Clinical Outcomes with First-line Endocrine Therapy or Chemotherapy in Postmenopausal HR+/HER2- Metastatic Breast Cancer

Overall Survival With Palbociclib and Aromatase Inhibitor Versus Aromatase Inhibitor Alone in Older Patients With HR+/HER2- Metastatic Breast Cancer

INTRODUCTION

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) in combination with endocrine therapy are the current standard of care for first-line (1L) treatment of hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (mBC). To investigate the effectiveness of palbociclib, the first-in-class CDK4/6i, plus an aromatase inhibitor (AI) in older patients, we compared overall survival (OS) in a Medicare population treated with 1L palbociclib + AI versus an AI alone.

METHODS

Patients aged ≥ 65 years who were diagnosed with de novo HR+/HER2- mBC from 2015 to 2019 were identified from the Surveillance, Epidemiology, and End Results (SEER)-linked Medicare database and were eligible if they initiated 1L palbociclib + AI or an AI alone. The primary endpoint was OS. Stabilized inverse probability of treatment weighting (sIPTW) was used to balance baseline patient characteristics.

RESULTS

Of 779 eligible patients, 296 received palbociclib + AI and 483 received AI alone as 1L treatment. After sIPTW, the median follow-up was 23.1 months with palbociclib + AI and 18.2 months with AI alone. Adjusted median OS was longer with palbociclib + AI versus AI alone (sIPTW: 37.6 vs. 25.5 months, HR = 0.73 [95% CI, 0.59-0.91]). In multivariable Cox proportional hazards regression, patients treated with palbociclib + AI versus AI alone had a 39% lower risk of death (HR = 0.61 [95% CI, 0.48-0.77]).

CONCLUSION

In routine US clinical practice, palbociclib + AI was associated with significantly prolonged OS versus AI alone in 1L treatment of patients aged ≥ 65 years with de novo HR+/HER2- mBC, adding to the growing body of evidence on the survival benefit of palbociclib + AI in this patient population.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06086340.

Comparison of endocrine therapy and chemotherapy as different systemic treatment modes for metastatic luminal HER2-negative breast cancer patients —A retrospective study

Purpose

The purpose of this study was to evaluate endocrine therapy and chemotherapy for first-line, maintenance, and second-line treatment of hormone receptor-positive HER-2-negative metastatic breast cancer (HR+HER-2-MBC) and the relationship between different treatment options and survival.

Patients and methods

The patients included in this study were all diagnosed with metastatic breast cancer (MBC) at Shandong Cancer Hospital from January 2013 to June 2017. Of the 951 patients with MBC, 307 patients with HR+HER-2-MBC were included in the analysis. The progression-free survival (PFS) and overall survival (OS) of the various treatment modes were evaluated using Kaplan–Meier analysis and the log-rank test. Because of the imbalance in data, we used the synthetic minority oversampling technique (SMOTE) algorithm to oversample the data to increase the balanced amount of data.

Results

This retrospective study included 307 patients with HR+HER-2-MBC; 246 patients (80.13%) and 61 patients (19.87%) were treated with first-line chemotherapy and first-line endocrine therapy, respectively. First-line endocrine therapy was better than first-line chemotherapy in terms of PFS and OS. After adjusting for known prognostic factors, patients receiving first-line chemotherapy had poorer PFS and OS outcomes than patients receiving first-line endocrine therapy. In terms of maintenance treatment, the endocrine therapy-endocrine therapy maintenance mode achieved the best prognosis, followed by the chemotherapy-endocrine therapy maintenance mode and chemotherapy-chemotherapy maintenance mode, and the no-maintenance mode has resulted in the worst prognosis. In terms of first-line/second-line treatment, the endocrine therapy/endocrine therapy mode achieved the best prognosis, while the chemotherapy/chemotherapy mode resulted in the worst prognosis. The chemotherapy/endocrine therapy mode achieved a better prognosis than the endocrine therapy/chemotherapy mode. There were no significant differences in the KI-67 index (<15%/15-30%/≥30%) among the patients receiving first-line treatment modes, maintenance treatment modes, and first-line/second-line treatment modes. There was no statistical evidence in this study to support that the KI-67 index affected survival. However, in the first-line/second-line model, after SMOTE, we could see that KI-67 ≥ 30% had a poor prognosis.

Conclusions

Different treatment modes for HR+HER-2-MBC were analyzed. Endocrine therapy achieved better PFS and OS outcomes than chemotherapy. Endocrine therapy should be the first choice for first-line, maintenance, and second-line treatment of HR+HER-2-MBC.