D,L-Methadone does not improve radio- and chemotherapy in glioblastoma in vitro

Opiate Use Patterns Following Surgery for High Grade Glioma

INTRODUCTION

Opiate drugs are commonly prescribed for postoperative pain relief following craniotomy. The aim of this study was to assess opiate use in patients undergoing craniotomy for high-grade glioma and to identify risk factors contributing to prolonged opiate use.

METHODS

A retrospective chart review was conducted on adult patients undergoing craniotomy for high-grade glioma between January 2016 and January 2020. Medical records were assessed for history of pain syndrome, and alcohol, nicotine, and other substance use. Opiate length of utilization and dose measured by morphine equivalent dose (MED) was collected. Statistical analyses were conducted using R Statistical Software (v4.1.2; R Core Team 2021).

RESULTS

A total of 295 patients met inclusion criteria, with 26.4% undergoing biopsy and 73.6% undergoing craniotomy for resection. The average immediate postoperative MED/day was 20.3 (SD 21.5) and average duration of outpatient opiate use was 15.1 days (SD 63.1 days). Male sex and history of tobacco use were associated with increased MED/day in the postoperative period. A stratified analysis showed that, for patients undergoing craniotomy, MED/day was significantly increased with male sex and history of tobacco use. For patients undergoing biopsy, MED/day was significantly increased with history of other substance use. History of pain syndrome significantly increased the odds of opiate prescription renewal. Age significantly reduced the odds of opiate prescription renewal.

CONCLUSIONS

Postoperative opiate use in this cohort is modest. Increased opiate use is associated with comorbidities known to modulate pain perception. Prospective studies should be conducted to provide more robust data.

Mapping the Evidence for Opioid-Mediated Changes in Malignancy and Chemotherapeutic Efficacy: Protocol for a Scoping Review

BACKGROUND

Numerous reports contend opioids can augment or inhibit malignancy. At present, there is no consensus on the risk or benefit posed by opioids on malignancy or chemotherapeutic activity. Distinguishing the consequences of opioid use from pain and its management is challenging. Additionally, opioid concentration data is often lacking in clinical studies. A scoping review approach inclusive of preclinical and clinical data will improve our understanding of the risk-benefit relationship concerning commonly prescribed opioids and cancer and cancer treatment.

OBJECTIVE

The aim of the study is to map diverse studies spanning from preclinical to clinical regarding opioids with malignancy and its treatment.

METHODS

This scoping review will use the Arksey six stages framework to (1) identify the research question; (2) identify relevant studies; (3) select studies meeting criteria; (4) extract and chart data; (5) collate, summarize, and report results; and (6) conduct expert consultation. An initial pilot study was undertaken to (1) parameterize the extent and scale of existing data for an evidence review, (2) identify key factors to be extracted in systematic charting efforts, and (3) assess opioid concentration as a variable for its relevance to the central hypothesis. Six databases will be searched with no filters: MEDLINE, Embase, CINAHL Complete, Cochrane Library, Biological Sciences Collection, and International Pharmaceutical Abstracts. Trial registries will include ClinicalTrials.gov, Cochrane CENTRAL, International Standard Randomised Controlled Trial Number Registry, European Union Clinical Trials Register, and World Health Organization International Clinical Trials Registry. Eligibility criteria will include preclinical and clinical study data on opioids effects on tumor growth or survival, or alteration on the antineoplastic activity of chemotherapeutics. We will chart data on (1) opioid concentration from human subjects with cancer, yielding a "physiologic range" to better interpret available preclinical data; (2) patterns of opioid exposure with disease and treatment-related patient outcomes; and (3) the influence of opioids on cancer cell survival, as well as opioid-related changes to cancer cell susceptibility for chemotherapeutics.

RESULTS

This scoping review will present results in narrative forms as well as with the use of tables and diagrams. Initiated in February 2021 at the University of Utah, this protocol is anticipated to generate a scoping review by August 2023. The results of the scoping review will be disseminated through scientific conference proceedings and presentations, stakeholder meetings, and by publication in a peer-reviewed journal.

CONCLUSIONS

The findings of this scoping review will provide a comprehensive description of the consequences of prescription opioids on malignancy and its treatment. By incorporating preclinical and clinical data, this scoping review will invite novel comparisons across study types that could inform new basic, translational, and clinical studies regarding risks and benefits of opioid use among patients with cancer.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/38167.

The µ-Opioid Receptor in Cancer and Its Role in Perineural Invasion: A Short Review and New Evidence

Cancer is a significant public health problem worldwide. While there has been a steady decrease in the cancer death rate over the last two decades, the number of survivors has increased and, thus, cancer-related sequela. Pain affects the life of patients with cancer and survivors. Prescription opioids continue as the analgesic of choice to treat moderate-to-severe cancer-related pain. There has been controversy on whether opioids impact cancer progression by acting on cancer cells or the tumor microenvironment. The μ-opioid receptor is the site of action of prescription opioids. This receptor can participate in an important mechanism of cancer spread, such as perineural invasion. In this review, current evidence on the role of the μ-opioid receptor in cancer growth is summarized and preliminary evidence about its effect on the cross-talk between sensory neurons and malignant cells is provided.

Time to initiate randomized controlled clinical trials with methadone in cancer patients

Public media coverage has fueled a demand for methadone as potential cure for cancer itself. Because patients have asked for respective prescriptions, clinical societies issued statements warning against the use of methadone as long as preclinical findings have not been supported by clinical evidence. In fact, not all preclinical data clearly support relevant effects. However, strong epidemiologic data suggest beneficial effects of methadone on cancer. Alternative explanations, namely better safety of methadone or hidden selection bias, seem less likely. This uncertainty can only be resolved by randomized controlled clinical trials. This review discusses all relevant data pertinent to methadone and cancer, uncovers supportive epidemiologic data, and suggests possible study designs.

Methadone-mediated sensitization of glioblastoma cells is drug and cell line dependent

PURPOSE

D,L-methadone (MET), an analgesic drug used for pain treatment and opiate addiction, has achieved attention from oncologists and social media as possible chemoensitizing agent in cancer therapy, notably brain cancer (glioblastoma multiforme, GBM). MET has been reported to enhance doxorubicin-induced cytotoxicity in GBM cells via activation of the µ-opioid receptor (MOR). Here, we extended this work and quantified the toxic effect of MET in comparison to other opioids alone and in combination with doxorubicin and the clinically more relevant alkylating drug temozolomide (TMZ), using a set of GBM cell lines and primary GBM cells.

METHODS

MOR expression in GBM cells was investigated by immunofluorescence and immunoblotting. Resistance to drugs alone and in combination with anticancer drugs was assessed by MTT assays. Concentration effect curves were fitted by nonlinear regression analysis and IC50 values were calculated. Apoptosis and necrosis rates were determined by annexin V/propidium iodide (PI)-flow cytometry.

RESULTS

MET alone was cytotoxic in all GBM cell lines and primary GBM cells at high micromolar concentrations (IC50 ~ 60-130 µM), observed both in the metabolic MTT assay and by quantifying apoptosis and necrosis, while morphine and oxycodone were not cytotoxic in this concentration range. Naloxone was not able to block MET-induced cytotoxicity, indicating that cell death-inducing effects of MET are not MOR-dependent. We recorded doxorubicin and TMZ concentration- response curves in combination with fixed MET concentrations. MET enhanced doxorubicin-induced cytotoxicity in only one cell line, and in primary cells it was observed only in a particular MET concentration range. In all assays, MET was not effective in sensitizing cells to TMZ. In two cell lines, MET even decreased the cell's sensitivity to TMZ.

CONCLUSION

MET was found to be cytotoxic in GBM cells in vitro only at high, clinically not relevant concentrations, where it was effective in inducing apoptosis and necrosis. Sensitizing effects were only observed in combination with doxorubicin, but not with TMZ, and are dependent on cell line and the applied drug concentration. Therefore, our findings do not support the use of MET in the treatment of GBM in combination with TMZ, as no sensitizing effect of MET was observed.

Cancer, the Media and Dealing with Knowledge

Among the primary function of the media are conveying personal understanding and expanding the subjective knowledge of the recipient citizen. A particular challenge arising during this process is the mediation of medical knowledge. In addition to pure factual knowledge, it often involves subjective experiences, hopes and wishes. One example of this is media reports about cancer therapies. As a result of widespread media coverage since 2017, the public is under the impression that methadone is a promising treatment for cancer. This chapter analyzes the part played by the media and the ethical debate. The ethical issues that arise concern good scientific practice, patient autonomy and the media coverage of methadone. We conclude that, according to the current state of research, the promotion of methadone as a cure for cancer is ethically unacceptable. In this case the media are not fulfilling their task of imparting knowledge, because they are not communicating the current state of research or the associated ethical questions.

Impact of anesthesia and analgesia techniques on glioblastoma progression. A narrative review

Glioblastoma (GBM) is an aggressive malignant CNS tumor with a median survival of 15 months after diagnosis. Standard therapy for GBM includes surgical resection, radiation, and temozolomide. Recently, anesthetics and analgesics have received attention for their potential involvement in mediating tumor growth. This narrative review investigated whether various members of the 2 aforementioned classes of drugs have a definitive impact on GBM progression by summarizing pertinent in vitro, in vivo, and clinical studies. Recent publications regarding general anesthetics have been inconsistent, showing that they can be pro-tumoral or antitumoral depending on the experimental context. The local anesthetic lidocaine has shown consistent antitumoral effects in vitro. Clinical studies looking at anesthetics have not concluded that their use improves patient outcomes. In vitro and in vivo studies looking at opioid involvement in GBM have demonstrated inconsistent findings regarding whether these drugs are pro-tumoral or antitumoral. Nonsteroidal anti-inflammatory drugs, and specifically COX-2 inhibitors, have shown inconsistent findings across multiple studies looking at whether they are beneficial in halting GBM progression. Until multiple repeatable studies show that anesthetics and analgesics can suppress GBM growth, there is no strong evidence to recommend changes in the anesthetic care of these patients.

Cytotoxic and Senolytic Effects of Methadone in Combination with Temozolomide in Glioblastoma Cells

Methadone is an analgesic drug used for pain treatment and heroin substitution. Recently, methadone has been proposed to be useful also for cancer therapy, including glioblastoma multiforme (GBM), the most severe form of brain cancer, because experiments on cultured glioma cells treated with doxorubicin showed promising results. Doxorubicin, however, is not used first-line in GBM therapy. Therefore, we analyzed the cytotoxic effect of methadone alone and in combination with temozolomide, a DNA-alkylating drug that is first-line used in GBM treatment, utilizing GBM-derived cell lines and a human fibroblast cell line. We show that methadone is cytotoxic on its own, inducing apoptosis and necrosis, which was observed at a concentration above 20 µg/mL. Methadone was similar toxic in isogenic MGMT expressing and non-expressing cells, and in LN229 glioblastoma and VH10T human fibroblasts. The apoptosis-inducing activity of methadone is not bound on the opioid receptor (OR), since naloxone, a competitive inhibitor of OR, did not attenuate methadone-induced apoptosis/necrosis. Administrating methadone and temozolomide together, temozolomide had no impact on methadone-induced apoptosis (which occurred 3 days after treatment), while temozolomide-induced apoptosis (which occurred 5 days after treatment) was unaffected at low (non-toxic) methadone concentration (5 µg/mL), and at high (toxic) methadone concentration (20 µg/mL) the cytotoxic effects of methadone and temozolomide were additive. Methadone is not genotoxic, as revealed by comet and γH2AX assay, and did not ameliorate the genotoxic effect of temozolomide. Further, methadone did not induce cellular senescence and had no effect on temozolomide-induced senescence. Although methadone was toxic on senescent cells, it cannot be considered a senolytic drug since cytotoxicity was not specific for senescent cells. Finally, we show that methadone had no impact on the MGMT promoter methylation. Overall, the data show that methadone on glioblastoma cells in vitro is cytotoxic and induces apoptosis/necrosis at doses that are above the level that can be achieved in vivo. It is not genotoxic, and does not ameliorate the cell killing or the senescence-inducing effect of temozolomide (no synergistic effect), indicating it has no impact on temozolomide-induced signaling pathways. The data do not support the notion that concomitant methadone treatment supports temozolomide-based chemotherapy.

Against Repurposing Methadone for Glioblastoma Therapy

Methadone, which is used as maintenance medication for outpatient treatment of opioid dependence or as an analgesic drug, has been suggested by preclinical in vitro and mouse studies to induce cell death and sensitivity to chemo- or radiotherapy in leukemia, glioblastoma, and carcinoma cells. These data together with episodical public reports on long-term surviving cancer patients who use methadone led to a hype of methadone as an anti-cancer drug in social and public media. However, clinical evidence for a tumoricidal effect of methadone is missing and prospective clinical trials, except in colorectal cancer, are not envisaged because of the limited preclinical data available. The present article reviews the pharmacokinetics, potential molecular targets, as well as the evidence for a tumoricidal effect of methadone in view of the therapeutically achievable doses in the brain. Moreover, it provides original in vitro data showing that methadone at clinically relevant concentrations fails to impair clonogenicity or radioresistance of glioblastoma cells.

Methadone does not potentiate the effect of doxorubicin in canine tumour cell lines

Opioid receptor activation was shown to enhance the efficacy of anti‐neoplastic drugs in several human cancer cell lines. In these cell lines, doxorubicin increased the number of opioid receptors and methadone concurrently enhanced cellular doxorubicin uptake. Triggered through lay press and media, animal owners started to challenge veterinary oncologists with questions about methadone use in anti‐cancer therapy. Especially in veterinary medicine, where side effects of chemotherapy are tolerated to a lesser extent and hence smaller doses are given, agents potentiating chemotherapeutic agents would be an optimal approach to treatment. Canine transitional cell carcinoma cells (TCC, K9TCC), canine osteosarcoma cells (OSA, Abrams) and canine hemangiosarcoma cells (HSA, DAL‐4) were incubated with different combinations of methadone, buprenorphine and doxorubicin, in order to test inhibition of cell proliferation. Opioid receptor density was assessed with fluorescence‐activated cell sorting in drug native and doxorubicin pretreated cells. In TCC and OSA cell lines opioid receptor density increased after doxorubicin pretreatment. In combination treatment, however, we did not find significant potentiation of doxorubicin's inhibitory effect on proliferation in these cell lines. Neither was there a significant increase of the effect of doxorubicin when the opioids were added 24 hr before doxorubicin. Hence, we could not confirm the hypothesis that opioids increase the anti‐proliferative effect of the anti‐neoplastic drug doxorubicin in any of these canine tumour cell lines. The lack of effect on a cellular level does not warrant a clinical approach to use opioids together with doxorubicin in dogs with cancer.

Safety aspects of opioid-naïve patients with high-grade glioma treated with D,L-Methadone: an observational case series

It was suggested that D, L-Methadone might improve the clinical course of glioma patients. Owing to massive press coverage, patients demand the prescription of D, L-Methadone, but regarding its adjunctive use in glioma therapy there is no standard medication plan. Furthermore, it is not known which side effects the administration of D, L-Methadone might harbor, especially if the patients are opioid-naïve and if D, L-Methadone therapy was managed by the patients themselves or their general practitioners. Opioid-naïve patients with high-grade glioma (new diagnosis or recurrent) receiving D, L-Methadone were included in this retrospective observational analysis. Side effects were assigned if the condition deteriorated in conjunction with the initiation of D, L-Methadone and resolved/ ameliorated after cessation of the intake/reduction of the dosage. Side effects were categorized according to the common toxicity criteria (CTC). Twenty-four patients were included. All patients were opioid-naïve and received D, L-Methadone from their general practitioners. Sixteen patients experienced side effects. The median dosage when side effects began to occur was 15.8 mg/ 24 h. Fatigue and mood changes were reported most frequently (14 of 24 patients). Five patients had severe side effects related to relatively high doses. In all cases, symptoms resolved after cessation or dose reduction. Our results show that D/L M intake lead to frequent occurrence of side effects in opioid-naïve patients especially when not handled with caution and close supervision. Patients, their relatives, their GPs and neuro-oncologists need to be informed about the broad spectrum of side effects in order to thoroughly counsel glioma patients.

Current state and future perspective of drug repurposing in malignant glioma

Malignant gliomas are still extremely difficult to treat because complete surgical resection is biologically not feasible due to the invasive nature of these diseases and the proximity of tumors to functionally sensitive areas. Moreover, adjuvant therapies are facing a strong therapeutic resistance since the central nervous system is a highly protected environment and the tumor cells display a vast intra-tumoral genetic and epigenetic variation. As a consequence, new therapeutics are urgently needed but the process of developing novel compounds that finally reach clinical application is highly time-consuming and expensive. Drug repurposing is an approach to facilitate and accelerate the discovery of new cancer treatments. In malignant glioma, like in other cancers, pre-existing physiological pathways that regulate cell growth, cell death or cell migration are dysregulated causing malignant transformation. A wide variety of drugs are clinically used to treat non-cancerous diseases interfering with these malignancy-associated pathways. Repurposed drugs have key advantages: They already have approval for clinical use by national regulatory authorities. Moreover, they are for the most part inexpensive and their side effect and safety profiles are well characterized. In this work, we provide an overview on current repurposing strategies for the treatment of malignant glioma.