Efficacy Of Tamoxifen In Patients Research Articles

Prevalence of the co-prescription of tamoxifen and CYP2D6 inhibitors in Saudi population: A cross sectional study

Consumption of Cytochrome P450 2D6 (CYP2D6) inhibiting drugs along with tamoxifen treatment results in decrease in plasma concentration of endoxifen, the major active tamoxifen metabolite. Simultaneous use of CYP2D6 inhibitors, such as selective serotonin reuptake inhibitors (SSIs), as well as lesser tamoxifen adherence may negatively impact tamoxifen efficacy in patients with breast cancer. The objective of our study was to assess the co-prescription of CYP2D6 inhibitors and tamoxifen use and also to relate concomitant CYP2D6 inhibitor use and tamoxifen adherence to breast cancer in Riyadh, Saudi Arabia. All patients treated for breast cancer who had at least one tamoxifen prescription in their electronic medical records (EMRs) from June 2015 to June 2017 were included. Patients who had other adjuvant hormonal therapy were excluded from the study. In total, 499 patients (25 males and 474 females) with breast cancer using tamoxifen were included. Our study was purely observational study revealed that prescription of weak inhibitors with tamoxifen increased in the second year as opposed to decrease in the prescription of strong inhibitors. Also, a substantial percentage of patient population were found to be non-adherent to the tamoxifen therapy in this study.

Relation of EGFR/PI3K/AKT signaling components with tamoxifen efficacy in patients with estrogen-dependent breast cancer

Background. It is generally accepted that crosstalk between the growth factor receptor and ER pathways implicated in tamoxifen resistance. The aim of the study was to examine the relationship between mRNA level, protein expression and gene polymorphism of the EGFR/PI3K/AKT signaling components with tamoxifen efficacy in patients with estrogen-dependent breast cancer. Materials and methods. The study included 95 breast cancer patients who had received adjuvant tamoxifen, of which 31 patients developed recurrence/metastasis after tamoxifen treatment (tamoxifen resistance group), 64 patients did not develop any diseases progression (tamoxifen sensitive group) during the 5 years of follow-up. Genotypes for ESR1 (rs2077647, rs2228480, rs1801132), EGFR (rs1468727, rs2227983), AKT1 (rs1130233) and PTEN (rs11202592) were analyzed using a TaqMan assay. Using reverse transcription-PCR, the relative expression of mRNA for ESR1, EGFR, AKT1 and PTEN was determined. ERα, EGFR, Akt (pS473) and PTEN expression level was evaluated using immunohistochemistry. Progression-free survival (PFS) was estimated by Kaplan – Meier analysis. Results. The minor allele of ESR1 rs2077647 was more prevalent in tamoxifen sensitive tumors compared to tamoxifen resistant tumors (p = 0.044). We found high AKT1 mRNA expression level in tamoxifen sensitive group compared with tamoxifen resistance patients (7.27 ± 5.29 and 0.02 ± 0.01, respectively, p = 0.014). ESR1 rs2228480 was significantly associated with tamoxifen resistance (p = 0.028). EGFR and Akt (pS473) protein expression level was significantly higher in the tamoxifen resistance group compared to tamoxifen sensitive breast cancer patients (p = 0.006 and 0.037, respectively). Patients carrying mutant genotypes of ESR1 rs2228480 had a poorer progression-free survival than those carrying wild and heterozygous variants (log rank p = 0.043). Positive EGFR tumor expression as well as positive Akt (pS473) expression were significantly associated with shorter PFS (log rank p = 0.014 and 0.048, respectively). Conclusion. Polymorphic sites of the ESR1 gene, AKT1 mRNA expression, EGFR expression level and Akt (pS473) protein expression can be potential molecular markers associated with tumor sensitivity/resistance to tamoxifen treatment.

IGF-1 Receptor Modulates FoxO1-Mediated Tamoxifen Response in Breast Cancer Cells.

Tamoxifen is a common adjuvant treatment for estrogen receptor (ER)α-positive patients with breast cancer; however, acquired resistance abrogates the efficacy of this therapeutic approach. We recently demonstrated that G protein-coupled estrogen receptor 1 (GPER1) mediates tamoxifen action in breast cancer cells by inducing insulin-like growth factor-binding protein-1 (IGFBP-1) to inhibit IGF-1-dependent signaling. To determine whether dysregulation of IGFBP-1 induction is associated with tamoxifen resistance, IGFBP-1 transcription was measured in tamoxifen-resistant MCF-7 cells (TamR) after tamoxifen (Tam) treatment. IGFBP-1 transcription was not stimulated in tamoxifen-treated TamR cells whereas decreased expression of FoxO1, a known modulator of IGFBP-1, was observed. Exogenous expression of FoxO1 rescued the ability of tamoxifen to induce IGFBP-1 transcription in TamR cells. As decreased IGF-1R expression is observed in tamoxifen-resistant cells, the requirement for IGF-1R expression on tamoxifen-stimulated IGFBP-1 transcription was investigated. In TamR and SK-BR-3 cells, both characterized by low IGF-1R levels, exogenous IGF-1R expression increased FoxO1 levels and IGFBP-1 expression, whereas IGF-1R knockdown in MCF-7 cells decreased tamoxifen-stimulated IGFBP-1 transcription. Interestingly, both 17β-estradiol (E2)-stimulated ERα phosphorylation and progesterone receptor (PR) expression were altered in TamR. PR is a transcription factor known to modulate FoxO1 transcription. In addition, IGF-1R knockdown decreased FoxO1 protein levels in MCF-7 cells. Furthermore, IGF-1R or FoxO1 knockdown inhibited the ability of tamoxifen to induce IGFBP-1 transcription and tamoxifen sensitivity in MCF-7 cells. These data provide a molecular mechanistic connection between IGF-1R expression and the FoxO1-mediated mechanism of tamoxifen action in breast cancer cells.Implications: Loss of IGF-1R expression is associated with decreased tamoxifen efficacy in patients with breast cancer and the development of tamoxifen resistance. This contribution identifies potential molecular mechanisms of altered tamoxifen sensitivity in breast cancer cells resulting from decreased IGF-1R expression. Mol Cancer Res; 15(4); 489-97. ©2017 AACR.

ANZ1001 SORBET: Study of estrogen receptor beta and efficacy of tamoxifen, a single arm, phase II study of the efficacy of tamoxifen in triple-negative but estrogen receptor beta-positive metastatic breast cancer.

TPS1136 Background: Targeted therapies are needed for triple negative breast cancer (BC). ERβ is expressed in at least 20% of triple negative BCs. ERβ binds estrogen and tamoxifen with a similar affinity to ERα. ERβ has 5 isoforms but only ERβ1 is fully functional. ERβ expression has been shown to be significantly associated with improved distant disease free survival and better overall survival in tamoxifen treated ERα negative patients in retrospective studies. This “proof of principle” study will determine the efficacy of tamoxifen in patients with triple negative but ERβ positive metastatic BC. Methods: This single arm phase II study, being conducted by the Australia and New Zealand Breast Cancer Trials Group, has a Simon's 2 stage optimal design. The primary end-point is objective response rate (complete and partial responses). Progression free survival and clinical benefit rate will also be assessed. Eligibility criteria include histologically or cytologically confirmed metastatic triple negative BC (ER and PR absent, HER2 ISH negative or IHC 0 or 1) and measureable disease as per RECIST 1.1. Consenting patients undergo central ERβ testing and confirmation of triple negative status on a metastatic biopsy sample. ERβ positive patients (ERβ1 nuclear staining with Allred score >4) are offered trial participation. To date 12 potentially eligible patients have been screened for ERβ; 4 had Allred score >4 (although 2 of these subsequently proved to be ineligible for the trial), 7 had Allred scores <4 and 1 result is pending. Consenting patients receive tamoxifen 20mg per oral daily until disease progression, unacceptable toxicity or withdrawal of consent. If there are ≥2 responses in the first stage of 28 patients, an additional 38 patients will be accrued. Tamoxifen will be considered worthy of further research if there are ≥6 responses in the total 66 patients recruited. Current accrual is 1. Registered on ANZCTR (12610000506099).

ANZ1001 SORBET: Study of Oestrogen Receptor Beta and Efficacy of Tamoxifen—A single-arm, phase II study of the efficacy of tamoxifen in triple-negative but estrogen receptor beta-positive metastatic breast cancer.

TPS126 Background: Patients with advanced triple negative breast cancer (BC) have limited treatment options and poor prognosis. At least 20% of triple negative BCs express estrogen receptor (ER) β, the second known isoform of the ER. ERβ binds estrogens and tamoxifen with a similar affinity to ERα and has 5 isoforms, but only ERβ1 is fully functional. There is no standardized method for measuring ERβ. Most published studies used antibodies to total ERβ and ERβ1 with immunohistochemistry (IHC) staining >10-20% or Allred scores to define positive. Two retrospective studies of the relationship between ERβ expression and tamoxifen in early BC have shown ERβ expression was significantly associated with better distant disease free survival and better overall survival in the tamoxifen treated ERα negative patients. This “proof of principle” study will determine the efficacy of tamoxifen in patients with triple negative but ERβ positive metastatic BC. Methods: This single arm phase II study has a Simon’s 2 stage optimal design. The primary end-point is objective response rate (complete and partial responses). Eligible patients have histologically or cytologically confirmed metastatic triple negative BC (ER and PR absent, HER2 ISH negative or IHC 0 or 1) and measureable disease as per RECIST 1.1. Consenting patients undergo central ERβ testing and confirmation of triple negative status on a metastatic biopsy sample. ERβ positive patients (ERβ1 nuclear staining with Allred score >4) are offered trial participation. Consenting patients receive tamoxifen 20mg per oral daily until disease progression, unacceptable toxicity or withdrawal of consent. If there are ≥2 responses in the first stage of 28 patients, an additional 38 patients will be accrued. Tamoxifen will be considered worthy of further research if there are ≥6 responses in the total 66 patients recruited. Progression free survival and clinical benefit rate will also be assessed.

Effect of Concomitant CYP2D6 Inhibitor Use and Tamoxifen Adherence on Breast Cancer Recurrence in Early-Stage Breast Cancer

The use of cytochrome P450 2D6-inhibiting drugs (CYP2D6 inhibitors) during tamoxifen treatment leads to a decrease in plasma concentration of endoxifen, the major active tamoxifen metabolite. Concomitant use of CYP2D6 inhibitors, such as selective serotonin reuptake inhibitors, as well as low tamoxifen adherence may negatively impact tamoxifen efficacy in patients with breast cancer. The objectives of this study were to relate concomitant CYP2D6 inhibitor use and tamoxifen adherence to breast cancer event-free time (EFT). Data were from PHARMO and included a community pharmacy dispensing database; PALGA, a nationwide pathology database; and the Dutch Medical Register in the Netherlands. Patients with breast cancer treated with adjuvant tamoxifen between 1994 and 2006 were included. A Cox proportional hazards model with a time-dependent definition for concomitant CYP2D6 inhibitor exposure was used. Adherence calculated over the first year after tamoxifen initiation was related to breast cancer events in the following period. In total, 1,962 patients with breast cancer using tamoxifen were included, among whom 150 (7.6%) frequently used a CYP2D6 inhibitor during tamoxifen treatment. No association between concomitant CYP2D6 inhibitor use and breast cancer recurrence was observed (adjusted hazard ratio [HR], 0.87; 95% CI, 0.42 to 1.79; P = .69). Poor tamoxifen adherence was associated with lower EFT (adjusted HR, 0.987; 95% CI, 0.975 to 0.999; P = .029). This observational study did not show an association between concomitant CYP2D6 inhibitor use and breast cancer recurrence among patients treated with adjuvant tamoxifen despite the strong biologic rationale. This study shows, to the best of our knowledge for the first time, that poor tamoxifen adherence is associated with an increased risk of breast cancer events.

The efficacy of tamoxifen in patients with advanced epithelial ovarian cancer

Activity of tamoxifen as a salvage therapy in patients with advanced epithelial ovarian cancer was evaluated by a number of studies. In this study, we evaluated efficacy of tamoxifen in our patients with platinum-resistant epithelial ovarian carcinoma. A retrospective analysis was conducted of patients who received tamoxifen at a dose 20 mg twice daily for the treatment of advanced epithelial ovarian cancer. Twenty-nine eligible patients were included to the study. There were 1 (3%) complete response, 2 (7%) partial response, 6 (21%) stable disease, and 20 (69%) progressive disease. All patients were progressed after initiation of tamoxifen. Median progression-free survival was 4 mo (95% CI: 2.98-5.02). Disease progression of 19 (65%) patients were shown within the first 6 mo after initiation of tamoxifen. Progression-free survival was between 6 and 12 mo for 7 (24%) patients and > or =12 mo for 3 (10%) patients. The median survival after initiation of tamoxifen was 15 mo (95% CI: 7.2-22.8). No toxicity attributable to tamoxifen was seen in any of the patients. The only independent prognostic factor that had a significant predictive value for progression- free survival was the response to tamoxifen treatment (p = 0.043, hazard ratio: 0.12, 95% CI: 0.01-0.94). Considering minimal side effects and ability to cause objective responses, there is a place for tamoxifen in treatment of patients with platinum-resistant ovarian cancer. A phase III trial is required to con- firm the value of the drug in patients presenting these clinical settings.

The role of tamoxifen in the treatment of symptomatic uterine leiomyomata — a pilot study

Objectives: To determine the efficacy of tamoxifen in patients with leiomyomata complaining of abdominal pains and vaginal bleeding. Study Design: Prospective, randomized, double blind study. A total of 10 patients received for 6 months 20 mg tamoxifen daily, and 10 women received placebo. All patients underwent serial pelvic and ultrasound exams and endometrial sampling was performed prior to initiation of treatment. After 5 years, the patients were interviewed again. Results: Uterine size was not affected by the use of tamoxifen. Patients reported a blood loss decrease of 40–50% at the end of the study ( P=0.0001). In the control group a slight increase in blood loss was reported. Hemoglobin levels remained unchanged in both groups. In the study group patients reported after 4 months of treatment a substantial decrease in the intensity of pain ( P=0.018). Seven patients in the study group and one patient in the control group developed ovarian cysts. Conclusions: Treatment with tamoxifen added only marginal benefit while causing unacceptable side effects. Tamoxifen does not seem to be a useful adjunct in the treatment of symptomatic uterine leiomyomata and its use for this indication should be discouraged.