Smart pH-sensitive and temporal-controlled polymeric micelles for effective combination therapy of doxorubicin and disulfiram

The combination of a chemotherapeutic drug with a multidrug resistance (MDR) modulator has emerged as a promising strategy for treating MDR cancer. To ensure two drugs could be simultaneously delivered to tumor region at the optimum ratio, and the MDR modulator could be released earlier and faster than the chemotherapeutic drug to inactivate P-glycoprotein (P-gp) and subsequently inhibit the pumping out of the chemotherapeutic drug, a smart pH-sensitive polymeric micelles system with high drug loading and precise drug ratio was designed and prepared by conjugating doxorubicin (DOX) to poly(styrene-co-maleic anhydride) (SMA) derivative with adipic dihydrazide (ADH) through a acid-cleavable hydrazone bond, and then encapsulating disulfiram (DSF), a P-gp inhibitor as well as an apoptosis inducer, into the micelles formed by the self-assembly of SMA-ADH-DOX (SAD) conjugate. The pH-sensitive polymeric micelles system enabled a temporal release of two drugs: encapsulated DSF was released fast to inhibit the activity of P-gp and restore cell apoptotic signaling pathways, while conjugated DOX was released in a sustained and pH-dependent manner and highly accumulated in drug resistant cells to exert therapeutic effect, due to the inactivation of P-gp by DSF. The smart co-delivery system was very effective in enhancing the cytotoxicity by increasing the intracellular accumulation of DOX and promoting the apoptotic response, and showed the most effective inhibitory effect on the growth of drug-resistant breast cancer xenografts as compared to other combinations of both drugs. In a word, this smart co-delivery system has significant promise for the clinical therapy of MDR cancer.

The status of disulfiram: a half of a century later

For more than 55 years, disulfiram has been approved by the Food and Drug Administration for the treatment of alcohol dependence. It is a unique medication that relies on "psychological threat" to avoid disulfiram-ethanol reactions. This paper reviews the history of disulfiram treatment, the current status of disulfiram treatment, the ensuing developments in disulfiram use in treating various addictions, and future directions. Clinical trials using disulfiram for the treatment of alcohol, cocaine, or co-occurring alcohol + cocaine dependence were included in this review. Disulfiram efficacy studies focusing on supervised, implant, and combination pharmacotherapies were also examined. In clinical trials, disulfiram has demonstrated inconsistent results in helping patients to abstain from alcohol, and patients poorly adhere to a disulfiram-treatment regimen. This has raised questions about disulfiram's practicality in the treatment of alcohol dependence. Recently, however, disulfiram has gained attention as a complementary agent to newer pharmacological medications, such as an opiate antagonist that specifically reduces alcohol craving. One hypothesis is that disulfiram would assist patients in gaining psychological control over drinking when given in conjunction with an opiate antagonist that would act directly on reducing alcohol craving. Preliminary evidence also suggests that disulfiram treatment could be a viable treatment for cocaine dependence because it was shown to reduce cocaine use among nonalcoholic, cocaine-dependent patients.

Short-term administration of disulfiram for reversal of latent HIV infection: a phase 2 dose-escalation study

BACKGROUND

In vitro, disulfiram activated HIV transcription in a primary T-cell model of HIV latency and in a pilot clinical study increased plasma HIV RNA in individuals with adequate drug exposure. We assessed the effect of disulfiram on HIV transcription in a dose-escalation study.

METHODS

In this prospective dose-escalation study, to optimise disulfiram exposure we included adults with HIV on suppressive antiretroviral therapy, with plasma HIV RNA of less than 50 copies per mL and a CD4 cell count greater than 350 cells per μL. Participants were allocated sequentially to one of three dosing groups (500 mg, 1000 mg, and 2000 mg) and received disulfiram daily for 3 days. Only the staff who did laboratory assays were masked to group assignment. The primary endpoint was change in cell-associated unspliced HIV RNA in CD4 cells. The primary analysis method was a negative binomial regression, with the number of copies as the outcome variable and the input total RNA or plasma volume as an exposure variable, which is equivalent to modelling copies or input. We used these models to estimate changes from before disulfiram to timepoints during and after disulfiram administration. This study is registered with ClinicalTrials.gov, number NCT01944371.

FINDINGS

Of 34 participants screened for eligibility at The Alfred Hospital (Melbourne, VIC, Australia), and San Francisco General Hospital (San Francisco, CA, USA), 30 people were enrolled between Sept 24, 2013, and March 31, 2014. The estimated fold increases in cell-associated unspliced HIV RNA from baseline were 1·7 (95% CI 1·3-2·2; p<0·0001) to the timepoint during disulfiram treatment and 2·1 (1·5-2·9; p<0·0001) to the timepoint after disulfiram in the 500 mg group; 1·9 (1·6-2·4; p<0·0001) and 2·5 (1·9-3·3; p<0·0001) in the 1000 mg group; and 1·6 (1·2-2·1; p=0·0026) and 2·1 (1·5-3·1; p=0·0001) in the 2000 mg group. No deaths occurred, and no serious adverse events were noted. Disulfiram was well tolerated at all doses.

INTERPRETATION

Short-term administration of disulfiram resulted in increases in cell-associated unspliced HIV RNA at all doses, consistent with activating HIV latency. Disulfiram may be suited for future studies of combination and prolonged therapy to activate latent HIV.

FUNDING

The Foundation for AIDS Research (amfAR); National Institute of Allergy and Infectious Diseases, National Institutes of Health; Australian National Health and Medical Research Council.

A phase IIb trial assessing the addition of disulfiram to chemotherapy for the treatment of metastatic non-small cell lung cancer

BACKGROUND

Disulfiram, an alcohol aversion agent, has been in use for >50 years. Numerous authors have reported an anticancer effect of this drug in vitro and in mouse models. More recently, several reports have claimed that disulfiram also possesses anti-stem cell activity. We set out to obtain initial data regarding the safety of combining this drug with chemotherapy and the possible effectiveness of disulfiram in a combination regimen in non-small cell lung cancer (NSCLC).

METHODS

This phase II, multicenter, randomized, double-blinded study assessed the safety and efficacy of adding of disulfiram to cisplatin and vinorelbine for six cycles. Newly diagnosed NSCLC patients were recruited. Patients with either stage IV or what was considered at the time "wet IIIb" (since 2009, these patients have been considered stage IV) were recruited. The patients were treated with only chemotherapy, and none were treated with either surgery or chemoradiation. Disulfiram was administered at a dose of 40 mg three times daily.

RESULTS

Forty patients were treated for more than two cycles, half with and half without disulfiram, which was well tolerated. An increase in survival was noted for the experimental group (10 vs. 7.1 months). Interestingly, there were only two long-term survivors, both in the disulfiram group.

CONCLUSION

The addition of disulfiram to a combination regimen of cisplatin and vinorelbine was well tolerated and appeared to prolong survival in patients with newly diagnosed non-small cell lung cancer. The results from this small study seem encouraging enough for assessment in larger trials. Disulfiram is an inexpensive and safe drug; if its addition to chemotherapy could be shown to prolong survival, an effective regimen could be established and used widely, even in resource-poor countries.

A conceptually new treatment approach for relapsed glioblastoma: coordinated undermining of survival paths with nine repurposed drugs (CUSP9) by the International Initiative for Accelerated Improvement of Glioblastoma Care

To improve prognosis in recurrent glioblastoma we developed a treatment protocol based on a combination of drugs not traditionally thought of as cytotoxic chemotherapy agents but that have a robust history of being well-tolerated and are already marketed and used for other non-cancer indications. Focus was on adding drugs which met these criteria: a) were pharmacologically well characterized, b) had low likelihood of adding to patient side effect burden, c) had evidence for interfering with a recognized, well-characterized growth promoting element of glioblastoma, and d) were coordinated, as an ensemble had reasonable likelihood of concerted activity against key biological features of glioblastoma growth. We found nine drugs meeting these criteria and propose adding them to continuous low dose temozolomide, a currently accepted treatment for relapsed glioblastoma, in patients with recurrent disease after primary treatment with the Stupp Protocol. The nine adjuvant drug regimen, Coordinated Undermining of Survival Paths, CUSP9, then are aprepitant, artesunate, auranofin, captopril, copper gluconate, disulfiram, ketoconazole, nelfinavir, sertraline, to be added to continuous low dose temozolomide. We discuss each drug in turn and the specific rationale for use- how each drug is expected to retard glioblastoma growth and undermine glioblastoma's compensatory mechanisms engaged during temozolomide treatment. The risks of pharmacological interactions and why we believe this drug mix will increase both quality of life and overall survival are reviewed.

Cu/Zn superoxide dismutase plays important role in immune response

Activation of macrophages leads to the secretion of cytokines and enzymes that shape the inflammatory response and increase metabolic processes. This, in turn, results in increased production of reactive oxygen species. The role of Cu/Zn superoxide dismutase (SOD-1), an important enzyme in cellular oxygen metabolism, was examined in activated peritoneal elicited macrophages (PEM) and in several inflammatory processes in vivo. LPS and TNF-alpha induced SOD-1 in PEM. SOD-1 induction by LPS was mainly via extracellular signal-regulated kinase-1 activation. Transgenic mice overexpressing SOD-1 demonstrated a significant increase in the release of TNF-alpha and of the metalloproteinases MMP-2 and MMP-9 from PEM. Disulfiram (DSF), an inhibitor of SOD-1, strongly inhibited the release of TNF-alpha, vascular endothelial growth factor, and MMP-2 and MMP-9 from cultured activated PEM. These effects were prevented by addition of antioxidants, further indicating involvement of reactive oxygen species. In vivo, transgenic mice overexpressing SOD-1 demonstrated a 4-fold increase in serum TNF-alpha levels and 2-fold stronger delayed-type hypersensitivity reaction as compared with control nontransgenic mice. Conversely, oral administration of DSF lowered TNF-alpha serum level by 4-fold, lowered the delayed-type hypersensitivity response in a dose-dependent manner, and significantly inhibited adjuvant arthritis in Lewis rats. The data suggest an important role for SOD-1 in inflammation, establish DSF as a potential inhibitor of inflammation, and raise the possibility that regulation of SOD-1 activity may be important in the treatment of immune-dependent pathologies.

Disulfiram treatment of alcoholism

PURPOSE

For 40 years, disulfiram has been the alcohol-aversive drug used most frequently by American physicians in the treatment of alcohol dependency disorders. We reviewed the clinical literature regarding the risks, benefits, indications, and efficacy of this controversial drug and summarized current knowledge of this therapy.

CONCLUSIONS

Disulfiram will produce an aversive reaction with ethanol, usually at a dose between 250 mg/day and 500 mg/day, although some patients may not have an aversive reaction at this level. Cardiac, hepatic, and neurologic toxicity can also occur within this dosage range. If disulfiram is to be used, the patient must clearly understand the risks of drinking while taking the drug, and the physician and patient must agree about the need for continued clinical supervision and monitoring for efficacy and side effects. The physician must also recognize that disulfiram is only an adjunctive therapy and that continued support, supervision, and other therapeutic measures are required. Disulfiram is probably effective in reducing the frequency of alcohol consumption in the compliant patient over the short term (e.g., 6 months). Certain subgroups of patients, such as those who are older, those who are more socially stable, and those who are well-motivated, may experience a beneficial effect for longer periods. The drug may be most effective in reducing short-term alcohol consumption when the compliance of the patient is supervised, although consideration of this kind of therapy includes the practical problems of supervising the patient and concerns that the supervising person may be placed in a difficult position. Prescription of disulfiram without accompanying education, counseling, and concomitant alcoholism therapy is not beneficial. Disulfiram has no proven effect on the long-term outcome of alcoholism.

Inhibition of carcinogenesis by minor anutrient constituents of the diet

A continuing study of chemopreventive agents has focused on several categories of naturally occurring compounds that inhibit carcinogen activation and are effective in preventing carcinogen-induced neoplasia when administered at short time-intervals before carcinogen challenge. The inhibitory compounds are: aromatic isothiocyanates found in cruciferous vegetables, monoterpenes present in citrus fruits and caraway-seed oil, and organosulphur compounds occurring in Allium species. Preliminary work indicates that glucobrassicin and indoles existing in cruciferous vegetables also have these attributes. Almost all carcinogens that are consumed in food require metabolic activation. Thus, inhibition of carcinogen activation reactions could be effective against this type of exposure. In addition, three naturally occurring compounds, i.e. phenethyl isothiocyanate, D-limonene and dipropyl sulphide inhibit activation of the tobacco-specific carcinogen NNK, and accordingly may have the capacity to diminish carcinogenic response to exposures to tobacco. The property of cruciferous vegetables, orange oil, benzyl isothiocyanate, and D-limonene, to act as both blocking and suppressing agents has been discussed. Two possible mechanisms for this multi-phase activity were presented. The first is that these inhibitory substances activate a complex integrated defence mechanism against toxic compounds which entails both blocking and suppressing components. The blocking component is the initial line of defence, and the suppressing component constitutes a 'fail-safe' backup to assure that if any of the toxic material attacks cellular constituents, its effects will be nullified. The second possible mechanism considered is that the inhibitors, because of high reactivity, have multiple biological effects that are separate and not part of a single, coordinated response. Inhibitors that have both blocking and suppressing effects could be particularly useful as chemopreventive agents. A simple interim classification of foods in terms of their potential impact on the occurrences of cancer has been proposed.

A multicenter phase II study of temozolomide plus disulfiram and copper for recurrent temozolomide-resistant glioblastoma

PURPOSE

Preclinical studies have suggested promising activity for the combination of disulfiram and copper (DSF/Cu) against glioblastoma (GBM) including re-sensitization to temozolomide (TMZ). A previous phase I study demonstrated the safety of combining DSF/Cu with adjuvant TMZ for newly diagnosed GBM. This phase II study aimed to estimate the potential effectiveness of DSF/Cu to re-sensitize recurrent GBM to TMZ.

METHODS

This open-label, single-arm phase II study treated recurrent TMZ-resistant GBM patients with standard monthly TMZ plus concurrent daily DSF 80 mg PO TID and Cu 1.5 mg PO TID. Eligible patients must have progressed after standard chemoradiotherapy and within 3 months of the last dose of TMZ. Known isocitrate dehydrogenase (IDH) mutant or secondary GBMs were excluded. The primary endpoint was objective response rate (ORR), and the secondary endpoints included progression-free survival (PFS), overall survival (OS), clinical benefit (response or stable disease for at least 6 months), and safety.

RESULTS

From March 2017 to January 2018, 23 recurrent TMZ-resistant GBM patients were enrolled across seven centers, and 21 patients were evaluable for response. The median duration of DSF/Cu was 1.6 cycles (range: 0.1-12.0). The ORR was 0%, but 14% had clinical benefit. Median PFS was 1.7 months, and median OS was 7.1 months. Only one patient (4%) had dose-limiting toxicity (grade three elevated alanine transaminase).

CONCLUSIONS

Addition of DSF/Cu to TMZ for TMZ-resistant IDH-wild type GBM appears well tolerated but has limited activity for unselected population.

Site-specific retinoic acid production in the brain of adult songbirds

The song system of songbirds, a set of brain nuclei necessary for song learning and production, has distinctive morphological and functional properties. Utilizing differential display, we searched for molecular components involved in song system regulation. We identified a cDNA (zRalDH) that encodes a class 1 aldehyde dehydrogenase. zRalDH was highly expressed in various song nuclei and synthesized retinoic acid efficiently. Brain areas expressing zRalDH generated retinoic acid. Within song nucleus HVC, only projection neurons not undergoing adult neurogenesis expressed zRalDH. Blocking zRalDH activity in the HVC of juveniles interfered with normal song development. Our results provide conclusive evidence for localized retinoic acid synthesis in an adult vertebrate brain and indicate that the retinoic acid-generating system plays a significant role in the maturation of a learned behavior.

Aldehyde dehydrogenase 2 plays a role in the bioactivation of nitroglycerin in humans

OBJECTIVE

Nitrates are used widely in clinical practice. However, the mechanism underlying the bioactivation of nitrates to release NO remains unclear. Recent animal data suggest that mitochondrial aldehyde dehydrogenase (ALDH2) plays a central role in nitrate bioactivation, but its role in humans is not known. We investigated the role of ALDH2 in the vascular effects of nitroglycerin (NTG) in humans in vivo.

METHODS AND RESULTS

Forearm blood flow (FBF) responses to intra-arterial infusions of NTG, sodium nitroprusside (SNP), and verapamil were measured in 12 healthy volunteers before and after ALDH2 inhibition by disulfiram. All drugs caused a dose-dependent vasodilatation. However, only the response to NTG was significantly reduced after disulfiram therapy (33% reduction in area under the curve [AUC]; P=0.002). Separately, 11 subjects of East Asian origin, with the loss-of-function glu504lys mutation in the ALDH2 gene, received intra-arterial NTG, SNP, and verapamil. Only the FBF response to NTG was lower in the volunteers with the glu504lys mutation compared with East Asian and non-Asian wild-type control subjects (40% reduction in AUC; P=0.02).

CONCLUSIONS

The findings suggest that ALDH2 is involved in the bioactivation of NTG in humans in vivo but accounts for less than half of the total bioactivation. This may be of clinical importance in patients with mutations in the ALDH2 gene and in those taking drugs that inhibit ALDH2.

Disulfiram, an old drug with new potential therapeutic uses for human cancers and fungal infections

Disulfiram, a drug used to treat alcoholism, has recently been indicated to play a primary as well as an adjuvant role in the treatment of many cancers and in the reversal of fungal drug-resistance. This review discusses the molecular mechanism of action of disulfiram and its potential use in the treatment of human cancers and fungal infections.

Naltrexone and disulfiram in patients with alcohol dependence and comorbid post-traumatic stress disorder

BACKGROUND

Although disulfiram and naltrexone have been approved by the Food and Drug Administration for the treatment of alcoholism, the effect of these medications on alcohol use outcomes and on psychiatric symptoms is still unknown in patients with co-occurring disorders post-traumatic stress disorder (PTSD).

METHODS

Patients (n = 254) with a major Axis I psychiatric disorder and comorbid alcohol dependence were treated for 12 weeks in a medication study at three Veterans Administration outpatient clinics. Randomization included (1) open randomization to disulfiram or no disulfiram; and (2) double-blind randomization to naltrexone or placebo. This resulted in four groups: (1) naltrexone alone; (2) placebo alone; (3) disulfiram and naltrexone; or (4) disulfiram and placebo. Outcomes were measures of alcohol use, PTSD symptoms, alcohol craving, GGT levels and adverse events.

RESULTS

93 individuals (36.6%) met DSM-IV criteria for PTSD. Subjects with PTSD had better alcohol outcomes with active medication (naltrexone, disulfiram or the combination) than they did on placebo; overall psychiatric symptoms of PTSD improved. Individuals with PTSD were more likely to report some side effects when treated with the combination.

CONCLUSIONS

The results of this study suggest that disulfiram and naltrexone are effective and safe for individuals with PTSD and comorbid alcohol dependence.

How effective is the standard dose of disulfiram? A review of the alcohol-disulfiram reaction in practice

The current maximum recommended dose of disulfiram, 200 mg daily, is often inadequate. Of 63 patients taking disulfiram under supervision who either risked drinking alcohol or who had a medically supervised challenge with alcohol, only half produced a significant response on a dose of 200-300 mg daily. Some patients need as much as 1.5 g daily but even at high dosage significant side effects are uncommon, reversible and rarely serious. A modification to the recommended technique for a medically supervised alcohol challenge is described, which minimises distress.

pH-triggered surface charge-switchable polymer micelles for the co-delivery of paclitaxel/disulfiram and overcoming multidrug resistance in cancer

Multidrug resistance (MDR) remains a major challenge for providing effective chemotherapy for many cancer patients. To address this issue, we report an intelligent polymer-based drug co-delivery system which could enhance and accelerate cellular uptake and reverse MDR. The nanodrug delivery systems were constructed by encapsulating disulfiram (DSF), a P-glyco-protein (P-gp) inhibitor, into the hydrophobic core of poly(ethylene glycol)-block-poly(l-lysine) (PEG-b-PLL) block copolymer micelles, as well as 2,3-dimethylmaleic anhydride (DMA) and paclitaxel (PTX) were grafted on the side chain of l-lysine simultaneously. The surface charge of the drug-loaded micelles represents as negative in plasma (pH 7.4), which is helpful to prolong the circulation time, and in a weak acid environment of tumor tissue (pH 6.5-6.8) it can be reversed to positive, which is in favor of their entering into the cancer cells. In addition, the carrier could release DSF and PTX successively inside cells. The results of in vitro studies show that, compared to the control group, the DSF and PTX co-loaded micelles with charge reversal exhibits more effective cellular uptake and significantly increased cytotoxicity of PTX to MCF-7/ADR cells which may be due to the inhibitory effect of DSF on the efflux function of P-gp. Accordingly, such a smart pH-sensitive nanosystem, in our opinion, possesses significant potential to achieve combinational drug delivery and overcome drug resistance in cancer therapy.

Disulfiram therapy--adverse drug reactions and interactions

Adverse drug reactions (ADR) to disulfiram treatment have been reported as single cases, but few systematic investigations exist. In this study we analysed the spontaneous ADR reports to the Danish Committee on Adverse Drug Reactions during 1968-1991. In that period 154 ADRs to disulfiram were reported, mainly of hepatic, neurological, skin, and psychiatric reactions, in decreasing order of frequency. The safety of disulfiram, estimated on the amount produced and the number of reactions reported, corresponds to an intermediate rate of adverse reactions (1 per 200-2000 treatment year). Over the 23-year period, 14 deaths were reported in Denmark and this corresponds to a rate of 1 per 25,000 treatment year; the chief cause was liver toxicity. Reports to the WHO collaborating Centre for International Drug Monitoring in Uppsala, Sweden, showed the same ADR profile, although with a higher rate of neurological and psychiatric and a lower rate of hepatic reactions. The latency time from the start of treatment to the manifestation of the ADR differed according to organ. Hepatitis occurred with a distinct peak after 2 months of treatment, skin reactions peaked after 2 weeks, and the rate of neurological ADR increased with duration of therapy. The relation of skin reactions and hepatitis to nickel allergy is discussed, as is the dose-dependency of neuropathy. Concomitant disulfiram treatment affects the metabolism of several drugs and the dynamics of others, leading to a number of clinically important drug interactions. The disulfiram drug interactions are reviewed.

Follow-up of 180 Alcoholic Patients for up to 7 Years After Outpatient Treatment: Impact of Alcohol Deterrents on Outcome

OBJECTIVE

(1) To perform a 9-year study of abstinence, lapse, and relapse in 180 chronic alcoholic patients, participants of the Outpatient Longterm Intensive Therapy for Alcoholics (OLITA); (2) To investigate the role of supervised alcohol deterrents (AD) in relapse prevention and as an adjunct for maintenance of long-term abstinence.

METHOD

This prospective open treatment study evaluates the long-term course of drinking outcomes and AD use of 180 chronic alcoholics consecutively admitted from 1993 to 2002. Subsamples are compared for (1) sham-AD versus verum-AD (disulfiram/calcium carbimide), (2) coped lapses versus finally detrimental lapses versus malignant relapses, and (3) AD use for 13 to 20 versus >20 months.

RESULTS

In this 9-year study, the cumulative probability of not having relapsed was 0.52, and that of not having consumed any alcohol was 0.26. Despite long-term use, disulfiram/calcium carbimide was well tolerated. Patients on sham-AD (due to contraindications to verum-AD) showed higher cumulative abstinence probability than patients on verum (S = 0.86 vs. S = 0.49, p = 0.03). Detrimental lapses and malignant relapses occurred earlier than successfully coped lapses (p < 0.001); patients with detrimental lapse and with malignant relapse had fewer days of AD intake and less subsequent days without AD than patients with coped lapse (p < 0.001). The cumulative abstinence probability was S = 0.75 for patients with long-term intake compared with S = 0.50 for patients who stopped AD between months 13 and 20 (p < 0.001).

CONCLUSIONS

An abstinence rate of >50% in this 9-year study strongly supports the concept of comprehensive, long-term outpatient treatment of alcoholics. Supervised, guided intake of AD, also over extended periods, can be used as a predominantly psychologically acting ingredient of successful alcoholism therapy.

Disulfiram and diethyldithiocarbamate intoxication affects the storage and release of striatal dopamine

Acute intoxication and chronic therapy with the alcohol consumption deterrent dithiocarbamate disulfiram have been associated with several neurological complications perhaps involving the impairment of neurotransmitter pathways. In this study we have tested the hypothesis that dopaminergic malfunction is a critical component in disulfiram-evoked neurotoxicity. Disulfiram antagonized the in vitro striatal binding of [3H]tyramine, a putative marker of the vesicular transporter for dopamine, and the uptake of [3H]dopamine into striatal synaptic vesicles, with inhibitory constants (Ki) in the range of reported blood dithiocarbamate levels in treated alcoholics. Furthermore, disulfiram provoked a loss of radioactivity from [3H]dopamine-preloaded striatal vesicles, when added directly to the incubation mixture. Several metal-containing fungicide analogs were also potent displacers of specifically bound [3H]tyramine. Diethyldithiocarbamate (DDC), the major metabolite of disulfiram, had none of these effects. The intraperitoneal injection of a high dose of disulfiram and DDC into rats, mimicking acute intoxication, induced in vivo overflow of striatal dopamine from both a reserpine-sensitive (vesicular) and an alpha-methyl-p-tyrosine-sensitive (cytoplasmic) pool. The vesicular component of in vivo dopamine release resulted mainly from a direct activity of disulfiram, on the organelles (interaction with the carrier for dopamine plus membrane permeabilization) and indirectly through the mediation of serotonergic 5-HT3 receptors. DDC acted poorly at the vesicle membrane, and the in vivo releasing effect of dopamine was only partially prevented by the inhibition of 5-HT3 receptors, thus suggesting the role of additional mechanisms. It is concluded that disulfiram intoxication may acutely disrupt dopamine balance, an effect probably underlying some of the central neurotoxic, extrapyramidal symptoms associated with dithiocarbamate overdose.

The efficacy of a coordinated pharmacological blockade in glioblastoma stem cells with nine repurposed drugs using the CUSP9 strategy

PURPOSE

Constructed from a theoretical framework, the coordinated undermining of survival paths in glioblastoma (GBM) is a combination of nine drugs approved for non-oncological indications (CUSP9; aprepitant, auranofin, captopril, celecoxib, disulfiram, itraconazole, minocycline, quetiapine, and sertraline) combined with temozolomide (TMZ). The availability of these drugs outside of specialized treatment centers has led patients to embark on combination treatments without systematic follow-up. However, no experimental data on efficacy using the CUSP9 strategy in GBM have been reported.

METHODS

Using patient-derived glioblastoma stem cell (GSC) cultures from 15 GBM patients, we described stem cell properties of individual cultures, determined the dose-response relationships of the drugs in the CUSP9, and assessed the efficacy the CUSP9 combination with TMZ in concentrations clinically achievable. The efficacy was evaluated by cell viability, cytotoxicity, and sphere-forming assays in both primary and recurrent GSC cultures.

RESULTS

We found that CUSP9 with TMZ induced a combination effect compared to the drugs individually (p < 0.0001). Evaluated by cell viability and cytotoxicity, 50% of the GSC cultures displayed a high sensitivity to the drug combination. In clinical plasma concentrations, the effect of the CUSP9 with TMZ was superior to TMZ monotherapy (p < 0.001). The Wnt-signaling pathway has been shown important in GSC, and CUSP9 significantly reduces Wnt-activity.

CONCLUSIONS

Adding experimental data to the theoretical rationale of CUSP9, our results demonstrate that the CUSP9 treatment strategy can induce a combination effect in both treatment-naïve and pretreated GSC cultures; however, predicting response in individual cultures will require further profiling of GSCs.