inhibit IGF-IR driven cellular functions such as survival, proliferation and invasion in multiple carcinoma cell models in vitro. In vivo, the IGF-Trap has favorable pharmacokinetic properties and could markedly reduce metastatic outgrowth of colon and lung carcinoma cells in the liver, outperforming IGF-IR and ligand-binding monoclonal antibodies. Moreover, IGF-Trap dose-response profiles correlate with their bio-availability profiles, as measured by the IGF kinase receptor-activation (KIRA) assay, providing a novel, surrogate biomarker for drug efficacy. Our studies identify the IGF-Trap as a potent, safe, anti-cancer therapeutic that could overcome some of the obstacles encountered by IGF-targeting biologicals that have already been evaluated in clinical settings.

Therapeutic Targeting of the IGF Axis

The insulin like growth factor (IGF) axis plays a fundamental role in normal growth and development, and when deregulated makes an important contribution to disease. Here, we review the functions mediated by ligand-induced IGF axis activation, and discuss the evidence for the involvement of IGF signaling in the pathogenesis of cancer, endocrine disorders including acromegaly, diabetes and thyroid eye disease, skin diseases such as acne and psoriasis, and the frailty that accompanies aging. We discuss the use of IGF axis inhibitors, focusing on the different approaches that have been taken to develop effective and tolerable ways to block this important signaling pathway. We outline the advantages and disadvantages of each approach, and discuss progress in evaluating these agents, including factors that contributed to the failure of many of these novel therapeutics in early phase cancer trials. Finally, we summarize grounds for cautious optimism for ongoing and future studies of IGF blockade in cancer and non-malignant disorders including thyroid eye disease and aging.