Sunitinib administered prior to radiotherapy in patients with non-resectable glioblastoma: results of a phase II study

Angiogenesis in Glioblastoma-Treatment Approaches

Glioblastoma, the most common primary malignant brain tumor in adults, carries a poor prognosis, with a median survival of just 15 months, significantly impacting patients' quality of life. The aggressive growth of these highly vascularized tumors relies heavily on angiogenesis, driven primarily by vascular endothelial growth factor-A. Therefore, VEGF signaling pathway has become a prime therapeutic target in GBM treatment over the past decade. While anti-angiogenic treatment showed promise, agents like bevacizumab have ultimately failed to improve overall survival. This highlights the presence of compensatory angiogenic mechanisms that bypass VEGF inhibition, necessitating further investigation into resistance mechanisms and the development of more effective therapeutic strategies. This review examined the current landscape of anti-angiogenic agents for GBM, analyzed the mechanisms driving resistance to these therapies, and explored potential strategies for enhancing their effectiveness.

A Review of FDA-Approved Multi-Target Angiogenesis Drugs for Brain Tumor Therapy

Neovascularization is an important process in brain tumor development, invasion and metastasis. Several research studies have indicated that the VEGF signaling target has potential for reducing angiogenesis in brain tumors. However, targeting VEGF signaling has not met the expected efficacy, despite initial enthusiasm. This is partly because tumors cleverly use alternative growth factor pathways, other than VEGF signaling, to restore angiogenesis. Multi-target inhibitors have been developed to inhibit several receptor kinases that play a role in the development of angiogenesis. By simultaneously affecting various receptor kinases, these treatments can potentially obstruct various angiogenic pathways that are involved in brain cancer advancement, often offering a more holistic strategy than treatments focusing on just one kinase. Since 2009, the FDA has approved a number of multi-kinase inhibitors that target angiogenic growth factor receptors (e.g., VEGFR, PDGFR, FGFR, RET, c-KIT, MET, AXL and others) for treatment of malignant diseases, including brain cancer. Here, we present some recent results from the literature regarding the preclinical and clinical effects of these inhibitors on brain tumors.

Neoadjuvant clinical trials in adults with newly diagnosed high-grade glioma: A systematic review

BACKGROUND

High-grade gliomas are devastating cancers that remain incurable with standard surgical resection and radiochemotherapy. Although beneficial against neoplasms, radiation lowers lymphocyte counts, weakens immune activation, and recruits suppressive myeloid cells impairing immune responses. Tumor environments treated with radiation experience long-term immunosuppression, reducing immunotherapy effectiveness and contributing to recurrence. Investigating pre-radiation treatments in newly diagnosed patients could identify active agents, assess immunotherapy impact, and enable multiomic analyses without radiation-induced confounding factors. This literature review was conducted to describe the feasibility, safety, and outcomes of postsurgical, pre-radiation clinical trials for adults with newly diagnosed high-grade glioma.

METHODS

A systematic review was performed of the English-language literature reporting results of clinical trials for adults with newly diagnosed high-grade glioma administered postsurgical treatment prior to radiation therapy. A search was conducted in PubMed and references cited in research and review articles were also considered.

RESULTS

From 1991 to 2024, 52 clinical trials were identified: 3 phase I, 38 phase II, 4 phase III, and 7 of unknown phase. Nine trials were randomized, 24 were multicenter trials, 21 investigated temozolomide-containing regimens, and 12 focused on inoperable tumors, involving a total of 2737 patients.

CONCLUSION

Pre-radiation neoadjuvant studies are feasible and may identify active drugs. This is particularly relevant in the era of personalized medicine with brain-penetrant drugs, targeted therapy, and immuno-oncology advancements. Investigating pre-radiation treatments in newly diagnosed high-grade glioma is a viable approach to rapidly identify active and inactive regimens while the immune system and tumor microenvironment remain intact.

Challenges and advances in glioblastoma targeted therapy: the promise of drug repurposing and biomarker exploration

Glioblastoma remains the most prevalent and aggressive primary malignant brain tumor in adults, characterized by limited treatment options and a poor prognosis. Previous drug repurposing efforts have yielded only marginal survival benefits, particularly those involving inhibitors targeting receptor tyrosine kinase and cyclin-dependent kinase-retinoblastoma pathways. This limited efficacy is likely due to several critical challenges, including the tumor's molecular heterogeneity, the dynamic evolution of its genetic profile, and the restrictive nature of the blood-brain barrier that impedes effective drug delivery. Emerging diagnostic tools, such as circulating tumor DNA and extracellular vesicles, offer promising non-invasive methods for real-time tumor monitoring, potentially enabling the application of targeted therapies to more selected patient populations. Moreover, innovative drug delivery strategies, including focused ultrasound, implantable drug-delivery systems, and engineered nanoparticles, hold potential for enhancing the bioavailability and therapeutic efficacy of treatments.

Unlocking Hope: Anti-VEGFR inhibitors and their potential in glioblastoma treatment

PURPOSE

This systematic review summarizes evidence of VEGFR gene mutations and VEGF/VEGFR protein expression in glioblastoma multiforme (GBM) patients, alongside the efficacy and safety of anti-VEGFR tyrosine kinase inhibitors (TKIs) for GBM treatment.

METHODS

A comprehensive literature review was conducted using PubMed up to August 2023. Boolean operators and MeSH term "glioma," along with specific VEGFR-related keywords, were utilized following thorough examination of existing literature.

RESULTS

VEGFR correlates with glioma grade and GBM progression, presenting a viable therapeutic target. Regorafenib and axitinib show promise among studied TKIs. Other multi-targeted TKIs (MTKI) and combination therapies exhibit potential, albeit limited by blood-brain barrier penetration and toxicity. Combining treatments like radiotherapy and enhancing BBB penetration may benefit patients. Further research is warranted in patient quality of life and biomarker-guided selection.

CONCLUSION

While certain therapies hold promise for GBM, future research should prioritize personalized medicine and innovative strategies for improved treatment outcomes.

Efficacy and safety of FLT3 inhibitors in monotherapy of hematological and solid malignancies: a systemic analysis of clinical trials

Introduction: FLT3 mutations are closely associated with the occurrence of hematological and solid malignancies, especially with acute myeloid leukemia. Currently, several FLT3 inhibitors are in clinical trials, and some have been applied in clinic. However, the safety, efficacy and pharmacodynamics of these FLT3 inhibitors have not been systemically analyzed before. Methods: We searched and reviewed clinical trial reports on the monotherapy of 13 FLT3 inhibitors, including sorafenib, lestaurtinib, midostaurin, gilteritinib, quizartinib, sunitinib, crenolanib, tandutinib, cabozantinib, pexidartinib, pacritinib, famitinib, and TAK-659 in patients with hematological and solid malignancies before May 31, 2023. Results: Our results showed the most common adverse events (AEs) were gastrointestinal adverse reactions, including diarrhea, hand-foot syndrome and nausea, while the most common hematological AEs were febrile neutropenia, anemia, and thrombocytopenia. Based on the published data, the mean overall survival (OS) and the mean progression-free survival (PFS) were 9.639 and 5.905 months, respectively. The incidence of overall response rate (ORR), complete remission (CR), partial response (PR), and stable disease (SD) for all these FLT3 inhibitors was 29.0%, 8.7%, 16.0%, and 42.3%, respectively. The ORRs of FLT3 inhibitors in hematologic malignancies and solid tumors were 40.8% and 18.8%, respectively, indicating FLT3 inhibitors were more effective for hematologic malignancies than for solid tumors. In addition, time to maximum plasma concentration (Tmax) in these FLT3 inhibitors ranged from 0.7-12.0 hours, but the elimination half-life (T1/2) range was highly variable, from 6.8 to 151.8 h. Discussion: FLT3 inhibitors monotherapy has shown significant anti-tumor effect in clinic, and the effectiveness may be further improved through combination medication.

Glioblastoma Therapy: Past, Present and Future

Glioblastoma (GB) stands out as the most prevalent and lethal form of brain cancer. Although great efforts have been made by clinicians and researchers, no significant improvement in survival has been achieved since the Stupp protocol became the standard of care (SOC) in 2005. Despite multimodality treatments, recurrence is almost universal with survival rates under 2 years after diagnosis. Here, we discuss the recent progress in our understanding of GB pathophysiology, in particular, the importance of glioma stem cells (GSCs), the tumor microenvironment conditions, and epigenetic mechanisms involved in GB growth, aggressiveness and recurrence. The discussion on therapeutic strategies first covers the SOC treatment and targeted therapies that have been shown to interfere with different signaling pathways (pRB/CDK4/RB1/P16ink4, TP53/MDM2/P14arf, PI3k/Akt-PTEN, RAS/RAF/MEK, PARP) involved in GB tumorigenesis, pathophysiology, and treatment resistance acquisition. Below, we analyze several immunotherapeutic approaches (i.e., checkpoint inhibitors, vaccines, CAR-modified NK or T cells, oncolytic virotherapy) that have been used in an attempt to enhance the immune response against GB, and thereby avoid recidivism or increase survival of GB patients. Finally, we present treatment attempts made using nanotherapies (nanometric structures having active anti-GB agents such as antibodies, chemotherapeutic/anti-angiogenic drugs or sensitizers, radionuclides, and molecules that target GB cellular receptors or open the blood-brain barrier) and non-ionizing energies (laser interstitial thermal therapy, high/low intensity focused ultrasounds, photodynamic/sonodynamic therapies and electroporation). The aim of this review is to discuss the advances and limitations of the current therapies and to present novel approaches that are under development or following clinical trials.

Targeted Glioma Therapy-Clinical Trials and Future Directions

Glioblastoma multiforme (GBM) is the most common type of glioma, with a median survival of 14.6 months post-diagnosis. Understanding the molecular profile of such tumors allowed the development of specific targeted therapies toward GBM, with a major role attributed to tyrosine kinase receptor inhibitors and immune checkpoint inhibitors. Targeted therapeutics are drugs that work by specific binding to GBM-specific or overexpressed markers on the tumor cellular surface and therefore contain a recognition moiety linked to a cytotoxic agent, which produces an antiproliferative effect. In this review, we have summarized the available information on the targeted therapeutics used in clinical trials of GBM and summarized current obstacles and advances in targeted therapy concerning specific targets present in GBM tumor cells, outlined efficacy endpoints for major classes of investigational drugs, and discussed promising strategies towards an increase in drug efficacy in GBM.

FLT3L-dependent dendritic cells control tumor immunity by modulating Treg and NK cell homeostasis

FLT3-L-dependent classical dendritic cells (cDCs) recruit anti-tumor and tumor-protecting lymphocytes. We evaluate cancer growth in mice with low, normal, or high levels of cDCs. Paradoxically, both low or high numbers of cDCs improve survival in mice with melanoma. In low cDC context, tumors are restrained by the adaptive immune system through influx of effector T cells and depletion of Tregs and NK cells. High cDC numbers favor the innate anti-tumor response, with massive recruitment of activated NK cells, despite high Treg infiltration. Anti CTLA-4 but not anti PD-1 therapy synergizes with FLT3-L therapy in the cDCHi but not in the cDCLo context. A combination of cDC boost and Treg depletion dramatically improves survival of tumor-bearing mice. Transcriptomic data confirm the paradoxical effect of cDC levels on survival in several human tumor types. cDCHi-TregLo state in such patients predicts best survival. Modulating cDC numbers via FLT3 signaling may have therapeutic potential in human cancer.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

Shaping the brain vasculature in development and disease in the single-cell era

The CNS critically relies on the formation and proper function of its vasculature during development, adult homeostasis and disease. Angiogenesis - the formation of new blood vessels - is highly active during brain development, enters almost complete quiescence in the healthy adult brain and is reactivated in vascular-dependent brain pathologies such as brain vascular malformations and brain tumours. Despite major advances in the understanding of the cellular and molecular mechanisms driving angiogenesis in peripheral tissues, developmental signalling pathways orchestrating angiogenic processes in the healthy and the diseased CNS remain incompletely understood. Molecular signalling pathways of the 'neurovascular link' defining common mechanisms of nerve and vessel wiring have emerged as crucial regulators of peripheral vascular growth, but their relevance for angiogenesis in brain development and disease remains largely unexplored. Here we review the current knowledge of general and CNS-specific mechanisms of angiogenesis during brain development and in brain vascular malformations and brain tumours, including how key molecular signalling pathways are reactivated in vascular-dependent diseases. We also discuss how these topics can be studied in the single-cell multi-omics era.

Kinomics platform using GBM tissue identifies BTK as being associated with higher patient survival

BTK is a dominant bioactive kinase expressed within both cancer and immune cells of GBM tissue. Complex cell co-cultures might better model the impact of kinase inhibitors as therapeutics in GBM.

Better understanding of GBM signalling networks in-vivo would help develop more physiologically relevant ex vivo models to support therapeutic discovery. A “functional proteomics” screen was undertaken to measure the specific activity of a set of protein kinases in a two-step cell-free biochemical assay to define dominant kinase activities to identify potentially novel drug targets that may have been overlooked in studies interrogating GBM-derived cell lines. A dominant kinase activity derived from the tumour tissue, but not patient-derived GBM stem-like cell lines, was Bruton tyrosine kinase (BTK). We demonstrate that BTK is expressed in more than one cell type within GBM tissue; SOX2-positive cells, CD163-positive cells, CD68-positive cells, and an unidentified cell population which is SOX2-negative CD163-negative and/or CD68-negative. The data provide a strategy to better mimic GBM tissue ex vivo by reconstituting more physiologically heterogeneous cell co-culture models including BTK-positive/negative cancer and immune cells. These data also have implications for the design and/or interpretation of emerging clinical trials using BTK inhibitors because BTK expression within GBM tissue was linked to longer patient survival.

Glioblastoma multiforme (GBM): An overview of current therapies and mechanisms of resistance

Glioblastoma multiforme (GBM) is a WHO grade IV glioma and the most common malignant, primary brain tumor with a 5-year survival of 7.2%. Its highly infiltrative nature, genetic heterogeneity, and protection by the blood brain barrier (BBB) have posed great treatment challenges. The standard treatment for GBMs is surgical resection followed by chemoradiotherapy. The robust DNA repair and self-renewing capabilities of glioblastoma cells and glioma initiating cells (GICs), respectively, promote resistance against all current treatment modalities. Thus, durable GBM management will require the invention of innovative treatment strategies. In this review, we will describe biological and molecular targets for GBM therapy, the current status of pharmacologic therapy, prominent mechanisms of resistance, and new treatment approaches. To date, medical imaging is primarily used to determine the location, size and macroscopic morphology of GBM before, during, and after therapy. In the future, molecular and cellular imaging approaches will more dynamically monitor the expression of molecular targets and/or immune responses in the tumor, thereby enabling more immediate adaptation of tumor-tailored, targeted therapies.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

A Systematic Review of Glioblastoma-Targeted Therapies in Phases II, III, IV Clinical Trials

Glioblastoma (GBM), the most frequent and aggressive glial tumor, is currently treated as first line by the Stupp protocol, which combines, after surgery, radiotherapy and chemotherapy. For recurrent GBM, in absence of standard treatment or available clinical trials, various protocols including cytotoxic drugs and/or bevacizumab are currently applied. Despite these heavy treatments, the mean overall survival of patients is under 18 months. Many clinical studies are underway. Based on clinicaltrials.org and conducted up to 1 April 2020, this review lists, not only main, but all targeted therapies in phases II-IV of 257 clinical trials on adults with newly diagnosed or recurrent GBMs for the last twenty years. It does not involve targeted immunotherapies and therapies targeting tumor cell metabolism, that are well documented in other reviews. Without surprise, the most frequently reported drugs are those targeting (i) EGFR (40 clinical trials), and more generally tyrosine kinase receptors (85 clinical trials) and (ii) VEGF/VEGFR (75 clinical trials of which 53 involving bevacizumab). But many other targets and drugs are of interest. They are all listed and thoroughly described, on an one-on-one basis, in four sections related to targeting (i) GBM stem cells and stem cell pathways, (ii) the growth autonomy and migration, (iii) the cell cycle and the escape to cell death, (iv) and angiogenesis.

Guanabenz Sensitizes Glioblastoma Cells to Sunitinib by Inhibiting GADD34-Mediated Autophagic Signaling

Limited therapeutic efficacy of temozolomide (TMZ) against glioblastomas highlights the importance of exploring new drugs for clinical therapy. Sunitinib, a multitargeted receptor tyrosine kinase inhibitor, is currently being tested as therapy for glioblastomas. Unfortunately, sunitinib still has insufficient activity to cure glioblastomas. Our aim was to determine the molecular mechanisms counteracting sunitinib drug sensitivity and find potential adjuvant drugs for glioblastoma therapy. Through in vitro experiments, transcriptome screening by RNA sequencing, and in silico analyses, we found that sunitinib induced glioma apoptotic death, and downregulated genes were enriched in oncogenic genes of glioblastoma. Meanwhile, sunitinib-upregulated genes were highly associated with the protective autophagy process. Blockade of autophagy significantly enhanced sunitinib's cytotoxicity. Growth arrest and DNA damage-inducible protein (GADD) 34 was identified as a candidate involved in sunitinib-promoted autophagy through activating p38-mitogen-activated protein kinase (MAPK) signaling. Higher GADD34 levels predicted poor survival of glioblastoma patients and induced autophagy formation in desensitizing sunitinib cytotoxicity. Guanabenz, an alpha2-selective adrenergic agonist and GADD34 functional inhibitor, was identified to enhance the efficacy of sunitinib by targeting GADD34-induced protective autophagy in glioblastoma cells, TMZ-resistant cells, hypoxic cultured cells, sphere-forming cells, and colony formation abilities. A better combined treatment effect with sunitinib and guanabenz was also observed by using xenograft mice. Taken together, the sunitinib therapy combined with guanabenz in the inhibition of GADD34-enhanced protective autophagy may provide a new therapeutic strategy for glioblastoma.

Identification of a Dexamethasone Mediated Radioprotection Mechanism Reveals New Therapeutic Vulnerabilities in Glioblastoma

(1) Background: Despite the indisputable effectiveness of dexamethasone (DEXA) to reduce inflammation in glioblastoma (GBM) patients, its influence on tumour progression and radiotherapy response remains controversial. (2) Methods: We analysed patient data and used expression and cell biological analyses to assess effects of DEXA on GBM cells. We tested the efficacy of tyrosine kinase inhibitors in vitro and in vivo. (3) Results: We confirm in our patient cohort that administration of DEXA correlates with worse overall survival and shorter time to relapse. In GBM cells and glioma stem-like cells (GSCs) DEXA down-regulates genes controlling G2/M and mitotic-spindle checkpoints, and it enables cells to override the spindle assembly checkpoint (SAC). Concurrently, DEXA up-regulates Platelet Derived Growth Factor Receptor (PDGFR) signalling, which stimulates expression of anti-apoptotic regulators BCL2L1 and MCL1, required for survival during extended mitosis. Importantly, the protective potential of DEXA is dependent on intact tyrosine kinase signalling and ponatinib, sunitinib and dasatinib, all effectively overcome the radio-protective and pro-proliferative activity of DEXA. Moreover, we discovered that DEXA-induced signalling creates a therapeutic vulnerability for sunitinib in GSCs and GBM cells in vitro and in vivo. (4) Conclusions: Our results reveal a novel DEXA-induced mechanism in GBM cells and provide a rationale for revisiting the use of tyrosine kinase inhibitors for the treatment of GBM.

Sunitinib-Containing Carborane Pharmacophore with the Ability to Inhibit Tyrosine Kinases Receptors FLT3, KIT and PDGFR-β, Exhibits Powerful In Vivo Anti-Glioblastoma Activity

Simple Summary

Glioblastoma is one of the most aggressive central nervous system tumors. Combinations of therapies, such as tyrosine kinase receptor inhibition and boron neutron capture therapy (BNCT), could offer greater patients benefits over single-therapies. The aim of our study was to assess the potential of sunitinib-carborane hybrid compound 1 as an anti-glioblastoma agent. We confirmed for 1 the ability to inhibit tyrosine kinase receptors, which could promote canonical and non-canonical effects, absence of mutagenicity, ability to cross the blood–brain barrier, and powerful in vivo anti-glioblastoma activity. The overall attractive profile of 1 makes it an interesting compound for a bimodal therapeutic strategy against high grade gliomas.

Abstract

Malignant gliomas are the most common malignant and aggressive primary brain tumors in adults, the prognosis being—especially for glioblastomas—extremely poor. There are no effective treatments yet. However, tyrosine kinase receptor (TKR) inhibitors and boron neutron capture therapy (BNCT), together, have been proposed as future therapeutic strategies. In this sense in our ongoing project of developing new anti-glioblastoma drugs, we identified a sunitinib-carborane hybrid agent, 1, with both in vitro selective cytotoxicity and excellent BNCT-behavior. Consequently, we studied the ability of compound 1 to inhibit TKRs, its promotion of cellular death processes, and its effects on the cell cycle. Moreover, we analyzed some relevant drug-like properties of 1, i.e., mutagenicity and ability to cross the blood–brain barrier. These results encouraged us to perform an in vivo anti-glioblastoma proof of concept assay. It turned out to be a selective FLT3, KIT, and PDGFR-β inhibitor and increased the apoptotic glioma-cell numbers and arrested sub-G1-phase cell cycle. Its in vivo activity in immunosuppressed mice bearing U87 MG human glioblastoma evidenced excellent anti-tumor behavior.

Bimodal Therapeutic Agents Against Glioblastoma, One of the Most Lethal Forms of Cancer

About 95 % of people diagnosed with glioblastoma die within five years. Glioblastoma is the most aggressive central nervous system tumour. It is necessary to make progress in the glioblastoma treatment so that advanced chemotherapy drugs or radiation therapy or, ideally, two-in-one hybrid systems should be implemented. Tyrosine kinase receptors-inhibitors and boron neutron capture therapy (BNCT), together, could provide a therapeutic strategy. In this work, sunitinib decorated-carborane hybrids were prepared and biologically evaluated identifying excellent antitumoral- and BNCT-agents. One of the selected hybrids was studied against glioma-cells and found to be 4 times more cytotoxic than sunitinib and 1.7 times more effective than ¹⁰ B-boronophenylalanine fructose complex when the cells were irradiated with neutrons.

Malignant Intracranial High Grade Glioma and Current Treatment Strategy

Malignant high-grade glioma (HGG) is the most common and extremely fatal type of primary intracranial tumor. These tumors recurred within 2 to 3 cm of the primary region of tumor resection in the majority of cases. Furthermore, the blood-brain barrier significantly limited the access of many systemically administered chemotherapeutics to the tumor, pointing towards a stringent need for new therapeutic patterns. Therefore, targeting therapy using local drug delivery for HGG becomes a priority for the development of novel therapeutic strategies. The main objectives to the effective use of chemotherapy for HGG include the drug delivery to the tumor region and the infusion of chemotherapeutic agents into the vascular supply of a tumor directly, which could improve the pharmacokinetic profile by enhancing drug delivery to the neoplasm tissue. Herein, we reviewed clinical and molecular features, different methods of chemotherapy application in HGGs, especially the existing and promising targeting therapies using local drug delivery for HGG which could effectively inhibit tumor invasion, proliferation and recurrence of HGG to combat the deadly disease. Undoubtedly, novel chemical medicines targeting these HGG may represent one of the most important directions in the Neuro-oncology.

Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma

Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.

Delay in starting radiotherapy due to neoadjuvant therapy does not worsen survival in unresected glioblastoma patients

PURPOSE

We retrospectively examined the potential effect on overall survival (OS) of delaying radiotherapy to administer neoadjuvant therapy in unresected glioblastoma patients.

PATIENTS AND METHODS

We compared OS in 119 patients receiving neoadjuvant therapy followed by standard treatment (NA group) and 96 patients receiving standard treatment without neoadjuvant therapy (NoNA group). The MaxStat package of R identified the optimal cut-off point for waiting time to radiotherapy.

RESULTS

OS was similar in the NA and NoNA groups. Median waiting time to radiotherapy after surgery was 13 weeks for the NA group and 4.2 weeks for the NoNA group. The longest OS was attained by patients who started radiotherapy after 12 weeks and the shortest by patients who started radiotherapy within 4 weeks (12.3 vs 6.6 months) (P = 0.05). OS was 6.6 months for patients who started radiotherapy before the optimal cutoff of 6.43 weeks and 19.1 months for those who started after this time (P = 0.005). Patients who completed radiotherapy had longer OS than those who did not, in all 215 patients and in the NA and NoNA groups (P = 0.000). In several multivariate analyses, completing radiotherapy was a universally favorable prognostic factor, while neoadjuvant therapy was never identified as a negative prognostic factor.

CONCLUSION

In our series of unresected patients receiving neoadjuvant treatment, in spite of the delay in starting radiotherapy, OS was not inferior to that of a similar group of patients with no delay in starting radiotherapy.

Targeting cellular pathways in glioblastoma multiforme

Glioblastoma multiforme (GBM) is a debilitating disease that is associated with poor prognosis, short median patient survival and a very limited response to therapies. GBM has a very complex pathogenesis that involves mutations and alterations of several key cellular pathways that are involved in cell proliferation, survival, migration and angiogenesis. Therefore, efforts that are directed toward better understanding of GBM pathogenesis are essential to the development of efficient therapies that provide hope and extent patient survival. In this review, we outline the alterations commonly associated with GBM pathogenesis and summarize therapeutic strategies that are aimed at targeting aberrant cellular pathways in GBM.

Crossing the Blood-Brain Barrier: Recent Advances in Drug Delivery to the Brain

CNS disorders are on the rise despite advancements in our understanding of their pathophysiological mechanisms. A major hurdle to the treatment of these disorders is the blood-brain barrier (BBB), which serves as an arduous janitor to protect the brain. Many drugs are being discovered for CNS disorders, which, however fail to enter the market because of their inability to cross the BBB. This is a pronounced challenge for the pharmaceutical fraternity. Hence, in addition to the discovery of novel entities and drug candidates, scientists are also developing new formulations of existing drugs for brain targeting. Several approaches have been investigated to allow therapeutics to cross the BBB. As the molecular structure of the BBB is better elucidated, several key approaches for brain targeting include physiological transport mechanisms such as adsorptive-mediated transcytosis, inhibition of active efflux pumps, receptor-mediated transport, cell-mediated endocytosis, and the use of peptide vectors. Drug-delivery approaches comprise delivery from microspheres, biodegradable wafers, and colloidal drug-carrier systems (e.g., liposomes, nanoparticles, nanogels, dendrimers, micelles, nanoemulsions, polymersomes, exosomes, and quantum dots). The current review discusses the latest advancements in these approaches, with a major focus on articles published in 2015 and 2016. In addition, we also cover the alternative delivery routes, such as intranasal and convection-enhanced diffusion methods, and disruption of the BBB for brain targeting.

Response Assessment in Neuro-Oncology Criteria and Clinical Endpoints

The Response Assessment in Neuro-Oncology (RANO) Working Group is an international multidisciplinary group whose goal is to improve response criteria and define endpoints for neuro-oncology trials. The RANO criteria for high-grade gliomas attempt to address the issues of pseudoprogression, pseudoresponse, and nonenhancing tumor progression. Incorporation of advanced MR imaging may eventually help improve the ability of these criteria to define enhancing and nonenhancing disease better. The RANO group has also developed criteria for neurologic response and evaluation of patients receiving immunologic therapies. RANO criteria have been developed for brain metastases and are in progress for meningiomas, leptomeningeal disease, spinal tumors, and pediatric tumors.

Investigational new drugs for brain cancer

INTRODUCTION

Despite substantial improvements in standards of care, the most common aggressive pediatric and adult high-grade gliomas (HGG) carry uniformly fatal diagnoses due to unique treatment limitations, high recurrence rates and the absence of effective treatments following recurrence. Recent advancements in our understanding of the pathophysiology, genetics and epigenetics as well as mechanisms of immune surveillance during gliomagenesis have created new knowledge to design more effective and target-directed therapies to improve patient outcomes.

AREAS COVERED

In this review, the authors discuss the critical genetic, epigenetic and immunologic aberrations found in gliomas that appear rational and promising for therapeutic developments in the presence and future. The current state of the latest therapeutic developments including tumor-specific targeted drug therapies, metabolic targeting, epigenetic modulation and immunotherapy are summarized and suggestions for future directions are offered. Furthermore, they highlight contemporary issues related to the clinical development, such as challenges in clinical trials and toxicities.

EXPERT OPINION

The commitment to understanding the process of gliomagenesis has created a catalogue of aberrations that depict multiple mechanisms underlying this disease, many of which are suitable to therapeutic inhibition and are currently tested in clinical trials. Thus, future treatment endeavors will employ multiple treatment modalities that target disparate tumor characteristics personalized to the patient's individual tumor.

Benefit, Risk, and Outcomes in Drug Development: A Systematic Review of Sunitinib

BACKGROUND

Little is known about the total patient burden associated with clinical development and where burdens fall most heavily during a drug development program. Our goal was to quantify the total patient burden/benefit in developing a new drug.

METHODS

We measured risk using drug-related adverse events that were grade 3 or higher, benefit by objective response rate, and trial outcomes by whether studies met their primary endpoint with acceptable safety. The differences in risk (death rate) and benefit (overall response rate) between industry and nonindustry trials were analyzed with an inverse-variance weighted fixed effects meta-analysis implemented as a weighted regression analysis. All statistical tests were two-sided.

RESULTS

We identified 103 primary publications of sunitinib monotherapy, representing 9092 patients and 3991 patient-years of involvement over 10 years and 32 different malignancies. In total, 1052 patients receiving sunitinib monotherapy experienced objective tumor response (15.7% of intent-to-treat population, 95% confidence interval [CI] = 15.3% to 16.0%), 98 died from drug-related toxicities (1.08%, 95% CI = 1.02% to 1.14%), and at least 1245 experienced grade 3-4 drug-related toxicities (13.7%, 95% CI = 13.3% to 14.1%). Risk/benefit worsened as the development program matured, with several instances of replicated negative studies and almost no positive trials after the first responding malignancies were discovered.

CONCLUSIONS

Even for a successful drug, the risk/benefit balance of trials was similar to phase I cancer trials in general. Sunitinib monotherapy development showed worsening risk/benefit, and the testing of new indications responded slowly to evidence that sunitinib monotherapy would not extend to new malignancies. Research decision-making should draw on evidence from whole research programs rather than a narrow band of studies in the same indication.

Development of targeted therapies in treatment of glioblastoma

Glioblastoma (GBM) is a type of tumor that is highly lethal despite maximal therapy. Standard therapeutic approaches provide modest improvement in progression-free and overall survival, necessitating the investigation of novel therapies. Oncologic therapy has recently experienced a rapid evolution toward "targeted therapy", with drugs directed against specific targets which play essential roles in the proliferation, survival, and invasiveness of GBM cells, including numerous molecules involved in signal transduction pathways. Inhibitors of these molecules have already entered or are undergoing clinical trials. However, significant challenges in their development remain because several preclinical and clinical studies present conflicting results. In this article, we will provide an up-to-date review of the current targeted therapies in GBM.

Combining radiotherapy with sunitinib: lessons (to be) learned

To improve the efficacy of radiotherapy (RTx), there is a growing interest in combining RTx with drugs that inhibit angiogenesis, i.e., the process of neo-vessel formation out of preexisting capillaries. A frequently used drug to inhibit angiogenesis is sunitinib (Sutent, SU11248), a receptor tyrosine kinase inhibitor that is currently FDA approved for the treatment of several cancer types. The current review presents an overview of the preclinical studies and clinical trials that combined sunitinib with RTx. We discuss the findings from preclinical and clinical observations with a focus on dose scheduling and commonly reported toxicities. In addition, the effects of combination therapy on tumor response and patient survival are described. Finally, the lessons learned from preclinical and clinical studies are summarized and opportunities and pitfalls for future clinical trials are presented.