Preliminary results from a phase I/II study of perillyl alcohol intranasal administration in adults with recurrent malignant gliomas

Molecular pharmacology and therapeutic advances of monoterpene perillyl alcohol

BACKGROUND

Perillyl alcohol (POH) is a aroma monoterpene commonly obtained from various plants' essential oil. Recently, increasing researches have demonstrated that POH may be useful, not only as flavor compound, but also as bioactive molecule because of a variety of biological activities.

PURPOSE

The aim of this review is to summarize the production, pharmacological activities and molecular mechanism, active derivatives, toxicity and parmacokinetics, and industrial application of POH.

METHODS

A systematic search of published articles up to January 2024 in Web of Science, China Knowledge Network, and PubMed databases is conducted using the following keywords: POH, POH derivatives, biological or pharmacological, production or synthesis, pharmacokinetics, toxicity and application.

RESULTS

Biotechnological production is considered to be a potential alternative approach to generate POH. POH provides diverse pharmacological benefits, including anticancer, antimicrobial, insecticidal, antioxidant, anti-inflammatory, hypotensive, vasorelaxant, antinociceptive, antiasthmatic, hepatoprotective effects, etc. The underlying mechanisms of action include modulation of NF-κB, JNK/c-Jun, Notch, Akt/mTOR, PI3K/Akt/eNOS, STAT3, Nrf2 and ERS response pathways, mitigation of mitochondrial dysfunction and membrane integrity damage, and inhibition of ROS accumulation, pro-inflammatory cytokines release and NLRP3 activation. What's more, the proteins or genes influenced by POH against diseases refer to Bax, Bcl-2, cyclin D1, CDK, p21, p53, HIF-1α, AP-1, caspase-3, M6P/IGF2R, PARP, VEGF, etc. Some clinical studies report that intranasal delivery of POH is a safe and effective treatment for cancer, but further clinical investigations are needed to confirm other health benefits of POH in human healthy. Depending on these health-promoting properties together with desirable flavor and safety, POH can be employed as dietary supplement, preservative and flavor additive in food and cosmetic fields, as building block in synthesis fields, as anticancer drug in medicinal fields, and as pesticides and herbicides in agricultural fields.

CONCLUSION

This review systematically summarizes the recent advances in POH and highlights its therapeutic effects and potential mechanisms as well as the clinical settings, which is helpful to develop POH into functional food and new candidate drug for prevention and management of diseases. Future studies are needed to conduct more biological activity studies of POH and its derivatives, and check their clinical efficacy and potential side effects.

Brain tumours: Non-invasive techniques to treat invasive pathologies

Brain and other central nervous system tumours are cancers of poor prognosis, for which current therapeutic possibilities do not match the expectations regarding a curative objective. If the treatment of central nervous system tumours is so difficult, it is partly due to the blood-brain barrier and the blood-tumour barrier, which need to be crossed to access the tumour. Driven by these insufficient results, more and more techniques and technologies are being explored and are evolving: the progress of surgery and radiotherapy, the growing place of immunotherapies, or the apparition of new non-invasive techniques. The latter are those which interest us here, where promising advances are taking the leap to clinical trials. Nose-to-brain delivery, receptor-mediated transcytosis and micro-bubbles-associated focused ultrasounds are three therapeutic propositions with encouraging results regarding the improvement of drug access to the brain. Even though they might have their share of limits and adverse effects, benefit-risk balance looks promising, and they may appear as new options to treat patients in the future.

Magnetic resonance imaging analysis predicts nanoparticle concentration delivered to the brain parenchyma

Ultrasound in combination with the introduction of microbubbles into the vasculature effectively opens the blood brain barrier (BBB) to allow the passage of therapeutic agents. Increased permeability of the BBB is typically demonstrated with small-molecule agents (e.g., 1-nm gadolinium salts). Permeability to small-molecule agents, however, cannot reliably predict the transfer of remarkably larger molecules (e.g., monoclonal antibodies) required by numerous therapies. To overcome this issue, we developed a magnetic resonance imaging analysis based on the ΔR₂* physical parameter that can be measured intraoperatively for efficient real-time treatment management. We demonstrate successful correlations between ΔR₂* values and parenchymal concentrations of 3 differently sized (18 nm–44 nm) populations of liposomes in a rat model. Reaching an appropriate ΔR₂* value during treatment can reflect the effective delivery of large therapeutic agents. This prediction power enables the achievement of desirable parenchymal drug concentrations, which is paramount to obtaining effective therapeutic outcomes.

ΔR₂* values from MRI analysis correlate with concentrations of liposomes in the size range of 18–44 nm in a rat model.

Detection of perillyl alcohol and its metabolite perillic acid in postsurgical glioblastoma tissue after intranasal administration of NEO100: illustrative case

BACKGROUND

Intranasal delivery of NEO100, a pharmaceutical-grade version of the natural monoterpene perillyl alcohol (POH), is undergoing clinical phase IIa testing as a treatment for glioblastoma (GBM). However, so far there is no evidence that intranasal delivery of NEO100 indeed results in POH reaching intracranial malignancies in a patient.

OBSERVATIONS

After surgical removal of her recurrent GBM tumor, a patient received daily intranasal NEO100 therapy for more than 3 years before a second recurrence emerged. At that time, a final dose of NEO100 was given shortly before the tumor tissue was surgically removed, and the tissue was processed for high-performance liquid chromatography analysis of POH and its primary metabolite, perillic acid (PA). Both molecules could readily be detected in the tumor tissue.

LESSONS

This is the first demonstration of POH and PA in brain tumor tissue from any patient. It reveals that intranasal administration of NEO100 is a valid approach to achieve delivery of this agent to a brain tumor. In view of the noninvasive and safe nature of this method, along with tentative indications of activity, our findings add confidence to the notion that intranasal administration of NEO100 holds potential as a new treatment option for brain-localized malignancies.

Intranasal Delivery in Glioblastoma treatment: Prospective Molecular Treatment Modalities

Glioblastoma multiforme (GBM) is rare and fatal glioma with limited treatment options. Treatments provide minimal improvement in prognosis and only 6.8% of GBM patients have a life expectancy greater than five years. Surgical resection of this malignant glioma is difficult due to its highly invasive nature and follow-up radiotherapy with concomitant temozolomide, the currently approved standard of care, and will only extend the life of patients by a few months. It has been nearly two decades since the approval of temozolomide and there have been no clinically relevant major breakthroughs since, painting a dismal picture for patients with GBM. Although the future of GBM management seems bleak, there are many new treatment options on the horizon that propose methods of delivery to circumvent current limitations in the standard of care, i.e., the blood brain barrier and treatment resistance mechanisms. The nose is a highly accessible non-invasive route of delivery that has been incorporated into many investigational studies within the past five years and potentially paves the path to a brighter future for the management of GBM. Intranasal administration has its limitations however, as drugs can be degraded and/or fail to reach the site of action. This has prompted many studies for implementation of nanoparticle systems to overcome these limitations and to accurately deliver drugs to the site of action. This review highlights the advances in intranasal therapy delivery and impact of nanotechnology in the management of GBM and discusses potential treatment modalities that show promise for further investigation.

Gather wisdom to overcome barriers: Well-designed nano-drug delivery systems for treating gliomas

Due to the special physiological and pathological characteristics of gliomas, most therapeutic drugs are prevented from entering the brain. To improve the poor prognosis of existing therapies, researchers have been continuously developing non-invasive methods to overcome barriers to gliomas therapy. Although these strategies can be used clinically to overcome the blood‒brain barrier (BBB), the accurate delivery of drugs to the glioma lesions cannot be ensured. Nano-drug delivery systems (NDDS) have been widely used for precise drug delivery. In recent years, researchers have gathered their wisdom to overcome barriers, so many well-designed NDDS have performed prominently in preclinical studies. These meticulous designs mainly include cascade passing through BBB and targeting to glioma lesions, drug release in response to the glioma microenvironment, biomimetic delivery systems based on endogenous cells/extracellular vesicles/protein, and carriers created according to the active ingredients of traditional Chinese medicines. We reviewed these well-designed NDDS in detail. Furthermore, we discussed the current ongoing and completed clinical trials of NDDS for gliomas therapy, and analyzed the challenges and trends faced by clinical translation of these well-designed NDDS.

The Monoterpenoid Perillyl Alcohol: Anticancer Agent and Medium to Overcome Biological Barriers

Perillyl alcohol (POH) is a naturally occurring monoterpenoid related to limonene that is present in the essential oils of various plants. It has diverse applications and can be found in household items, including foods, cosmetics, and cleaning supplies. Over the past three decades, it has also been investigated for its potential anticancer activity. Clinical trials with an oral POH formulation administered to cancer patients failed to realize therapeutic expectations, although an intra-nasal POH formulation yielded encouraging results in malignant glioma patients. Based on its amphipathic nature, POH revealed the ability to overcome biological barriers, primarily the blood-brain barrier (BBB), but also the cytoplasmic membrane and the skin, which appear to be characteristics that critically contribute to POH's value for drug development and delivery. In this review, we present the physicochemical properties of POH that underlie its ability to overcome the obstacles placed by different types of biological barriers and consequently shape its multifaceted promise for cancer therapy and applications in drug development. We summarized and appraised the great variety of preclinical and clinical studies that investigated the use of POH for intranasal delivery and nose-to-brain drug transport, its intra-arterial delivery for BBB opening, and its permeation-enhancing function in hybrid molecules, where POH is combined with or conjugated to other therapeutic pharmacologic agents, yielding new chemical entities with novel mechanisms of action and applications.

Perillyl alcohol for pediatric TP53- and RAS-mutated SHH-medulloblastoma: an in vitro and in vivo translational pre-clinical study

PURPOSE

Inhalation of perillyl alcohol (POH) recently emerged as an investigational promising antiglioma strategy. However, little attention has been paid to its therapeutic potential for other brain tumors, especially in the pediatric setting.

METHODS

The effects of POH were explored in medulloblastoma cell models belonging to the SHH variant with activation of RAS (ONS-76) or with TP53 mutations (DAOY and UW402), by means of proliferation and invasion assays. Interactions with methotrexate, thiotepa, or ionizing radiation were also assessed. Mice bearing subcutaneous tumors were treated with intraperitoneal injections. Alternatively, animals with intracranial tumors were exposed to intranasal POH alone or combined with radiation. Tumor growth was measured by bioluminescence. Analyses of cytotoxicity to the nasal cavity were also performed, and the presence of POH in the brain, lungs, and plasma was surveyed through chromatography/mass spectrometry.

RESULTS

POH decreased cell proliferation and colony formation, with conspicuous death, though the invasive capacity was only affected in the NRAS-mutated cell line. Median-drug effect analysis displayed synergistic combinations with methotrexate. Otherwise, POH showed to be a reasonable radiosensitizer. In vivo, intraperitoneal injection significantly decreased tumor volume. However, its inhalation did not affect orthotopic tumors, neither alone or followed by cranial irradiation. Nasal cavity epithelium showed unimportant alterations, though, no traces of POH or its metabolites were detected in tissue samples.

CONCLUSION

POH presents robust in vitro antimedulloblastoma effects and sensitizes cell lines to other conventional therapeutics, reducing tumor volume when administered intraperitoneally. Nevertheless, further improvement of delivery devices and/or drug formulations are needed to better characterize its effectiveness through inhalation.

Tea tree oil extract causes mitochondrial superoxide production and apoptosis as an anticancer agent, promoting tumor infiltrating neutrophils cytotoxic for breast cancer to induce tumor regression

The antitumor activity of the tea tree oil (TTO) derived product, Melaleuca Alternifolia Concentrate (MAC) was characterized mechanistically at the molecular and cellular level. MAC was analyzed for its anticancer activity against human prostate (LNCaP) and breast (MCF-7) cancer cell lines growing in vitro. MAC (0.02-0.06% v/v) dose-dependently induced the intrinsic (mitochondrial) apoptotic pathway in both the LNCaP and MCF-7 cell lines, involving increased mitochondrial superoxide production, loss of mitochondrial membrane potential (MMP), caspase 3/7 activation, as well as the presence of TUNEL⁺ and cleaved-PARP⁺ cell populations. At concentrations of 0.01-0.04% v/v, MAC caused cell cycle arrest in the G_0/1-phase, as well as autophagy. The in vivo anticancer actions of MAC were examined as a treatment in the FVB/N c-Neu murine model for spontaneously arising breast cancers. Intratumoral MAC injections (1-4% v/v) significantly suppressed tumor progression in a dose-dependent manner and was associated with greater levels of tumor infiltrating neutrophils exhibiting anticancer cytotoxic activity. Induction of breast cancer cell death by MAC via the mitochondrial apoptotic pathway was also replicated occurring in tumors treated in vivo. In conclusion, our data highlights the potential for the Melaleuca-derived MAC product inducing anticancer neutrophil influx, supporting its application as a novel therapeutic agent.

Antitumor effect of Melaleuca alternifolia essential oil and its main component terpinen-4-ol in combination with target therapy in melanoma models

Essential oils (EOs) have been recently emerging for their promising biological activities in preventing tumorigenesis or progression of different tumor histotypes, including melanoma. In this study, we investigated the antitumor activity of a panel of EOs in different tumor models. The ability of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol, to sensitize the target therapy currently used for melanoma treatment was also assessed. Our results demonstrated that EOs differently affect the viability of human cancer cells and led us to select six EOs effective in melanoma and lung cancer cells, without toxic effects in human fibroblasts. When combined with dabrafenib and/or trametinib, Melaleuca alternifolia synergistically reduced the viability of melanoma cells by activating apoptosis. Through machine learning classification modeling, α-terpineol, tepinolene, and terpinen-4-ol, three components of Melaleuca alternifolia, were identified as the most likely relevant components responsible for the EO's antitumor effect. Among them, terpinen-4-ol was recognized as the Melaleuca alternifolia component responsible for its antitumor and proapoptotic activity. Overall, our study holds promise for further analysis of EOs as new anticancer agents and supports the rationale for their use to improve target therapy response in melanoma.

NEO100 enables brain delivery of blood‒brain barrier impermeable therapeutics

BACKGROUND

Intracarotid injection of mannitol has been applied for decades to support brain entry of therapeutics that otherwise do not effectively cross the blood-brain barrier (BBB). However, the elaborate and high-risk nature of this procedure has kept its use restricted to well-equipped medical centers. We are developing a more straightforward approach to safely open the BBB, based on the intra-arterial (IA) injection of NEO100, a highly purified version of the natural monoterpene perillyl alcohol.

METHODS

In vitro barrier permeability with NEO100 was evaluated by transepithelial/transendothelial electrical resistance and antibody diffusion assays. Its mechanism of action was studied by western blot, microarray analysis, and electron microscopy. In mouse models, we performed ultrasound-guided intracardiac administration of NEO100, followed by intravenous application of Evan's blue, methotrexate, checkpoint-inhibitory antibodies, or chimeric antigen receptor (CAR) T cells.

RESULTS

NEO100 opened the BBB in a reversible and nontoxic fashion in vitro and in vivo. It enabled greatly increased brain entry of all tested therapeutics and was well tolerated by animals. Mechanistic studies revealed effects of NEO100 on different BBB transport pathways, along with translocation of tight junction proteins from the membrane to the cytoplasm in brain endothelial cells.

CONCLUSION

We envision that this procedure can be translated to patients in the form of transfemoral arterial catheterization and cannulation to the cerebral arteries, which represents a low-risk procedure commonly used in a variety of clinical settings. Combined with NEO100, it is expected to provide a safe, widely available approach to enhance brain entry of any therapeutic.

Perillyl alcohol reduces parasite sequestration and cerebrovascular dysfunction during experimental cerebral malaria

Cerebral malaria (CM) is a severe immunovasculopathy which presents high mortality rate (15-20%), despite the availability of artemisinin-based therapy. More effective immunomodulatory and/or antiparasitic therapies are urgently needed. Experimental Cerebral Malaria (ECM) in mice is used to elucidate aspects involved in this pathology since manifests many of the neurological features of CM. In the present study, we evaluated the potential mechanisms involved in the protection afforded by perillyl alcohol (POH) in mouse strains susceptible to CM caused by Plasmodium berghei ANKA (PbA) infection through intranasal preventive treatment. Additionally, to evaluate the interaction of POH with the cerebral endothelium using an in vitro model of human brain endothelial cells (HBEC). Pharmacokinetic approaches demonstrated constant and prolonged levels of POH in the plasma and brain after a single intranasal dose. Treatment with POH effectively prevented vascular dysfunction. Furthermore, treatment with POH reduced the endothelial cell permeability and PbA s in the brain and spleen. Finally, POH treatment decreased the accumulation of macrophages and T and B cells in the spleen and downregulated the expression of endothelial adhesion molecules (ICAM-1, VCAM-1, and CD36) in the brain. POH is a potent monoterpene that prevents cerebrovascular dysfunction in vivo and in vitro, decreases parasite sequestration, and modulates different processes related to the activation, permeability, and integrity of the blood brain barrier (BBB), thereby preventing cerebral oedema and inflammatory infiltrates.

Phase I trial of intranasal NEO100, highly purified perillyl alcohol, in adult patients with recurrent glioblastoma

Background

Better treatments for glioblastoma (GBM) patients, in particular in the recurrent setting, are urgently needed. Clinical trials performed in Brazil indicated that intranasal delivery of perillyl alcohol (POH) might be effective in this patient group. NEO100, a highly purified version of POH, was current good manufacturing practice (cGMP) manufactured to evaluate the safety and efficacy of this novel approach in a Phase I/IIa clinical trial in the United States.

Methods

A total of 12 patients with recurrent GBM were enrolled into Phase I of this trial. NEO100 was administered by intranasal delivery using a nebulizer and nasal mask. Dosing was 4 times a day, every day. Four cohorts of 3 patients received the following dosages: 96 mg/dose (384 mg/day), 144 mg/dose (576 mg/day), 192 mg/dose (768 mg/day), and 288 mg/dose (1152 mg/day). Completion of 28 days of treatment was recorded as 1 cycle. Adverse events were documented, and radiographic response via Response Assessment in Neuro-Oncology (RANO) criteria was evaluated every 2 months. Progression-free and overall survival were determined after 6 and 12 months, respectively (progression-free survival-6 [PFS-6], overall survival-12 [OS-12]).

Results

Intranasal NEO100 was well tolerated at all dose levels and no severe adverse events were reported. PFS-6 was 33%, OS-12 was 55%, and median OS was 15 months. Four patients (33%), all of them with isocitrate dehydrogenase 1 (IDH1)-mutant tumors, survived >24 months.

Conclusion

Intranasal glioma therapy with NEO100 was well tolerated. It correlated with improved survival when compared to historical controls, pointing to the possibility that this novel intranasal approach could become useful for the treatment of recurrent GBM.

Focused Ultrasound and Microbubbles-Mediated Drug Delivery to Brain Tumor

The presence of blood–brain barrier (BBB) and/or blood–brain–tumor barriers (BBTB) is one of the main obstacles to effectively deliver therapeutics to our central nervous system (CNS); hence, the outcomes following treatment of malignant brain tumors remain unsatisfactory. Although some approaches regarding BBB disruption or drug modifications have been explored, none of them reach the criteria of success. Convention-enhanced delivery (CED) directly infuses drugs to the brain tumor and surrounding tumor infiltrating area over a long period of time using special catheters. Focused ultrasound (FUS) now provides a non-invasive method to achieve this goal via combining with systemically circulating microbubbles to locally enhance the vascular permeability. In this review, different approaches of delivering therapeutic agents to the brain tumors will be discussed as well as the characterization of BBB and BBTB. We also highlight the mechanism of FUS-induced BBB modulation and the current progress of this technology in both pre-clinical and clinical studies.

Intranasal administration of perillyl alcohol-loaded nanoemulsion and pharmacokinetic study of its metabolite perillic acid in plasma and brain of rats using ultra-performance liquid chromatography/tandem mass spectrometry

Perillyl alcohol (POH) is a monocyclic terpene that has strong antitumor activity. Brain tumors are particularly difficult to treat with therapeutic agents, and clinical trials have shown their low tolerance through oral administration. We proposed the entrapment of POH into an oil-in-water chitosan nanoemulsion aiming its intranasal administration for brain targeting. An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantitation of total metabolite perillic acid (PA) in plasma and brain of rats. The rat samples containing the metabolite were treated by liquid-liquid extraction with acetonitrile. The mobile phase was 0.1% formic acid in water (solvent A) and 0.1% formic acid in methanol (solvent B), at a flow rate of 0.3 mL min^-1 in gradient elution. The chromatography was run for 10 min, and analytical curves were built in acetonitrile, plasma, and brain. The PA was detected in positive ion mode with multiple reaction monitoring. The method has shown high selectivity, sensitivity, and throughput. The low quantification limits of 162, 178, and 121 ng mL^-1 for acetonitrile, brain, and plasma, respectively, indicate a good detectability of the method. The repeatability and precision observed were within the limits recommended in the literature. The accuracy of the method was verified through high recovery rates (106-118%). The validated method was successfully applied to the pharmacokinetic study of the metabolite PA after the intranasal administration of free or POH-loaded nanoemulsion in rats. The results showed that chitosan nanoemulsion improved the plasma and brain bioavailability of POH, representing a promising alternative to free POH treatment.

Pharmacokinetic properties of the temozolomide perillyl alcohol conjugate (NEO212) in mice

Background

NEO212 is a novel small-molecule anticancer agent that was generated by covalent conjugation of the natural monoterpene perillyl alcohol (POH) to the alkylating agent temozolomide (TMZ). It is undergoing preclinical development as a therapeutic for brain-localized malignancies. The aim of this study was to characterize metabolism and pharmacokinetic (PK) properties of NEO212 in preclinical models.

Methods

We used mass spectrometry (MS) and modified high-performance liquid chromatography to identify and quantitate NEO212 and its metabolites in cultured glioblastoma cells, in mouse plasma, brain, and excreta after oral gavage.

Results

Our methods allowed identification and quantitation of NEO212, POH, TMZ, as well as primary metabolites 5-aminoimidazole-4-carboxamide (AIC) and perillic acid (PA). Intracellular concentrations of TMZ were greater after treatment of U251TR cells with NEO212 than after treatment with TMZ. The half-life of NEO212 in mouse plasma was 94 min. In mice harboring syngeneic GL261 brain tumors, the amount of NEO212 was greater in the tumor-bearing hemisphere than in the contralateral normal hemisphere. The brain:plasma ratio of NEO212 was greater than that of TMZ. Excretion of unaltered NEO212 was through feces, whereas its AIC metabolite was excreted via urine.

Conclusions

NEO212 preferentially concentrates in brain tumor tissue over normal brain tissue, and compared to TMZ has a higher brain:plasma ratio, altogether revealing favorable features to encourage its further development as a brain-targeted therapeutic. Its breakdown into well-characterized, long-lived metabolites, in particular AIC and PA, will provide useful equivalents for PK studies during further drug development and clinical trials with NEO212.

Intranasal perillyl alcohol therapy improves survival of patients with recurrent glioblastoma harboring mutant variant for MTHFR rs1801133 polymorphism

Background

Polymorphisms in MTHFR gene influence risk and overall survival of patients with brain tumor. Global genomic DNA (gDNA) methylation profile from tumor tissues is replicated in peripheral leukocytes. This study aimed to draw a correlation between rs1801133 MTHFR variants, gDNA methylation and overall survival of patients with recurrent glioblastoma (rGBM) under perillyl alcohol (POH) treatment.

Methods

gDNA from whole blood was extracted using a commercially available kit (Axygen) and quantified by spectrophotometry. Global gDNA methylation was determined by ELISA and rs1801133 polymorphism by PCR-RFLP. Statistical analysis of gDNA methylation profile and rs1801133 variants included Mann-Whitney, Kruskal-Wallis, Spearman point-biserial correlation tests (SPSS and Graphpad Prism packages; significant results for effect size higher than 0.4). Prognostic value of gDNA methylation and rs1801133 variants considered survival profiles at 25 weeks of POH treatment, having the date of protocol adhesion as starting count and death as the final event.

Results

Most rGBM patients showed global gDNA hypomethylation (median = 31.7%) and a significant, moderate and negative correlation between TT genotype and gDNA hypomethylation (median = 13.35%; rho = − 0.520; p = 0.003) compared to CC variant (median = 32.10%), which was not observed for CT variant (median = 33.34%; rho = − 0.289; p = 0.06). gDNA hypermethylated phenotype (median = 131.90%) exhibited significant, moderate and negative correlations between TT genotype (median = 112.02%) and gDNA hypermethylation levels when compared to CC (median = 132.45%; rho = − 0,450; p = 0.04) or CT (median = 137.80%; rho = − 0.518; p = 0.023) variants. TT variant of rs1801133 significantly decreased gDNA methylation levels for both patient groups, when compared to CC (d values: hypomethylated = 1.189; hypermethylated = 0.979) or CT (d values: hypomethylated = 0.597; hypermethylated = 1.167) variants. Positive prognostic for rGBM patients may be assigned to gDNA hypermethylation for survivors above 25 weeks of treatment (median = 88 weeks); and TT variant of rs1801133 regardless POH treatment length.

Conclusion

rGBM patients under POH-based therapy harboring hypermethylated phenotype and TT variant for rs1801133 had longer survival. Intranasal POH therapy mitigates detrimental effects of gDNA hypomethylation and improved survival of patients with rGBM harboring TT mutant variant for MTHFR rs1801133 polymorphism.

Trial registration

CONEP -9681- 25,000.009267 / 2004. Registered 12th July, 2004.

Efficient brain targeting and therapeutic intracranial activity of bortezomib through intranasal co-delivery with NEO100 in rodent glioblastoma models

OBJECTIVE

Many pharmaceutical agents are highly potent but are unable to exert therapeutic activity against disorders of the central nervous system (CNS), because the blood-brain barrier (BBB) impedes their brain entry. One such agent is bortezomib (BZM), a proteasome inhibitor that is approved for the treatment of multiple myeloma. Preclinical studies established that BZM can be effective against glioblastoma (GBM), but only when the drug is delivered via catheter directly into the brain lesion, not after intravenous systemic delivery. The authors therefore explored alternative options of BZM delivery to the brain that would avoid invasive procedures and minimize systemic exposure.

METHODS

Using mouse and rat GBM models, the authors applied intranasal drug delivery, where they co-administered BZM together with NEO100, a highly purified, GMP-manufactured version of perillyl alcohol that is used in clinical trials for intranasal therapy of GBM patients.

RESULTS

The authors found that intranasal delivery of BZM combined with NEO100 significantly prolonged survival of tumor-bearing animals over those that received vehicle alone and also over those that received BZM alone or NEO100 alone. Moreover, BZM concentrations in the brain were higher after intranasal co-delivery with NEO100 as compared to delivery in the absence of NEO100.

CONCLUSIONS

This study demonstrates that intranasal delivery with a NEO100-based formulation enables noninvasive, therapeutically effective brain delivery of a pharmaceutical agent that otherwise does not efficiently cross the BBB.

Therapeutic Potential of Curcumin in the Treatment of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor. Despite standard multimodality treatment, the highly aggressive nature of GBM makes it one of the deadliest human malignancies. The anti-cancer effects of dietary phytochemicals like curcumin provide new insights to cancer treatment. Evaluation of curcumin's efficacy against different malignancies including glioblastoma has been a motivational research topic and widely studied during the recent decade. In this review, we discuss the recent observations on the potential therapeutic effects of curcumin against glioblastoma. Curcumin can target multiple signaling pathways involved in developing aggressive and drug-resistant features of glioblastoma, including pathways associated with glioma stem cell activity. Notably, combination therapy with curcumin and chemotherapeutics like temozolomide, the GBM standard therapy, as well as radiotherapy has shown synergistic response, highlighting curcumin's chemo- and radio-sensitizing effect. There are also multiple reports for curcumin nanoformulations and targeted forms showing enhanced therapeutic efficacy and passage through blood-brain barrier, as compared with natural curcumin. Furthermore, in vivo studies have revealed significant anti-tumor effects, decreased tumor size and increased survival with no notable evidence of systemic toxicity in treated animals. Finally, a pharmacokinetic study in patients with GBM has shown a detectable intratumoral concentration, thereby suggesting a potential for curcumin to exert its therapeutic effects in the brain. Despite all the evidence in support of curcumin's potential therapeutic efficacy in GBM, clinical reports are still scarce. More studies are needed to determine the effects of combination therapies with curcumin and importantly to investigate the potential for alleviating chemotherapy- and radiotherapy-induced adverse effects.

Overview of Current Drug Delivery Methods Across the Blood-Brain Barrier for the Treatment of Primary Brain Tumors

Existing drug delivery methods have not led to a significant increase in survival for patients with malignant primary brain tumors. While the combination of conventional therapies consisting of surgery, radiotherapy, and chemotherapy has improved survival for some types of brain tumors (e.g., WNT medulloblastoma), other types of brain tumors (e.g., glioblastoma and diffuse midline glioma) still have a poor prognosis. The reason for the differences in response can be largely attributed to the blood-brain barrier (BBB), a specialized structure at the microvasculature level that regulates the transport of molecules across the blood vessels into the brain parenchyma. This structure hampers the delivery of most chemotherapeutic agents for the treatment of primary brain tumors. Several drug delivery methods such as nanoparticles, convection enhanced delivery, focused ultrasound, intranasal delivery, and intra-arterial delivery have been developed to overcome the BBB in primary brain tumors. However, prognosis of most primary brain tumors still remains poor. The heterogeneity of the BBB in primary brain tumors and the distinct vasculature of tumors make it difficult to design a drug delivery method that targets the entire tumor. Drug delivery methods that combine strategies such as focused ultrasound and nanoparticles might be a more successful approach. However, more research is needed to optimize and develop new drug delivery techniques to improve survival of patients with primary brain tumors.

How to Make Anticancer Drugs Cross the Blood-Brain Barrier to Treat Brain Metastases

The incidence of brain metastases has increased in the last 10 years. However, the survival of patients with brain metastases remains poor and challenging in daily practice in medical oncology. One of the mechanisms suggested for the persistence of a high incidence of brain metastases is the failure to cross the blood-brain barrier of most chemotherapeutic agents, including the more recent targeted therapies. Therefore, new pharmacological approaches are needed to optimize the efficacy of anticancer drug protocols. In this article, we present recent findings in molecular data on brain metastases. We then discuss published data from pharmacological studies on the crossing of the blood-brain barrier by anticancer agents. We go on to discuss future developments to facilitate drug penetration across the blood-brain barrier for the treatment of brain metastases among cancer patients, using physical methods or physiological transporters.

Nasal Drug Delivery of Anticancer Drugs for the Treatment of Glioblastoma: Preclinical and Clinical Trials

Glioblastoma (GBM) is the most lethal form of brain tumor, being characterized by the rapid growth and invasion of the surrounding tissue. The current standard treatment for glioblastoma is surgery, followed by radiotherapy and concurrent chemotherapy, typically with temozolomide. Although extensive research has been carried out over the past years to develop a more effective therapeutic strategy for the treatment of GBM, efforts have not provided major improvements in terms of the overall survival of patients. Consequently, new therapeutic approaches are urgently needed. Overcoming the blood–brain barrier (BBB) is a major challenge in the development of therapies for central nervous system (CNS) disorders. In this context, the intranasal route of drug administration has been proposed as a non-invasive alternative route for directly targeting the CNS. This route of drug administration bypasses the BBB and reduces the systemic side effects. Recently, several formulations have been developed for further enhancing nose-to-brain transport, mainly with the use of nano-sized and nanostructured drug delivery systems. The focus of this review is to provide an overview of the strategies that have been developed for delivering anticancer compounds for the treatment of GBM while using nasal administration. In particular, the specific properties of nanomedicines proposed for nose-to-brain delivery will be critically evaluated. The preclinical and clinical data considered supporting the idea that nasal delivery of anticancer drugs may represent a breakthrough advancement in the fight against GBM.

Prospect of natural products in glioma: A novel avenue in glioma management

Glioma is one of the most perplexing cancers because of its infiltrating nature, molecular signaling, and location in central nervous system. Blood-brain barrier acts as a natural barrier to the glioma making it difficult to access by conventional chemotherapy. Clinicians are using natural compounds or their derivatives for several diseases including different cancers. However, the feasibility of using natural compounds in glioma is not explored in details. Natural compounds can act over a wide variety of signaling pathways such as survival and metabolic pathways and induce cell death. Some of the natural agents have additional benefits of crossing biological barriers such as blood-brain barrier with ease having few or no impact on the surrounding healthy cells. All of these benefits make natural compounds a prospective candidate for the glioma management. This article evaluates the benefits of using natural compounds for glioma therapy and their possible mechanism of actions. We have discussed the natural compounds assessed currently for glioma therapy and proposed a few novel natural compounds with potential antiglioma effect based on their mechanism of action.

Novel N-arylamide derivatives of (S)-perillic acid ((S)-PA): in vitro and in vivo cytotoxicity and antitumor evaluation

Hepatocellular carcinoma (HC) and glioblastoma (GBA) are the most commonly aggressive malignant liver and brain tumors. Based on an established method for the synthesis of amide, two novel analogues (4 and 5) of (S)-perillic acid were synthesized and their structures were affirmed using nuclear magnetic resonance spectroscopic analysis. An MTT cytotoxic assay showed that our derivatives (4 and 5) demonstrated a substantial anti-proliferative effect against HC (HepG2) and GBA (U251) cell lines. Particularly, compound 5 showed growth inhibitory (IC50) effects on U251 (IC50 = 3.10 ± 0.12 μg mL-1) and HepG2 cells (IC50 = 1.49 ± 0.43 μg mL-1), which fall within the acceptable standard recommended by the National institute of cancer (Bethesda, MD, USA) for the selection of anticancer drug candidates. Consequently, we assessed the in vivo antitumor and organ/tissue toxicity of 4, 5 and 5-fluorouracil (5-FU) in hepatoma H22-inoculated mice. The results obtained indicated remarkable tumor growth inhibition with no substantial toxicological effects on the mice and the organs/tissues in the treated groups compared well with the control.

Therapeutic potential of monoterpene α-thujone, the main compound of Thuja occidentalis L. essential oil, against malignant glioblastoma multiforme cells in vitro

Thuja occidentalis L. is indigenous for Northern America and commonly cultivated in Europe. Raw materials obtained from this tree are widely applied in the ethnomedicine and phytotherapy of numerous ailments, incl. scurvy, cystitis, rheumatism and cancer. Despite wide medicinal applications of Thuja occidentalis, still little is known on its therapeutic potential in tumor treatment. α-thujone is the main component of Thuja occidentalis essential oil, which has been suggested to possess anti-tumor activities. This monoterpene easily penetrates the blood-brain barrier. Therefore, we examined its effects on the malignancy of glioblastoma multiforme (GBM) cells, with the special emphasis on the mechanisms of its effect on cell viability and invasiveness. α-thujone exerted the attenuating effect on the viability and proliferation of GBM cells when administered at the concentrations between 100 and 500 μg/ml (660 μM - 3.2 mM). This effect was correlated with the induction of apoptosis in GBM cell populations and with considerable inhibition of GBM cells motility. Mechanistic analyses demonstrated the induction of oxidative stress and autophagy in α-thujone-treated tumor cells, whereas normal astrocytes displayed considerably lower sensitivity to α-thujone. Our observations demonstrate that α-thujone exerts pro-apoptotic and anti-invasive effects on GBM cells. They confirm the potential of α-thujone for the treatment of glioblastoma multiforme.

The Rolipram-Perillyl Alcohol Conjugate (NEO214) Is A Mediator of Cell Death through the Death Receptor Pathway

Glioblastoma (GBM) is a highly aggressive primary brain tumor with a poor prognosis. Treatment with temozolomide, standard of care for gliomas, usually results in drug resistance and tumor recurrence. Therefore, there is a great need for drugs that target GBM. NEO214 was generated by covalently linking rolipram to perillyl alcohol (POH) via a carbamate bond to form the rolipram-perillyl alcohol conjugate. We show here that NEO214 is effective against both temozolomide-sensitive and temozolomide-resistant glioma cells. Furthermore, NEO214 is effective for different mechanisms of temozolomide resistance: overexpression of MGMT (O⁶-methylguanine methyl-transferase); deficiency in specific mismatch repair proteins; and overexpression of base excision repair (BER) proteins. NEO214-induced cytotoxicity involves apoptosis triggered by endoplasmic reticulum (ER) stress, as well as activating the Death Receptor 5 (DR5)/TNF-related apoptosis-inducing ligand (TRAIL/Apo2L) pathway. In vitro studies show that glioma cells treated with NEO214 express DR5 and exhibit cell death in the presence of recombinant TRAIL, a growth factor constitutively produced by astrocytes. Our in vitro 3D coculture data show that induction of DR5 in glioma cells with NEO214 and TRAIL cause tumor cell death very effectively and specifically for glioma cells. In vivo studies show that NEO214 has antitumor efficacy in orthotropic syngeneic rodent tumor models. Furthermore, NEO214 has therapeutic potential especially for brain tumors because this drug can cross the blood-brain barrier (BBB), and is effective in the TRAIL-rich astrocyte microenvironment. NEO214 is a strong candidate for use in the treatment of GBMs.

Evaluation of phytomedicinal potential of perillyl alcohol in an in vitro Parkinson's Disease model

Preclinical Research & Development Parkinson's disease (PD) is the second most common neurodegenerative disorder that affects approximately 10 million people worldwide. The risk of developing PD and similar neurodegenerative disorders increases with age and an estimated 4% people are diagnosed with the disease before reaching the age of 50. Oxidative stress, cytotoxicity, and mitochondrial dysfunction are common features exhibited in the development of PD. The 6-hyroxydopamine (6-OHDA) model of PD is one of the most well characterized and studied models of the disease. 6-OHDA, a neurotoxin, can induce most characteristic features of the disease, including mitochondrial dysfunction in-vivo and in-vitro. SH-SY5Y is a neuroblastoma cell line of human origin that has been used for dose response studies on PD in the past. Based on previous data, we have used SH-SY5Y cells as an in-vitro model of PD to analyse the phytomedicinal potential of perillyl alcohol (PA), a monoterpenoid obtained from essential oils of various plants such as sage, peppermint and lavender. We have found that pretreatment with PA (10 μM and 20 μM) mitigated 6-OHDA (150 μM) induced cytotoxicity in a dose-dependent manner. We observed marked restoration of cell viability and mitochondrial membrane potential (MMP) as well as reduced reactive oxygen species generation, Cytochrome c immunofluorescence and DNA fragmentation after treatment with PA. On the basis of on our data, we have come to the conclusion that PA demonstrates sufficient neuroprotective activity to provide new avenues in therapy of PD and its apparent target being restoration of MMP can lead to better understanding of the disease.

Intranasal Perillyl Alcohol for Glioma Therapy: Molecular Mechanisms and Clinical Development

Intracranial malignancies, such as primary brain cancers and brain-localized metastases derived from peripheral cancers, are particularly difficult to treat with therapeutic agents, because the blood-brain barrier (BBB) effectively minimizes brain entry of the vast majority of agents arriving from the systemic circulation. Intranasal administration of cancer drugs has the potential to reach the brain via direct nose-to-brain transport, thereby circumventing the obstacle posed by the BBB. However, in the field of cancer therapy, there is a paucity of studies reporting positive results with this type of approach. A remarkable exception is the natural compound perillyl alcohol (POH). Its potent anticancer activity was convincingly established in preclinical studies, but it nonetheless failed in subsequent clinical trials, where it was given orally and displayed hard-to-tolerate gastrointestinal side effects. Intriguingly, when switched to intranasal delivery, POH yielded highly promising activity in recurrent glioma patients and was well tolerated. As of 2018, POH is the only intranasally delivered compound in the field of cancer therapy (outside of cancer pain) that has advanced to active clinical trials. In the following, we will introduce this compound, summarize its molecular mechanisms of action, and present the latest data on its clinical evaluation as an intranasally administered agent for glioma.

MicroRNA-1225-5p behaves as a tumor suppressor in human glioblastoma via targeting of IRS1

Background

MicroRNAs (miRNAs) play an important role in cancer initiation, progression, and metastasis by directly regulating their target genes.

Materials and methods

In this study, we observed that the miR-1225-5p expression level in glioblastoma tissues was significantly lower as compared with that in normal brain tissues, and its low expression was significantly associated with histopathological grade and poor patient prognosis.

Results

Through establishing a miR-1225-5p overexpression glioblastoma cell line, we found that ectopic overexpression of miR-1225-5p inhibited the proliferation, migration, and invasion of glioblastoma cells in vitro. Moreover, the growth of a glioblastoma xenograft tumor was attenuated by overexpression of miR-1225-5p. Further integrative studies suggested that the insulin receptor substrate 1 (IRS1) was a direct functional target of miR-1225-5p in glioblastoma, and the mRNA and protein levels of IRS1 in six human glioblastoma cell lines (A172, SW1783, U87, LN-229, SW1088, and T98G) were significantly higher as compared with normal human astrocytes.

Conclusion

These results suggest that miR-1225-5p may be a novel candidate for glioblastoma therapy.

Current natural therapies in the treatment against glioblastoma

Glioblastoma (GBM) is the most common and aggressive brain tumor, which causes the highest number of deaths worldwide. It is a highly vascularized tumor, infiltrative, and its tumorigenic capacity is exacerbated. All these hallmarks are therapeutic targets in GBM treatment, including surgical removal followed by radiotherapy and chemotherapy. Current therapies have not been sufficient for the effective patient's management, so the classic therapies have had to expand and incorporate new alternative treatments, including natural compounds. This review summarizes natural products and their physiological effects in in vitro and in vivo models of GBM, specifically by modulating signaling pathways involved in angiogenesis, cell migration/invasion, cell viability, apoptosis, and chemoresistance. The most important aspects of natural products and their derivatives were described in relation to its antitumoral effects. As a final result, it can be obtained that within the compounds with more evidence that supports or suggests its clinical use are the cannabinoids, terpenes, and curcumin, because many have been shown to have a significant effect in decreasing the progress of GBM through known mechanisms, such as chemo-sensitization or decrease migration and cell invasion. Natural compounds emerge as promising therapies to attack the progress of GBM.

Hydroxyl Group and Vasorelaxant Effects of Perillyl Alcohol, Carveol, Limonene on Aorta Smooth Muscle of Rats

The present study used isometric tension recording to investigate the vasorelaxant effect of limonene (LM), carveol (CV), and perillyl alcohol (POH) on contractility parameters of the rat aorta, focusing in particular on the structure-activity relationship. LM, CV, and POH showed a reversible inhibitory effect on the contraction induced by electromechanical and pharmacomechanical coupling. In the case of LM, but not CV and POH, this effect was influenced by preservation of the endothelium. POH and CV but not LM exhibited greater pharmacological potency on BayK-8644-induced contraction and on electromechanical coupling than on pharmacomechanical coupling. In endothelium-denuded preparations, the order of pharmacological potency on electrochemical coupling was LM < CV < POH. These compounds inhibited also, with grossly similar pharmacological potency, the contraction induced by phorbol ester dibutyrate. The present results suggest that LM, CV and POH induced relaxant effect on vascular smooth muscle by means of different mechanisms likely to include inhibition of PKC and IP3 pathway. For CV and POH, hydroxylated compounds, it was in electromechanical coupling that the greater pharmacological potency was observed, thus suggesting a relative specificity for a mechanism likely to be important in electromechanical coupling, for example, blockade of voltage-dependent calcium channel.

Hsp90 inhibitor NMS-E973 exerts the anticancer effect against glioblastoma via induction of PUMA-mediated apoptosis

BACKGROUND

Glioblastoma is one of the most aggressive and common malignancies of the central nervous system in humans. Owing to the correlation of high Hsp90 expression with prognosis and clinical pathology features of diverse types of cancer, targeting Hsp90 with small-molecule inhibitors has become a promising anticancer strategy.

PURPOSE

In this study, we aimed to explore the possibility of anticancer effect of NMS-E973 in giloblastoma and elucidate the mechanism.

METHODS

Cell based MTT assay and colony formation assay were used to detect cell viability. Apoptosis was analyzed by nuclear staining with Hoechst 33258 and Annexin V/propidium iodide staining followed by flow cytometry. Western-blot and RT-PCR were used to detect gene expression. Xenograft assay was used to explore the anticancer effect of NMS-E973 in vivo.

RESULTS

We found that NMS-E973 induces apoptosis and inhibits cell growth in glioblastoma cells in cell culture and xenograft models. As a proapoptotic Bcl-2 member, PUMA was induced by NMS-E973 in a p53-dependent manner in glioblastoma in cell culture, thereby inducing apoptosis in glioblastoma cells. Furthermore, PUMA was induced by NMS-E973 treatment in xenograft tumors, and deficiency in PUMA significantly suppressed the antitumor effects of NMS-E973.

CONCLUSION

Our study suggests that PUMA-mediated apoptosis is important for the therapeutic responses of NMS-E973. Induction of PUMA might be a potential biomarker for predicting NMS-E973 responses.

Efficacy of a ketogenic diet with concomitant intranasal perillyl alcohol as a novel strategy for the therapy of recurrent glioblastoma

It has been hypothesized that persistent ketotic hypoglycemia represents a potential therapeutic strategy against high-grade gliomas. Perillyl alcohol (POH) is a non-toxic, naturally-occurring, hydroxylated monoterpene that exhibits cytotoxicity against temozolomide-resistant glioma cells, regardless of O6-methylguanine-methyltransferase promoter methylation status. The present study aimed to evaluate the toxicity and therapeutic efficacy of intranasal POH when administered in combination with a ketogenic diet (KD) program for the treatment of patients with recurrent glioblastoma. The 32 enrolled patients were divided into two groups, KD or standard diet, with intranasal POH treatment (n=17 and n=15, respectively). The nutritional status and anthropometric parameters of the patients were measured. Patients that adhered to the KD maintained a strict dietary regimen, in addition to receiving 55 mg POH four times daily, in an uninterrupted administration schedule for three months. Neurological examination and magnetic resonance imaging analysis were used to monitor disease progression. A total of 9/17 patients in the KD group survived and maintained compliance with the KD. After three months of well-tolerated treatment, a partial response (PR) was observed for 77.8% (7/9) of the patients, stable disease (SD) in 11.1% (1/9) and 11.1% (1/9) presented with progressive disease (PD). Among the patients assigned to the standard diet group, the PR rate was 25% (2/8 patients), SD 25% (2/8) and PD 50% (4/8 patients). The patients assigned to the KD group presented with reduced serum lipid levels and decreased low-density lipoprotein cholesterol levels. These results are encouraging and suggest that KD associated with intranasal POH may represent a viable option as an adjunct therapy for recurrent GBM.

An Overview of the Biological Effects of Some Mediterranean Essential Oils on Human Health

Essential oils (EOs), extracted from aromatic plants, are interesting natural products and represent an important part of the traditional pharmacopeia. The use of some EOs as alternative antimicrobial and pharmaceutical agents has attracted considerable interest recently. Most of the EOs and their single constituents have been reported to inhibit several phytopathogens, human pathogens, and insects as well as their effective uses in food and pharmaceutical industries. The current review discussed the chemical composition and bioactivity of some important EOs extracted from some Mediterranean plants and their principal bioactive single constituents. Information has been furnished on the mechanisms, mode of actions, and factors affecting the bioactivity of some single constituents from different Mediterranean plant EOs. The current review gives an insight into some common plant EOs belonging to Lamiaceae, Apiaceae, Rutaceae, and Verbenaceae families commonly growing in Mediterranean region. Further information has been provided about the medical uses of some EOs for several human diseases covering the pharmacological effects (anti-inflammatory, antioxidant, and anticarcinogenic). The antimicrobial effects have been also considered in the current review. Although plant EOs are considered promising natural alternatives for many chemical drugs, they still need more specific research for wide application especially in food and pharmaceutical industries.

Reverse ethnopharmacology and drug discovery

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnopharmacological investigations of traditional medicines have made significant contributions to plant-derived drugs, as well as the advancement of pharmacology. Drug discovery from medicinal flora is more complex than generally acknowledged because plants are applied for different therapeutic indications within and across cultures. Therefore we propose the concept of "reverse ethnopharmacology" and compare biomedical uses of plant taxa with their ethnomedicinal and popular uses and test the effect of these on the probability of finding biomedical and specifically anticancer drugs.

MATERIALS AND METHODS

For this analysis we use data on taxonomy and medical indications of plant derived biomedical drugs, clinical trial, and preclinical trial drug candidates published by Zhu et al. (2011) and compare their therapeutic indications with their ethnomedicinal and popular uses as reported in the NAPRALERT^® database. Specifically, we test for increase or decrease of the probability of finding anticancer drugs based on ethnomedicinal and popular reports with Bayesian logistic regression analyses.

RESULTS

Anticancer therapy resulted as the most frequent biomedicinal indication of the therapeutics derived from the 225 drug producing higher plant taxa and showed an association with ethnomedicinal and popular uses in women's medicine, which was also the most important popular use-category. Popular remedies for dysmenorrhoea, and uses as emmenagogues, abortifacients and contraceptives showed a positive effect on the probability of finding anticancer drugs. Another positive effect on the probability of discovering anticancer therapeutics was estimated for popular herbal drugs associated with the therapy of viral and bacterial infections, while the highest effect was found for popular remedies used to treat cancer symptoms. However, this latter effect seems to be influenced by the feedback loop and divulgence of biomedical knowledge on the popular level.

CONCLUSION

We introduce the concept of reverse ethnopharmacology and show that it is possible to estimate the probability of finding biomedical drugs based on ethnomedicinal uses. The detected associations confirm the classical ethnopharmacological approach where a popular remedy for disease category X results in a biomedical drug for disease category X but does also point out the existence of cross-over relationships where popular remedies for disease category X result in biomedical therapeutics for disease category Y (Zhu et al., 2011).

Repurposing L-Menthol for Systems Medicine and Cancer Therapeutics? L-Menthol Induces Apoptosis through Caspase 10 and by Suppressing HSP90

The objective of the present study was to repurpose L-menthol, which is frequently used in oral health and topical formulations, for cancer therapeutics. In this article, we argue that monoterpenes such as L-menthol might offer veritable potentials in systems medicine, for example, as cheaper anti-cancer compounds. Other monoterpenes such as limonene, perillyl alcohol, and geraniol have been shown to induce apoptosis in various cancer cell lines, but their mechanisms of action are yet to be completely elucidated. Earlier, we showed that L-menthol modulates tubulin polymerization and apoptosis to inhibit cancer cell proliferation. In the present report, we used an apoptosis-related gene microarray in conjunction with proteomics analyses, as well as in silico interpretations, to study gene expression modulation in human adenocarcinoma Caco-2 cell line in response to L-menthol treatment. The microarray analysis identified caspase 10 as the important initiator caspase, instead of caspase 8. The proteomics analyses showed downregulation of HSP90 protein (also corroborated by its low transcript abundance), which in turn indicated inhibition of AKT-mediated survival pathway, release of pro-apoptotic factor BAD from BAD and BCLxL complex, besides regulation of other factors related to apoptosis. Based on the combined microarray, proteomics, and in silico data, a signaling pathway for L-menthol-induced apoptosis is being presented for the first time here. These data and literature analysis have significant implications for "repurposing" L-menthol beyond oral medicine, and in understanding the mode of action of plant-derived monoterpenes towards development of cheaper anticancer drugs in future.

Perillyl Alcohol and Its Drug-Conjugated Derivatives as Potential Novel Methods of Treating Brain Metastases

Metastasis to the central nervous system remains difficult to treat, and such patients are faced with a dismal prognosis. The blood-brain barrier (BBB), despite being partially compromised within malignant lesions in the brain, still retains much of its barrier function and prevents most chemotherapeutic agents from effectively reaching the tumor cells. Here, we review some of the recent developments aimed at overcoming this obstacle in order to more effectively deliver chemotherapeutic agents to the intracranial tumor site. These advances include intranasal delivery to achieve direct nose-to-brain transport of anticancer agents and covalent modification of existing drugs to support enhanced penetration of the BBB. In both of these areas, use of the natural product perillyl alcohol, a monoterpene with anticancer properties, contributed to promising new results, which will be discussed here.

A Time-Based and Intratumoral Proteomic Assessment of a Recurrent Glioblastoma Multiforme

Tumors consist of cells in different stages of transformation with molecular and cellular heterogeneity. By far, heterogeneity is the hallmark of glioblastoma multiforme (GBM), the most malignant and aggressive type of glioma. Most proteomic studies aim in comparing tumors from different patients, but here we dive into exploring the intratumoral proteome diversity of a single GBM. For this, we profiled tumor fragments from the profound region of the same patient’s GBM but obtained from two surgeries a year’s time apart. Our analysis also included GBM‘s fragments from different anatomical regions. Our quantitative proteomic strategy employed 4-plex iTRAQ peptide labeling followed by a four-step strong cation chromatographic separation; each fraction was then analyzed by reversed-phase nano-chromatography coupled on-line with an Orbitrap-Velos mass spectrometer. Unsupervised clustering grouped the proteomic profiles into four major distinct groups and showed that most changes were related to the tumor’s anatomical region. Nevertheless, we report differentially abundant proteins from GBM’s fragments of the same region but obtained 1 year apart. We discuss several key proteins (e.g., S100A9) and enriched pathways linked with GBM such as the Ras pathway, RHO GTPases activate PKNs, and those related to apoptosis, to name a few. As far as we know, this is the only report that compares GBM fragments proteomic profiles from the same patient. Ultimately, our results fuel the forefront of scientific discussion on the importance in exploring the richness of subproteomes within a single tissue sample for a better understanding of the disease, as each tumor is unique.

Terpinen-4-ol: A Novel and Promising Therapeutic Agent for Human Gastrointestinal Cancers

Background

Terpinen-4-ol, a naturally occurring monoterpene is the main bioactive component of tea-tree oil and has been shown to have many biological activities.

Aim

To study the antitumor effects of terpinen-4-ol and its mechanism of action in prostate and GI malignancies, alone and in combination with chemotherapeutic and biological agents.

Methods

Terpinen-4-ol was administrated alone or combined with standard chemotherapy (Oxaliplatin, Fluorouracil, Gemcitabine, Tarceva) and biological agent (Cetuximab). It was also combined with humanized anti-CD24 mAbs (was developed by us). Killing effects were measured qualitatively by light microscopy and quantitatively using the MTT and FACS analysis, following treatment of colorectal, pancreatic, gastric and prostate cancer cells. Terpinen-4-ol effect on tumor development was evaluated in xenograft model.

Results

Terpinen-4-ol induces a significant growth inhibition of colorectal, pancreatic, prostate and gastric cancer cells in a dose-dependent manner (10–90% in 0.005–0.1%). Terpinen-4-ol and various anti-cancer agents (0.2μM oxaliplatin and 0.5μM fluorouracil) demonstrated a synergistic inhibitory effect (83% and 91%, respectively) on cancer cell proliferation. In KRAS mutated colorectal cancer cells, which are resistant to anti-EGFR therapy, combining of terpinen-4-ol with cetuximab (1 μM) resulted in impressive efficacy of 80–90% growth inhibition. Sub-toxic concentrations of terpinen-4-ol potentiate anti-CD24 mAb (150μg/ml)-induced growth inhibition (90%). Considerable reduction in tumor volume was seen following terpinen-4-ol (0.2%) treatment alone and with cetuximab (10mg/kg) (40% and 63%, respectively) as compare to the control group.

Conclusion

Terpinen-4-ol significantly enhances the effect of several chemotherapeutic and biological agents. The possible molecular mechanism for its activity involves induction of cell-death rendering this compound as a potential anti-cancer drug alone and in combination in the treatment of numerous malignancies. Terpinen-4-ol restores the activity of cetuximab in cancers with mutated KRAS.

In Vivo Anti-Tumor Activity and Toxicological Evaluations of Perillaldehyde 8,9-Epoxide, a Derivative of Perillyl Alcohol

Recent studies have revealed the high cytotoxicity of p-menthane derivatives against human tumor cells. In this study, the substance perillaldehyde 8,9-epoxide, a p-menthane class derivative obtained from (S)-(−)-perillyl alcohol, was selected in order to assess antitumor activity against experimental sarcoma 180 tumors. Toxicological effects related to the liver, spleen, kidneys and hematology were evaluated in mice submitted to treatment. The tumor growth inhibition rate was 38.4%, 58.7%, 35.3%, 45.4% and 68.1% at doses of 100 and 200 mg/kg/day for perillaldehyde 8,9-epoxide, perillyl alcohol and 25 mg/kg/day for 5-FU intraperitoneal treatments, respectively. No toxicologically significant effect was found in liver and kidney parameters analyzed in Sarcoma 180-inoculated mice treated with perillaldehyde 8,9-epoxide. Histopathological analyses of the liver, spleen, and kidneys were free from any morphological changes in the organs of the animals treated with perillaldehyde 8,9-epoxide. In conclusion, the data suggest that perillaldehyde 8,9-epoxide possesses significant antitumor activity without systemic toxicity for the tested parameters. By comparison, there was no statistical difference for the antitumor activity between perillaldehyde 8,9-epoxide and perillyl alcohol.

Novel delivery methods bypassing the blood-brain and blood-tumor barriers

Glioblastoma (GBM) is the most common primary brain tumor and carries a grave prognosis. Despite years of research investigating potentially new therapies for GBM, the median survival rate of individuals with this disease has remained fairly stagnant. Delivery of drugs to the tumor site is hampered by various barriers posed by the GBM pathological process and by the complex physiology of the blood-brain and blood-cerebrospinal fluid barriers. These anatomical and physiological barriers serve as a natural protection for the brain and preserve brain homeostasis, but they also have significantly limited the reach of intraparenchymal treatments in patients with GBM. In this article, the authors review the functional capabilities of the physical and physiological barriers that impede chemotherapy for GBM, with a specific focus on the pathological alterations of the blood-brain barrier (BBB) in this disease. They also provide an overview of current and future methods for circumventing these barriers in therapeutic interventions. Although ongoing research has yielded some potential options for future GBM therapies, delivery of chemotherapy medications across the BBB remains elusive and has limited the efficacy of these medications.

New therapeutic strategies regarding endovascular treatment of glioblastoma, the role of the blood-brain barrier and new ways to bypass it

The treatment protocols for glioblastoma multiforme (GBM) involve a combination of surgery, radiotherapy and adjuvant chemotherapy. Despite this multimodal approach, the prognosis of patients with GBM remains poor and there is an urgent need to develop novel strategies to improve quality of life and survival in this population. In an effort to improve outcomes, intra-arterial drug delivery has been used in many recent clinical trials; however, their results have been conflicting. The blood-brain barrier (BBB) is the major obstacle preventing adequate concentrations of chemotherapy agents being reached in tumor tissue, regardless of the method of delivering the drugs. Therapeutic failures have often been attributed to an inability of drugs to cross the BBB. However, during the last decade, a better understanding of BBB physiology along with the development of new technologies has led to innovative methods to circumvent this barrier. This paper focuses on strategies and techniques used to bypass the BBB already tested in clinical trials in humans and also those in their preclinical stage. We also discuss future therapeutic scenarios, including endovascular treatment combined with BBB disruption techniques, for patients with GBM.

Chemotherapeutic effect of a novel temozolomide analog on nasopharyngeal carcinoma in vitro and in vivo

BACKGROUND

Many patients with nasopharyngeal carcinoma (NPC) face poor prognosis. Due to its hidden anatomical location, the tumor is usually diagnosed quite late, and despite initially successful treatment with radiation and cisplatin, many patients will relapse and succumb to the disease. New treatment options are urgently needed. We have performed preclinical studies to evaluate the potential NPC therapeutic activity of a newly developed analog of temozolomide (TMZ), an alkylating agent that is the current chemotherapeutic standard of care for patients with malignant glioma.

RESULTS

TMZ was covalently conjugated to the natural monoterpene perillyl alcohol (POH), creating the novel fusion compound NEO212. Its impact on two NPC cell lines was studied through colony formation assays, cell death ELISA, immunoblots, and in vivo testing in tumor-bearing mice. In vitro, NEO212 effectively triggered tumor cell death, and its potency was significantly greater than that of its individual components, TMZ or POH alone. Intriguingly, merely mixing TMZ with POH also was unable to achieve the superior potency of the conjugated compound NEO212. Treatment of NPC cells with NEO212 inactivated the chemoprotective DNA repair protein MGMT (O6-methylguanine methyltransferase), resulting in significant chemosensitization of cells to a second round of drug treatment. When tested in vivo, NEO212 reduced tumor growth in treated animals.

CONCLUSION

Our results demonstrate anticancer activity of NEO212 in preclinical NPC models, suggesting that this novel compound should be evaluated further for the treatment of patients with NPC.

Novel chemotherapeutics and other therapies for treating high-grade glioma

INTRODUCTION

Despite extensive research, high-grade glioma (HGG) remains a dire diagnosis with no change in the standard of care in almost a decade. However, recent advancements uncovering molecular biomarkers of brain tumors and tumor-specific antigens targeted by immunotherapies provide opportunities for novel personalized treatment regimens to improve survival.

AREAS COVERED

In this review, the authors provide a comprehensive overview of recent therapeutic advancements in HGG. Furthermore, they describe new molecular biomarkers and molecular classifications, in addition to updated research on bevacizumab, targeted molecular therapies, immunotherapy and alternative delivery methods that overcome the blood-brain barrier to reach the target tumor tissue. Challenges regarding each therapy are also outlined. The authors also provide some insight into a novel non-chemotherapeutic treatment for malignant glioma, NovoTTFA, as well as a summary of current treatment options for recurrence.

EXPERT OPINION

Current research for treating malignant gliomas are paving the path to personalized therapy, including immunotherapy, that involve integrated genomic and histolopathologic data, as well as a multi-modal treatment regimen. Immunotherapy will potentially be the next addition to the current standard of care, specialized to the antigens presented on the tumors. The results of the current trials of multi-antigen vaccines are eagerly anticipated.

Na/K-ATPase as a target for anticancer drugs: studies with perillyl alcohol

Background

Na/K-ATPase (NKA) is inhibited by perillyl alcohol (POH), a monoterpene used in the treatment of tumors, including brain tumors. The NKA α₁ subunit is known to be superexpressed in glioblastoma cells (GBM). This isoform is embedded in caveolar structures and is probably responsible for the signaling properties of NKA during apoptosis. In this work, we showed that POH acts in signaling cascades associated with NKA that control cell proliferation and/or cellular death.

Methods

NKA activity was measured by the amount of non-radioactive Rb⁺ incorporation into cultured GBM cell lines (U87 and U251) and non-tumor cells (mouse astrocytes and VERO cells). Cell viability was measured by lactate dehydrogenase levels in the supernatants of POH-treated cells. Activated c-Jun N-terminal Kinase (JNK) and p38 were assessed by western blotting. Apoptosis was detected by flow cytometry and immunocytochemistry, and the release of interleukins was measured by ELISA.

Results

All four cell types tested showed a similar sensitivity for POH. Perillic acid (PA), the main metabolite of POH, did not show any effect on these cells. Though the cell viability decreased in a dose-dependent manner when cells were treated with POH, the maximum cytotoxic effect of PA obtained was 30% at 4 mM. 1.5 mM POH activated p38 in U87 cells and JNK in both U87 and U251 cells as well as mouse astrocytes. Dasatinib (an inhibitor of the Src kinase family) and methyl β-cyclodextrin (which promotes cholesterol depletion in cell membranes) reduced the POH-induced activation of JNK1/2 in U87 cells, indicating that the NKA-Src complex participates in this mechanism. Inhibition of JNK1/2 by the JNK inhibitor V reduced the apoptosis of GBM cells that resulted from POH administration, indicating the involvement of JNK1/2 in programmed cell death. 1.5 mM POH increased the production of interleukin IL-8 in the U251 cell supernatant, which may indicate a possible strategy by which cells avoid the cytotoxic effects of POH.

Conclusions

A signaling mechanism mediated by NKA may have an important role in the anti-tumor action of POH in GBM cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0374-5) contains supplementary material, which is available to authorized users.