Survival of glioma and colorectal cancer patients using tricyclic antidepressants post-diagnosis

Depression and Quality of Life in Patients with Gliomas: A Narrative Review

In patients with gliomas, depression is a common complication that may cause severe psychological barriers and deteriorate the patient’s quality of life (QoL). Currently, the Hospital Anxiety and Depression Scale (HADS) is the most commonly used tool to diagnose depression in patients with gliomas. Female sex, unmarried status, low education level, high tumor grade, and a history of mental illness may increase the risks of depression and depressive symptoms in patients with gliomas. The QoL of patients with gliomas can be directly reduced by depression. Therefore, the evaluation and intervention of mood disorders could improve the overall QoL of patients with gliomas. Antidepressant use has become a treatment strategy for patients with gliomas and comorbid depression. This narrative review summarizes the current issues related to depression in patients with gliomas, including the prevalence, risk factors, and diagnostic criteria of depression as well as changes in QoL caused by comorbid depression and antidepressant use. The purpose of this review is to guide clinicians to assess the psychological status of patients with gliomas and to provide clinicians and oncologists with a new treatment strategy to improve the prognosis of such patients.

Antitumoral Effects of Tricyclic Antidepressants: Beyond Neuropathic Pain Treatment

Simple Summary

Tricyclic antidepressants (TCAs) are old and known therapeutic agents whose good safety profile makes them good candidates for drug repurposing. As the relevance of nerves in cancer development and progression is being unveiled, attention now turns to the use of nerve-targeting drugs, such as TCAs, as an interesting approach to combat cancer. In this review, we discuss current evidence about the safety of TCAs, their application to treat neuropathic pain in cancer patients, and in vitro and in vivo demonstrations of the antitumoral effects of TCAs. Finally, the results of ongoing clinical trials and future directions are discussed.

Abstract

Growing evidence shows that nerves play an active role in cancer development and progression by altering crucial molecular pathways and cell functions. Conversely, the use of neurotropic drugs, such as tricyclic antidepressants (TCAs), may modulate these molecular signals with a therapeutic purpose based on a direct antitumoral effect and beyond the TCA use to treat neuropathic pain in oncology patients. In this review, we discuss the TCAs’ safety and their central effects against neuropathic pain in cancer, and the antitumoral effects of TCAs in in vitro and preclinical studies, as well as in the clinical setting. The current evidence points out that TCAs are safe and beneficial to treat neuropathic pain associated with cancer and chemotherapy, and they block different molecular pathways used by cancer cells from different locations for tumor growth and promotion. Likewise, ongoing clinical trials evaluating the antineoplastic effects of TCAs are discussed. TCAs are very biologically active compounds, and their repurposing as antitumoral drugs is a promising and straightforward approach to treat specific cancer subtypes and to further define their molecular targets, as well as an interesting starting point to design analogues with increased antitumoral activity.

Review of pharmacological treatment of depression in patients with primary brain tumour and proposal of modification in management strategy

This brief paper describes the challenges with treatment of depression in brain tumour patients particularly in the absence of any currently accepted guidelines for treating this perculiar subset of patients. The proposal offered here is to move to pharmacologic treatment with other modalities in a methodical pattern only after surgical intervention. This is because simply treating with medications based on physician / patient choice as currently recommended may not achieve optimal results in majority of cases in view of the multiple aetiological factors that interplay. A flowchart treatment plan is presented to guide management in a streamlined fashion.

Psychotropic Drugs Show Anticancer Activity by Disrupting Mitochondrial and Lysosomal Function

Background and Purpose: Drug repositioning is a promising strategy for discovering new therapeutic strategies for cancer therapy. We investigated psychotropic drugs for their antitumor activity because of several epidemiological studies reporting lower cancer incidence in individuals receiving long term drug treatment.

Experimental Approach: We investigated 27 psychotropic drugs for their cytotoxic activity in colorectal carcinoma, glioblastoma and breast cancer cell lines. Consistent with the cationic amphiphilic structure of the most cytotoxic compounds, we investigated their effect on mitochondrial and lysosomal compartments.

Results: Penfluridol, ebastine, pimozide and fluoxetine, fluspirilene and nefazodone showed significant cytotoxicity, in the low micromolar range, in all cell lines tested. In MCF7 cells these drugs caused mitochondrial membrane depolarization, increased the acidic vesicular compartments and induced phospholipidosis. Both penfluridol and spiperone induced AMPK activation and autophagy. Neither caspase nor autophagy inhibitors rescued cells from death induced by ebastine, fluoxetine, fluspirilene and nefazodone. Treatment with 3-methyladenine partially rescued cell death induced by pimozide and spiperone, whereas enhanced the cytotoxic activity of penfluridol. Conversely, inhibition of lysosomal cathepsins significantly reduced cell death induced by ebastin, penfluridol, pimozide, spiperone and mildly in fluoxetine treated cells. Lastly, Spiperone cytotoxicity was restricted to colorectal cancer and breast cancer and caused apoptotic cell death in MCF7 cells.

Conclusions: The cytotoxicity of psychotropic drugs with cationic amphiphilic structures relied on simultaneous mitochondrial and lysosomal disruption and induction of cell death that not necessarily requires apoptosis. Since dual targeting of lysosomes and mitochondria constitutes a new promising therapeutic approach for cancer, particularly those in which the apoptotic machinery is defective, these data further support their clinical development for cancer therapy.

Impact of Polypharmacy for Chronic Ailments in Colon Cancer Patients: A Review Focused on Drug Repurposing

Colorectal cancer is characterized by high incidence worldwide. Despite increased awareness and early diagnosis thanks to screening programmes, mortality remains high, particularly for patients with metastatic involvement. Immune checkpoint inhibitors or poly (ADP-ribose) polymerase (PARP)-inhibitors have met with disappointing results when used in this setting, opposed to other malignancies. New drugs with different mechanisms of action are needed in this disease. Drug repurposing might offer new therapeutic options, as patients with metastatic colorectal cancer often share risk factors for other chronic diseases and thus frequently are on incidental therapy with these drugs. The aim of this review is to summarise the published results of the activity of drugs used to treat chronic medications in patients affected by colorectal cancer. We focused on antihypertensive drugs, Non-Steroid Anti-inflammatory Drugs (NSAIDs), metformin, antidepressants, statins and antibacterial antibiotics. Our review shows that there are promising results with beta blockers, statins and metformin, whereas data concerning antidepressants and antibacterial antibiotics seem to show a potentially harmful effect. It is hoped that further prospective trials that take into account the role of these drugs as anticancer medications are conducted.

Pharmacological treatment of depression in people with a primary brain tumour

BACKGROUND

This is the second updated version of the Cochrane Review published in Issue 3, 2010 and first updated in Issue 5, 2013. People with a primary brain tumour often experience depression, for which drug treatment may be prescribed. However, they are also at high risk of epileptic seizures, cognitive impairment, and fatigue, all of which are potential adverse side effects of antidepressants. The benefit, or harm, of pharmacological treatment of depression in people with a primary brain tumour is unclear.

OBJECTIVES

To assess the benefits and harms of pharmacological treatment of depression in people with a primary brain tumour.

SEARCH METHODS

We updated the search to include CENTRAL, MEDLINE, Embase, and PsycINFO to September 2019. As in the original review, we also handsearched Neuro-Oncology, Journal of Neuro-Oncology, Journal of Neurology, Neurosurgery and Psychiatry, and Journal of Clinical Oncology: for the current update we handsearched the latest three years of articles from these journals (up to November 2019).

SELECTION CRITERIA

We searched for all randomised controlled trials (RCTs), controlled clinical trials, cohort studies, and case-control studies of any pharmacological treatment of depression in people with a histologically diagnosed primary brain tumour.

DATA COLLECTION AND ANALYSIS

No studies met the inclusion criteria.

MAIN RESULTS

We found no eligible studies evaluating the benefits of any pharmacological treatment of depression in people with a primary brain tumour.

AUTHORS' CONCLUSIONS

We identified no high-quality studies that investigated the value of pharmacological treatment of depression in people with a primary brain tumour. RCTs and detailed prospective studies are required to inform the effective pharmacological treatment of this common and important complication of brain tumours. Since the last version of this review none of the related new literature has provided additional information to change these conclusions.

Antidepressant use and colorectal cancer morbidity and mortality: A dose-response meta analysis

The risk of colorectal cancer associated to antidepressant use remains unclear. The purpose of this meta-analysis was to investigate the risk of colorectal cancer associated to antidepressant use.Medline, Embase, Web of Science, and Cochrane Database were accessed from the dates of their establishment to October 2018, to collect study of antidepressant use and colorectal cancer morbidity and mortality. Then a meta-analysis was conducted using Stata 12.0 software.A total of 11 publications involving 109,506 participants were included. The meta-analysis showed that antidepressant use was not associated with colorectal cancer morbidity (relevant risk (RR): 0.97; 95% confidence interval (CI): 0.94-1.01) and mortality (RR: 1.08; 95% CI: 0.99-1.17). Subgroup analysis showed selective serotonin reuptake inhibitor (RR: 0.99; 95% CI: 0.96-1.03) or serotonin norepinephrine reuptake inhibitor (RR: 1.04; 95% CI: 0.86-1.26) were not associated with colorectal cancer risk; however, TCA was associated with colorectal cancer risk decrement (RR: 0.92; 95% CI: 0.87-0.98). Furthermore, the results also showed that antidepressant use was not associated with colorectal cancer risk in Europe and North America (RR: 0.97; 95% CI: 0.92-1.02) and Asia (RR: 1.00; 95% CI: 0.95-1.26). Additionally, a dose-response showed per 1 year of duration of antidepressant use incremental increase was not associated with colorectal cancer risk (RR: 0.96; 95% CI: 0.87-1.09).Evidence suggests that antidepressant use was not associated with colorectal cancer morbidity and mortality. The cumulative duration of antidepressant use did not utilized played critical roles.

Adherence to antidepressant medications is associated with reduced premature mortality in patients with cancer: A nationwide cohort study

BACKGROUND

Depression and anxiety are common in cancer and antidepressants (AD) are efficacious treatment. The relationship between AD adherence and mortality in cancer is unclear. This study aimed to evaluate the association between adherence to AD and all-cause mortality in a population-based cohort of patients with cancer.

MATERIALS AND METHODS

We conducted a 4-year historical prospective cohort study including 42,075 patients with cancer who purchased AD at least once during the study period. Adherence to AD was modeled as nonadherence (<20%), poor (20-50%), moderate (50-80%), and good (>80%) adherence. We conducted multivariable survival analyses adjusted for demographic and clinical variables that may affect mortality.

RESULTS

During 1,051,489 person-years at risk follow-up, the adjusted hazard ratios (HR) for mortality were 0.89 (95% confidence interval [CI]: 0.83-0.95), 0.77 (95% CI: 0.66-0.72), and 0.80 (95% CI: 0.76-0.85) for the poor, moderate, and good adherence groups, respectively, compared to the nonadherent group. Analysis of the entire sample and a subgroup with depression, for cancer subtypes, revealed similar patterns for breast, colon, lung, and prostate cancers, but not for melanoma patients. Multivariate predictors of premature mortality included male gender (HR 1.48 [95% CI: 1.42-1.55]), current/past smoking status (HR 1.1, [95% CI: 1.04-1.15]; P < .0001), low socioeconomic status (HR 1.1, [95% CI: 1.03-1.17]; P < .0001) and more physical comorbidities.

CONCLUSIONS

The present study is the first to demonstrate that higher adherence to AD is associated with a decrease of all-cause mortality in a large nationwide cohort of cancer patients. Our data add to the pressing need to encourage adherence to AD among cancer patients.

The dual roles of autophagy in gliomagenesis and clinical therapy strategies based on autophagic regulation mechanisms

Autophagy, a self-digestion intracellular catabolic process, plays a crucial role in cellular homeostasis under conditions of starvation, oxidative stress and genotoxic stress. The capability of maintaining homeostasis contributes to preventing malignant behavior in normal cells. Many studies have provided compelling evidence that autophagy is involved in brain tumor recurrence and chemotherapy and radiotherapy resistance. Gliomas, as the primary central nervous system (CNS) tumors, are characterized by rapid, aggressive growth and recurrence and have a poor prognosis and bleak outlook even with modern multimodality strategies involving maximal surgical resection, radiotherapy and alkylating agent-based chemotherapy. Autophagy-associated signaling pathways, such as the extracellular signal-regulated kinase1/2 (ERK1/2) pathway, class I phosphatidylinositol 3-phosphate kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and nuclear factor kappa-B (NF-κB) pathway, act as tumor suppressors or protect tumor cells against chemotherapy/radiotherapy-induced cytotoxicity in gliomagenesis. Through these pathways, both lethal autophagy and protective autophagy play crucial roles in tumor initiation, chemoresistance and glioma stem cell differentiation. Moreover, lethal autophagy and protective autophagy have been identified as novel therapeutic targets in glioma according to the mechanisms described above. Here, we discuss the multiple impacts of the autophagic response on distinct phases of gliomagenesis and the advanced progress of therapies based on this concept.

Use of antidepressants after colon cancer diagnosis and risk of recurrence

OBJECTIVE

Prior research examining the association between use of antidepressants after colon cancer diagnosis and risk of recurrence is scant. We evaluated this association among colon cancer patients diagnosed at two integrated health care delivery systems in the United States.

METHODS

We conducted a cohort study of stage I to IIIA colon cancer patients diagnosed at greater than or equal to 18 years of age at Kaiser Permanente Colorado and Kaiser Permanente Washington during 1995 to 2014. We used pharmacy records to identify dispensings for antidepressants and tumor registry records and patients' medical charts to identify cancer recurrences. Using Cox proportional hazards models, we estimated the adjusted hazard ratio (HR) of colon cancer recurrence comparing patients who used antidepressants after diagnosis to those who did not. We also evaluated the risk associated with use of selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) separately.

RESULTS

Among the 1923 eligible colon cancer patients, 807 (42%) used an antidepressant after diagnosis and 139 had a colon cancer recurrence during an average 5.6 years of follow-up. Use of antidepressants after colon cancer diagnosis was not associated with risk of recurrence (HR: 1.14; 95% confidence interval [CI], 0.69-1.87). The HR for use of SSRIs was 1.22 (95% CI, 0.64-2.30), and for TCAs, it was 1.18 (95% CI, 0.68-2.07).

CONCLUSIONS

Our findings suggest that use of antidepressants after colon cancer diagnosis was common and not associated with risk of recurrence. Future larger studies with greater power to examine risk associated with individual antidepressants would be valuable additions to the evidence base.

Drug Repositioning in Glioblastoma: A Pathway Perspective

Glioblastoma multiforme (GBM) is the most malignant primary adult brain tumor. The current standard of care is surgical resection, radiation, and chemotherapy treatment, which extends life in most cases. Unfortunately, tumor recurrence is nearly universal and patients with recurrent glioblastoma typically survive <1 year. Therefore, new therapies and therapeutic combinations need to be developed that can be quickly approved for use in patients. However, in order to gain approval, therapies need to be safe as well as effective. One possible means of attaining rapid approval is repurposing FDA approved compounds for GBM therapy. However, candidate compounds must be able to penetrate the blood-brain barrier (BBB) and therefore a selection process has to be implemented to identify such compounds that can eliminate GBM tumor expansion. We review here psychiatric and non-psychiatric compounds that may be effective in GBM, as well as potential drugs targeting cell death pathways. We also discuss the potential of data-driven computational approaches to identify compounds that induce cell death in GBM cells, enabled by large reference databases such as the Library of Integrated Network Cell Signatures (LINCS). Finally, we argue that identifying pathways dysregulated in GBM in a patient specific manner is essential for effective repurposing in GBM and other gliomas.

Effect of Treating Depressive Disorders on Mortality of Cancer Patients

Depression can have debilitating effects on patients with a chronic morbid disease, in particular, cancer. It has been found that patients with a depressive disorder have a poorer prognosis and increased mortality. There is a debate as to whether the treatment of the depressive disorder is beneficial to these patients. Studies demonstrate varying results with pharmacotherapy and behavioral therapy. All cancer patients should be periodically assessed for depressive disorder and the symptoms not dismissed as part of their cancer presentation due to the increased mortality.

Antidepressants and colorectal cancer: A population-based nested case-control study

BACKGROUND

Experimental evidence indicates that serotonin is associated with both proliferative and pro-carcinogenic effects on colorectal tumors. The present study aims to investigate the associations between antidepressant use and colorectal cancer in an epidemiological sample.

METHODS

We conducted a population-based case-control study utilizing Taiwan's National Health Insurance Research Database (NHIRD). We identified 49,342 cases with colorectal cancer and 240,985 controls between 1997 and 2008. We conducted conditional logistic regression analyses to assess the association between antidepressant use and colorectal cancer risk. Sensitivity analyses were conducted to assess whether genotoxic antidepressants (i.e. antidepressants which may exert procarcinogenic effects) would increase risk for colorectal cancer.

RESULTS

Selective serotonin reuptake inhibitors (adjusted OR=1.00, 95% CI=0.94-1.06), tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and serotonin antagonist and reuptake inhibitors were not associated with increased incidence of colorectal cancer. Monoamine oxidase inhibitors were, however, associated with an increased incidence of colorectal cancer (adjusted OR=1.22, 95% CI=1.06-1.41). Higher cumulative dose of mirtazapine was associated with a decreased incidence of colorectal cancer (adjusted OR=0.39, 95% CI=0.17-0.90). A small sample size of individuals who received mirtazapine, however, precludes definitive conclusions regarding protective effects with mirtazapine.

LIMITATIONS

We could not discern the effects of obesity and other risk factors for colorectal cancer from the NHIRD.

CONCLUSIONS

Contemporary first-line antidepressants (i.e. SSRI, SNRI), as well as older agents (i.e. TCA), are not associated with increased incidence of colorectal cancer.

Repurposing some older drugs that cross the blood-brain barrier and have potential anticancer activity to provide new treatment options for glioblastoma

Glioblastoma is a brain neoplasm with limited 5-year survival rates. Developments of new treatment regimens that improve patient survival in patients with glioblastoma are needed. It is likely that a number of existing drugs used in other conditions have potential anticancer effects that offer significant survival benefit to glioblastoma patients. Identification of such drugs could provide a novel treatment paradigm.

Dual Targeting of the Autophagic Regulatory Circuitry in Gliomas with Repurposed Drugs Elicits Cell-Lethal Autophagy and Therapeutic Benefit

The associations of tricyclic antidepressants (TCAs) with reduced incidence of gliomas and elevated autophagy in glioma cells motivated investigation in mouse models of gliomagenesis. First, we established that imipramine, a TCA, increased autophagy and conveyed modest therapeutic benefit in tumor-bearing animals. Then we screened clinically approved agents suggested to affect autophagy for their ability to enhance imipramine-induced autophagy-associated cell death. The anticoagulant ticlopidine, which inhibits the purinergic receptor P2Y12, potentiated imipramine, elevating cAMP, a modulator of autophagy, reducing cell viability in culture, and increasing survival in glioma-bearing mice. Efficacy of the combination was obviated by knockdown of the autophagic regulatory gene ATG7, implicating cell-lethal autophagy. This seemingly innocuous combination of TCAs and P2Y12 inhibitors may have applicability for treating glioma.

Chemical Library Screening and Structure-Function Relationship Studies Identify Bisacodyl as a Potent and Selective Cytotoxic Agent Towards Quiescent Human Glioblastoma Tumor Stem-Like Cells

Cancer stem-like cells reside in hypoxic and slightly acidic tumor niches. Such microenvironments favor more aggressive undifferentiated phenotypes and a slow growing "quiescent state" which preserves them from chemotherapeutic agents that essentially target proliferating cells. Our objective was to identify compounds active on glioblastoma stem-like cells, including under conditions that mimick those found in vivo within this most severe and incurable form of brain malignancy. We screened the Prestwick Library to identify cytotoxic compounds towards glioblastoma stem-like cells, either in a proliferating state or in more slow-growing "quiescent" phenotype resulting from non-renewal of the culture medium in vitro. Compound effects were assessed by ATP-level determination using a cell-based assay. Twenty active molecules belonging to different pharmacological classes have thus been identified. Among those, the stimulant laxative drug bisacodyl was the sole to inhibit in a potent and specific manner the survival of quiescent glioblastoma stem-like cells. Subsequent structure-function relationship studies led to identification of 4,4'-dihydroxydiphenyl-2-pyridyl-methane (DDPM), the deacetylated form of bisacodyl, as the pharmacophore. To our knowledge, bisacodyl is currently the only known compound targeting glioblastoma cancer stem-like cells in their quiescent, more resistant state. Due to its known non-toxicity in humans, bisacodyl appears as a new potential anti-tumor agent that may, in association with classical chemotherapeutic compounds, participate in tumor eradication.

Common mechanisms of pain and depression: are antidepressants also analgesics?

Neither pain, nor depression exist as independent phenomena per se, they are highly subjective inner states, formed by our brain and built on the bases of our experiences, cognition and emotions. Chronic pain is associated with changes in brain physiology and anatomy. It has been suggested that the neuronal activity underlying subjective perception of chronic pain may be divergent from the activity associated with acute pain. We will discuss the possible common pathophysiological mechanism of chronic pain and depression with respect to the default mode network of the brain, neuroplasticity and the effect of antidepressants on these two pathological conditions. The default mode network of the brain has an important role in the representation of introspective mental activities and therefore can be considered as a nodal point, common for both chronic pain and depression. Neuroplasticity which involves molecular, cellular and synaptic processes modifying connectivity between neurons and neuronal circuits can also be affected by pathological states such as chronic pain or depression. We suppose that pathogenesis of depression and chronic pain shares common negative neuroplastic changes in the central nervous system (CNS). The positive impact of antidepressants would result in a reduction of these pathological cellular/molecular processes and in the amelioration of symptoms, but it may also increase survival times and quality of life of patients with chronic cancer pain.

Depression in glioma: a primer for clinicians and researchers

Depression is one of the leading causes of global disability, and a considerable hidden morbidity among patients with glioma. In this narrative review, we summarise what is currently known about depression in glioma, the main unanswered questions and the types of studies that should be prioritised in order to find out. We conclude by calling for a prospective Phase II study of antidepressants in depressed glioma patients, to test methodologies for a multicentre randomised controlled trial.

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.

Mitochondrial dysfunction in gliomas

Mitochondrial (mt) dysfunction in gliomas has been linked to abnormalities of mt energy metabolism, marked by a metabolic shift from oxidative phosphorylation to glycolysis ("Warburg effect"), disturbances in mt membrane potential regulation and apoptotic signaling, as well as to somatic mutations involving the Krebs cycle enzyme isocitrate dehydrogenase. Evolving biological concepts with potential therapeutic implications include interaction between microtubule proteins and mitochondria (mt) in the control of closure of voltage-dependent anion channels and in the regulation of mt dynamics and the mt-endoplasmic reticulum network. The cytoskeletal protein βIII-tubulin, which is overexpressed in malignant gliomas, has emerged as a prosurvival factor associated in part with mt and also as a marker of chemoresistance. Mt-targeted therapeutic strategies that are discussed include the following: (1) metabolic modulation with emphasis on dichloroacetate, a pyruvate dehydrogenase kinase inhibitor; (2) tumor cell death via apoptosis induced by tricyclic antidepressants, microtubule-modulating drugs, and small molecules or compounds capable of inflicting reactive oxygen species-dependent tumor cell death; and (3) pretreatment mt priming and mt-targeted prodrug cancer therapy.