The expanding use of third-generation aromatase inhibitors: what the general internist needs to know

Adverse Event Profiles of the Third-Generation Aromatase Inhibitors: Analysis of Spontaneous Reports Submitted to FAERS

The third-generation aromatase inhibitors (AIs), represented by letrozole, anastrozole, and exemestane, have been used as a standard first-line adjuvant therapy for postmenopausal breast cancer patients with positive hormone receptor. However, their safety in the real world has not been systematically analyzed. We used the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) to investigate adverse event (AE) profiles of the three AIs, covering the period from Q1 2004 to Q3 2023. The time-to-event onset profiles and cumulative incidence were analyzed by Weibull shape parameter test and Kaplan-Meier method, respectively. The disproportionality analysis was utilized to assess drug toxicity risk. Based on the FAERS database, 18,035, 8242, and 7011 reports listing letrozole, anastrozole, and exemestane as primary suspected drugs were extracted, respectively. AEs associated with anastrozole displayed the latest onset (p < 0.0001); meanwhile, WSP test showed that all three AIs had early failure-type profiles. At the preferred term level, we acquired 95, 59, and 42 significant signals associated with letrozole, anastrozole, and exemestane, which involved 18, 13, and 15 system organ classes, respectively. The three AIs all reported that their strongest AE signal was trigger finger. Neutropenia was the most frequent AE for letrozole, while the highest occurrences of anastrozole and exemestane were arthralgia. We also found that interstitial lung disease, a rare but serious AE, showed strong signal intensity in all three AIs. Additionally, letrozole was also associated with lots of other rare but serious AEs in hematologic, respiratory, and hepatic systems, which were not recorded in the instructions. Our analysis of safety warning signals of the third-generation AIs from the FAERS database provided reference for clinical safe and rational drug use.

Aromatase enzyme: Paving the way for exploring aromatization for cardio-renal protection

Documented male-female differences in the risk of cardiovascular and chronic kidney diseases have been largely attributed to estrogens. The cardiovascular and renal protective effects of estrogens are mediated via the activation of estrogen receptors (ERα and ERβ) and G protein-coupled estrogen receptor, and involve interactions with the renin-angiotensin-aldosterone system. Aromatase, also called estrogen synthase, is a cytochrome P-450 enzyme that plays a pivotal role in the conversion of androgens into estrogens. Estrogens are biosynthesized in gonadal and extra-gonadal sites by the action of aromatase. Evidence suggests that aromatase inhibitors, which are used to treat high estrogen-related pathologies, are associated with the development of cardiovascular events. We review the potential role of aromatization in providing cardio-renal protection and highlight several meta-analysis studies on cardiovascular events associated with aromatase inhibitors. Overall, we present the potential of aromatase enzyme as a fundamental contributor to cardio-renal protection.

ESR1 Gene Mutations and Liquid Biopsy in ER-Positive Breast Cancers: A Small Step Forward, a Giant Leap for Personalization of Endocrine Therapy?

The predominant forms of breast cancer (BC) are hormone receptor-positive (HR+) tumors characterized by the expression of estrogen receptors (ERs) and/or progesterone receptors (PRs). Patients with HR+ tumors can benefit from endocrine therapy (ET). Three types of ET are approved for the treatment of HR+ BCs and include selective ER modulators, aromatase inhibitors, and selective ER downregulators. ET is the mainstay of adjuvant treatment in the early setting and the backbone of the first-line treatment in an advanced setting; however, the emergence of acquired resistance can lead to cancer recurrence or progression. The mechanisms of ET resistance are often related to the occurrence of mutations in the ESR1 gene, which encodes the ER-alpha protein. As ESR1 mutations are hardly detectable at diagnosis but are present in 30% to 40% of advanced BC (ABC) after treatment, the timeline of testing is crucial. To manage this resistance, ESR1 testing has recently been recommended; in ER+ HER2- ABC and circulating cell-free DNA, so-called liquid biopsy appears to be the most convenient way to detect the emergence of ESR1 mutations. Technically, several options exist, including Next Generation Sequencing and ultra-sensitive PCR-based techniques. In this context, personalization of ET through the surveillance of ESR1 mutations in the plasma of HR+ BC patients throughout the disease course represents an innovative way to improve the standard of care.

The inhibition of steroid hormones determines the fate of IPC-366 tumor cells, highlighting the crucial role of androgen production in tumor processes

Inflammatory mammary cancer (IMC) is a disease that affects female dogs. It is characterized by poor treatment options and no efficient targets. However, anti-androgenic and anti-estrogenic therapies could be effective because IMC has a great endocrine influence, affecting tumor progression. IPC-366 is a triple negative IMC cell line that has been postulated as a useful model to study this disease. Therefore, the aim of this study was to inhibit steroid hormones production at different points of the steroid pathway in order to determine its effect in cell viability and migration in vitro and tumor growth in vivo. For this purpose, Dutasteride (anti-5αReductase), Anastrozole (anti-aromatase) and ASP9521 (anti-17βHSD) and their combinations have been used. Results revealed that this cell line is positive to estrogen receptor β (ERβ) and androgen receptor (AR) and endocrine therapies reduce cell viability. Our results enforced the hypothesis that estrogens promote cell viability and migration in vitro due to the function of E1SO4 as an estrogen reservoir for E2 production that promotes the IMC cells proliferation. Also, an increase in androgen secretion was associated with a reduction in cell viability. Finally, in vivo assays showed large tumor reduction. Hormone assays determined that high estrogen levels and the reduction of androgen levels promote tumor growth in Balb/SCID IMC mice. In conclusion, estrogen levels reduction may be associated with a good prognosis. Also, activation of AR by increasing androgen production could result in effective therapy for IMC because their anti-proliferative effect.

The relationship between anxiety and vaginal-related sexual health in postmenopausal breast cancer survivors on aromatase inhibitors therapies: a cross sectional study

PURPOSE

Sexual health problems and anxiety are disruptive symptoms in breast cancer survivors; however, little is known about these symptoms in postmenopausal breast cancer survivors on aromatase inhibitors therapies. This study aimed to determine the relationship between anxiety and vaginal-related sexual health problems in this population.

METHODS

We analyzed cross-sectional data from a cohort study of postmenopausal women breast cancer survivors receiving aromatase inhibitors. Vaginal-related sexual health problems were assessed with the Breast Cancer Prevention Trial Symptom Checklist. Anxiety was assessed with the anxiety subscale of the Hospital Anxiety and Depression Scale. We used multivariable logistic regression to evaluate relationship between anxiety and vaginal-related sexual health adjusted for clinical and sociodemographic variables.

RESULTS

Among 974 patients, 305 (31.3%) reported anxiety and 403 (41.4%) had vaginal-related sexual health problems. Compared to those without anxiety, patients with borderline and clinically abnormal anxiety reported higher rates of vaginal-related sexual health problems (36.8% vs. 49% and 55.7% respectively, p < 0.001). In multivariate analyses adjusted for clinical and sociodemographic factors, abnormal anxiety was associated with a higher rate of vaginal-related sexual health problems, with adjusted odds ratios of 1.69 (95% CI 1.06-2.70, p = 0.03). Vaginal-related sexual health problems were more frequent among patients who were under 65 years of age, received Taxane-based chemotherapy, reported depression, and were married/living with a partner (p < 0.05).

CONCLUSION

Among postmenopausal breast cancer survivors on aromatase inhibitors therapies, anxiety was significantly associated with vaginal-related sexual health problems. As treatments for sexual health problems are limited, results suggest that psychosocial interventions for anxiety could potentially be adapted to simultaneously address sexual health needs.

The genomic landscape associated with resistance to aromatase inhibitors in breast cancer

Aromatase inhibitors (AI) are drugs that are widely used in treating estrogen receptor (ER)-positive breast cancer patients. Drug resistance is a major obstacle to aromatase inhibition therapy. There are diverse reasons behind acquired AI resistance. This study aims at identifying the plausible cause of acquired AI resistance in patients administered with non-steroidal AIs (anastrozole and letrozole). We used genomic, transcriptomic, epigenetic, and mutation data of breast invasive carcinoma from The Cancer Genomic Atlas database. The data was then separated into sensitive and resistant sets based on patients' responsiveness to the non-steroidal AIs. A sensitive set of 150 patients and a resistant set of 172 patients were included for the study. These data were collectively analyzed to probe into the factors that might be responsible for AI resistance. We identified 17 differentially regulated genes (DEGs) among the two groups. Then, methylation, mutation, miRNA, copy number variation, and pathway analyses were performed for these DEGs. The top mutated genes (FGFR3, CDKN2A, RNF208, MAPK4, MAPK15, HSD3B1, CRYBB2, CDC20B, TP53TG5, and MAPK8IP3) were predicted. We also identified a key miRNA - hsa-mir-1264 regulating the expression of CDC20B. Pathway analysis revealed HSD3B1 to be involved in estrogen biosynthesis. This study reveals the involvement of key genes that might be associated with the development of AI resistance in ER-positive breast cancers and hence may act as a potential prognostic and diagnostic biomarker for these patients.

Targeting the formation of estrogens for treatment of hormone dependent diseases-current status

Local formation and action of estrogens have crucial roles in hormone dependent cancers and benign diseases like endometriosis. Drugs that are currently used for the treatment of these diseases act at the receptor and at the pre-receptor levels, targeting the local formation of estrogens. Since 1980s the local formation of estrogens has been targeted by inhibitors of aromatase that catalyses their formation from androgens. Steroidal and non-steroidal inhibitors have successfully been used to treat postmenopausal breast cancer and have also been evaluated in clinical studies in patients with endometrial, ovarian cancers and endometriosis. Over the past decade also inhibitors of sulfatase that catalyses the hydrolysis of inactive estrogen-sulfates entered clinical trials for treatment of breast, endometrial cancers and endometriosis, with clinical effects observed primarily in breast cancer. More recently, inhibitors of 17beta-hydroxysteroid dehydrogenase 1, an enzyme responsible for formation of the most potent estrogen, estradiol, have shown promising results in preclinical studies and have already entered clinical evaluation for endometriosis. This review aims to provide an overview of the current status of the use of hormonal drugs for the major hormone-dependent diseases. Further, it aims to explain the mechanisms behind the -sometimes- observed weak effects and low therapeutic efficacy of these drugs and the possibilities and the advantages of combined treatments targeting several enzymes in the local estrogen formation, or drugs acting with different therapeutic mechanisms.

Identification of Non-steroidal Aromatase Inhibitors via In silico and In vitro Studies

INTRODUCTION

Breast cancer is the most common cancer affecting women worldwide, including Pakistan. More than half of breast cancer patients have hormone-dependent breast cancer, which is developed due to the over-production of estrogen (the main hormone in breast cancer).

METHOD

The biosynthesis of estrogen is catalyzed by the aromatase enzyme, which thus serves as a target for the treatment of breast cancer. During the current study, biochemical, computational, and STD-NMR methods were employed to identify new aromatase inhibitors. A series of phenyl-3- butene-2-one derivatives 1-9 were synthesized and evaluated for human placental aromatase inhibitory activity. Among them, four compounds 2, 3, 4, and 8 showed a moderate to weak inhibitory activity (IC50 = 22.6 - 47.9 µM), as compared to standard aromatase inhibitory drugs, letrozole (IC50 = 0.0147 ± 1.45 µM), anastrozole (IC50 = 0.0094 ± 0.91 µM), and exemestane (IC50 = 0.2 ± 0.032 µM). Kinetic studies on two moderate inhibitors, 4 and 8, revealed a competitive- and mixed-type of inhibition, respectively.

RESULT

Docking studies on all active compounds indicated their binding adjacent to the heme group and interaction with Met374, a critical residue of aromatase. STD-NMR further highlighted the interactions of these ligands with the aromatase enzyme.

CONCLUSION

STD-NMR-based epitope mapping indicated close proximity of the alkyl chain followed by an aromatic ring with the receptor (aromatase). These compounds were also found to be non-cytotoxic against human fibroblast cells (BJ cells). Thus, the current study has identified new aromatase inhibitors (compounds 4, and 8) for further pre-clinical and clinical research.

Synthesis, investigation of biological effects and in silico studies of new benzimidazole derivatives as aromatase inhibitors

Inhibition of aromatase enzymes is very important in the prevention of estrogen-related diseases and the regulation of estrogen levels. Aromatase enzyme is involved in the final stage of the biosynthesis of estrogen, in the conversion of androgens to estrogen. The development of new compounds for the inhibition of aromatase enzymes is an important area for medicinal chemists in this respect. In the present study, new benzimidazole derivatives have been designed and synthesized which have reported anticancer activity in the literature. Their anticancer activity was evaluated against human A549 and MCF-7 cell lines by MTT assay. In the series, concerning MCF-7 cell line, the most potent compounds were the 4-benzylpiperidine derivatives 2c, 2g, and 2k with IC50 values of 0.032 ± 0.001, 0.024 ± 0.001, and 0.035 ± 0.001 µM, respectively, compared to the reference drug cisplatin (IC50 = 0.021 ± 0.001 µM). Then, these compounds were subject to further in silico aromatase enzyme inhibition assays to determine the possible binding modes and interactions underlying their activity. Thanks to molecular docking studies, the effectiveness of these compounds against aromatase enzyme could be simulated. Consequently, it has been found that these compounds can be settled very properly to the active site of the aromatase enzyme.

Estrogen receptor-positive (ER+) breast cancer treatment: Are multi-target compounds the next promising approach?

Endocrine therapy is currently the main therapeutic approach for estrogen receptor-positive (ER⁺) breast cancer, the most frequent subtype of breast cancer in women worldwide. For this subtype of tumors, the current clinical treatment includes aromatase inhibitors (AIs) and anti-estrogenic compounds, such as Tamoxifen and Fulvestrant, being AIs the first-line treatment option for post-menopausal women. Moreover, the recent guidelines also suggest the use of these compounds by pre-menopausal women after suppressing ovaries function. However, besides its therapeutic efficacy, the prolonged use of this type of therapies may lead to the development of several adverse effects, as well as, endocrine resistance, limiting the effectiveness of such treatments. In order to surpass this issues and clinical concerns, during the last years, several studies have been suggesting alternative therapeutic approaches, considering the function of aromatase, ERα and ERβ. Here, we review the structural and functional features of these three targets and their importance in ER⁺ breast cancer treatment, as well as, the current treatment strategies used in clinic, emphasizing the importance of the development of multi-target compounds able to simultaneously modulate these key targets, as a novel and promising therapeutic strategy for this type of cancer.

Focus on the glycerophosphocholine pathway in choline phospholipid metabolism of cancer

Activated choline metabolism is a hallmark of carcinogenesis and tumor progression, which leads to elevated levels of phosphocholine and glycerophosphocholine in all types of cancer tested so far. Magnetic resonance spectroscopy applications have played a key role in detecting these elevated choline phospholipid metabolites. To date, the majority of cancer-related studies have focused on phosphocholine and the Kennedy pathway, which constitutes the biosynthesis pathway for membrane phosphatidylcholine. Fewer and more recent studies have reported on the importance of glycerophosphocholine in cancer. In this review article, we summarize the recent literature on glycerophosphocholine metabolism with respect to its cancer biology and its detection by magnetic resonance spectroscopy applications.

Identification of Novel Scaffolds with Dual Role as Antiepileptic and Anti-Breast Cancer

Aromatase inhibitors with an $\mathrm{IC}_{50}$ IC 50 value ranging from 1.4 to 49.7 µM are known to act as antiepileptic drugs besides being potential breast cancer inhibitors. The aim of the present study is to identify novel antiepileptic aromatase inhibitors with higher activity exploiting the ligand-based pharmacophore approach utilizing the experimentally known inhibitors. The resultant Hypo1 consists of four features and was further validated by using three different strategies. Hypo1 was allowed to screen different databases to identify lead molecules and were further subjected to Lipinski's Rule of Five and ADMET to establish their drug-like properties. Consequently, the obtained 68-screened molecules were subjected to molecular docking by GOLD v5.2.2. Furthermore, the compounds with the highest dock scores were assessed for molecular interactions. Later, the MD simulation was applied to evaluate the protein backbone stabilities and binding energies adapting GROMACS v5.0.6 and MM/PBSA which was followed by the density functional theory (DFT), to analyze their orbital energies, and further the energy gap between them. Eventually, the number of Hit molecules was culled to three projecting Hit1, Hit2, and Hit3 as the potential lead compounds based on their highest dock scores, hydrogen bond interaction, lowest energy gap, and the least binding energies and stable MD results.

Sulfonanilide Derivatives in Identifying Novel Aromatase Inhibitors by Applying Docking, Virtual Screening, and MD Simulations Studies

Breast cancer is one of the leading causes of death noticed in women across the world. Of late the most successful treatments rendered are the use of aromatase inhibitors (AIs). In the current study, a two-way approach for the identification of novel leads has been adapted. 81 chemical compounds were assessed to understand their potentiality against aromatase along with the four known drugs. Docking was performed employing the CDOCKER protocol available on the Discovery Studio (DS v4.5). Exemestane has displayed a higher dock score among the known drug candidates and is labeled as reference. Out of 81 ligands 14 have exhibited higher dock scores than the reference. In the second approach, these 14 compounds were utilized for the generation of the pharmacophore. The validated four-featured pharmacophore was then allowed to screen Chembridge database and the potential Hits were obtained after subjecting them to Lipinski's rule of five and the ADMET properties. Subsequently, the acquired 3,050 Hits were escalated to molecular docking utilizing GOLD v5.0. Finally, the obtained Hits were consequently represented to be ideal lead candidates that were escalated to the MD simulations and binding free energy calculations. Additionally, the gene-disease association was performed to delineate the associated disease caused by CYP19A1.

Targeting GRP78 and antiestrogen resistance in breast cancer

Breast cancer is the most prevalent cancer in women, with over 200,000 new cases diagnosed each year. Over 70% of breast cancers express the estrogen receptor-α, and drugs targeting these receptors such as tamoxifen or Faslodex(®) often fail to cure these patients. Many estrogen receptor-positive tumors lose drug sensitivity, making endocrine resistance a major clinical problem. Recently, investigation into the molecular mechanisms of endocrine resistance has highlighted a causative role of the unfolded protein response in antiestrogen resistance. In particular, the master regulator of the unfolded protein response, GRP78, was observed to be elevated in endocrine-resistant breast cancer and directly affected antiestrogen therapy responsiveness. GRP78 was found to impact many different cellular processes that may affect breast cancer survival. Recently, various compounds have been reported to affect GRP78 activity and it may be advantageous to combine these drugs with antiestrogens to overcome endocrine therapy resistance.

The use of adjuvant endocrine breast cancer therapy in the oldest old

In order to report specifically on the use of adjuvant endocrine therapy (ET) in the oldest old breast cancer (BC) patients, we compared treatment patterns including drug compliance and persistence in a cohort of patients who were ≥ 80 years at diagnosis (n = 79) with those of "younger elderly" patients who were 60-79 years old (n = 358). The geriatric cohort more commonly declined the recommended ET (non-compliance: 13.0% vs. 4.5%, p = 0.011). Of the patients who initiated ET, only a minority of the older patients completed the planned therapy duration of five years (39.6% vs. 71.3%, p < 0.001). However, when applying strict criteria for non-persistence, this was found in comparable frequency (17.0% vs. 12.0%, p = 0.370). In older patients, medication was more often discontinued by the physician due to serious medical reasons independent of BC (17.0% vs. 4.7%, p = 0.003). Older women were treated by a general practitioner more often and not by an oncologist (54.4% vs. 23.9%, p < 0.001). Studies on compliance/persistence on cancer therapy in the oldest old demand a detailed follow-up of the patients and the consideration of principles of geriatric medicine. Efforts should be made to make sure that all physicians, but above all general practitioners, who are predominantly involved in the treatment of elderly BC patients, are provided with current knowledge and skills, as to ensure optimal patient management.

Compliance and persistence of endocrine adjuvant breast cancer therapy

This study evaluates compliance and persistence in adjuvant endocrine breast cancer (BC) therapy by clearly analyzing reasons of therapy cessation by differentiating clinical meaningful situations. In order to illuminate the complex field of personal motivation to therapy, a single institution study with a more individual-based approach might better be suited to provide a detailed case documentation than the more epidemiologic approach of large database studies. An unselected cohort of 698 patients (≤ 80 years) diagnosed with hormonal receptor-positive BC from 1997 to 2008 at the University Hospital Basel, Switzerland, was analyzed. The term "non-persistence" was exclusively used for patients where the discontinuation of endocrine therapy (ET) could have been modified by more intensive care and improved counseling (e.g., in women who lost faith/motivation to therapy or those who suffered from therapy-related side effects). These cases must be differentiated from cases where therapy cessation was inevitable (e.g., due to recurrent disease or severe intercurrent illness). Out of the 685 patients to whom ET was recommended, 42 patients (6.1%) refused and never began treatment (non-compliance). Women younger than 50 were more likely to be non-compliant (P < 0.001). 12.9% of the patients who started therapy were non-persistent to therapy. Patients who were treated by general practitioners tended to be non-persistent more often compared to those treated by oncologists (17.7% vs. 11.3%; P = 0.07). The aim of a non-persistence rate between 10 and 15% is realistic when patients are treated by specialized oncologists. Interventions are needed to support patients, particularly the younger ones, to comply with therapy. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in BC treatment, are provided with current knowledge as to guarantee an optimal patient management.

The importance of nonpharmacogenetic factors in endocrine therapy

Nonpharmacogenetic factors may play a key role in the success of oral endocrine therapy for breast cancer. Adherence, defined as following medical advice as well as persistence and duration of use for patients prescribed endocrine therapy, may impact significantly on recurrence and survival. Side effects from tamoxifen or aromatase inhibitors may lead to patients stopping or switching therapy, while comorbidities, consequent coprescribing and patient perceptions may also influence outcomes. Interventions to improve adherence and persistence are required and could have as great an effect on survival as applying pharmacogenetic principles to the endocrine management of breast cancer.

Eligibility, compliance and persistence of extended adjuvant endocrine therapy for breast cancer

BACKGROUND

Extended therapy (ET) beyond the standard five years of tamoxifen-containing treatment is a widely discussed therapy option in adjuvant endocrine breast cancer (BC) therapy which might offer an opportunity for further protection against late relapses. In this study we evaluated eligibility, compliance and persistence of extended adjuvant endocrine BC therapy.

PATIENTS AND METHODS

Data concerning all BC patients (≤75 years) who initiated endocrine adjuvant therapy between 1999 and 2005 (n = 286) was analyzed.

RESULTS

One hundred and thirty-eight patients were valid candidates for an ET according current guidelines; this represents 48.3% of the individuals who started endocrine therapy five years ago. Of these, 89 (64.5%) received a corresponding offer/recommendation by their treating physicians. Advanced age (p = 0.002), favorable disease stage (p = 0.011), and follow-up at a general practitioner (p < 0.001) were significant factors where a recommendation for an ET was not made. Of the 89 patients who were offered an ET, 64 followed this proposal (compliance: 84.7%). Eighteen patients (28.1%) were non-persistent to the ET; therapy-related adverse effects were the main reason for discontinuation. Sixteen patients received an ET beyond current guidelines (tamoxifen or an aromatase inhibitor alone was given longer than five years); this represents 11.0% of all patients who completed five years of endocrine therapy.

CONCLUSIONS

Only a minority of the patients who started an endocrine therapy were actually eligible for an ET. Patients who were offered/recommended an ET had a high rate of compliance and persistence. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in the treatment of BC patients, are provided with current therapy guidelines as to guarantee an optimal patient management.

Quality measurement and system change of cancer care delivery

Cancer care quality measurement and system change may serve as a case example for larger possibilities in the health care system related to other diseases. Cancer care quality gaps and variation exist across both technical and patient-centered cancer quality measures, especially among vulnerable populations. There is a need to develop measures that address the following dimensions of quality and its context: disparities, overuse, patient-centeredness, and uncertainty. Developments that may promote system change in cancer care delivery include changes in the information market, organizational accountability, and consumer empowerment. Information market changes include public cancer care quality reporting, enabled by health information exchange, and incentivized by pay-for-performance. Moving organizational accountability, reimbursement, and quality measurement from individual episodes of care to multiple providers providing coordinated cancer care may address quality gaps associated with the fragmentation of care delivery. Consumer empowerment through new technologies, such as personal health records, may lead to the collection of patient-centered quality measures and promote patient self-management. Across all of these developments, leadership and ongoing research to guide informed system changes will be necessary to transform the cancer care delivery system.

Eligibility, compliance and persistence of sequential therapy with aromatase inhibitors following 2-3 years of tamoxifen in endocrine adjuvant breast cancer therapy

OBJECTIVE

This study evaluated the eligibility, compliance and persistence of sequential therapy, i.e. a switch to an aromatase inhibitor (AI) following 2-3 years of tamoxifen, in adjuvant endocrine breast cancer (BC) treatment.

METHODS

Data concerning 388 BC patients (age ≤70 years) who started endocrine adjuvant therapy between 1998 and 2008 were analyzed.

RESULTS

From the 263 patients who started therapy with tamoxifen, 167 (63.5%) were eligible for a sequential therapy. Fifty-nine patients (35.3%) were offered a switch by their physicians; women who had their follow-up at oncological units received the offer more often when compared to those treated by general practitioners (p < 0.001). Out of these 59 patients, 50 followed the proposal (compliance 84.7%). Of those who agreed to a sequential therapy, 2 (4%) were non-persistent to endocrine therapy; in 9 cases (18.0%), a re-switch to tamoxifen was done due to AI-related adverse side effects.

CONCLUSIONS

Only a minority of the patients who started an endocrine adjuvant BC therapy was eligible for sequential therapy. Patients who underwent a switch had a high rate of persistence. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in the treatment of BC patients, are provided with current therapy guidelines.

Promoter-specific effects of metformin on aromatase transcript expression

Phase III aromatase inhibitors (AIs) are proving successful in the treatment of hormone-dependent postmenopausal breast cancer. Side-effects associated with total body aromatase inhibition have prompted new research into the development of breast-specific AIs. The identification of tissue- and disease-specific usage of aromatase promoters has made the inhibition of aromatase at the transcriptional level an interesting approach. We have previously demonstrated that AMPK-activating drugs, including metformin, were potent inhibitors of aromatase expression in primary human breast adipose stromal cells (hASCs). This study examines the promoter-specific effects of metformin on inhibiting aromatase expression in hASCs. Tumour-associated promoters PII/PI.3 were activated using forskolin (FSK)/phorbol ester (PMA), whereas normal adipose associated promoter PI.4 was activated using dexamethasone (DEX)/tumour necrosis factor-α (TNFα). Results demonstrate that metformin significantly decreased the FSK/PMA-, but not the DEX/TNFα-mediated expression of total aromatase at concentrations of 10, 20, and 50 μM (P ≤ 0.05). Using PCR to amplify promoter-specific transcripts of aromatase, it appears that the inhibition of the FSK/PMA-mediated expression of aromatase is due to decreases in PII/PI.3-specific transcripts, whereas no effect of metformin is observed on any promoter-specific transcript, including PI.4, in DEX/TNFα-treated hASCs. This report therefore supports the hypothesis that metformin would act as a breast-specific inhibitor of aromatase expression in the context of postmenopausal breast cancer.