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Characterizing of Breast Cancer translational PEARL clinical trial

ABSTRACT: Introduction In HR+/HER2- metastatic breast cancer (MBC) is imperative to identify patients who respond poorly to CDK4/6i and to discover therapeutic targets to reverse this resistance. Non-luminal breast cancer subtype and high levels of CCNE1 are candidate biomarkers in this setting but further validation is needed. Methods We performed mRNA gene expression profiling and correlation with progression-free-survival (PFS) on 455 tumor samples included in the phase III PEARL study, that assigned HR+/HER2- MBC patients to receive palbociclib+ET vs capecitabine. ER+/HER2- breast cancer cell lines were used to generate and characterize resistance to palbociclib+ET. Results Non-luminal subtype was more prevalent in metastatic (14%) than in primary tumor samples (4%). Patients with non-luminal tumors had median PFS of 2.4months (m) with palbociclib+ET and 9.3m with capecitabine; HR:4.16, adjusted p-value<0.0001. Tumors with high CCNE1 expression (above median) had also worse median PFS with palbociclib+ET (6.2m) than with capecitabine (9.3m); HR:1.55, adjusted p-value=0.0036. In patients refractory to palbociclib+ET (PFS in the lower quartile) we found higher levels of Polo Like Kinase 1 (PLK1). In an independent data set (PALOMA3), tumors with high PLK1 show worse median PFS than those with low PLK1 expression under palbociclib+ET treatment. In ER+/HER2- cell line models we show that PLK1 inhibition reverses resistance to palbociclib+ET. Conclusion We confirm the association of non-luminal subtype and CCNE1 with resistance to CDK4/6i+ET in HR+ MBC. High levels of PLK1 mRNA identify patients with poor response to palbociclib, suggesting PLK1 could also play a role in the setting of resistance to CDK4/6i.

ORGANISM(S): Homo sapiens

PROVIDER: GSE223700 | GEO | 2023/01/26

REPOSITORIES: GEO

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Project description:There is clinical need to predict sensitivity of metastatic hormone receptor-positive and HER2-negative (HR+/HER2-) breast cancer to endocrine therapy, and targeted RNA sequencing (RNAseq) offers diagnostic potential to measure both transcriptional activity and functional mutation. We developed the SET ER/PR index to measure gene expression microarray probe sets that were correlated with hormone receptors (ESR1 and PGR) and robust to pre-analytical and analytical influences. We tested SET ER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SETER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SET ER/PR index in metastatic samples predicted longer progression-free (PFS) and overall survival (OS) when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.534, 95% CI 0.299 to 0.955, p = 0.035; OS: HR 0.315, 95% CI 0.157 to 0.631, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1% to 98% of ESR1 transcripts (all had high SETER/PR index). A signature based on probe sets with good pre-analytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SET ER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript. We tested SET ER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SET ER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SET ER/PR index in metastatic samples predicted longer progression-free (PFS) and overall survival (OS) when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.485, 95% CI 0.265 to 0.889, p = 0.019; OS: HR 0.314, 95% CI 0.155 to 0.637, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1% to 98% of ESR1 transcripts (all had high SET ER/PR index). A signature based on probe sets with good pre-analytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SET ER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript.

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Characterizing of Breast Cancer translational PEARL clinical trial

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