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.

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.

Adjuvant effect of low-carbohydrate diet on outcomes of patients with recurrent glioblastoma under intranasal perillyl alcohol therapy.

BACKGROUND: Standard of care for glioblastoma (GB), consisting of cytotoxic chemotherapy, steroids, and high-dose radiation, induces changes in the tumor microenvironment through its effects on glucose availability, which is a determinant for tumor progression (TP). Low-carbohydrate diet (LCD) reduces the glucose levels needed to drive the Warburg effect. METHODS: To investigate LCD's effect on GB therapy, we have begun a clinical trial using LCD as an addition to intranasal perillyl alcohol (POH) for recurrent GB (rGB) patients. This study involved 29 individuals and evaluated, over a period of 1 year, the adjuvant effect of LCD associated with POH therapy in terms of toxicity, extent of peritumoral edema, reduced corticosteroid use, seizure frequency, and overall survival. POH group (n = 14) received solely intranasal POH without specific diet regimen, whereas POH/LCD group (n = 15) received intranasal POH in combination with nutritional intervention. Patients' assessment was based on clinical reviews and magnetic resonance data. RESULTS: In the 1-year follow-up, the POH/LCD group showed a 4.4-fold decrease in the proportion of patients who needed treatment with corticosteroids, as well as a reduction in tumor size and peritumoral edema, as compared to the POH group. While 75% of patients undergoing POH treatment experienced seizures, this fraction was reduced to 56% in the POH/LCD group. A 2.07-fold increase in the proportion of patients with stable disease, along with a 2.8-fold decrease in the proportion of patients with TP, was seen in the POH/LCD group. CONCLUSION: The results presented in this study show that the LCD associated with intranasal POH therapy may represent a viable option as adjunctive therapy for rGB to improve survival without compromising patients' quality of life. Prospective cohort studies are needed to confirm these findings and validate the efficacy of this novel therapeutic strategy.

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.

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.

Perillyl alcohol, a pleiotropic natural compound suitable for brain tumor therapy, targets free radicals.

Monoterpenes such as limonene and perillyl alcohol (POH) are promising natural compounds with pro-oxidant properties partly due to endoplasmic reticulum (ER) stress-induced cytotoxicity, and antioxidant activity owing to their activity as free radical scavengers, inhibition of coenzyme Q synthesis, activation of antioxidant-responsive elements (inducing detoxification enzymes) and induction of apoptosis. Activation of ER-stress responses generates reactive oxygen species (ROS), which are highly reactive free radicals mainly produced during mitochondrial electron transfer for adenosine triphosphate (ATP) synthesis. When cells are subjected to oxidative stress conditions, there is an accumulation of ROS that can lead to irreversible cell injury caused primarily by lipid peroxidation, protein aggregation and/or DNA damage. Malignant tumors, such as glioblastoma multiforme, display elevated rates of oxygen consumption, necrosis and abnormal structural microvasculature. Alterations in the tumor microenvironment are tightly linked to tumor progression and occur as a result of activation of complex signaling networks involving inter-clonal cooperation, cell-matrix interactions and an ongoing inflammatory response leading to genetic and epigenetic alterations. This review will focus on the pro- and anti-oxidant activities of POH, which are greatly dependent on the respective ROS levels within the tumor microenvironment and involve the ER stress response system. As well, some critical aspects of tumor-associated metabolic changes and the consequences of endogenous ROS production for tumor progression will be discussed.

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.

Long-term outcome in patients with recurrent malignant glioma treated with Perillyl alcohol inhalation.

AIM: This retrospective study aimed to evaluate the long-term response and toxicity of recurrent malignant glioma patients to inhalation chemotherapy with perillyl alcohol (POH). PATIENTS AND METHODS: The cohort included 117 men and 81 women with primary glioblastoma multiforme (GBM; n=154), grade III astrocytoma (AA; n=26) and anaplastic oligodendroglioma (AO; n=5). POH inhalation schedule 4-times daily started with 66.7 mg/dose; 266 mg/day and escalated up to 133.4 mg/dose; 533.6 mg/day. Clinical toxicity and overall survival following treatment were compared with tumor size, topography, extent of peritumoral edema and histological classification. RESULTS: Adhesion to the protocol was high (>95%), POH (533.6 mg/daily) occasionally caused nose soreness but rarely nosebleed. Tumor size, peritumoral edema and the oligodendroglial component influenced response to treatment. CONCLUSION: After 4 years under exclusive POH treatment, 19% of patients still remain in clinical remission. Long-term POH inhalation chemotherapy is a safe and non-invasive strategy efficient for recurrent malignant glioma.

Efficacy of monoterpene perillyl alcohol upon survival rate of patients with recurrent glioblastoma.

PURPOSE: The monoterpene perillyl alcohol (POH) a Ras inhibitor with potential capacity to arrest gliomagenesis is being used in a phase I/II clinical trial in adults with recurrent malignant glioma. The present study aimed to investigate the efficacy of intranasal administration of monoterpene POH upon survival rate of patients with recurrent glioblastoma (GBM) in comparison with historical control group of GBM patients. PATIENTS AND METHODS: It was included 89 adults with recurrent GBM receiving daily intranasal administration of 440 mg POH and 52 matched GBM patients as historical control untreated group only with supportive treatment. RESULTS: Patients with recurrent primary GBM treated with POH survived significantly longer (log rank test, P < 0.0001) than untreated group. Patients with recurrent primary GBM in deep location survived significantly longer than with lobar location (log rank test, P < 0.0001). Median survival rate of secondary GBM was 11.2 months, longer (log rank test, P = 0.0366) than primary GBM (5.9 months). Radiographic improvement and reduction of corticosteroid dosage (36%) further associated with a delay towards progression. CONCLUSION: Intranasal administration of POH increased the overall survival of patients with recurrent GBM in comparison with historical untreated controls, but especially patients with secondary GBM and primary GBM with tumor localized in deep regions of the brain. The side effects of POH treatment were almost nonexistent, even in patients treated for over 4 years.

The anticancer drug perillyl alcohol is a Na/K-ATPase inhibitor.

The monoterpene perillyl alcohol (POH) is a drug used in the treatment of several malignant tumors, including gliomas. The present study defines a POH inhibitory effect on Na/K-ATPase activity from kidney and brain guinea pig extracts and from a human glioblastoma cell line. This inhibition showed a high degree of selectivity toward the kidney enzyme expressing, as do glioblastoma cells, the α(1) subunit. Kinetic studies with purified enzymes showed a noncompetitive POH inhibition profile to Na(+) and K(+) and an uncompetitive inhibition towards ATP. Furthermore, potassium activated p-nitrophenylphosfatase activity of these purified preparations was not inhibited by POH, suggesting that this drug, differently from the classical inhibitor ouabain, acted in the initial phase of the enzyme's catalytic cycle. We suggest that POH antitumor action could be linked to its Na/K-ATPase binding properties.

Correlation of tumor topography and peritumoral edema of recurrent malignant gliomas with therapeutic response to intranasal administration of perillyl alcohol.

BACKGROUND: The aim of this study was to establish a correlation of tumor topography and peritumoral brain edema with the therapeutic response to intranasal administration of perillyl alcohol (POH) in a cohort of patients with recurrent malignant gliomas. METHODS: The retrospective study reviewed clinical and neuroradiological data from patients with recurrent malignant gliomas who received intranasal daily administration of POH 440 mg. The following parameters were assessed: demographic characteristics, initial symptoms, overall survival, tumor topography and tumor size, presence of midline shift and extent of peritumoral edema. Statistical analysis was carried out with log rank tests and overall survival as assessed by Kaplan-Meier method including 95% confidence intervals. RESULTS: A cohort of 67 patients included 52 (78%) with glioblastoma (GBM), ten (15%) with anaplastic astrocytoma (AA) and five (7%) with anaplastic oligodendroglioma (AO). Accordingly to tumor topography lobar localization was present in all (5/5) AO; eight (8/10) and 41 GBM patients whereas in the basal ganglia two AA and 11 GBM patients. It was also observed a relation between the tumor size and area of peritumoral brain edema (PTBE). Patients with good therapeutic response showed reduction of tumor size and PTBE area, but poor prognosis was associated with lack of response to treatment and persistence of high PTBE. Patients with tumor in the basal ganglia survived significantly longer than those with lobar gliomas (log rank test, p = 0.0003). Presence of midline shift (>1 cm) was a statistically significant risk factor for shorter survival (log rank test, p = 0.0062) CONCLUSIONS: This study suggests that: (1) patients with recurrent gliomas with localization in the basal ganglia survive significantly longer than those with tumors at lobar localization; (2) presence of PTBE contributes to symptoms, likely to be implicated in the morbidity and invading potential of malignant gliomas. These findings support the theory that interaction between glioma cells at distinct brain microenvironment can influence the oncobiological behavior of glioma cells and ultimately to the prognosis.

Anaplastic oligodendroglioma responding favorably to intranasal delivery of perillyl alcohol: a case report and literature review.

BACKGROUND: In recent years, molecular genetics and biology are exerting significant influence on the practice of neuro-oncology, with oligodendrogliomas being the most prominent example. To explore therapeutic strategies and evaluate the clinical results, we report a case of a patient with anaplastic oligodendroglioma managed with intranasal delivery of POH. CASE DESCRIPTION: A 62 year-old white woman presented with complaints of seizures and frontal headache in June 1999. Nervous system examination was normal. Her Karnofsky performance score was 90. A contrast-enhanced MRI scan of the brain revealed a regular space-occupying lesion in the right frontal lobe that enhanced with gadolinium. A radical surgical excision of the tumor was carried out, and the histopathological diagnosis was an anaplastic oligodendroglioma. Subsequently, there were 2 recurrent/progressive lesions, in July 2002 and October 2004, despite combination treatment using surgery, radiotherapy, and chemotherapy. Intranasal delivery of 0.3% concentration of POH 4 times daily was performed. A follow-up MRI scan after 5 months of treatment revealed reduction in size of the enhancing lesion. CONCLUSION: Whereas surgery continues to be the primary treatment for oligodendroglioma, the scheme for postoperative therapy has shifted primarily because of the lesion's relative chemosensitivity. This article evaluates the effects of intranasal delivery of POH in a case of regression of anaplastic oligodendroglioma.