Convection Enhanced Delivery of Topotecan for Gliomas: A Single-Center Experience

Electrokinetic convection-enhanced delivery for infusion into the brain from a hydrogel reservoir

Electrokinetic convection-enhanced delivery (ECED) utilizes an external electric field to drive the delivery of molecules and bioactive substances to local regions of the brain through electroosmosis and electrophoresis, without the need for an applied pressure. We characterize the implementation of ECED to direct a neutrally charged fluorophore (3 kDa) from a doped biocompatible acrylic acid/acrylamide hydrogel placed on the cortical surface. We compare fluorophore infusion profiles using ECED (time = 30 min, current = 50 µA) and diffusion-only control trials, for ex vivo (N = 18) and in vivo (N = 12) experiments. The linear intensity profile of infusion to the brain is significantly higher in ECED compared to control trials, both for in vivo and ex vivo. The linear distance of infusion, area of infusion, and the displacement of peak fluorescence intensity along the direction of infusion in ECED trials compared to control trials are significantly larger for in vivo trials, but not for ex vivo trials. These results demonstrate the effectiveness of ECED to direct a solute from a surface hydrogel towards inside the brain parenchyma based predominantly on the electroosmotic vector.

A pharmacological toolkit for human microglia identifies Topoisomerase I inhibitors as immunomodulators for Alzheimer's disease

While efforts to identify microglial subtypes have recently accelerated, the relation of transcriptomically defined states to function has been largely limited to in silico annotations. Here, we characterize a set of pharmacological compounds that have been proposed to polarize human microglia towards two distinct states - one enriched for AD and MS genes and another characterized by increased expression of antigen presentation genes. Using different model systems including HMC3 cells, iPSC-derived microglia and cerebral organoids, we characterize the effect of these compounds in mimicking human microglial subtypes in vitro. We show that the Topoisomerase I inhibitor Camptothecin induces a CD74high/MHChigh microglial subtype which is specialized in amyloid beta phagocytosis. Camptothecin suppressed amyloid toxicity and restored microglia back to their homeostatic state in a zebrafish amyloid model. Our work provides avenues to recapitulate human microglial subtypes in vitro, enabling functional characterization and providing a foundation for modulating human microglia in vivo.

Combined Effect of Plasma-Activated Water and Topotecan in Glioblastoma Cells

The increase in cancer diagnoses and cancer deaths, severe side effects of existing treatments and resistance to traditional treatments have generated a need for new anticancer treatments. Glioblastoma multiforme (GBM) is the most common, malignant and aggressive brain cancer. Despite many innovations regarding GBM treatment, the final outcome is still very poor, making it necessary to develop new therapeutic approaches. Cold atmospheric plasma (CAP) as well as plasma-activated liquids (PAL) are being studied as new possible approaches against cancer. The anticancer activity of PAL such as "plasma-activated water" (PAW) is dependent on the reactive chemical compounds present in the solution. Possible combinatory effects with conventional therapies, such as chemotherapeutics, may expand the potential of PAL for cancer treatment. We aim to explore the therapeutic properties of a combination of PAW and topotecan (TPT), an antineoplastic agent with major cytotoxic effects during the S phase of the cell cycle, on a GBM cancer cell line (U-251mg). Combined treatments with PAW and TPT showed a reduction in the metabolic activity and cell mass, an increase in apoptotic cell death and a reduction in the long-term survival. Single applications of PAW+TPT treatments showed a cytotoxic effect in the short term and an antiproliferative effect in the long term, warranting future exploration of combining PAW with chemotherapeutic agents as new therapeutic approaches.

Medical Device Advances in the Treatment of Glioblastoma

Despite decades of research and the growing emergence of new treatment modalities, Glioblastoma (GBM) frustratingly remains an incurable brain cancer with largely stagnant 5-year survival outcomes of around 5%. Historically, a significant challenge has been the effective delivery of anti-cancer treatment. This review aims to summarize key innovations in the field of medical devices, developed either to improve the delivery of existing treatments, for example that of chemo-radiotherapy, or provide novel treatments using devices, such as sonodynamic therapy, thermotherapy and electric field therapy. It will highlight current as well as emerging device technologies, non-invasive versus invasive approaches, and by doing so provide a detailed summary of evidence from clinical studies and trials undertaken to date. Potential limitations and current challenges are discussed whilst also highlighting the exciting potential of this developing field. It is hoped that this review will serve as a useful primer for clinicians, scientists, and engineers in the field, united by a shared goal to translate medical device innovations to help improve treatment outcomes for patients with this devastating disease.

Recent advances in drug delivery and targeting to the brain

Our body keeps separating the toxic chemicals in the blood from the brain. A significant number of drugs do not enter the central nervous system (CNS) due to the blood-brain barrier (BBB). Certain diseases, such as tumor growth and stroke, are known to increase the permeability of the BBB. However, the heterogeneity of this permeation makes it difficult and unpredictable to transport drugs to the brain. In recent years, research has been directed toward increasing drug penetration inside the brain, and nanomedicine has emerged as a promising approach. Active targeting requires one or more specific ligands on the surface of nanoparticles (NPs), which brain endothelial cells (ECs) recognize, allowing controlled drug delivery compared to conventional targeting strategies. This review highlights the mechanistic insights about different cell types contributing to the development and maintenance of the BBB and summarizes the recent advancement in brain-specific NPs for different pathological conditions. Furthermore, fundamental properties of brain-targeted NPs will be discussed, and the standard lesion features classified by neurological pathology are summarized.

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.

Convection-Enhanced Delivery in Children: Techniques and Applications

Since its first description in 1994, convection-enhanced delivery (CED) has become a reliable method of administering drugs directly into the brain parenchyma. More predictable and effective than simple diffusion, CED bypasses the challenging boundary of the blood brain barrier, which has frustrated many attempts at delivering large molecules or polymers into the brain parenchyma. Although most of the clinical work with CED has been carried out on adults with incurable neoplasms, principally glioblastoma multiforme, an increasing number of studies have recognized its potential for paediatric applications, which now include treatment of currently incurable brain tumours such as diffuse intrinsic pontine glioma (DIPG), as well as metabolic and neurotransmitter diseases. The roadmap for the development of hardware and use of pharmacological agents in CED has been well-established, and some neurosurgical centres throughout the world have successfully undertaken clinical trials, admittedly mostly early phase, on the basis of in vitro, small animal and large animal pre-clinical foundations. However, the clinical efficacy of CED, although theoretically logical, has yet to be unequivocally demonstrated in a clinical trial; this applies particularly to neuro-oncology.This review aims to provide a broad description of the current knowledge of CED as applied to children. It reviews published studies of paediatric CED in the context of its wider history and developments and underlines the challenges related to the development of hardware, the selection of pharmacological agents, and gene therapy. It also reviews the difficulties related to the development of clinical trials involving CED and looks towards its potential disease-modifying opportunities in the future.

Drug Design: Where We Are and Future Prospects

Medicinal chemistry is facing new challenges in approaching precision medicine. Several powerful new tools or improvements of already used tools are now available to medicinal chemists to help in the process of drug discovery, from a hit molecule to a clinically used drug. Among the new tools, the possibility of considering folding intermediates or the catalytic process of a protein as a target for discovering new hits has emerged. In addition, machine learning is a new valuable approach helping medicinal chemists to discover new hits. Other abilities, ranging from the better understanding of the time evolution of biochemical processes to the comprehension of the biological meaning of the data originated from genetic analyses, are on their way to progress further in the drug discovery field toward improved patient care. In this sense, the new approaches to the delivery of drugs targeted to the central nervous system, together with the advancements in understanding the metabolic pathways for a growing number of drugs and relating them to the genetic characteristics of patients, constitute important progress in the field.

Convection-enhanced delivery for high-grade glioma

Glioblastoma (GBM) is the most common adult primary malignant brain tumor and is associated with a dire prognosis. Despite multi-modality therapies of surgery, radiation, and chemotherapy, its 5-year survival rate is 6.8%. The presence of the blood-brain barrier (BBB) is one factor that has made GBM difficult to treat. Convection-enhanced delivery (CED) is a modality that bypasses the BBB, which allows the intracranial delivery of therapies that would not otherwise cross the BBB and avoids systemic toxicities. This review will summarize prior and ongoing studies and highlights practical considerations related to clinical care to aid providers caring for a high-grade glioma patient being treated with CED. Although not the main scope of this paper, this review also touches upon relevant technical considerations of using CED, an area still under much development.

Real-Time Positron Emission Tomography Evaluation of Topotecan Brain Kinetics after Ultrasound-Mediated Blood-Brain Barrier Permeability

Glioblastoma (GBM) is the most common primary adult brain malignancy with an extremely poor prognosis and a median survival of fewer than two years. A key reason for this high mortality is that the blood-brain barrier (BBB) significantly restricts systemically delivered therapeutics to brain tumors. High-intensity focused ultrasound (HIFU) with microbubbles is a methodology being used in clinical trials to noninvasively permeabilize the BBB for systemic therapeutic delivery to GBM. Topotecan is a topoisomerase inhibitor used as a chemotherapeutic agent to treat ovarian and small cell lung cancer. Studies have suggested that topotecan can cross the BBB and can be used to treat brain metastases. However, pharmacokinetic data demonstrated that topotecan peak concentration in the brain extracellular fluid after systemic injection was ten times lower than in the blood, suggesting less than optimal BBB penetration by topotecan. We hypothesize that HIFU with microbubbles treatment can open the BBB and significantly increase topotecan concentration in the brain. We radiolabeled topotecan with 11C and acquired static and dynamic positron emission tomography (PET) scans to quantify [11C] topotecan uptake in the brains of normal mice and mice after HIFU treatment. We found that HIFU treatments significantly increased [11C] topotecan brain uptake. Moreover, kinetic analysis of the [11C] topotecan dynamic PET data demonstrated a substantial increase in [11C] topotecan volume of distribution in the brain. Furthermore, we found a decrease in [11C] topotecan brain clearance, confirming the potential of HIFU to aid in the delivery of topotecan through the BBB. This opens the potential clinical application of [11C] topotecan as a tool to predict topotecan loco-regional brain concentration in patients with GBMs undergoing experimental HIFU treatments.