Influence of green tea consumption on endoxifen steady-state concentration in breast cancer patients treated with tamoxifen

Alzheimer's Disease and Green Tea: Epigallocatechin-3-Gallate as a Modulator of Inflammation and Oxidative Stress

Alzheimer's disease (AD) is the most common cause of dementia, characterised by a marked decline of both memory and cognition, along with pathophysiological hallmarks including amyloid beta peptide (Aβ) accumulation, tau protein hyperphosphorylation, neuronal loss and inflammation in the brain. Additionally, oxidative stress caused by an imbalance between free radicals and antioxidants is considered one of the main risk factors for AD, since it can result in protein, lipid and nucleic acid damage and exacerbate Aβ and tau pathology. To date, there is a lack of successful pharmacological approaches to cure or even ameliorate the terrible impact of this disease. Due to this, dietary compounds with antioxidative and anti-inflammatory properties acquire special relevance as potential therapeutic agents. In this context, green tea, and its main bioactive compound, epigallocatechin-3-gallate (EGCG), have been targeted as a plausible option for the modulation of AD. Specifically, EGCG acts as an antioxidant by regulating inflammatory processes involved in neurodegeneration such as ferroptosis and microglia-induced cytotoxicity and by inducing signalling pathways related to neuronal survival. Furthermore, it reduces tau hyperphosphorylation and aggregation and promotes the non-amyloidogenic route of APP processing, thus preventing the formation of Aβ and its subsequent accumulation. Taken together, these results suggest that EGCG may be a suitable candidate in the search for potential therapeutic compounds for neurodegenerative disorders involving inflammation and oxidative stress, including Alzheimer's disease.

Toward model-informed precision dosing for tamoxifen: A population-pharmacokinetic model with a continuous CYP2D6 activity scale

BACKGROUND

Tamoxifen is important in the adjuvant treatment of breast cancer. A plasma concentration of the active metabolite endoxifen of > 16 nM is associated with a lower risk of breast cancer-recurrence. Since inter-individual variability is high and > 20 % of patients do not reach endoxifen levels > 16 nM with the standard dose tamoxifen, therapeutic drug monitoring is advised. However, ideally, the correct tamoxifen dose should be known prior to start of therapy. Our aim is to develop a population pharmacokinetic (POP-PK) model incorporating a continuous CYP2D6 activity scale to support model informed precision dosing (MIPD) of tamoxifen to determine the optimal tamoxifen starting dose.

METHODS

Data from eight different clinical studies were pooled (539 patients, 3661 samples) and used to develop a POP-PK model. In this model, CYP2D6 activity per allele was estimated on a continuous scale. After inclusion of covariates, the model was subsequently validated using an independent external dataset (378 patients). Thereafter, dosing cut-off values for MIPD were determined.

RESULTS

A joint tamoxifen/endoxifen POP-PK model was developed describing the endoxifen formation rate. Using a continuous CYP2D6 activity scale, variability in predicting endoxifen levels was decreased by 37 % compared to using standard CYP2D6 genotype predicted phenotyping. After external validation and determination of dosing cut-off points, MIPD could reduce the proportion of patients with subtherapeutic endoxifen levels at from 22.1 % toward 4.8 %.

CONCLUSION

Implementing MIPD from the start of tamoxifen treatment with this POP-PK model can reduce the proportion of patients with subtherapeutic endoxifen levels at steady-state to less than 5 %.

Interactions between natural products and cancer treatments: underlying mechanisms and clinical importance

Natural products, also referred to as dietary supplements, complementary and alternative medicines, and health or food supplements are widely used by people living with cancer. These products are predominantly self-selected and taken concurrently with cancer treatments with the intention of improving quality of life, immune function and reducing cancer symptoms and treatment side effects. Concerns have been raised that concurrent use may lead to interactions resulting in adverse effects and unintended treatment outcomes. This review provides an overview of the mechanisms by which these interactions can occur and the current evidence about specific clinically important natural product-drug interactions. Clinical studies investigating pharmacokinetic interactions provide evidence that negative treatment outcomes may occur when Hypericum perforatum, Grapefruit, Schisandra sphenanthera, Curcuma longa or Hydrastis canadensis are taken concurrently with common cancer treatments. Conversely, pharmacodynamic interactions between Hangeshashinto (TJ-14) and some cancer treatments have been shown to reduce the side effects of diarrhoea and oral mucositis. In summary, research in this area is limited and requires further investigation.

Medicinal chemistry aspects and synthetic strategies of coumarin as aromatase inhibitors: an overview

Coumarin is a bicyclic oxygen bearing heterocyclic scaffold formed by fusion of benzene with the pyrone ring. Because of its unique physicochemical characteristics and the ease with which it may be transformed into a wide range of functionalized coumarins during synthesis, coumarin provides a privileged scaffold for medicinal chemists. As a result, many coumarin derivatives have been developed, synthesized, and evaluated to target a variety of therapeutic domains, thereby making it an attractive template for designing novel anti-breast cancer compounds. The main culprit in estrogen overproduction in the estrogen-dependent breast cancer (EDBC), is the enzyme aromatase (AR), and it is thought to be a significant target for the effective treatment of EDBC. Considering coumarins versatility, this review presents a detailed overview of diverse study of aromatase as a target for coumarins. An overview of structure-activity relationship analysis of coumarin core is also included so as to summarize the desired pharmacophoric features essential for design and development of aromatase inhibitors (AIs) using coumarin core. Identification of key synthesis techniques that could aid researchers in designing and developing novel analogues with significant anti-breast cancer properties along with their mechanism of action have also been covered in the current review.

Evaluation of Concomitant Use of Anticancer Drugs and Herbal Products: From Interactions to Synergic Activity

CAM is used by about 40% of cancer patients in Western Countries, with peaks of 80% for breast cancer patients. Cancer patients use CAM to boost immune function, to control cancer symptoms and treatment-related side effects, and to improve health-related quality of life (HR-QoL) and survival. Unfortunately, self-prescription of natural remedies in cancer patients can lead to unexpected toxicities and can reduce the effectiveness of cancer therapy. Although CAM usually refers to all the "natural or organic" products/methods that are generally considered less toxic, there are concerns about drug interactions, especially in patients participating in clinical trials with experimental agents. Despite the claims of the promising and potential benefits made by prescribers, many CAMs lack clear scientific evidence of their safety and efficacy. Given the widespread use of CAM-both clearly declared and overt-in this review, we focused on the most important known data on the risk of interactions between biologics and oncology drugs with the goal of opening up CAM in accordance with the meaning of integrative medicine.

A Review of the Pharmacological Potential of Spatholobus suberectus Dunn on Cancer

Spatholobus suberectus Dunn (SSD) has been extensively employed in Traditional Chinese Medicine to treat several ailments. SSD and its active compounds are effective therapeutic agents for treating a variety of diseases with negligible side effects. Therefore, we aimed to investigate its phytochemistry, pharmacology, and potential therapeutic effects exclusively in cancer prevention and treatment. Phytochemical and pharmacological information was collected and arranged in a rational order. SSD has been frequently attributed to having antioxidant, anti-diabetic, anti-inflammatory, hematopoietic, neuroprotective, antimicrobial, and anticancer properties. Evidence has indicated that the bioactive constituents in SSD have attracted increasing scientific attention due to their preventive role in cancers. Further, the present review provides the current information on the health implications of SSD, thus allowing for future clinical trials to explore its restorative benefits. All data of in vitro and animal investigations of SSD, as well as its effect on human health, were obtained from an electronic search and library database. The diverse pharmacological potential of SSD provides an opportunity for preclinical drug discovery, and this comprehensive review strongly indicates that SSD is an excellent anti-tumorigenic agent that modulates or prevents breast cancer.

The influence of green tea extract on nintedanib's bioavailability in patients with pulmonary fibrosis

Nintedanib is an oral small-molecule kinase inhibitor and first-line treatment for idiopathic pulmonary fibrosis. Nintedanib is a substrate of the drug efflux transporter ABCB1. Green tea flavonoids --especially epigallocatechin gallate (EGCG)-- are potent ABCB1 modulators. We investigated if concomitant administration of green tea extract (GTE) could result in a clinically relevant herb-drug interaction. Patients were randomized between A-B and B-A, with A being nintedanib alone and B nintedanib with GTE. Both periods lasted 7 days, in which nintedanib was administered twice daily directly after a meal. In period B, patients additionally received capsules with GTE (500 mg BID, >60% EGCG). Pharmacokinetic sampling for 12 h was performed at day 7 of each period. Primary endpoint was change in geometric mean for the area under the curve (AUC_0-12 h). A linear mixed model was used to analyse AUCs and maximal concentration (C_max). In 26 included patients, the nintedanib AUC_0-12 h was 21% lower (95% CI -29% to -12%; P < 0.001) in period B (with GTE) compared to period A. C_max did not differ significantly between periods; - 14% (95% CI -29% to +4%; P = 0.12). The detrimental effect was predominant in patients with the ABCB1 3435 C>T wild type variant. No differences in toxicities were observed. Exposure to nintedanib decreased with 21% when administered 60 min after GTC for only 7 days. This is a statistically significant interaction which could potentially impair treatment efficacy. Before patients and physicians should definitely be warned to avoid this combination, prospective clinical validation of an exposure-response relationship is necessary.

Effects and mechanisms of dietary bioactive compounds on breast cancer prevention

Breast cancer (BC) is the most often diagnosed cancer among females globally and has become an increasing global health issue over the last decades. Despite the substantial improvement in screening methods for initial diagnosis, effective therapy remains lacking. Still, there has been high recurrence and disease progression after treatment of surgery, endocrine therapy, chemotherapy, and radiotherapy. Considering this view, there is a crucial requirement to develop safe, freely accessible, and effective anticancer therapy for BC. The dietary bioactive compounds as auspicious anticancer agents have been recognized to be active and their implications in the treatment of BC with negligible side effects. Hence, this review focused on various dietary bioactive compounds as potential therapeutic agents in the prevention and treatment of BC with the mechanisms of action. Bioactive compounds have chemo-preventive properties as they inhibit the proliferation of cancer cells, downregulate the expression of estrogen receptors, and cell cycle arrest by inducing apoptotic settings in tumor cells. Therapeutic drugs or natural compounds generally incorporate engineered nanoparticles with ideal sizes, shapes, and enhance their solubility, circulatory half-life, and biodistribution. All data of in vitro, in vivo, and clinical studies of dietary bioactive compounds and their impact on BC were collected from Science Direct, PubMed, and Google Scholar. The data of chemopreventive and anticancer activity of dietary bioactive compounds were collected and orchestrated in a suitable place in the review. These shreds of data will be extremely beneficial to recognize a series of additional diet-derived bioactive compounds to treat BC with the lowest side effects.

Clinical CYP2D6 Genotyping to Personalize Adjuvant Tamoxifen Treatment in ER-Positive Breast Cancer Patients: Current Status of a Controversy

Simple Summary

Tamoxifen is an important adjuvant endocrine therapy in estrogen receptor (ER)-positive breast cancer patients. It is mainly catalyzed by the enzyme CYP2D6 into the most active metabolite endoxifen. Genetic variation in the CYP2D6 gene influences endoxifen formation and thereby potentially therapy outcome. However, the association between CYP2D6 genotype and clinical outcome on tamoxifen is still under debate, as contradictory outcomes have been published. This review describes the latest insights in both CYP2D6 genotype and endoxifen concentrations, as well CYP2D6 genotype and clinical outcome, from 2018 to 2020.

Abstract

Tamoxifen is a major option for adjuvant endocrine treatment in estrogen receptor (ER) positive breast cancer patients. The conversion of the prodrug tamoxifen into the most active metabolite endoxifen is mainly catalyzed by the enzyme cytochrome P450 2D6 (CYP2D6). Genetic variation in the CYP2D6 gene leads to altered enzyme activity, which influences endoxifen formation and thereby potentially therapy outcome. The association between genetically compromised CYP2D6 activity and low endoxifen plasma concentrations is generally accepted, and it was shown that tamoxifen dose increments in compromised patients resulted in higher endoxifen concentrations. However, the correlation between CYP2D6 genotype and clinical outcome is still under debate. This has led to genotype-based tamoxifen dosing recommendations by the Clinical Pharmacogenetic Implementation Consortium (CPIC) in 2018, whereas in 2019, the European Society of Medical Oncology (ESMO) discouraged the use of CYP2D6 genotyping in clinical practice for tamoxifen therapy. This paper describes the latest developments on CYP2D6 genotyping in relation to endoxifen plasma concentrations and tamoxifen-related clinical outcome. Therefore, we focused on Pharmacogenetic publications from 2018 (CPIC publication) to 2021 in order to shed a light on the current status of this debate.

Exploring Herbal Medicine Use during Palliative Cancer Care: The Integrative Physician as a Facilitator of Pharmacist-Patient-Oncologist Communication

Oncology patients frequently use herbal and other forms of complementary medicine, often without the knowledge of oncologists, pharmacists, and other healthcare professionals responsible for their care. Oncology healthcare professionals may lack the knowledge needed to guide their patients on the safe and effective use of herbal medicinal products, a number of which have potentially harmful effects, which include direct toxicity and negative herb–drug interactions. The current review addresses the prevalence and expectations of oncology patients from herbal medicine, as well as evidence for the beneficial or harmful effects of this practice (potential and actual), especially when the herbal products are used in conjunction with anticancer agents. Models of integrative oncology care are described, in which open and effective communication among oncologists, pharmacists, and integrative physicians on the use of herbal medicine by their patients occurs. This collaboration provides patients with a nonjudgmental and multidisciplinary approach to integrative medicine, echoing their own health-belief models of care during conventional cancer treatments. The role of the integrative physician is to facilitate this process, working with oncologists and pharmacists in the fostering of patient-centered palliative care, while ensuring a safe and effective treatment environment. Case scenario: W. is a 56 year old female artist who was recently diagnosed with localized hormone receptor-positive breast cancer. Following lumpectomy and sentinel node dissection, she is scheduled to begin adjuvant chemotherapy with a regimen which will include adriamycin, cyclophosphamide, and paclitaxel (AC-T protocol). She is worried about developing peripheral neuropathy and its impact on her ability to paint, and she asks about a number of dietary supplements which she heard could prevent this from happening: omega-3, vitamin E, alpha-lipoic acid, and acetyl-l-carnithine. She is concerned, however, that the supplements may negatively interact with her chemotherapy regimen.