Expert consensus to optimize the treatment of elderly patients with luminal metastatic breast cancer

Real-world experience with CDK4/6 inhibitors in hormone receptor-positive metastatic and recurrent breast cancer: findings from an Asian population

PURPOSE

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) combined with endocrine therapy have demonstrated significant clinical benefits in progression-free and overall survival. This study investigates the outcomes associated with two kinds of CDK4/6i in patients with hormone receptor (HR)-positive metastatic and relapsed breast cancer to inform real-world evidence of treatment strategies.

METHODS

This retrospective study included 340 Taiwanese patients with HR-positive advanced breast cancer from the Taipei Veterans General Hospital, between 2018 and 2023. We analyzed patient characteristics, treatment strategies and outcomes associated with two CDK4/6i. The efficacy of patients who experienced economic burden and interrupted CDK4/6i treatment after 2 years of National Health Insurance (NHI) reimbursement was also investigated.

RESULTS

Patients receiving ribociclib and palbociclib showed no significant differences in age, histology, body mass index(BMI), or pathologic status. The distribution of disease status and endocrine therapy partners was comparable between the two groups. Dose reduction was similar, while patients with palbociclib tended to discontinue CDK4/6i usage, and those with ribociclib tended to switch to the other CDK4/6i or endocrine partners. There was no significant difference in progression-free survival (PFS) between the two CDK4/6i in the first-line setting. Adverse prognostic factors were increasing HER2 IHC score, higher Ki-67 levels, visceral and liver metastasis, prior chemotherapy, and endocrine therapy resistance, while higher BMI, bone-only metastasis, and letrozole treatment were associated with a lower risk of progression. The limited follow-up time in our study was insufficient to assess the outcomes of patients treated with interrupted CDK4/6i for up to two years under the NHI reimbursement policy.

CONCLUSION

Treatment outcomes between the two types of CDK4/6i did not differ significantly, indicating the safety and efficacy of CDK4/6i for the Asian population. Ribociclib and palbociclib showed similar efficacy in PFS in the real-world setting.

Elderly patients with hormone receptor-positive HER2-negative metastatic breast cancer treated with CDK4/6 inhibitors in a multicentre cohort

INTRODUCTION

Cyclin-dependent kinases 4/6 inhibitors (CDK 4/6i) combined with endocrine therapy have become the gold standard in hormone receptor-positive (HR +) HER2-negative (HER2-) metastatic breast cancer (MBC). However, there is a significant lack of data regarding the efficacy and safety of these treatments in elderly patients. We present the results of a real-world data (RWD) cohort stratified by age at treatment initiation (≥ 70 years compared to patients < 70 years).

METHODS

Clinico-pathological data of HR + HER2- MBC patients who were candidates for CDK4/6i therapy between January 2017 and December 2020 at the Institut Català d'Oncologia (Spain) were retrospectively collected. The primary goal was to assess Progression-Free Survival (PFS), Overall Survival (OS), and safety outcomes within this patient population.

RESULTS

A total of 274 patients with MBC who received CDK4/6i treatment were included in the study. Among them, 84 patients (30.8%) were aged ≥ 70 years, with a mean age of 75, while 190 patients (69.2%) were under the age of 70, with a mean age of 55.7 years. The most frequently observed grade 3-4 toxicity was neutropenia, with similar rates in both the < 70 group (43.9%) and the ≥ 70 group (47.9%) (p = 0.728). The median Progression-Free Survival (mPFS) for the first-line CDK4/6i treatment was 22 months (95% CI, 15.4-39.8) in the < 70 group and 20.8 months (95% CI 11.2-NR) in the ≥ 70 group (p = 0.67). Similarly, the median PFS for the second-line CDK4/6i treatment was 10.4 months (95% CI, 7.4-15.1) and 7.1 months (95% CI 4.4-21.3) (p = 0.79), respectively. Median overall survival (mOS) was not reached either for the first- and second-line treatment.

CONCLUSIONS

Our RWD suggests that elderly patients, when compared to those under 70, experience similar survival outcomes and exhibit comparable tolerance for CDK4/6i therapy.

Locoregional Ablative Radiation Therapy for Patients With Breast Cancer Unsuitable for Surgical Resection

PURPOSE

Patients with breast cancer who are unsuitable for surgical resection are typically managed with palliative systemic therapy alone. We report outcomes of 5-fraction ablative radiation therapy for nonresected breast cancers.

METHODS AND MATERIALS

This is a retrospective analysis of an institutional registry of patients with breast cancer who were unsuitable for resection and underwent 35 to 40 Gy/5 fractions to the primary breast tumor or regional lymph nodes from 2014 to 2021. Primary outcomes were cumulative incidence of local failure and grade ≥3 toxicity (Common Terminology Criteria for Adverse Events, version 5.0).

RESULTS

We reviewed 57 patients who received 61 treatment courses (median age of 81 years; range, 38-99). Unresectable tumor (10%), patient refusal (18%), medical inoperability (35%), and metastatic disease (37%) were the causes of not having surgery. Five patients (8%) had previously undergone adjuvant locoregional radiation therapy. Fifty-four percent (n = 33/61) of treatment courses targeted the breast only, 31% (n = 19/61) both the breast and lymph nodes, and 15% (n = 9/61) the lymph nodes only. Sixty-seven percent (n = 35/52) of the courses that targeted the breast were delivered with partial breast irradiation and 33% (n = 17/52) with whole breast radiation therapy (median dose of 25 Gy in 5 fractions) ± simultaneous integrated boost to the primary tumor. Most primary tumors (65%, n = 34/52) and target lymph nodes (61%, n = 17/28) were treated with a dose of 35 Gy in 5 fractions. Most treatments (52%) were delivered with intensity modulated radiation therapy (IMRT). Radiation therapy was delivered daily (20%), every other day (18%), twice weekly (36%), or weekly (26%). The 2-year cumulative incidence of local failure was 11.4% and grade≥3 toxicity was 15.1%. The grade ≥3 toxicity was 6.5% for IMRT treatments, versus 7.7% for non-IMRT treatments targeting partial breast or lymph nodes (hazard ratio, 1.13, P = .92), versus 38.9% for non-IMRT treatments targeting the entire breast (hazard ratio, 6.91, P = .023). All grade ≥3 toxicity cases were radiation dermatitis. No cases of brachial plexopathy were observed.

CONCLUSIONS

Thirty-five to 40 Gy in 5 fractions is a safe and effective breast stereotactic body radiation therapy (SBRT) regimen and may be an attractive option for patients who are not surgical candidates. Highly conformal techniques (ie, IMRT or partial breast irradiation) were associated with a reduced risk of toxicity and should be the preferred treatment approaches.

First- vs second-line CDK 4/6 inhibitor use for patients with hormone receptor positive, human epidermal growth-factor receptor-2 negative, metastatic breast cancer in the real world setting

PURPOSE

To compare CDK4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) in the first- versus second-line setting for treatment of hormone receptor positive (HR+), HER2 negative, metastatic breast cancer (MBC) using real-world evidence.

METHODS

Patients with HR+, HER2 negative MBC, diagnosed between 2/3/2015 and 11/2/2021 and having ≥ 3 months follow-up were identified from the nationwide electronic health record-derived Flatiron Health de-identified database. Treatment cohorts included: (1) first-line ET with a CDK 4/6i (1st-line CDK4/6i) versus (2) first-line ET alone followed by second-line ET with a CDK4/6i (2nd-line CDK4/6i). Differences in baseline characteristics were tested using chi-square tests and two-sample t-tests. Time to third-line therapy, time to start of chemotherapy, and overall survival were compared using Kaplan-Maier method.

RESULTS

The analysis included 2771 patients (2170 1st-line CDK4/6i and 601 2nd-line CDK4/6i). Patients receiving 1st-line CDK4/6i were younger (75% vs 68% < 75 years old, p = 0.0001), less likely uninsured or not having insurance status documented (10% vs. 13%, p = 0.04), of better performance status (50% vs 43% with ECOG 0, p = 0.03), and more likely to have de novo MBC (36% vs. 24%, p < 0.001). Time to third-line therapy (49 vs 22 months, p < 0.001) and time to chemotherapy (68 vs 41 months, p < 0.001) were longer in those receiving first-line CDK4/6i. Overall survival (54 vs 49 months, p = 0.33) was similar between groups.

CONCLUSION

Use of CDK4/6i with first-, vs second-, line ET was associated with longer time to receipt of 3rd-line therapy and longer time to receipt of chemotherapy.

Adjuvant chemotherapy and survival outcomes in older women with HR+/HER2- breast cancer: a propensity score-matched retrospective cohort study using the SEER database

OBJECTIVES

This study aimed to investigate the impact of adjuvant chemotherapy (ACT) on survival outcomes in older women with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer (BC).

DESIGN

A retrospective cohort study using data from the Surveillance, Epidemiology, and End Results database, which contains publicly available information from US cancer registries.

SETTING AND PARTICIPANTS

The study included 45 762 older patients with BC aged over 65 years diagnosed between 2010 and 2015.

METHODS

Patients were divided into two groups based on age: 65-79 years and ≥80 years. Propensity score matching (PSM) was employed to balance clinicopathological characteristics between patients who received ACT and those who did not. Data analysis used the χ2 test and Kaplan-Meier method, with a subgroup analysis conducted to identify potential beneficiaries of ACT.

OUTCOME MEASURES

Overall survival (OS) and cancer-specific survival (CSS).

RESULTS

Due to clinicopathological characteristic imbalances between patients with BC aged 65-79 years and those aged ≥80 years, PSM was used to categorise the population into two groups for analysis: the 65-79 years age group (n=38 128) and the ≥80 years age group (n=7634). Among patients aged 65-79 years, Kaplan-Meier analysis post-PSM indicated that ACT was effective in improving OS (p<0.05, HR=0.80, 95% CI 0.73 to 0.88), particularly in those with advanced disease stages, but did not show a significant benefit in CSS (p=0.09, HR=1.13, 95% CI 0.98 to 1.31). Conversely, for patients aged ≥80 years, ACT did not demonstrate any improvement in OS (p=0.79, HR=1.04, 95% CI 0.79 to 1.36) or CSS (p=0.09, HR=1.46, 95% CI 0.69 to 2.26) after matching. Subgroup analysis also revealed no positive impact on OS and CSS.

CONCLUSIONS

Patients with HR+/HER2- BC ≥80 years of age may be considered exempt from ACT because no benefits were found in terms of OS and CSS.

Real-world treatment patterns and effectiveness of palbociclib plus an aromatase inhibitor in patients with metastatic breast cancer aged 75 years or older

Background

Elderly patients are generally underrepresented in oncology clinical trials; therefore, real-world data are needed to inform clinical management of elderly patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (mBC). This subanalysis of the P-REALITY X study (NCT05361655) evaluated palbociclib treatment patterns and comparative effectiveness of palbociclib plus an aromatase inhibitor (AI) versus an AI alone among patients with HR+/HER2- mBC aged ≥ 75 years treated in routine clinical practice in the United States.

Methods

This retrospective observational cohort study used electronic health records from the Flatiron Health Analytic Database. Palbociclib treatment patterns, overall survival (OS), real-world progression-free survival (rwPFS), and time to chemotherapy (TTC) were evaluated. Three methods were used for comparative analyses: (1) an unadjusted analysis, (2) stabilized inverse probability treatment weighting (sIPTW; primary analysis), and (3) propensity score matching (PSM; sensitivity analysis).

Results

A total of 961 patients aged ≥ 75 years with HR+/HER2- mBC were identified who started palbociclib plus an AI (n = 313) or an AI alone (n = 648) as first-line (1L) therapy between February 2015 and March 2020 (data cut-off: September 30, 2020). Among patients in the palbociclib plus an AI group with a documented palbociclib starting dose (n = 306), approximately 75% started palbociclib at 125 mg/day, and approximately 40% experienced dose adjustment. After sIPTW, patients treated with palbociclib plus an AI versus an AI alone had significantly improved OS (median of 43.0 vs. 32.4 months; hazard ratio [HR], 0.66 [95% confidence interval (CI), 0.51-0.84]; P = 0.0007), rwPFS (median of 20.0 vs. 15.0 months; HR, 0.72 (0.59-0.89); P = 0.0021), and TTC (median of 40.2 vs. 27.4 months; HR, 0.69 [0.55-0.87]; P = 0.0014). These significant improvements in OS, rwPFS, and TTC remained consistent in the unadjusted analysis and after PSM.

Conclusion

This real-world comparative analysis demonstrated that 1L palbociclib plus an AI is associated with improved effectiveness compared with an AI alone among patients with HR+/HER2- mBC aged ≥ 75 years. These findings support palbociclib plus an AI as a standard-of-care 1L treatment for elderly patients with HR+/HER2- mBC.

Narrative Review of Multidisciplinary Management of Central Nervous Involvement in Patients with HER2-Positive Metastatic Breast Cancer: Focus on Elderly Patients

The tumor biology of human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) promotes the development of central nervous system (CNS) metastases, with 25% of patients with HER2-positive BC developing CNS metastases. Furthermore, the incidence of HER2-positive BC brain metastases has increased in the last decades, likely because of the improved survival with targeted therapies and better detection methods. Brain metastases are detrimental to quality of life and survival and represent a challenging clinical problem, particularly in elderly women, who comprise a substantial proportion of patients diagnosed with BC and often have comorbidities or an age-related decline in organ function. Treatment options for patients with BC brain metastases include surgical resection, whole-brain radiation therapy, stereotactic radiosurgery, chemotherapy, and targeted agents. Ideally, local and systemic treatment decisions should be made by a multidisciplinary team, with input from several specialties, based on an individualized prognostic classification. In elderly patients with BC, additional age-associated conditions, such as geriatric syndromes or comorbidities, and the physiologic changes associated with aging, may impact their ability to tolerate cancer therapy and should be considered in the treatment decision-making process. This review describes the treatment options for elderly patients with HER2-positive BC and brain metastases, focusing on the importance of multidisciplinary management, the different points of view from the distinct disciplines, and the role of oncogeriatric and palliative care in this vulnerable patient group.