Reversible and Irreversible Inhibition of Cytochrome P450 Enzymes by Methylophiopogonanone A

Methylophiopogonanone A (MOA), an abundant homoisoflavonoid bearing a methylenedioxyphenyl moiety, is one of the major constituents in the Chinese herb Ophiopogon japonicas This work aims to assess the inhibitory potentials of MOA against cytochrome P450 enzymes and to decipher the molecular mechanisms for P450 inhibition by MOA. The results showed that MOA concentration-dependently inhibited CYP1A, 2C8, 2C9, 2C19, and 3A in human liver microsomes (HLMs) in a reversible way, with IC₅₀ values varying from 1.06 to 3.43 μM. By contrast, MOA time-, concentration-, and NADPH-dependently inhibited CYP2D6 and CYP2E1, along with K_I and k_inact values of 207 µM and 0.07 minute^-1 for CYP2D6, as well as 20.9 µM and 0.03 minutes^-1 for CYP2E1. Further investigations demonstrated that a quinone metabolite of MOA could be trapped by glutathione in an HLM incubation system, and CYP2D6, 1A2, and 2E1 were the major contributors to catalyze the metabolic activation of MOA to the corresponding O-quinone intermediate. Additionally, the potential risks of herb-drug interactions triggered by MOA or MOA-related products were also predicted. Collectively, our findings verify that MOA is a reversible inhibitor of CYP1A, 2C8, 2C9, 2C19, and 3A but acts as an inactivator of CYP2D6 and CYP2E1. SIGNIFICANCE STATEMENT: Methylophiopogonanone A (MOA), an abundant homoisoflavonoid isolated from the Chinese herb Ophiopogon japonicas, is a reversible inhibitor of CYP1A, 2C8, 2C9, 2C19, and 3A but acts as an inactivator of CYP2D6 and CYP2E1. Further investigations demonstrated that a quinone metabolite of MOA could be trapped by glutathione in a human liver microsome incubation system, and CYP2D6, 1A2, and 2E1 were the major contributors to catalyze the metabolic activation of MOA to the corresponding O-quinone intermediate.

Pharmacogenomics of breast cancer: highlighting CYP2D6 and tamoxifen

PURPOSE

To review recent pharmacogenomics studies on breast cancer patients undergoing tamoxifen therapy, highlighting how our knowledge on cytochrome P450 2D6 (CYP2D6) can help to guide the development of adjuvant therapies for these patients.

METHODS

A comprehensive literature search was conducted. Articles reporting findings pertaining to the effect of CYP2D6 on the therapeutic efficacy of tamoxifen, those reporting how targeting CYP2D6 could inform tamoxifen-based therapy development, and those on the tamoxifen effects on cell lines and animal models were included in the review.

RESULTS

With CYP2D6 being the primary enzyme for tamoxifen metabolism, single-nucleotide polymorphisms (SNPs) in this gene were one of the determinants in the rate of tamoxifen metabolism, thereby potentially having an effect on the efficacy of tamoxifen-based therapies. Our review indicates the potential effectiveness of targeting these SNPs, including those for the CYP2D6*10 allele (c. 100C > T), in modifying the level of tamoxifen metabolism. These findings suggest the importance of pharmacogenomics research in our understanding of the efficacy of adjuvant therapies. However, the involvement of multiple enzymes in tamoxifen metabolism, dietary factors, ethnic differences in gene frequencies, and patients' compliance to tamoxifen therapies in studies do present challenges in pharmacogenomics research.

CONCLUSIONS

Pharmacogenomics could play important roles in mediating the advancement of tamoxifen-based adjuvant therapies. Research efforts should be directed towards the exploration of further SNPs of CYP2D6 that affect tamoxifen metabolism, as well as epigenetic changes in CYP2D6, enabling the design of precision medicine and confirming clinical validity in the use of pharmacogenomics for tamoxifen.

Non-CYP2D6 Variants Selected by a GWAS Improve the Prediction of Impaired Tamoxifen Metabolism in Patients with Breast Cancer

A certain minimum plasma concentration of (Z)-endoxifen is presumably required for breast cancer patients to benefit from tamoxifen therapy. In this study, we searched for DNA variants that could aid in the prediction of risk for insufficient (Z)-endoxifen exposure. A metabolic ratio (MR) corresponding to the (Z)-endoxifen efficacy threshold level was adopted as a cutoff value for a genome-wide association study comprised of 287 breast cancer patients. Multivariate regression was used to preselect variables exhibiting an independent impact on the MR and develop models to predict below-threshold MR values. In total, 15 single-nucleotide polymorphisms (SNPs) were significantly associated with below-threshold MR values. The strongest association was with rs8138080 (WBP2NL). Two alternative models for MR prediction were developed. The predictive accuracy of Model 1, including rs7245, rs6950784, rs1320308, and the CYP2D6 genotype, was considerably higher than that of the CYP2D6 genotype alone (AUC 0.879 vs 0.758). Model 2, which was developed using the same three SNPs as for Model 1 plus rs8138080, appeared as an interesting alternative to the full CYP2D6 genotype testing. In conclusion, the four novel SNPs, tested alone or in combination with the CYP2D6 genotype, improved the prediction of impaired tamoxifen-to-endoxifen metabolism, potentially allowing for treatment optimization.

Prospective observational study to evaluate the efficacy and safety of the pollen extract Sérélys® in the management of women with menopausal symptoms

Safety concerns or contraindications to the use of hormones have resulted in a rise of the use of herbal medicinal products for the management of menopausal symptoms. The pollen extract Sérélys^® represents, due to its ingredients and mode of action, a new and innovative alternative for the management of these symptoms. The aim of the present study was to demonstrate the efficacy and safety of Sérélys^®. A prospective, open, observational, and multicentre study was performed on 104 menopausal women. The patients received over 3 months the pollen extract Sérélys^® containing the extracts PI82 and GC Fem in a dosage of twice 160 mg extract and 5 mg vitamin E. Using a validated menopausal rating score, the improvement of menopausal symptoms was recorded. A significant decrease of different menopausal symptoms was observed between the starting point of the study and after 12 weeks (p < .0001). Hot flashes were reduced by 48.5%, sleep disturbance by 50.1%, depressive mood by 51.2%, irritability by 47.9%, fatigue by 47.8%, vaginal dryness by 39.63% and muscles and joint pain by 27.4%. The pollen extract Sérélys^® reduced significant menopausal symptoms showing a very low side effect profile.

The use of antidepressants in oncology: a review and practical tips for oncologists

Background

The use of psychotropic drugs, namely those with an antidepressant profile (ADs), is a mandatory part of an integrated treatment of psychiatric disorders among cancer patients. We aimed to synthetize the most relevant data emerging from published studies to provide tips about the use of ADs in oncology.

Design

A search was made of the major databases over the last 30 years (Embase/Medline, PsycLIT, PsycINFO, the Cochrane Library), including narrative reviews, systematic reviews and meta-analyses summarizing the results from observational studies and randomized clinical trials assessing effectiveness, safety profile, interactions, contraindications and use of ADs in oncology with regard to both psychiatric (depressive spectrum, stress-related, anxiety disorders) and cancer-related symptoms (e.g. pain, hot flashes and fatigue).

Results

The weight of evidence supports the efficacy of ADs for more severe major depression in individuals with cancer and as an adjuvant treatment in cancer-related symptoms, although the methodological limitations of reported randomized controlled trials do not permit definite conclusions. Data also indicate that there should be caution in the use of ADs in cancer patients in terms of their safety profile and potential clinically significant interactions with other prescribed medications. Practical recommendations that have been made for the use of ADs in cancer patients, in the context of a multimodal approach to depression treatment, have been summarized here.

Conclusions

ADs are a relatively safe and effective treatment for more severe major depression in cancer patients. However, more research is urgently needed regarding the efficacy of ADs in different cancer types and cancer settings, their interactions with anticancer agents and their additive benefit when integrated with psychosocial interventions.

Augmentation of Endoxifen Exposure in Tamoxifen-Treated Women Following SSRI Switch

BACKGROUND AND OBJECTIVE

The anti-oestrogen tamoxifen requires metabolic activation to endoxifen by cytochrome P450 (CYP) enzymes, predominantly CYP2D6. Potent CYP2D6-inhibiting antidepressants can seriously disrupt tamoxifen metabolism, probably influencing the efficacy of tamoxifen. For this reason, paroxetine and fluoxetine are recommended not to be used with tamoxifen in breast cancer patients. We investigated the effects of switching potent CYP2D6-inhibiting antidepressants to weak CYP2D6-inhibiting antidepressants on the plasma pharmacokinetics of tamoxifen.

METHODS

Ten breast cancer patients who were treated with tamoxifen in combination with a potent CYP2D6-inhibiting antidepressant (paroxetine or fluoxetine) for at least 4 weeks were enrolled. Under close supervision by a psychiatrist, patients were switched to treatment with escitalopram or venlafaxine (weak CYP2D6-inhibiting antidepressants). Before and after the switch, pharmacokinetic blood sampling was performed over 24 h. Pharmacokinetic parameters were estimated using noncompartmental analysis. Adverse effects were recorded during the study.

RESULTS

Endoxifen exposure was ~3-fold higher during escitalopram co-administration than during paroxetine or fluoxetine co-administration (median 387 nM·h [range 159-637 nM·h] versus 99.2 nM·h [range 70.0-210 nM·h]; P = 0.012; Wilcoxon signed-rank test). The ratio of endoxifen to N-desmethyltamoxifen and the ratio of 4-hydroxytamoxifen to tamoxifen increased by 3.3- and ~1.5-fold, reflecting increased CYP2D6 activity. Antidepressant switching did not result in psychiatric problems or antidepressant-related adverse effects.

CONCLUSION

In this study, switching to the weak CYP2D6 inhibitor escitalopram was safe and feasible and resulted in clinically relevant rises in endoxifen concentrations. We therefore advise switching paroxetine and fluoxetine to escitalopram in patients using tamoxifen. However, switching should always be weighed in individual patients.

Pharmacogenomics toward personalized tamoxifen therapy for breast cancer

Tamoxifen has been used not only for the treatment or prevention of recurrence in patients with estrogen receptor positive breast cancers but also for recurrent breast cancer. Because CYP2D6 is known to be an important enzyme responsible for the generation of the potent tamoxifen metabolite, ‘endoxifen’, lots of studies reported that genetic variation which reduced its enzyme activity were associated with poor clinical outcome of breast cancer patients treated with tamoxifen. However, there are some discrepant reports questioning the association between CYP2D6 genotype and clinical outcome after tamoxifen therapy. Dose-adjustment study of tamoxifen based on CYP2D6 genotypes provides the evidence that dose adjustment is useful for the patients carrying reduced or null allele of CYP2D6 to maintain the effective endoxifen level. This review describes critical issues in pharmacogenomic studies as well as summarizes the results of the association of CYP2D6 genotype with tamoxifen efficacy.

Psychopharmacology in cancer

Depression, anxiety, delirium, and other psychiatric symptoms are highly prevalent in the cancer setting, and pharmacological intervention is an important component in the overall psychosocial care of the patient. Psychopharmacology is also used as a primary or adjuvant treatment for the management of cancer-related symptoms stemming from the disease itself and/or its treatment, including sleep disturbance, loss of appetite, neuropathic pain, nausea, fatigue, and hot flashes. Psychiatrists, oncologists, and palliative care physicians working as members of a multidisciplinary team have the opportunity to target multiple symptoms that negatively affect a patient's quality of life with the strategic use of psychotropic medications when deemed appropriate. This article aims to review the indications for use of antidepressants, psychostimulants, anxiolytics, antipsychotics, and mood stabilizers in oncology. An updated review of the relevant literature is discussed and referenced in each section.

Efficacy and safety of pharmacotherapy in cancer-related psychiatric disorders across the trajectory of cancer care: a review

At least 25-30% of patients with cancer and an even higher percentage of patients in an advanced phase of illness meet the criteria for a psychiatric diagnosis, including depression, anxiety, stress-related syndromes, adjustment disorders, sleep disorders and delirium. A number of studies have accumulated over the last 35 years on the use of psychotropic drugs as a pillar in the treatment of psychiatric disorders. Major advances in psycho-oncology research have also shown the efficacy of psychotropic drugs as adjuvant treatment of cancer-related symptoms, such as pain, hot flushes, pruritus, nausea and vomiting, fatigue, and cognitive impairment. The knowledge about pharmacokinetics and pharmacodynamics, clinical use, safety, side effects and efficacy of psychotropic drugs in cancer care is essential for an integrated and multidimensional approach to patients treated in different settings, including community-based centres, oncology, and palliative care. A search of the major databases (MEDLINE, Embase, PsycLIT, PsycINFO, the Cochrane Library) was conducted in order to summarize relevant data concerning the efficacy and safety of pharmacotherapy for cancer-related psychiatric disorders in cancer patients across the trajectory of the disease.

Major depressive disorder in breast cancer: a critical systematic review of pharmacological and psychotherapeutic clinical trials

BACKGROUND

While women with breast cancer often face varying levels of psychological distress, there is a subgroup whose symptomatology reaches a threshold for diagnosis of major depressive disorder (MDD). Major depressive disorder is known to influence patient outcomes, such as health-related quality of life and treatment adherence. There are no systematic reviews that evaluate pharmacological and psychotherapeutic treatment trials for MDD among individuals with breast cancer.

METHODS

Two authors independently searched MEDLINE, EMBASE, Cochrane and Clinical Trials.gov databases through February 20, 2013 without language restrictions. Core journals, reference lists and citation tracking were also searched. Articles on breast cancer patients were included if they (1) included participants with a diagnosis of MDD; (2) investigated pharmacological or psychotherapeutic treatments for MDD compared to placebo or usual care in a randomized controlled trial (RCT).

RESULTS

Two RCTs on antidepressant treatment met inclusion criteria. However, no RCTs investigating the effects of psychological treatments for MDD in breast cancer were identified. Notwithstanding the paucity of data investigating the effects of psychological treatments for MDD in breast cancer, numerous psychotherapeutic strategies targeting depressive symptoms were identified. Mianserin had significant antidepressant effects when compared to placebo in a 6-week, parallel-group, RCT of Stage I-II breast cancer in women with MDD. Desipramine and paroxetine were reported to be no more efficacious than placebo in a 6-week, RCT of Stage I-IV breast cancer in women with MDD.

CONCLUSIONS

The evidence reviewed herein underscores the paucity of data available to guide clinicians in treatment decisions for MDD in individuals with breast cancer. Therefore, the treatment of MDD in breast cancer is primarily based on clinical experience. Some antidepressants (for example, paroxetine) should be avoided in women concurrently taking tamoxifen due to relevant interactions involving the cytochrome CYP2D6.

Evidence-Based Treatment of Depression in Patients With Cancer

Purpose

Depression is a common condition in patients with cancer, although there has been a relative paucity of research on the effectiveness of treatment in this population. This review summarizes the psychosocial and pharmacologic treatment of depression in patients with cancer based on a consideration of evidence regarding etiologic factors and treatment outcomes.

Methods

A review of the evidence base for psychosocial and pharmacologic interventions for depression in patients with cancer was performed, including original studies, systematic reviews, and meta-analytic studies in the literature.

Results

Recent evidence from randomized controlled trials has demonstrated the efficacy of psychosocial and pharmacologic treatments to alleviate depression in patients with cancer. Further research is needed to establish their relative and combined efficacy and their role in the treatment of depression that is less severe and occurs in association with more advanced disease. First-line recommendations for the treatment of depression in patients with cancer are difficult to derive based on current evidence, because comparative studies have not been conducted to support the superiority of one treatment modality over another in this population.

Conclusion

Both psychosocial and pharmacologic interventions have been shown to be efficacious in treating depression in cancer, but further research is needed to establish their relative and combined benefit. Future research directions include the development and evaluation of novel interventions targeted to specific biologic and psychosocial risk factors.