Treatment decisions and the impact of adverse events before and during extended endocrine therapy in postmenopausal early breast cancer

Selection of Patients With Early-Stage Breast Cancer for Extended Endocrine Therapy: A Secondary Analysis of the IDEAL Randomized Clinical Trial

Importance

There is a need for biomarkers that predict late recurrence risk and extended endocrine therapy (EET) benefit among patients with early-stage breast cancer (EBC). MammaPrint, a 70-gene expression risk-of-recurrence assay, has been found to project significant EET benefit in patients with assay-classified low-risk tumors.

Objective

To determine the test's utility in identifying which patients with EBC in the IDEAL (Investigation on the Duration of Extended Adjuvant Letrozole) trial could benefit from 5-year vs 2.5-year letrozole treatment.

Design, Setting, and Participants

This secondary analysis of the IDEAL randomized clinical trial evaluated postmenopausal women with hormone receptor-positive EBC who were assigned to either 2.5 or 5 years of EET, with 10 years of follow-up after randomization. A 70-gene assay was used to classify tumors as high, low, or ultralow risk. Adverse event (AE) frequency and treatment compliance were evaluated. Statistical analyses were performed from April 2022 to September 2024.

Interventions

After 5 years of endocrine therapy, patients were randomized to 2.5 or 5 years of EET with letrozole.

Main Outcomes and Measures

Primary end point was distant recurrence (DR). Cox proportional hazard regression models and likelihood ratios tested the interaction between treatment and gene expression assay.

Results

Among 515 women included (mean [SD] age at randomization, 59.9 [9.5] years), 265 were in the 2.5-year treatment arm and 250 in the 5-year treatment arm. Of these patients, 223 (43.3%) patients with 70-gene assay-classified low-risk tumors had a significant absolute benefit of 10.1% for DR (hazard ratio, 0.32; 95% CI, 0.12-0.87; P = .03). Treatment interaction was not significant for DR. Of patients with either 70-gene assay-classified high-risk tumors (259 [50.3%]) or ultralow risk tumors (33 [6.4%]), 5 years vs 2.5 years of EET was not associated with improved benefit for DR. As expected, rates of AEs and treatment discontinuation were comparable among the different 70-gene assay risk groups in each treatment arm.

Conclusions and Relevance

This secondary analysis of the IDEAL trial found that the 70-gene assay identified patients with low-risk tumors who could benefit from 5-year vs 2.5-year EET. These findings suggest that this gene expression assay could go beyond guiding neoadjuvant and adjuvant chemotherapy decisions to informing the optimal duration of adjuvant endocrine therapy.

Trial Registration

EU Clinical Trials Register Eudra CT: 2006-003958-16.

Association between endocrine therapy and cognitive decline in older women with early breast cancer: Findings from the prospective CLIMB study

INTRODUCTION

Studies investigating the long-term effects of breast cancer treatment on cognition in older women with breast cancer are lacking, even though preserving cognition is highly valued by the older population. Specifically, concerns have been raised regarding the detrimental effects of endocrine therapy (ET) on cognition. Therefore, we investigated cognitive functioning over time and predictors for cognitive decline in older women treated for early breast cancer.

METHODS

We prospectively enrolled Dutch women aged ≥70 years with stage I-III breast cancer in the observational CLIMB study. The Mini-Mental State Examination (MMSE) was performed before ET initiation and after 9, 15 and 27 months. Longitudinal MMSE scores were analysed and stratified for ET. Linear mixed models were used to identify possible predictors of cognitive decline.

RESULTS

Among the 273 participants, the mean age was 76 years (standard deviation 5), and 48% received ET. The mean baseline MMSE score was 28.2 (standard deviation 1.9). Cognition did not decline to clinically meaningful differences, irrespective of ET. MMSE scores of women with pre-treatment cognitive impairments slightly improved over time (significant interaction terms) in the entire cohort and in women receiving ET. High age, low educational level and impaired mobility were independently associated with declining MMSE scores over time, although the declines were not clinically meaningful.

CONCLUSION

Cognition of older women with early breast cancer did not decline in the first two years after treatment initiation, irrespective of ET. Our findings suggest that the fear of declining cognition does not justify the de-escalation of breast cancer treatment in older women.

Influence of Glutathione-S-Transferase A1*B Allele on the Metabolism of the Aromatase Inhibitor, Exemestane, in Human Liver Cytosols and in Patients Treated With Exemestane

Exemestane (EXE) is used to treat postmenopausal women diagnosed with estrogen receptor positive (ER+) breast cancer. A major mode of metabolism of EXE and its active metabolite, 17β-dihydroexemestane, is via glutathionylation by glutathione-S-transferase (GST) enzymes. The goal of the present study was to investigate the effects of genetic variation in EXE-metabolizing GST enzymes on overall EXE metabolism. Ex vivo assays examining human liver cytosols from 75 subjects revealed the GSTA1 *B*B genotype was associated with significant decreases in S-(androsta-1,4-diene-3,17-dion-6α-ylmethyl)-L-glutathione (P = 0.034) and S-(androsta-1,4-diene-17β-ol-3-on-6α-ylmethyl)-L-gutathione (P = 0.014) formation. In the plasma of 68 ER+ breast cancer patients treated with EXE, the GSTA1 *B*B genotype was associated with significant decreases in both EXE-cysteine (cys) (29%, P = 0.0056) and 17β-DHE-cys (34%, P = 0.032) as compared with patients with the GSTA1*A*A genotype, with significant decreases in EXE-cys (Ptrend = 0.0067) and 17β-DHE-cys (Ptrend = 0.028) observed in patients with increasing numbers of the GSTA1*B allele. A near-significant (Ptrend = 0.060) trend was also observed for urinary EXE-cys levels from the same patients. In contrast, plasma and urinary 17β-DHE-Gluc levels were significantly increased (36%, P = 0.00097 and 52%, P = 0.0089; respectively) in patients with the GSTA1 *B*B genotype. No significant correlations were observed between the GSTM1 null genotype and EXE metabolite levels. These data suggest that the GSTA1*B allele is associated with interindividual differences in EXE metabolism and may play a role in interindividual variability in overall response to EXE. SIGNIFICANCE STATEMENT: The present study is the first comprehensive pharmacogenomic investigation examining the role of genetic variability in GST enzymes on exemestane metabolism. The GSTA1 *B*B genotype was found to contribute to interindividual differences in the metabolism of EXE both ex vivo and in clinical samples from patients taking EXE for the treatment of ER+ breast cancer. Since GSTA1 is a major hepatic phase II metabolizing enzyme in EXE metabolism, the GSTA1*B allele may be an important biomarker for treatment outcomes and toxicities.

Women with breast cancer's perceptions of nurse-led telephone-based motivational interviewing consultations to enhance adherence to adjuvant endocrine therapy: a qualitative study

BACKGROUND

Daily adjuvant endocrine therapy (AET) for 5 or 10 years is the standard of care for women diagnosed with non-metastatic hormone receptor-positive breast cancer. However, many women experience AET-related issues that may hamper quality of life and adherence. Here, we aimed to describe women's perceptions of motivational interviewing (MI)-guided consultations delivered by a trained nurse navigator over the telephone to enhance AET adherence.

METHODS

Eighteen women who were first prescribed AET for non-metastatic breast cancer in the last 5 years, who self-reported AET-related issues, and who participated in at least two MI-guided consultations over a year were interviewed about their perceptions of the intervention, using a semi-structured interview guide. Audio recordings were transcribed verbatim and analyzed using a thematic analysis approach.

RESULTS

Three main themes emerged from the data about women's perceptions on MI-guided consultations. These consultations were described as (1) a person-centred experience, (2) providing key information about AET, and (3) supportive of present and future AET experience, by contributing to AET side-effect management, motivation, adherence, calming negative emotions, improving well-being and self-esteem, and making women to feel empowered.

CONCLUSIONS

Nurse-led telephone-based MI-guided consultations about AET were found to respond to participants' needs and to enhance participants' perceptions of being informed and being supported in experiencing various facets of AET. Telephone-based consultations for AET are perceived as a promising strategy in an increasing virtual care world.

The Patient's Voice: Adherence, Symptoms, and Distress Related to Adjuvant Endocrine Therapy After Breast Cancer

BACKGROUND

While adjuvant endocrine therapy (AET) for early-stage, hormone-sensitive breast cancer confers a 40-50% reduction in recurrence risk, adherence to AET is suboptimal, and no efficacious interventions exist to improve adherence. A qualitative study was conducted to understand patient experiences on AET, motivators and barriers to adherence, side effects, and distress, with the goal of developing a patient-centered, evidence-based intervention.

METHOD

From November 2017 to November 2018, female patients with early-stage, hormone receptor-positive breast cancer taking AET were recruited. Patients with low and high medication adherence of varying ages, levels of distress, and years taking AET were purposefully enrolled. In-depth semi-structured interviews were conducted, audio recorded, and transcribed. Study staff created a thematic framework, and three independent researchers coded interviews using NVivo 11, achieving high inter-coder agreement (Kappa = .96).

RESULTS

Thirty interviews were conducted with patients who were, on average, 55.13 years old (SD = 12.37) and had been taking AET for a mean of 1.76 years (SD = 0.75). The sample was stratified by adherence level (low = 20; high = 10). Recurrent themes related to adherence included a commitment to AET to prevent recurrence despite distressing side effects, lack of strategies to cope with symptoms and distress, and desire for emotional support from others taking AET. Patients were highly accepting of a proposed psychosocial intervention to manage AET.

CONCLUSION

Patients are committed to taking AET to prevent breast cancer recurrence, but need and desire psychosocial support and skills training. Themes from this study are modifiable targets for a psychosocial, evidence-based intervention to promote adherence, coping with side effects, and distress management.

Breast Cancer Index Predicts Extended Endocrine Benefit to Individualize Selection of Patients with HR+ Early-stage Breast Cancer for 10 Years of Endocrine Therapy

PURPOSE

Individualized selection of patients with early-stage hormone receptor-positive (HR⁺) breast cancer for extended endocrine therapy (EET) is required to balance modest gains in outcome with toxicities of prolonged use. This study examined the Breast Cancer Index [BCI; HOXB13/IL17BR ratio (H/I)] as a predictive biomarker of EET benefit in patients from the Investigation on the Duration of Extended Adjuvant Letrozole trial.

EXPERIMENTAL DESIGN

BCI was tested in primary tumor specimens from 908 patients randomized to receive 2.5 versus 5 years of extended letrozole. The primary endpoint was recurrence-free interval. Cox models and likelihood ratios tested the interaction between EET and BCI (H/I).

RESULTS

BCI (H/I)-high significantly predicted benefit from extended letrozole in the overall cohort [HR 0.42; 95% confidence interval (CI), 0.21-0.84; P = 0.011] and any aromatase inhibitor subset [HR 0.34; 95% CI, 0.16-0.73; P = 0.004), whereas BCI (H/I)-low patients did not derive significant benefit (HR 0.95; 95% CI, 0.58-1.56; P = 0.84 and HR 0.90; 95% CI, 0.53-1.55; P = 0.71, respectively) treatment to biomarker interaction was significant (P = 0.045, P = 0.025, respectively). BCI identified approximately 50% of patients with clinically high-risk disease that did not benefit, and with clinically low-risk disease that derived significant benefit, from an additional 2.5 years of EET.

CONCLUSIONS

BCI (H/I) predicted preferential benefit from 5 versus 2.5 years of EET and identified patients with improved outcomes from completing 10 years of adjuvant endocrine therapy. Findings expand the clinical utility of BCI (H/I) to a broader range of patients and beyond prognostic risk factors as a predictive endocrine response biomarker for early-stage HR⁺ breast cancer.

Overestimation of Late Distant Recurrences in High-Risk Patients With ER-Positive Breast Cancer: Validity and Accuracy of the CTS5 Risk Score in the TEAM and IDEAL Trials

PURPOSE

Most distant recurrences (DRs) in women with hormone receptor-positive breast cancer occur after 5 years from diagnosis. The Clinical Treatment Score post-5 years (CTS5) estimates DRs after 5 years of adjuvant endocrine therapy (AET). The aim of this study was to externally validate the CTS5 as a prognostic/predictive tool.

METHODS

The CTS5 categorizes patients who have been disease free for 5 years into low, intermediate, and high risk and calculates an absolute risk for developing DRs between 5 and 10 years. Discrimination and calibration were assessed using data from the TEAM and IDEAL trials. The predictive value of the CTS5 was tested with data from the IDEAL trial.

RESULTS

A total of 5,895 patients from the TEAM trial and 1,591 patients from the IDEAL trial were included. When assessing the CTS5 discrimination, significantly more DRs were found at 10 years after diagnosis in the CTS5 high- and intermediate-risk groups than in the low-risk group (hazard ratio, 5.7 [95% CI, 3.6 to 8.8] and 2.8 [95% CI, 1.7 to 4.4], respectively). In low- and intermediate-risk patients, the CTS5-predicted DR rates were higher, although not statistically significantly so, than observed rates. However, in high-risk patients, the CTS5-predicted DR rates were significantly higher than observed rates (29% v 19%, respectively; P < .001). The CTS5 was not predictive for extended AET duration.

CONCLUSION

The CTS5 score as applied to patients treated in the TEAM and IDEAL cohorts discriminates between risk categories but overestimates the risk of late DRs in high-risk patients. Therefore, the numerical risk assessment from the CTS5 calculator in its current form should be interpreted with caution when used in daily clinical practice, particularly in high-risk patients.