Classics in Chemical Neuroscience: Selegiline, Isocarboxazid, Phenelzine, and Tranylcypromine.

The discovery of monoamine oxidase inhibitors (MAOIs) in the 1950s marked a significant breakthrough in medicine, creating a powerful new category of drug: the antidepressant. In the years and decades that followed, MAOIs have been used in the treatment of several pathologies including Parkinson's disease, Alzheimer's disease, and various cancers and as anti-inflammatory agents. Despite once enjoying widespread use, MAOIs have dwindled in popularity due to side effects, food-drug interactions, and the introduction of other antidepressant drug classes such as tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). The recently published prescriber's guide for the use of MAOIs in treating depression has kindled a resurgence of their use in the clinical space. It is therefore timely to review key aspects of the four "classic" MAOIs: high-dose selegiline, isocarboxazid, phenelzine, and tranylcypromine. This review discusses their chemical synthesis, metabolism, pharmacology, adverse effects, and the history and importance of these drugs within the broader field of chemical neuroscience.

Synergistic Effects of Tranylcypromine and NRF2 Inhibitor: A Repurposing Strategy for Effective Cancer Therapy.

Drug repurposing has emerged as an attractive strategy for accelerating drug discovery for cancer treatment. In this study, we investigated combining Tranylcypromine (TCP) with a number of well-characterized drugs. Among these combinations, NRF2 inhibitor (ML385) exhibited synergistic effects in combination with TCP. Specifically, our results showed that the combination of TCP and ML385 resulted in a significant reduction in tumor proliferation while neither drug affected cancer cell growth meaningfully on its own. While further studies are needed to understand fully the extent of the synergistic efficacy, the underlying respective mechanisms and the potential side effects of this approach, our study has yielded a promising start for the development of an effective combination cancer therapy.

Repurposing antidepressants for anticancer drug discovery.

Drug repurposing is an attractive strategy for identifying new indications for existing drugs. Three approved antidepressants have advanced into clinical trials for cancer therapy. In particular, further medicinal chemistry efforts with tranylcypromine (TCP) have led to the discovery of several TCP-based histone lysine specific demethylase 1 (LSD1) inhibitors that display therapeutic promise for treating cancer in the clinic. Thus repurposing antidepressants could be a promising strategy for cancer treatment. In this review, we illustrate the anticancer mechanisms of action of antidepressants and also discuss the challenges and future directions of repurposing antidepressants for anticancer drug discovery, to provide an overview of approved antidepressant cancer therapies.

Combination of Tranylcypromine and Mirtazapine in Difficult-to-Treat Depression.

BACKGROUND: About one third of depression patients do not respond to the first antidepressant trial. Difficult-to-treat depression was suggested to characterize the often chronic and severe course of disease. Previous data indicate that tranylcypromine is effective in case of treatment-refractory depression. Many antidepressants are contraindicated in combination with tranylcypromine and other monoamine-oxidase inhibitors because of the risk of serotonin syndrome. The combination of tranylcypromine and amitriptyline was reported to be efficacious and safe in patients with electroconvulsive therapy-resistant major depression. METHODS: In this retrospective chart review, we report a series of 3 cases, in which patients with electroconvulsive therapy-resistant depression were treated with the combination of tranylcypromine and mirtazapine. There are no published clinical data on this combination yet. Disease severity and treatment response were retrospectively assessed with the Clinical Global Impression-Severity and Improvement Scales. RESULTS: All 3 patients had severe difficult-to-treat depression with chronic course of disease and several times of inpatient treatment without achieving remission. The combination treatment was tolerated well, although the patients had somatic comorbidities. One patient developed mild and self-limiting neuroleptic malignant syndrome in the long-term course after dose increase of concomitant aripiprazole. All 3 patients showed either much or very much improvement. CONCLUSIONS: Under tight clinical controls in inpatient setting and after exhausting of alternatives, the combination of tranylcypromine and mirtazapine could be considered in patients, who do not achieve adequate improvement through common treatment options recommended in the guidelines. The combination has to be ceased, if symptoms of possible serotonin syndrome occur.

A proof of concept phase I/II pilot trial of LSD1 inhibition by tranylcypromine combined with ATRA in refractory/relapsed AML patients not eligible for intensive therapy.

All-trans-retinoic acid (ATRA) is highly active in acute promyelocytic leukemia but not in other types of acute myeloid leukemia (AML). Previously, we showed that ATRA in combination with Lysine-specific demethylase 1 (LSD1) inhibition by tranylcypromine (TCP) can induce myeloid differentiation in AML blasts. This phase I/II clinical trial investigated the safety and efficacy of TCP/ATRA treatment as salvage therapy for relapsed/refractory (r/r) AML. The combination was evaluated in 18 patients, ineligible for intensive treatment. The overall response rate was 20%, including two complete remissions without hematological recovery and one partial response. We also observed myeloid differentiation upon TCP/ATRA treatment in patients who did not reach clinical remission. Median overall survival (OS) was 3.3 months, and one-year OS 22%. One patient developed an ATRA-induced differentiation syndrome. The most frequently reported adverse events were vertigo and hypotension. TCP plasma levels correlated with intracellular TCP concentration. Increased H3K4me1 and H3k4me2 levels were observed in AML blasts and white blood cells from some TCP/ATRA treated patients. Combined TCP/ATRA treatment can induce differentiation of AML blasts and lead to clinical response in heavily pretreated patients with r/r AML with acceptable toxicity. These findings emphasize the potential of LSD1 inhibition combined with ATRA for AML treatment.

The MAO Inhibitor Tranylcypromine Alters LPS- and Aß-Mediated Neuroinflammatory Responses in Wild-type Mice and a Mouse Model of AD.

Monoamine oxidase (MAO) has been implicated in neuroinflammation, and therapies targeting MAO are of interest for neurodegenerative diseases. The small-molecule drug tranylcypromine, an inhibitor of MAO, is currently used as an antidepressant and in the treatment of cancer. However, whether tranylcypromine can regulate LPS- and/or Aß-induced neuroinflammation in the brain has not been well-studied. In the present study, we found that tranylcypromine selectively altered LPS-induced proinflammatory cytokine levels in BV2 microglial cells but not primary astrocytes. In addition, tranylcypromine modulated LPS-mediated TLR4/ERK/STAT3 signaling to alter neuroinflammatory responses in BV2 microglial cells. Importantly, tranylcypromine significantly reduced microglial activation as well as proinflammatory cytokine levels in LPS-injected wild-type mice. Moreover, injection of tranylcypromine in 5xFAD mice (a mouse model of AD) significantly decreased microglial activation but had smaller effects on astrocyte activation. Taken together, our results suggest that tranylcypromine can suppress LPS- and Aß-induced neuroinflammatory responses in vitro and in vivo.

Antidepressant drugs can modify cytotoxic action of temozolomide.

Cancer patients often require antidepressant treatment due to comorbid depressive disorder. However, recent studies have demonstrated that antidepressant drugs affect the efficacy of chemotherapy and promote progression of cancer. Apart from the main mood-improving effect, antidepressant drugs also produce analgesic, anxiolytic, hypnotic and pro-cognitive actions. Patients suffering from brain cancer constitute the greatest percentage of depressive cancer patients. However, vital safety and efficacy issues related to combined therapy with temozolomide, the first-line cytostatic in patients diagnosed with glioblastoma multiforme, and antidepressant drugs have yet to be addressed. The aim of the present studies was to evaluate the effect of three antidepressant drugs (imipramine, fluoxetine and tranylcypromine) on the cytotoxic efficacy of temozolomide on T98G cells, a human glioblastoma cell line. In our experiments, we used a complex experimental in vitro system to mimic the instability of a tumour's oxygen supply, thereby reproducing conditions that occur inside the tumour. The effect of the interaction between temozolomide and antidepressant drugs on viability, apoptosis and intensity of divisions of glioblastoma cells was evaluated under different oxygen conditions. The results of our studies demonstrated that imipramine and tranylcypromine reduced the cytotoxic efficacy of temozolomide under some oxygen conditions while fluoxetine did not demonstrate such effects.

Tranylcypromine, a lysine-specific demethylase 1 (LSD1) inhibitor, suppresses lesion growth and improves generalized hyperalgesia in mouse with induced endometriosis.

BACKGROUND: Growing evidence indicates that endometriosis is an epigenetic disease. Encouragingly, histone deacetylases (HDACs) and DNA methyltransferases have been shown to be promising targets by numerous in vitro studies. However, only a few studies have shown promising effects of HDAC inhibition in preclinical studies in endometriosis. While lysine-specific demethylase 1 (LSD1) is recently found to be aberrantly expressed in endometriosis, and that the treatment of endometriotic stromal cells with tranylcypromine (TC), an LSD1 inhibitor, significantly reduced cellular proliferation, cell cycle progression, and invasiveness, the in vivo effect of TC treatment is currently lacking. This study sought to evaluate the effect of TC in a mouse model of endometriosis. METHODS: Forty-seven female C57BL/6 mice were used in this experimentation. All mice, except those randomly selected to form Sham surgery (M) and specificity control (S) groups, received an endometriosis-inducing surgery. Group S was set up mainly to ensure that the reduced generalized hyperalgesia in mice treated with TC is not due to any possible analgesic effect of TC, but rather resulting from the treatment effect specific to endometriosis. Two weeks after the surgery, mice that received surgery were further divided randomly into 3 groups: 1) untreated group (U); 2) low-dose TC group (L); 3) high-dose TC group (H). Group S received the same treatment as in group H. Two weeks after treatment, all mice were sacrificed and their ectopic endometrial tissues were harvested and analyzed by immunohistochemistry analysis. Hotplate test was administrated to all mice before the induction, treatment and sacrifice. Lesion size, hotplate latency, immunoreactivity against markers of proliferation, angiogenesis, H3K4 methylation, and of epithelial-mesenchymal transition (EMT). RESULTS: TC treatment significantly and substantially reduced the lesion size and improved generalized hyperalgesia in a dose-dependent fashion in mice with induced endometriosis. In addition, TC treatment resulted in reduced immunoreactivity to biomarkers of proliferation, angiogenesis, and H3K4 methylation, leading to arrested EMT and lesion growth. CONCLUSION: In light of our previously reported reduced cellular proliferation, cell cycle progression and invasiveness resulting from the LSD1 inhibition in in vitro studies, our data strongly suggest that LSD1 is a promising therapeutic target for endometriosis. TRIAL REGISTRATION: Not applicable.

TCPs: privileged scaffolds for identifying potent LSD1 inhibitors for cancer therapy.

Since the first lysine-specific demethylase (KDM), lysine-specific demethylase 1 (LSD1), was characterized in 2004, several families of KDMs have been identified. LSD1 can specifically demethylate H3K4me1/2, H3K9me1/2 as well as some nonhistone substrates. It has been demonstrated to be an oncogene as well as a drug target. Hence, tens of small-molecule LSD1 inhibitors have been designed, synthesized and applied for cancer treatment. However, the two LSD1 inhibitors that have been advanced into early phase clinical trials are trans-2-phenylcyclopropylamine (TCP) derivatives, which indicate that TCP is a druggable scaffold for LSD1 inhibitor. Here, we review the design, synthesis and properties of reported TCP-based LSD1 inhibitors as well as their biological roles.

Discovery of a Novel Inhibitor of Histone Lysine-Specific Demethylase 1A (KDM1A/LSD1) as Orally Active Antitumor Agent.

We report the stereoselective synthesis and biological activity of a novel series of tranylcypromine (TCPA) derivatives (14a-k, 15, 16), potent inhibitors of KDM1A. The new compounds strongly inhibit the clonogenic potential of acute leukemia cell lines. In particular three molecules (14d, 14e, and 14g) showing selectivity versus MAO A and remarkably inhibiting colony formation in THP-1 human leukemia cells, were assessed in mouse for their preliminary pharmacokinetic. 14d and 14e were further tested in vivo in a murine acute promyelocytic leukemia model, resulting 14d the most effective. Its two enantiomers were synthesized: the (1S,2R) enantiomer 15 showed higher activity than its (1R,2S) analogue 16, in both biochemical and cellular assays. Compound 15 exhibited in vivo efficacy after oral administration, determining a 62% increased survival in mouse leukemia model with evidence of KDM1A inhibition. The biological profile of compound 15 supports its further investigation as a cancer therapeutic.

Antidepressant treatment with MAO-inhibitors during general and regional anesthesia: a review and case report of spinal anesthesia for lower extremity surgery without discontinuation of tranylcypromine.

Monoamine oxidase-(MAO)-inhibitors are a treatment of last resort in treatment resistant depression, which is regarded as a condition of increased psychiatric risk. General and regional anesthesia for elective surgery during use of long-term MAO-inhibitors remains a matter of debate because of an increased risk of drug interactions and decreased sympathetic stability. A series of case reports and new comparative studies reveal the safety of anesthesia/analgesia in non-cardiac surgery without discontinuation of the MAO-inhibitor if best effort is made for maintenance of sympathetic homeostasis and if known drug interactions are avoided. Very few reports with severe adverse incidents have been noted. Severe cardiovascular morbidity, a contraindication of MAO-inhibitors, probably contributed to peri- and postoperative complications. According to new studies, the risk of pharmacokinetic drug interactions is lower for tranylcypromine than for phenelzine. In the present case, a 66-year-old psychiatric patient on permanent treatment with 20 mg/day tranylcypromine was admitted for forefoot surgery. Anesthetic premedication consisted of 7.5 mg oral midazolam. Intravenous midazolam (0.5 mg) was dispensed for intraoperative sedation. After local anesthesia of the puncture site with 30 mg isobar prilocaine, spinal anesthesia was achieved by a single shot of 13.5 mg hyperbar bupivacaine (0.5%) intrathecally. Postoperative regional and general analgesia were accomplished by a peripheral nerve block with 50 mg isobar bupivacaine as well as oral etoricoxib and oxycodone. No peri- or postoperative complications were encountered. It is concluded that general or regional anesthesia for noncardiac surgery without discontinuation of MAO-inhibitor treatment may be a safe intervention after careful evaluation of an individual's perioperative and psychiatric risk. The increased psychiatric risk in patients treated with MAO-inhibitors outweighs the increased, however manageable, perioperative risk from continuing treatment during surgery.

Antidepressive treatment with monoamine oxidase inhibitors and the occurrence of intraoperative hemodynamic events: a retrospective observational cohort study.

OBJECTIVE: To investigate the occurrence of intraoperative hemodynamic events when antidepressive treatment with monoamine oxidase inhibitors (MAOIs) was continued during anesthesia. METHOD: A retrospective observational cohort study was conducted among patients who were admitted for elective surgery requiring anesthesia in 8 Dutch hospitals (2004-2010). The index group included current users of irreversible (tranylcypromine) and reversible (moclobemide) MAOIs. The reference group included a sample of nonusers matched to the index group on hospital, type and period of surgery, and type of anesthesia (ratio 1:3). The outcome of interest was the occurrence of the following intraoperative hemodynamic events: hypotension or hypertension and tachycardia or bradycardia. RESULTS: Approximately 280,000 surgical procedures were performed in the participating hospitals in the total observational period of 33 years. The index group included 26 and 25 users of tranylcypromine and moclobemide, respectively. The reference groups included 149 nonusers. Intraoperative hypotension occurred less frequently in users of tranylcypromine (46%) than in nonusers (73%) (P = .01). The occurrence of hypertension, bradycardia, and tachycardia during anesthesia was not different between users of tranylcypromine (27%, 50%, and 12%, respectively) and those in the reference group (35%, 61%, and 26%, respectively). The occurrence of hypotension, hypertension, bradycardia, and tachycardia was not different between users of moclobemide and the reference group. CONCLUSIONS: Severe adverse hemodynamic events, such as hypertension and tachycardia, did not occur more frequently in users of both the irreversible MAOI tranylcypromine and the reversible MAO-A inhibitor moclobemide compared to nonusers. These findings suggest that there is no longer much justification to discontinue these MAOIs before surgery, with the considerable risk of compromising patients' psychiatric status.

Inhibition of the LSD1 (KDM1A) demethylase reactivates the all-trans-retinoic acid differentiation pathway in acute myeloid leukemia.

Acute promyelocytic leukemia (APL), a cytogenetically distinct subtype of acute myeloid leukemia (AML), characterized by the t(15;17)-associated PML-RARA fusion, has been successfully treated with therapy utilizing all-trans-retinoic acid (ATRA) to differentiate leukemic blasts. However, among patients with non-APL AML, ATRA-based treatment has not been effective. Here we show that, through epigenetic reprogramming, inhibitors of lysine-specific demethylase 1 (LSD1, also called KDM1A), including tranylcypromine (TCP), unlocked the ATRA-driven therapeutic response in non-APL AML. LSD1 inhibition did not lead to a large-scale increase in histone 3 Lys4 dimethylation (H3K4(me2)) across the genome, but it did increase H3K4(me2) and expression of myeloid-differentiation-associated genes. Notably, treatment with ATRA plus TCP markedly diminished the engraftment of primary human AML cells in vivo in nonobese diabetic (NOD)-severe combined immunodeficient (SCID) mice, suggesting that ATRA in combination with TCP may target leukemia-initiating cells. Furthermore, initiation of ATRA plus TCP treatment 15 d after engraftment of human AML cells in NOD-SCID γ (with interleukin-2 (IL-2) receptor γ chain deficiency) mice also revealed the ATRA plus TCP drug combination to have a potent anti-leukemic effect that was superior to treatment with either drug alone. These data identify LSD1 as a therapeutic target and strongly suggest that it may contribute to AML pathogenesis by inhibiting the normal pro-differentiative function of ATRA, paving the way for new combinatorial therapies for AML.

Lysine-specific demethylase 1 (LSD1/KDM1A/AOF2/BHC110) is expressed and is an epigenetic drug target in chondrosarcoma, Ewing's sarcoma, osteosarcoma, and rhabdomyosarcoma.

Lysine-specific demethylase 1 (GeneID 23028), a flavin-dependent monoamine oxidoreductase and a histone demethylase, serves as an epigenetic coregulator of transcription. Lysine-specific demethylase 1 is up-regulated in neuroblastoma and in bladder, breast, colorectal, gastric, lung, and neuroendocrine cancers, and its overexpression drives the cell cycle of otherwise nontransformed human cells, suggesting oncogenic properties. Lysine-specific demethylase 1 was recently reported to be also overexpressed in several different mesenchymal tumors. We investigated lysine-specific demethylase 1 expression in over 500 sarcomas by gene expression profiling and tissue microarray-coupled immunohistochemical analyses and confirmed lysine-specific demethylase 1 overexpression in rhabdomyosarcoma and synovial sarcoma. We also show for the first time that lysine-specific demethylase 1 is also overexpressed in chondrosarcoma, Ewing's sarcoma, and osteosarcoma wherein it localizes in cell nuclei. We further show that a US Food and Drug Administration-approved drug that inhibits lysine-specific demethylase 1 also inhibits chondrosarcoma, Ewing's sarcoma, osteosarcoma, and rhabdomyosarcoma cell growth in vitro. These data suggest that lysine-specific demethylase 1 plays a role in sarcoma pathology and that lysine-specific demethylase 1 inhibition strategies might represent a novel means to inhibiting growth of lysine-specific demethylase 1-overexpressing sarcomas.

Withdrawal from high-dose tranylcypromine.

A 34-year-old man with a history of multiple substance abuse (now abstinent for six years) became addicted to tranylcypromine, consuming up to 240 mg/day. After discontinuing the drug, he developed thrombocytopenia (52,000/ul) and delirium; there were no other anticholinergic signs. The delirium was unresponsive to haloperidol and diazepam. Intravenous administration of physostigmine (2 mg) on hospital day 6 resulted in prompt, but temporary, clearing of the delirium. Following a recurrence of the delirium after 30 minutes, he was started on an intravenous infusion of physostigmine (2 mg/hr) with good results. Physostigmine administration did not produce any cholinergic signs. By hospital day 8, he did not require any more physostigmine. Thrombocytopenia resolved on hospital day 9 without therapeutic intervention. On hospital day 10, the patient was asymptomatic and left the hospital on his own recognizance.

Experience with tranylcypromine in early Parkinson's disease.

A leading hypothesis of the pathogenesis of neuronal degeneration of the substantia nigra dopamine-containing cells in Parkinson's disease (PD) is excessive oxidative stress. In part, this oxidative stress is the result of the oxidation of dopamine by the action of monoamine oxidases (MAO) A and B to generate hydrogen peroxide and subsequent oxygen free radicals. Because of this hypothesis we have treated patients with early PD, not yet requiring any symptomatic treatment, with tranylcypromine, a drug that inhibits both MAO's. These patients were required to observe a tyramine-restricted diet. Thirty-seven patients on tranylcypromine have been followed by us for up to 33 months. Four patients discontinued the drug because of pending surgery. Of the remaining 33, six had adverse effects that lead to discontinuation of the drug, mainly impotency in men. Another common adverse effect encountered was insomnia, but this problem was not a cause of stopping the drug. Depression lifted in all five patients who had this problem at the time tranylcypromine was initiated. Only two patients have so far required treatment with levodopa or a dopamine agonist, and this need occurred within the first 6 months of treatment. The evaluation of all 37 patients revealed that parkinsonian symptoms improved slightly on introduction of tranylcypromine as measured by the United Parkinson's Disease Rating Scale, the Hoehn & Yahr Staging Scale, and the Schwab & England Activities of Daily Living Scale. Follow-up evaluations for a minimum of 6 months between the first post-tranylcypromine visit and the most recent visit revealed only slight worsening of parkinsonian signs and symptoms, with a mean interval of almost 1.5 years. A longer period of follow-up is needed to determine how long the severity of PD will remain mild in this group of patients.

[Use of nonopiate agents for anesthesia in ENT patients at high surgical-anesthesiological risk]. / Primenenie neopiatnykh sredstv dlia anestezii u LOR-bol'nykh vysokogo operatsionno-anesteziologicheskogo riska.

Optimal methods of endotracheal anesthesia using non-opiate drugs of four classes (clofelin, transamine, contrykal, ketanes) have been fundamentally grounded developed and tried in extensive and traumatic operations for ENT malignant and vascular tumors as well as inflammation in patients of high anesthesiological operative risk. The drugs were used in 174 patients including 13 children. 87.9% of the patients had concomitant diseases: blood hypertension, coronary heart disease, chronic nonspecific pulmonary diseases, bronchial asthma, asthmatic bronchitis, diabetes mellitus, anemia. Adequate stable anesthesia was achieved in reduced dosage of conventional anesthesiological agents.