Prognostic value of estrogen receptor (ER) and progesterone receptor (PR) expression levels in <i>de novo</i> and recurrent HR+/HER2- metastatic breast cancer (MBC) patients (pts) treated with CDK4/6 inhibitors (CDK4/6i) and endocrine therapy (ET): R

e13078 Background: Differences in clinical outcomes have been observed between pts with de novo (dnMBC) and recurrent metastatic breast cancer (rMBC). We investigated the prognostic value of ER and PR expression levels in primary tumors in HR+/HER2 dnMBC and rMBC treated with CDK4/6i and ET. Methods: We retrospectively analyzed clinical data of HR+/HER2- MBC pts administered palbociclib (PAL), ribociclib (RIB) or abemaciclib (ABM) combined with first- or second-line ET. Duration of CDK4/6i treatment (dCDKi), second progression free survival (PFS2), and overall survival (OS) were analyzed using R statistical software (version 4.4.1). Results: A total of 2120 patients (pts) from 16 Polish cancer centers treated between Sep 2017 and Dec 2024 were analyzed: 1120 (52.8%) and 1000 (47.2%) with rMBC and dnMBC, respectively; mean age 62±12 years, luminal A and B cancers 784 (41.8%) and 1093 (58.2%) cases, respectively. ER expression of 0-10%, 11-66%, and 67-100% was found in 36 (1.7%), 163 (7.7%), and 1921 (90.6%) cases and respective PR expression in 524 (25.0%), 510 (24.4%), and 1059 (50.6%) cases. 707 pts (33.3%) received PAL, 1008 (47.5%) RIB, and 405 (19.1%) ABM; 1273 (60%) received aromatase inhibitor and 847 (40%) fulvetrant. The median follow-up was 31.4 months. Cancer phenotype and PR expression level were prognostic in dnMBC and rMBC, whereas ER expression level only in dnMBC (Table 1). Conclusions: Our results indicate biological differences between dnMBC and rMBC that may impact treatment efficacy. These differences may be due to intrinsic or acquired resistance and support the need for repeat biopsy for rMBC. dnMBC Expression (%) dCDKi PFS2 OS ER 0-6667-100 14.4 (8.5-20.8)23.1 (19.8-25.4)p=0.004 26.4 (16.5-40.5)38.1 (36.4-42)p=0.006 33.1 (20.2-RN)52.3 (45.6-66.8)p=0.003 PR 0-1011-6667-100 16.9 (13.4-22.4)18.0 (15.1-24.3)26.4 (22.9-35.4)p&lt;0.001 29.8 (24.5-39.6)31.9 (29.2-39)43.8 (38.5-55.4)p&lt;0.001 41.2 (34.5-66.8)46.8 (41.3-NR)58.4 (47.6-85.5)p&lt;0.001 Phenotype luminal Aluminal B 28.6 (23.3-35.4)18.4 (16.1-23.0)p&lt;0.001 47 (40.5-63.5)33.1 (30.1-37.3)p&lt;0.001 64.4 (47.6-NR)44.3 (39.8-54.2)p&lt;0.001 rMBC Expression (%) dCDKi PFS2 OS ER 0-6667-100 13.9 (10.4-18.3)16.2 (14.8-18.7)p=0.23 32.7 (22.2-46.4)30.7 (28.5-33.5)p=0.66 37.2 (27.9-68.6)40.8 (38.2-47.1)p=0.5 PR 0-1011-6667-100 13.0 (9.4-15.1)16.1 (13.0-19.7)20.0 (17.2-22.9)p&lt;0.001 22.2 (19.5-28.6)35.2 (31.7-40.5)32.3 (27.8-39.6)p&lt;0.001 29.7 (24.4-37.2)47.6 (40-87.4)45.4 (38.8-68.9)p&lt;0.001 Phenotype luminal Aluminal B 19.3 (15.9-22.0)11.4 (9.4-14.1)p&lt;0.001 33.6 (29.3-40.7)22.2 (20-28.3)p&lt;0.001 47.6 (38.8-61.6)29.8 (25.4-34.4)p&lt;0.001 RN, not reached; dCDKi, PFS2, OS are in months.

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Publication Details

Journal
Journal of Clinical Oncology
Published
2025-05-28
DOI
https://doi.org/10.1200/jco.2025.43.16_suppl.e13078
Primary Topic
Advanced Breast Cancer Therapies
Type
article
Field-Weighted Citation Impact
0.00
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article

Prognostic value of estrogen receptor (ER) and progesterone receptor (PR) expression levels in de novo and recurrent HR+/HER2- metastatic breast cancer (MBC) patients (pts) treated with CDK4/6 inhibitors (CDK4/6i) and endocrine therapy (ET): R

Bartłomiej Tomasik, Joanna Kiszka, Joanna Streb, Katarzyna Soter et al.
Journal of Clinical Oncology
Advanced Breast Cancer Therapies
article

Prognostic value of estrogen receptor (ER) and progesterone receptor (PR) expression levels in de novo and recurrent HR+/HER2- metastatic breast cancer (MBC) patients (pts) treated with CDK4/6 inhibitors (CDK4/6i) and endocrine therapy (ET): R

Bartłomiej Tomasik, Joanna Kiszka, Joanna Streb, Katarzyna Soter, Iwona Danielewicz, Katarzyna Pogoda, Justyna Żubrowska, Michał Bieńkowski, Aleksandra Łacko, Bartosz Szymanowski, Renata Duchnowska, Maria Litwiniuk, Barbara Radecka, Aleksandra Grela-Wojewoda, Karolina Winsko-Szczęsnowicz, Ewa Kalinka‐Warzocha, Tomasz Lewandowski, Marek Szwiec, A Balata, Agnieszka Kowalewska-Felczak
article en

Abstract

e13078 Background: Differences in clinical outcomes have been observed between pts with de novo (dnMBC) and recurrent metastatic breast cancer (rMBC). We investigated the prognostic value of ER and PR expression levels in primary tumors in HR+/HER2 dnMBC and rMBC treated with CDK4/6i and ET. Methods: We retrospectively analyzed clinical data of HR+/HER2- MBC pts administered palbociclib (PAL), ribociclib (RIB) or abemaciclib (ABM) combined with first- or second-line ET. Duration of CDK4/6i treatment (dCDKi), second progression free survival (PFS2), and overall survival (OS) were analyzed using R statistical software (version 4.4.1). Results: A total of 2120 patients (pts) from 16 Polish cancer centers treated between Sep 2017 and Dec 2024 were analyzed: 1120 (52.8%) and 1000 (47.2%) with rMBC and dnMBC, respectively; mean age 62±12 years, luminal A and B cancers 784 (41.8%) and 1093 (58.2%) cases, respectively. ER expression of 0-10%, 11-66%, and 67-100% was found in 36 (1.7%), 163 (7.7%), and 1921 (90.6%) cases and respective PR expression in 524 (25.0%), 510 (24.4%), and 1059 (50.6%) cases. 707 pts (33.3%) received PAL, 1008 (47.5%) RIB, and 405 (19.1%) ABM; 1273 (60%) received aromatase inhibitor and 847 (40%) fulvetrant. The median follow-up was 31.4 months. Cancer phenotype and PR expression level were prognostic in dnMBC and rMBC, whereas ER expression level only in dnMBC (Table 1). Conclusions: Our results indicate biological differences between dnMBC and rMBC that may impact treatment efficacy. These differences may be due to intrinsic or acquired resistance and support the need for repeat biopsy for rMBC. dnMBC Expression (%) dCDKi PFS2 OS ER 0-6667-100 14.4 (8.5-20.8)23.1 (19.8-25.4)p=0.004 26.4 (16.5-40.5)38.1 (36.4-42)p=0.006 33.1 (20.2-RN)52.3 (45.6-66.8)p=0.003 PR 0-1011-6667-100 16.9 (13.4-22.4)18.0 (15.1-24.3)26.4 (22.9-35.4)p&lt;0.001 29.8 (24.5-39.6)31.9 (29.2-39)43.8 (38.5-55.4)p&lt;0.001 41.2 (34.5-66.8)46.8 (41.3-NR)58.4 (47.6-85.5)p&lt;0.001 Phenotype luminal Aluminal B 28.6 (23.3-35.4)18.4 (16.1-23.0)p&lt;0.001 47 (40.5-63.5)33.1 (30.1-37.3)p&lt;0.001 64.4 (47.6-NR)44.3 (39.8-54.2)p&lt;0.001 rMBC Expression (%) dCDKi PFS2 OS ER 0-6667-100 13.9 (10.4-18.3)16.2 (14.8-18.7)p=0.23 32.7 (22.2-46.4)30.7 (28.5-33.5)p=0.66 37.2 (27.9-68.6)40.8 (38.2-47.1)p=0.5 PR 0-1011-6667-100 13.0 (9.4-15.1)16.1 (13.0-19.7)20.0 (17.2-22.9)p&lt;0.001 22.2 (19.5-28.6)35.2 (31.7-40.5)32.3 (27.8-39.6)p&lt;0.001 29.7 (24.4-37.2)47.6 (40-87.4)45.4 (38.8-68.9)p&lt;0.001 Phenotype luminal Aluminal B 19.3 (15.9-22.0)11.4 (9.4-14.1)p&lt;0.001 33.6 (29.3-40.7)22.2 (20-28.3)p&lt;0.001 47.6 (38.8-61.6)29.8 (25.4-34.4)p&lt;0.001 RN, not reached; dCDKi, PFS2, OS are in months.

Journal of Clinical OncologyVol. 43(16_suppl)
Poznan University of Medical Sciences (PL), Jagiellonian University (PL), Medical University of Białystok (PL), University of Opole (PL), Wojskowy Instytut Medycyny Lotniczej (PL), Holy Cross University (PL), Gdynia Maritime University (PL), Wroclaw Research Centre EIT+ (Poland) (PL), Polish Mother’s Memorial Hospital Research Institute (PL), The Maria Sklodowska-Curie National Research Institute of Oncology (PL), University of Zielona Góra (PL), University of Warmia and Mazury in Olsztyn (PL), Gdańsk Medical University (PL)
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Advanced Breast Cancer Therapies
DOISourceOpenAlex
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