Temozolomide-Doxorubicin Conjugate as a Double Intercalating Agent and Delivery by Apoferritin for Glioblastoma Chemotherapy

Systemic and targeted activation of Nrf2 reverses doxorubicin-induced cognitive impairments and sensorimotor deficits in mice

While cancer survivorship has increased due to advances in treatments, chemotherapy often carries long-lived neurotoxic side effects which reduce quality of life. Commonly affected domains include memory, executive function, attention, processing speed and sensorimotor function, colloquially known as chemotherapy-induced cognitive impairment (CICI) or "chemobrain". Oxidative stress and neuroimmune signaling in the brain have been mechanistically linked to the deleterious effects of chemotherapy on cognition and sensorimotor function. With this in mind, we tested if activation of the master regulator of antioxidant response nuclear factor E2-related factor 2 (Nrf2) alleviates cognitive and sensorimotor impairments induced by doxorubicin. The FDA-approved systemic Nrf2 activator, diroximel fumarate (DRF) was used, along with our recently developed prodrug 1c which has the advantage of specifically releasing monomethyl fumarate at sites of oxidative stress. DRF and 1c both reversed doxorubicin-induced deficits in executive function, spatial and working memory, as well as decrements in fine motor coordination and grip strength, across both male and female mice. Both treatments reversed doxorubicin-induced loss of synaptic proteins and microglia phenotypic transition in the hippocampus. Doxorubicin-induced myelin damage in the corpus callosum was reversed by both Nrf2 activators. These results demonstrate the therapeutic potential of Nrf2 activators to reverse doxorubicin-induced cognitive impairments, motor incoordination, and associated structural and phenotypic changes in the brain. The localized release of monomethyl fumarate by 1c has the potential to diminish unwanted effects of fumarates while retaining efficacy.

Encapsulation of copper phenanthroline within horse spleen apoferritin: characterisation, cytotoxic activity and ability to retain temozolomide

Protein capsules are promising drug delivery vehicles for cancer research therapies. Apoferritin (AFt) is a self-assembling 12 nm diameter hollow nanocage with many desirable features for drug delivery, however, control of drug retention inside the protein cage remains challenging. Here we report the encapsulation of copper(ii)-1,10-phenanthroline (Cu(phen)) within the horse spleen AFt (HSAFt) nanocage, by diffusion of the metal through the pores between the protein subunits. Transmission electron microscopy revealed the formation of organised copper adducts inside HSAFt, without affecting protein integrity. These structures proved stable during storage (>4 months at -20 °C). Exposure to physiologically relevant conditions (37 °C) showed some selectivity in cargo release after 24 h at pH 5.5, relevant to the internalisation of AFt within the endosome (60% release), compared to pH 7.4, relevant to the bloodstream (40% release). Co-encapsulation of temozolomide, a prodrug used to treat glioblastoma multiforme, and Cu(phen) enabled entrapment of an average of 339 TMZ molecules per cage. In vitro results from MTT and clonogenic assays identified cytotoxic activity of the Cu(phen), HSAFt-Cu(phen) and HSAFt-Cu(phen)-TMZ adducts against colorectal cancer cells (HCT-116) and glioblastoma cells (U373V, U373M). However, the presence of the metal also contributed to more potent activity toward healthy MRC5 fibroblasts, a result that requires further investigation to assess the clinical viability of this system.

The Temozolomide-Doxorubicin paradox in Glioblastoma in vitro-in silico preclinical drug-screening

Adjuvant Temozolomide is considered the front-line Glioblastoma chemotherapeutic treatment; yet not all patients respond. Latest trends in clinical trials usually refer to Doxorubicin; yet it can lead to severe side-effects if administered in high doses. While Glioblastoma prognosis remains poor, little is known about the combination of the two chemotherapeutics. Patient-derived spheroids were generated and treated with a range of Temozolomide/Doxorubicin concentrations either as monotherapy or in combination. Optical microscopy was used to monitor the growth pattern and cell death. Based on the monotherapy experiments, we developed a probabilistic mathematical framework in order to describe the drug-induced effect at the single-cell level and simulate drug doses in combination assuming probabilistic independence. Doxorubicin was found to be effective in doses even four orders of magnitude less than Temozolomide in monotherapy. The combination therapy doses tested in vitro were able to lead to irreversible growth inhibition at doses where monotherapy resulted in relapse. In our simulations, we assumed both drugs are anti-mitotic; Temozolomide has a growth-arrest effect, while Doxorubicin is able to cumulatively cause necrosis. Interestingly, under no mechanistic synergy assumption, the in silico predictions underestimate the in vitro results. In silico models allow the exploration of a variety of potential underlying hypotheses. The simulated-biological discrepancy at certain doses indicates a supra-additive response when both drugs are combined. Our results suggest a Temozolomide-Doxorubicin dual chemotherapeutic scheme to both disable proliferation and increase cytotoxicity against Glioblastoma.

The nanoprodrug of polytemozolomide combines with MGMT siRNA to enhance the effect of temozolomide in glioma

Temozolomide (TMZ) is a conventional chemotherapeutic drug for glioma, however, its clinical application and efficacy is severely restricted by its drug resistance properties. O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme, which can repair the DNA damage caused by TMZ. A large number of clinical data show that reducing the expression of MGMT can enhance the chemotherapeutic efficacy of TMZ. Therefore, in order to improve the resistance of glioma to TMZ, an angiopep-2 (A2) modified nanoprodrug of polytemozolomide (P(TMZ)n) that combines with MGMT siRNA (siMGMT) targeting MGMT was developed (A2/T/D/siMGMT). It not only increased the amount of TMZ within tumor lesion site, but also reduced MGMT expression in glioma. The in vitro experiments indicated that the A2/T/D/siMGMT effectively enhanced the cellular uptake of TMZ and siMGMT, and resulted in a significant cell apoptosis and cytotoxicity in the glioma cells. The in vivo experiments showed that glioma growth was inhibited and the survival time of animals were prolonged remarkably after A2/T/D/siMGMT was injected via tail vein. The results showed that the therapeutic effect of A2/T/D/siMGMT in the treatment of glioma was significantly improved.

Low-dose pleiotropic radiosensitive nanoformulations for three-pronged radiochemotherapy of hypoxic brain glioblastoma under BOLD/DWI monitoring

Background

Hypoxia-mediated radioresistance is the main obstacle to the successful treatment of glioblastoma (GBM). Enhancing hypoxic radiosensitivity and alleviating tumor hypoxia are both effective means to improve therapeutic efficacy, and the combination of the two is highly desirable and meaningful.

Results

Herein, we construct a low-dose pleiotropic radiosensitive nanoformulation consisting of a high-Z atomic nanocrystal core and mesoporous silica shell, surface-modified with angiopep-2 (ANG) peptide and loaded with nitric oxide (NO) donor and hypoxia-activated prodrug (AQ4N). Benefiting from ANG-mediated transcytosis, this nanoformulation can efficiently cross the BBB and accumulate preferentially in the brain. Low-dose radiation triggers this nanoformulation to exert a three-pronged synergistic therapeutic effect through high-Z-atom-dependent dose deposition enhancement, NO-mediated hypoxia relief, and AQ4N-induced hypoxia-selective killing, thereby significantly inhibiting GBM in situ growth while prolonging survival and maintaining stable body weight in the glioma-bearing mice. Meanwhile, the proposed in vivo 9.4 T BOLD/DWI can realize real-time dynamic assessment of local oxygen supply and radiosensitivity to monitor the therapeutic response of GBM.

Conclusions

This work provides a promising alternative for hypoxia-specific GBM-targeted comprehensive therapy, noninvasive monitoring, and precise prognosis.

Graphical Abstract

Doxorubicin Conjugates: An Efficient Approach for Enhanced Therapeutic Efficacy with Reduced Side Effects

Continuous drug delivery modification is the scientific approach and is a basic need for the efficient therapeutic efficacy of active drug molecules. Polymer-drug conjugates have long been a hallmark of the drug delivery sector, with various conjugates on the market or in clinical trials. Improved drug solubilization, extended blood circulation, decreased immunogenicity, controlled release behavior, and increased safety are the advantages of conjugating drugs to the polymeric carrier like polyethylene glycol (PEG). Polymer therapies have evolved over the last decade, resulting in polymer-drug conjugates with diverse topologies and chemical properties. Traditional nondegradable polymeric carriers like PEG and hydroxy propyl methacrylate have been clinically employed to fabricate polymer-drug conjugates. Still, functionalized polymer-drug conjugates are increasingly being used to increase localized drug delivery and ease of removal. Researchers have developed multifunctional carriers that can "see and treat" patients using medicinal and diagnostic chemicals. This review focused on the various conjugation approaches for attaching the doxorubicin to different polymers to achieve enhanced therapeutic efficacy, that is, increased bioavailability and reduced adverse effects.

Polymeric and small molecule-conjugates of temozolomide as improved therapeutic agents for glioblastoma multiforme

Temozolomide (TMZ), an imidazotetrazine, is a second-generation DNA alkylating agent used as a first-line treatment of glioblastoma multiforme (GBM). It was approved by FDA in 2005 and declared a blockbuster drug in 2008. Although TMZ has shown 100% oral bioavailability and crosses the blood-brain barrier effectively, however it suffers from limitations such as a short half-life (∼1.8 h), rapid metabolism, and lesser accumulation in the brain (∼10-20%). Additionally, development of chemoresistance has been associated with its use. Since it is a potential chemotherapeutic agent with an unmet medical need, advanced delivery strategies have been explored to overcome the associated limitations of TMZ. Nanocarriers including liposomes, solid lipid nanoparticles (SLNs), nanostructure lipid carriers (NLCs), and polymeric nanoparticles have demonstrated their ability to improve its circulation time, stability, tissue-specific accumulation, sustained release, and cellular uptake. Because of the appreciable water solubility of TMZ (∼5 mg/mL), the physical loading of TMZ in these nanocarriers is always challenging. Alternatively, the conjugation approach, wherein TMZ has been conjugated to polymers or small molecules, has been explored with improved outcomes in vitro and in vivo. This review emphasized the practical evidence of the conjugation strategy to improve the therapeutic potential of TMZ in the treatment of glioblastoma multiforme.

Esterase-responsive and size-optimized prodrug nanoparticles for effective intracranial drug delivery and glioblastoma treatment

Glioblastoma multiforme (GBM) is the intracranial malignancy with the highest rates of morbidity and mortality. Chemotherapy is often ineffective against GBM due to the presence of the blood-brain barrier (BBB); however, the application of nanotechnology is expected to overcome this limitation. Poly(lactic-co-glycolic acid) (PLGA) is a degradable and nontoxic functional polymer with good biocompatibility that is widely used in the pharmaceutical industry. Previous studies have shown that the ability of PLGA nanoparticles (NPs) to penetrate the BBB is largely determined by their size; however, determination of the optimal PLGA NP size requires further research. Here, we report a tandutinib-based prodrug (proTan), which responds to the GBM microenvironment, that was combined with NPs to overcome the BBB. AMD3100-PLGA NPs loaded with proTan inhibited tumor growth and effectively prolonged the survival of tumor-bearing mice.

Ultrasmall Nanoparticle Delivery of Doxorubicin Improves Therapeutic Index for High-Grade Glioma

Purpose: Despite dramatic growth in the number of small molecule drugs developed to treat solid tumors, durable therapeutic options to control primary central nervous system malignancies are relatively scarce. Chemotherapeutic agents which appear biologically potent in model systems have often been found to be marginally effective at best when given systemically in clinical trials. This work presents for the first time an ultrasmall (< 8 nm) multimodal core-shell silica nanoparticle, Cornell prime dots (or C' dots), for the efficacious treatment of high-grade gliomas. Experimental Design: This work presents first-in-kind renally-clearable ultrasmall (< 8 nm) multimodal Cornell prime dots (or C' dots) with surface-conjugated doxorubicin via pH-sensitive linkers for the efficacious treatment in two different clinically relevant high-grade glioma models. Results: Optimal drug-per-particle ratios of as-developed nanoparticle-drug conjugates were established and used to obtain favorable pharmacokinetic profiles. The in vivo efficacy results showed significantly improved biological, therapeutic, and toxicological properties over the native drug after intravenous administration in platelet-derived growth factor-driven genetically engineered mouse model, and an epidermal growth factor expressing patient-derived xenograft (EGFR PDX) model. Conclusions: Ultrasmall C' dot-drug conjugates showed great translational potential over doxorubicin for improving the therapeutic outcome of patients with high-grade gliomas, even without a cancer-targeting moiety.

Research progress of anti-glioma chemotherapeutic drugs (Review)

Glioma is the most common primary intracranial malignancy in the central nervous system. At present, the most important treatment option is surgical resection of the tumor combined with radiotherapy and chemotherapy. The principle of operation is to remove the tumor to the maximal extent on the basis of preserving brain function. However, prominent invasive and infiltrative proliferation of glioma tumor cells into the surrounding normal tissues frequently reduces the efficacy of treatment. This in turn worsens the prognosis, because the tumor cannot be completely removed, which can readily relapse. Chemotherapeutic agents when applied individually have demonstrated limited efficacy for the treatment of glioma. However, multiple different chemotherapeutic agents can be used in combination with other treatment modalities to improve the efficacy while circumventing systemic toxicity and drug resistance. Therefore, it is pivotal to unravel the inhibitory mechanism mediated by the different chemotherapeutic drugs on glioma cells in preclinical studies. The aim of the present review is to provide a summary for understanding the effects of different chemotherapeutic drugs in glioma, in addition to providing a reference for the preclinical research into novel chemotherapeutic agents for future clinical application.

[12]aneN3-Conjugated AIEgens with Two-Photon Imaging Property for Synergistic Gene/Photodynamic Therapy in Vitro and in Vivo

Six amphiphiles (TTC-L-M-1/2/3/4/5/6), each consisting of hydrophilic macrocyclic polyamine triazole-[12]aneN3 (M) and hydrophobic photosensitizer tetraphenylethenethiophene modified cyanoacrylate (TTC) moiety linked with alkyl chains (L), have been designed and synthesized for...

Visible Light and Glutathione Dually Responsive Delivery of a Polymer-Conjugated Temozolomide Intermediate for Glioblastoma Chemotherapy

Temozolomide (TMZ) is a prodrug of 5-(3-methyltriazene-1-yl)imidazole-4-carboxamide (MTIC, short-lived) and used as a first-line therapy drug for glioblastoma multiforme (GBM). However, little progress has been made in regulating the kinetics of TMZ to MTIC degradation to improve the therapeutic effect, particularly in the case of TMZ-resistant GBM. In this work, we introduced a strategy to cage MTIC by N-acylation of the triazene moiety to boost the MTIC stability, designed a diblock copolymer-based MTIC prodrug installed with a disulfide linkage, and achieved self-assembled polymer micelles without the concern of MTIC leakage under physiological conditions. Polymer micelles could be induced to disassemble by stimuli factors such as glutathione (GSH) and visible light irradiation through thiol/sulfide exchange and homolytic sulfide scission mechanisms, which contributed to MTIC release in GSH-dependent and GSH-independent pathways. The in vitro results demonstrated that microenvironment-responsive polymeric micelles benefited the suppression of both TMZ-sensitive and TMZ-resistant GBM cells. The chemistry of polymer-MTIC prodrug provided a new option for TMZ-based glioma treatment.

Nanoparticulation of Prodrug into Medicines for Cancer Therapy

This article provides a broad spectrum about the nanoprodrug fabrication advances co-driven by prodrug and nanotechnology development to potentiate cancer treatment. The nanoprodrug inherits the features of both prodrug concept and nanomedicine know-how, attempts to solve underexploited challenge in cancer treatment cooperatively. Prodrugs can release bioactive drugs on-demand at specific sites to reduce systemic toxicity, this is done by using the special properties of the tumor microenvironment, such as pH value, glutathione concentration, and specific overexpressed enzymes; or by using exogenous stimulation, such as light, heat, and ultrasound. The nanotechnology, manipulating the matter within nanoscale, has high relevance to certain biological conditions, and has been widely utilized in cancer therapy. Together, the marriage of prodrug strategy which shield the side effects of parent drug and nanotechnology with pinpoint delivery capability has conceived highly camouflaged Trojan horse to maneuver cancerous threats.

Doxorubicin-Induced Cognitive Impairment: The Mechanistic Insights

Chemotherapy can significantly prolong the survival of patients with breast cancer; Nevertheless, the majority of patients receiving chemotherapy such as doxorubicin may have cognitive deficits that manifest as impairments in learning, reasoning, attention, and memory. The phenomenon of chemotherapy-induced cognitive decline is termed as chemotherapy-related cognitive impairment (CRCI) or chemo-brain. Doxorubicin (DOX), a commonly used drug in adjuvant chemotherapy for patients with breast cancer, has been reported to induce chemo-brain through a variety of mechanisms including DNA damage, oxidative stress, inflammation, dysregulation of apoptosis and autophagy, changes in neurotransmitter levels, mitochondrial dysfunction, glial cell interactions, neurogenesis inhibition, and epigenetic factors. These mechanisms do not operate independently but are inter-related, coordinately contributing to the development of chemo-brain. Here we review the relationships of these mechanisms and pathways in attempt to provide mechanistic insights into the doxorubicin-induced cognitive impairment.

Apoferritin: a potential nanocarrier for cancer imaging and drug delivery

Introduction: As a protein-based biomaterial for potential cancer targeting delivery, apoferritin has recently attracted interest.Areas covered: In this review, we discuss the development of this cage-like protein as an endogenous nanocarrier that can hold molecules in its cavity. We present the specific characterizations and formulations of apoferritin nanocarriers, and outline the recent progress of the protein as an appropriate tumor-delivery vehicle in different therapeutic strategies to treat solid tumors. Finally, we propose how the application for cancer drug repurposing delivery within apoferritin could expand cancer treatment in the future.Expert opinion: Being a ubiquitous iron storage protein that exists in many living organisms, apoferritin is promising as a cancer tumor-targeting nanocarrier. By exploiting its versatility, apoferritin could be used for cancer repurposed drug delivery and could reduce the high cost of new drug discovery development and shorten the formulation process.

Small interfering RNA (siRNA) to target genes and molecular pathways in glioblastoma therapy: Current status with an emphasis on delivery systems

Glioblastoma multiforme (GBM) is one of the worst brain tumors arising from glial cells, causing many deaths annually. Surgery, chemotherapy, radiotherapy and immunotherapy are used for GBM treatment. However, GBM is still an incurable disease, and new approaches are required for its successful treatment. Because mutations and amplifications occurring in several genes are responsible for the progression and aggressive behavior of GBM cells, genetic approaches are of great importance in its treatment. Small interfering RNA (siRNA) is a new emerging tool to silence the genes responsible for disease progression, particularly cancer. SiRNA can be used for GBM treatment by down-regulating genes such as VEGF, STAT3, ELTD1 or EGFR. Furthermore, the use of siRNA can promote the chemosensitivity of GBM cells. However, the efficiency of siRNA in GBM is limited via its degradation by enzymes, and its off-targeting effects. SiRNA-loaded carriers, especially nanovehicles that are ligand-functionalized by CXCR4 or angiopep-2, can be used for the protection and targeted delivery of siRNA. Nanostructures can provide a platform for co-delivery of siRNA plus anti-tumor drugs as another benefit. The prepared nanovehicles should be stable and biocompatible in order to be tested in human studies.

Biophysical Characterization and Anticancer Activities of Photosensitive Phytoanthraquinones Represented by Hypericin and Its Model Compounds

Photosensitive compounds found in herbs have been reported in recent years as having a variety of interesting medicinal and biological activities. In this review, we focus on photosensitizers such as hypericin and its model compounds emodin, quinizarin, and danthron, which have antiviral, antifungal, antineoplastic, and antitumor effects. They can be utilized as potential agents in photodynamic therapy, especially in photodynamic therapy (PDT) for cancer. We aimed to give a comprehensive summary of the physical and chemical properties of these interesting molecules, emphasizing their mechanism of action in relation to their different interactions with biomacromolecules, specifically with DNA.

Environmentally Self-Adaptative Nanocarriers Suppress Glioma Proliferation and Stemness via Codelivery of shCD163 and Doxorubicin

Gliomas-devastating intracranial tumors with a dismal outcome-are in dire need of innovative treatment. Although nanodrugs have been utilized as a target therapy for certain types of solid tumors, their therapeutic effects in gliomas are limited due to the complications of the systemic circulation, blood-brain barrier (BBB), and specific glioma environment. Thus, we aimed to establish a nanoliposome adaptable to different environments by codelivery of shCD163 and doxorubicin (DOX) to treat gliomas. In this study, we first synthesized pH-sensitive DSPE-cRGD-Hz-PEG₂₀₀₀ to form an environmentally self-adaptative nanoliposome (cRGD-DDD Lip) via a thin film method. We used in vitro BBB models, in vitro cell uptake experiments, and in vivo biodistribution assays to confirm the long circulation time and low cell uptake of the cRGD-DDD Lip as a result of the poly(ethylene glycol) (PEG) shell of cRGD-DDD Lip in the neutral pH systemic circulation. Moreover, the cRGD-DDD Lip bypassed the BBB and attached to the intracranial glioma following the removal of the PEG shell and the exposure of cRGD to the weakly acidic tumor microenvironment. We further assembled the shCD163/DOX@cRGD-DDD Lip through cRGD-DDD Lip loading of shCD163 and DOX. In vitro, cell proliferation and self-renewal of glioma cells were inhibited by the shCD163/DOX@cRGD-DDD Lip due to the toxicity of DOX and the suppression of shCD163 via the CD163 pathway. In vivo, the shCD163/DOX@cRGD-DDD Lip disturbed the progression of in situ gliomas by inhibiting the growth and stemness of glioma cells and prevented the recurrence of gliomas after resection. In conclusion, the cRGD-DDD Lip may be a promising nanodrug-loading platform to cope with different environments and the shCD163/DOX@cRGD-DDD Lip may potentially be a novel nanodrug for glioma therapy.

The effect of temozolomide in combination with doxorubicin in glioblastoma cells in vitro

BACKGROUND

Prior to 2000, the DNA alkylating agents nitrosoureas were used as standard treatment of glioblastoma. Current treatments for glioblastoma patients consist of surgery followed by radiation in combination with temozolomide. Despite therapeutic advances, the prognosis for glioblastoma patients remains grim, with a five-year overall survival below 15%. In this study, our team analyzed the interaction between temozolomide and doxorubicin in a glioblastoma cell line, in vitro.

MATERIALS AND METHOD

The cell line, established from a patient who underwent surgery at the "Bagdasar Arseni Emergency Hospital", was exposed to 10 µM and 100 µM of temozolomide and 10 nM and 100 nM of doxorubicin, respectively, over a period of 7, 10 and 14 days, in monotherapy and in combination.

RESULTS

The results showed that both temozolomide (66.5% cytotoxicity for the 10 µM dose at 14 days) de and doxorubicin (66.8% cytotoxicity for the 10 nM dose after 14 days) were very effective in killing cancer cells in monotherapy, but failed to produce a synergistic effect when used in combination.

CONCLUSION

While the results may be discouraging, they present an interesting prospect into how certain drug interactions can impact treatment response.