Differential impact of tamoxifen and aromatase inhibitors on thrombin generation: the prospective HEMOBREAST cohort

Venous thromboembolism associated with medically assisted reproduction (MAR): British fertility society policy and practice guidance for assessment and prevention

The association between Medically Assisted Reproduction (MAR) and thromboembolic complications has been reported widely in multiple published studies. Although venous thromboembolism (VTE) is not thought to be a common complication of MAR, it is associated with high morbidity and is often preventable. Since VTE usually occurs after completion of MAR treatment and is often managed outside of the treating fertility unit, these complications are likely to be underreported and there may be limited awareness of the risks among clinicians. As we continue to see a rise in the total number of MAR treatment cycles, particularly in women over 40 years of age, along with a steady increase in the number of fertility preservation cycles for both medical and social indications, it is likely that we will see an increase in absolute numbers of VTE complications. Currently, there is a lack of management guidance and reporting of VTE events associated with assisted conception treatment. The aim of this guidance is to provide clinicians with information on VTE risk factors, guidance on assessing VTE risk and the best practice recommendations on risk reducing strategies for individuals at risk of VTE undergoing ovarian stimulation and embryo transfer cycles.

Hemostatic imbalance induced by tamoxifen in estrogen receptor-positive breast cancer patients: An observational study

BACKGROUND

Estrogen receptor (ER)-positive (ER+) breast cancer accounts for approximately 75% of all breast cancers. Tamoxifen, a selective estrogen receptor modulator, is the standard adjuvant treatment. Although better tolerated than aromatase inhibitors, tamoxifen increases the risk of venous thromboembolism (VTE) 1.4-fold.

AIM

To assess the hemostatic imbalance induced by tamoxifen in adjuvant treatment of ER+ breast cancer.

METHOD

Twenty-five patients in remission from ER+ breast cancer under tamoxifen were included. One hundred and thirty one age- and BMI-matched healthy controls were included to establish reference ranges of thrombin generation assay (TGA) parameters. TGA was performed in the absence and presence of exogenous activated protein C (APC) to calculate the normalized APC sensitivity ratio (nAPCsr), a marker of APC resistance.

RESULTS

All TG parameters except the endogenous thrombin potential (ETP) (-APC) were significantly impacted by tamoxifen (p < 0.001). In absence of APC, regardless of TGA parameters, at least 50% of results were outside the reference ranges except for ETP, which was above the upper reference limit in only two individuals. The most impacted parameter was the Peak Height with 52% (-APC) and 80% (+APC) of results above the upper reference range limit, respectively. The nAPCsr was significantly higher in tamoxifen users (mean ± standard deviation = 3.18 ± 0.91) compared to the control group (2.19 ± 0.92, p < 0.0001).

CONCLUSION

This observational study showed that patients in remission from ER+ breast cancer taking tamoxifen had altered thrombin generation, as well as an acquired APC resistance. Moreover, this is the first study using the validated ETP-based APC resistance assay in tamoxifen-treated patients.

The interplay between tamoxifen and endoxifen plasma concentrations and coagulation parameters in patients with primary breast cancer

BACKGROUND

Tamoxifen is an effective treatment for primary breast cancer but increases the risk for venous thromboembolism. Tamoxifen decreases anticoagulant proteins, including antithrombin (AT), protein C (PC) and tissue factor (TF) pathway inhibitor, and enhances thrombin generation (TG). However, the relation between plasma concentrations of both tamoxifen and its active metabolite endoxifen and coagulation remains unknown.

METHODS

Tamoxifen and endoxifen were measured in 141 patients from the prospective open-label intervention TOTAM-study after 3 months (m) and 6 m of tamoxifen treatment. Levels of AT and PC, the procoagulant TF, and TG parameters were determined at both timepoints if samples were available (n = 53-135 per analysis). Levels of coagulation proteins and TG parameters were correlated and compared between: 1) quartiles of tamoxifen and endoxifen levels, and 2) 3 m and 6 m of treatment.

RESULTS

At 3 m, levels of AT, PC, TF and TG parameters were not associated with tamoxifen nor endoxifen levels. At 6 m, median TF levels were lower in patients in the 3rd (56.6 [33] pg/mL), and 4th (50.1 [19] pg/mL) endoxifen quartiles compared to the 1st (lowest) quartile (76 [69] pg/mL) (P=0.027 and P=0.018, respectively), but no differences in anticoagulant proteins or TG parameters were observed. An increase in circulating TF levels (3 m: 46.0 [15] versus 6 m: 54.4 [39] pg/mL, P < 0.001) and TG parameters was observed at the 6 m treatment timepoint, while AT and PC levels remained stable.

CONCLUSIONS

Our results indicate that higher tamoxifen and endoxifen levels are not correlated with an increased procoagulant state, suggesting tamoxifen dose escalation does not further promote hypercoagulability.

[Venous thromboembolism and breast cancer]

Breast cancer is the most common cancer in women. Patients with breast cancer have a 4-fold increased risk of venous thromboembolism (VTE) compared to age- and sex-matched controls without cancer. VTE remains the second leading cause of death in cancer patients and an independent risk factor for mortality. In women with breast cancer, the main risk factors for developing VTE are increasing age, obesity, disease stage, central catheter placement and cancer treatments, including surgery, chemotherapy, hormonotherapy and cyclin-dependent kinase 4/6 inhibitors. In women receiving tamoxifen, the risk of VTE is particularly increased within the first 6 months after initiation of hormonotherapy, although some evidence suggests that this risk may persist through the first 2 years of treatment. The risk of VTE appears to be lower in patients receiving aromatase inhibitors. In breast cancer patients receiving cyclin-dependent kinase 4/6 inhibitors, the rate of VTE is approximately 6%. Current clinical practice guidelines for the treatment and prevention of VTE in patients with cancer suggest that thromboprophylaxis should not be used routinely in ambulatory cancer patients receiving chemotherapy or hormonotherapy. The risk-benefit ratio of thromboprophylaxis should be assessed on a case-by-case basis and be the subject of multidisciplinary discussion.

Effect of the P-glycoprotein inhibitor tamoxifen on edoxaban plasma levels in women with breast cancer

BACKGROUND

Concomitant use of P-glycoprotein inhibitors can reduce clearance of edoxaban and increase its plasma concentration. Caution is advised with simultaneous use of edoxaban and the frequently used P-glycoprotein inhibitor tamoxifen. However, pharmacokinetic data are lacking.

OBJECTIVES

This study aimed to assess the effect of tamoxifen on edoxaban clearance.

METHODS

This was a prospective, self-controlled, pharmacokinetic study in breast cancer participants starting tamoxifen. Edoxaban was given at a dose of 60 mg once daily for 4 consecutive days, first without tamoxifen and later with concomitant tamoxifen in steady-state. On day 4 of both edoxaban sequences, serial blood samples were taken. A population pharmacokinetic model was developed using nonlinear mixed effects modelling in which the effect of tamoxifen on edoxaban clearance was assessed. Additionally, mean area under the curves (AUC) were estimated. Geometric least square means (GLM) ratios were calculated and no interaction was concluded if the 90 % CI was within the 80-125 % no-effect boundaries.

RESULTS

Twenty-four women with breast cancer scheduled for tamoxifen were included. The median age was 56 years (IQR 51-63). The average edoxaban clearance was 32.0 L/h (95 % CI, 11.1-35.0 L/h). There was no effect of tamoxifen on edoxaban clearance, with a fraction of 100 % (95 % CI 92-108) compared to clearance without tamoxifen. The mean AUCs were 1923 ng*h/ml (SD 695) without tamoxifen and 1947 ng*h/ml (SD 595) with tamoxifen (GLM-ratio 100.4; 90 % CI 98.6-102.2).

CONCLUSIONS

Concomitant use of the P-glycoprotein inhibitor tamoxifen does not lead to reduced clearance of edoxaban in patients with breast cancer.

Venous thromboembolism in Japanese patients with breast cancer: subgroup analysis of the Cancer-VTE Registry

BACKGROUND

This subgroup analysis of the Cancer-VTE Registry, a nationwide, large-scale, multicenter observational study with a 1-year follow-up, assessed real-world data on venous thromboembolism (VTE) among Japanese patients with breast cancer.

METHODS

Patients with stage II-IV pretreatment breast cancer screened for VTE at enrollment were included. During the 1-year follow-up period, incidences of VTE, bleeding, and all-cause death, and background factors associated with VTE risk were examined.

RESULTS

Of 9,630 patients in the Cancer-VTE Registry analysis set, 993 (10.3%) had breast cancer (973 [98.0%] did not have and 20 [2.0%] had VTE at baseline). The mean age was 58.4 years, 73.4% of patients had stage II cancer, and 94.8% had an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0. Risk factors for VTE at baseline by univariable analysis were age ≥ 65 years, ECOG PS of 2, VTE history, and D-dimer > 1.2 μg/mL. During follow-up, the incidence of symptomatic VTE was 0.4%; incidental VTE requiring treatment, 0.1%; composite VTE (symptomatic VTE and incidental VTE requiring treatment), 0.5%; bleeding, 0.2%; cerebral infarction/transient ischemic attack/systemic embolic event, 0.2%; and all-cause death, 2.1%. One patient with symptomatic VTE developed pulmonary embolism (PE) and died. Incidences of VTE and all-cause death were higher in patients with VTE vs without VTE at baseline.

CONCLUSIONS

In Japanese patients with breast cancer, VTE screening before initiating cancer treatment revealed a 2.0% prevalence of VTE. During follow-up, one patient had a fatal outcome due to PE, but the incidences of VTE were low.

CLINICAL TRIAL REGISTRATION

UMIN000024942; UMIN Clinical Trials Registry: https://www.umin.ac.jp/ctr/ .

Stratification of Tamoxifen Synergistic Combinations for the Treatment of ER+ Breast Cancer

Breast cancer alone accounts for the majority of cancer deaths among women, with the most commonly diagnosed subtype being estrogen receptor positive (ER+). Survival has greatly improved for patients with ER+ breast cancer, due in part to the development of antiestrogen compounds, such as tamoxifen. While treatment of the primary disease is often successful, as many as 30% of patients will experience recurrence and metastasis, mainly due to developed endocrine therapy resistance. In this study, we discovered two tamoxifen combination therapies, with simeprevir and VX-680, that reduce the tumor burden in animal models of ER+ breast cancer more than either compound or tamoxifen alone. Additionally, these tamoxifen combinations reduced the expression of HER2, a hallmark of tamoxifen treatment, which can facilitate acquisition of a treatment-resistant phenotype. These combinations could provide clinical benefit by potentiating tamoxifen treatment in ER+ breast cancer.

Hypercoagulability State Combined with Post-Treatment Hypofibrinolysis in Invasive Breast Cancer: A Seven-Year Follow-Up Evaluating Disease-Free and Overall Survival

(1) Background: Cancer treatment, including chemotherapy, endocrine therapy, targeted therapy and radiotherapy, has been identified as an important independent risk factor for venous thromboembolism in cancer patients. The aim of the study was to evaluate the effect of adjuvant therapy on the coagulation and fibrinolysis components in invasive breast cancer. (2) Methods: Tissue factor pathway inhibitor (TFPI), tissue factor (TF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) antigen (concentration) and TFPI and TF activities were examined in the blood samples of 60 breast cancer patients treated by adjuvant chemotherapy, endocrine therapy, radiotherapy and immunotherapy. Blood samples were taken 24 h before primary surgery and 8 months after tumour removal surgery. (3) Results: Adjuvant therapy administrated to breast cancer patients significantly increased the concentration of plasma TF, the PAI-1 antigen and also the activity of TFPI and TF, but significantly decreased the level of the t-PA antigen. Combined chemotherapy and endocrine therapy, but not monotherapy, has an important effect on haemostatic biomarker levels. (4) Conclusions: Breast cancer patients receiving adjuvant therapy have an elevated risk of developing a hypercoagulability and hypofibrinolysis state leading to venous thromboembolism.

Impact of Stereotactic Body Radiotherapy on Thrombin Generation and Platelet Aggregation in Patients with Non-Small Cell Lung Cancer

Patients with localized non-small cell lung cancer (NSCLC) considered unfit for surgery are at substantially increased risk of venous thromboembolism. Radiotherapy may further increase this risk. We aim to investigate the impact of stereotactic body radiotherapy (SBRT) on thrombin generation and platelet aggregation. We included 110 patients with localized NSCLC treated with SBRT. Blood samples were obtained prior to SBRT, immediately after SBRT completion, and 4-6 weeks following SBRT. Ex vivo and in vivo thrombin generations were analyzed using a calibrated automated thrombogram and commercial enzyme-linked immunosorbent assays. Platelet aggregation was evaluated using multiple electrode aggregometry. No significant differences were found in ex vivo or in vivo thrombin generation between blood samples before and immediately after SBRT treatment. Platelet aggregation was lower immediately after SBRT than before SBRT (TRAP: P = 0.04 and ASPI: P = 0.02) but remained within the reference interval. SBRT did not affect in vivo and ex vivo thrombin generation or platelet aggregation. SBRT did not cause prothrombotic changes in the coagulation in this study population of SBRT-treated patients with localized NSCLC.