Proteomic profiling reveals that ESR1 mutations enhance cyclin-dependent kinase signaling

Three quarters of all breast cancers express the estrogen receptor (ER, ESR1 gene), which promotes tumor growth and constitutes a direct target for endocrine therapies. ESR1 mutations have been implicated in therapy resistance in metastatic breast cancer, in particular to aromatase inhibitors. ESR1 mutations promote constitutive ER activity and affect other signaling pathways, allowing cancer cells to proliferate by employing mechanisms within and without direct regulation by the ER. Although subjected to extensive genetic and transcriptomic analyses, understanding of protein alterations remains poorly investigated. Towards this, we employed an integrated mass spectrometry based proteomic approach to profile the protein and phosphoprotein differences in breast cancer cell lines expressing the frequent Y537N and Y537S ER mutations. Global proteome analysis revealed enrichment of mitotic and immune signaling pathways in ER mutant cells, while phosphoprotein analysis evidenced enriched activity of proliferation associated kinases, in particular CDKs and mTOR. Integration of protein expression and phosphorylation data revealed pathway-dependent discrepancies (motility vs proliferation) that were observed at varying degrees across mutant and wt ER cells. Additionally, protein expression and phosphorylation patterns, while under different regulation, still recapitulated the estrogen-independent phenotype of ER mutant cells. Our study is the first proteome-centric characterization of ESR1 mutant models, out of which we confirm estrogen independence of ER mutants and reveal the enrichment of immune signaling pathways at the proteomic level.

Quality of Life in Male Breast Cancer: Prospective Study of the International Male Breast Cancer Program (EORTC10085/TBCRC029/BIG2-07/NABCG)

INTRODUCTION

Prospective data about quality of life (QoL) in men with breast cancer (BC) are lacking. A prospective registry (EORTC10085) of men with all BC stages, including a QoL correlative study, was performed as part of the International Male Breast Cancer Program.

METHODS

Questionnaires at BC diagnosis included the EORTC QLQ-C30 and BR23 (BC specific module), adapted for men. High functioning and global health/QoL scores indicate high functioning levels/high QoL; high symptom-focused measures scores indicate high symptoms/problems levels. EORTC reference data for healthy men and women with BC were used for comparisons.

RESULTS

Of 422 men consenting to participate, 363 were evaluable. Median age was 67 years, and median time between diagnosis and survey was 1.1 months. A total of 114 men (45%) had node-positive early disease, and 28 (8%) had advanced disease. Baseline mean global health status score was 73 (SD: 21), better than in female BC reference data (62, SD: 25). Common symptoms in male BC were fatigue (22, SD: 24), insomnia (21, SD: 28), and pain (16, SD: 23), for which women's mean scores indicated more burdensome symptoms at 33 (SD: 26), 30 (SD: 32), and 29 (SD: 29). Men's mean sexual activity score was 31 (SD: 26), with less sexual activity in older patients or advanced disease.

CONCLUSIONS

QoL and symptom burden in male BC patients appears no worse (and possibly better) than that in female patients. Future analyses on impact of treatment on symptoms and QoL over time, may support tailoring of male BC management.

Receptor conversion and survival in breast cancer liver metastases

BACKGROUND

Breast cancer liver metastases (BCLM) is a common cause of breast cancer-related death. The prognostic and predictive value of receptor expression and St Gallen classification is challenged by receptor status discordance in distant metastases. The aim of this study was to determine the rate of receptor conversion from breast cancer to BCLM and the impact on survival.

METHOD

Patients registered with BCLM in two Swedish national cancer registers were recruited retrospectively. Data on receptor expression in primary breast cancer and BCLM were collected, as well as information about predictive factors for survival. The rate of receptor and subtype conversion was analyzed. A Cox regression model was used to investigate predictive factors for survival.

RESULTS

A cohort of 132 patients with BCLM was identified. Estrogen receptor (ER), progesterone receptor (PgR) and HER2 converted in 17, 33 and 10%, respectively. PgR was lost in BCLM while 8/10 HER2 conversions went from negative to positive. The BC subtype was re-classified in 21% of the BCLM. Median survival after BCLM was 13 months and HER2 amplification was associated with improved survival (HR 0.28 CI 0.085-0.90). The highest predictive value (Harrell´s C-index) was obtained when including both BC and BCLM status.

CONCLUSIONS

Receptor and subtype conversions are common in BCLM, and a liver biopsy is warranted to tailor BCLM treatment. HER2 amplification is associated with improved survival in a BCLM cohort.

Long-term outcomes of implant-based immediate breast reconstruction with and without radiotherapy: a population-based study

BACKGROUND

Radiotherapy (RT) is a risk factor for impaired outcomes after implant-based immediate breast reconstruction (IBR). Large studies including long-term follow-up are relatively scarce. The purpose of this analysis was to assess long-term effects of RT in implant-based IBR, distinguishing between implant removal because of postoperative complications versus patient preference.

METHODS

This population-based cohort study included all patients with breast cancer who underwent implant-based IBR in Stockholm between 2005 and 2015. Data were collected through national registers and medical charts. The main endpoint was implant removal owing to postoperative complications (wound breakdown, infection, bleeding) or patient preference (dissatisfaction, pain, capsular contracture), with or without conversion to autologous reconstruction.

RESULTS

Some 1749 implant-based IBRs in 1687 women were included. Median follow-up was 72 (range 1-198) months. Reconstructions were divided according to receipt of RT: No RT (n = 856, 48.9 per cent), adjuvant RT (n = 749, 42.8 per cent), and previous RT (n = 144, 8.2 per cent). Implant removal occurred after 266 reconstructions (15.2 per cent); 68 (7.9 per cent) in the no RT, 158 (21.1 per cent) in the adjuvant RT, and 40 (27.8 per cent) in the previous RT group. Implant removal was because of postoperative complications in 152 instances (57.1 per cent) and was most common in the first 3 years. This was especially observed in the previous RT group, where 15 of 23 implant removals occurred during the first 6 months. Implant removal owing to patient preference (114 of 266, 42.9 per cent) became more common with increasing follow-up.

CONCLUSION

Implant removal after implant-based IBR is significantly associated with RT. The reason for implant removal shifts over time from postoperative complications to patient preference.

Major surgical postoperative complications and survival in breast cancer: Swedish population-based register study in 57 152 women

BACKGROUND

Postoperative complications may activate prometastatic systemic pathways through tissue damage, wound healing, infection, and inflammation. Postoperative complications are associated with inferior survival in several types of cancer. The aim was to determine the association between postoperative complications and survival in breast cancer.

METHODS

This population-based cohort included women operated for T1-3 N0-3 M0 invasive breast cancer in Sweden from 2008 to 2017. Only major surgical postoperative complications leading to readmission and/or reoperation within 30 days were considered. Main outcomes were overall survival (OS) and breast cancer-specific survival (BCSS). Prospectively collected nationwide register data were used. Multivariable Cox models were adjusted for clinical and socioeconomic confounders and co-morbidity.

RESULTS

Among 57 152 women, major surgical postoperative complications were registered for 1854 patients. Median follow-up was 6.22 (0.09-11.70) years. Overall, 9163 patients died, and 3472 died from breast cancer. Major surgical postoperative complications were more common after mastectomy with or without immediate reconstruction (7.3 and 4.3 per cent respectively) than after breast-conserving surgery (2.3 per cent). Unadjusted 5-year OS and BCSS rates were 82.6 (95 per cent c.i. 80.8 to 84.5) and 92.1 (90.8 to 93.5) per cent respectively for women with a major surgical postoperative complication, and 88.8 (88.6 to 89.1) and 95.0 (94.8 to 95.2) per cent for those without a complication (P < 0.001). After adjustment, all-cause and breast cancer mortality rates remained higher after a major surgical postoperative complication (OS: HR 1.32, 95 per cent c.i. 1.15 to 1.51; BCSS: HR 1.31, 1.04 to 1.65). After stratification for type of breast surgery, this association remained significant only for women who had mastectomy without reconstruction (OS: HR 1.41, 1.20 to 1.66; BCSS: HR 1.36, 1.03 to 1.79).

CONCLUSION

Major surgical postoperative complications are associated with inferior survival, especially after mastectomy. These results underline the importance of surgical de-escalation.

Proteogenomic Workflow Reveals Molecular Phenotypes Related to Breast Cancer Mammographic Appearance

Proteogenomic approaches have enabled the generat̲ion of novel information levels when compared to single omics studies although burdened by extensive experimental efforts. Here, we improved a data-independent acquisition mass spectrometry proteogenomic workflow to reveal distinct molecular features related to mammographic appearances in breast cancer. Our results reveal splicing processes detectable at the protein level and highlight quantitation and pathway complementarity between RNA and protein data. Furthermore, we confirm previously detected enrichments of molecular pathways associated with estrogen receptor-dependent activity and provide novel evidence of epithelial-to-mesenchymal activity in mammography-detected spiculated tumors. Several transcript-protein pairs displayed radically different abundances depending on the overall clinical properties of the tumor. These results demonstrate that there are differentially regulated protein networks in clinically relevant tumor subgroups, which in turn alter both cancer biology and the abundance of biomarker candidates and drug targets.

PD-1 protein and gene expression as prognostic factors in early breast cancer

BACKGROUND

There is a paucity of data on the prognostic value of programmed cell death protein 1 (PD-1) protein and gene expression in early breast cancer (BC) and the present study's aim was to comprehensively investigate it.

METHODS

The study consisted of three parts: a correlative analysis of PD-1 protein and gene expression from an original patient cohort of 564 patients with early BC; a systematic review and trial-level meta-analysis on the association between PD-1 protein expression and disease-free survival/overall survival (OS) in early BC; and a pooled gene expression analysis from publicly available transcriptomic datasets regarding PDCD1 expression.

RESULTS

In the study cohort, PD-1 protein, but not gene expression, was associated with improved OS (HRadj=0.73, 95% CI 0.55 to 0.97, p=0.027 and HRadj=0.88, 95% CI 0.68 to 1.13, p=0.312, respectively). In the trial-level meta-analysis, PD-1 protein expression was not found to be statistically significantly associated with outcomes in the overall population. Finally, in the pooled gene expression analysis, higher PDCD1 expression was associated with better OS in multivariable analysis in the entire population (HRadj=0.89, 95% CI 0.80 to 0.99, p=0.025) and in basal-like tumours.

CONCLUSIONS

PD-1 protein and gene expression seem to be promising prognostic factors in early BC. Standardisation of detection and assessment methods is of utmost importance.

Prognostic potential of automated Ki67 evaluation in breast cancer: different hot spot definitions versus true global score

PURPOSE

The proliferation-associated biomarker Ki67 has potential utility in breast cancer, including aiding decisions based on prognosis, but has unacceptable inter- and intralaboratory variability. The aim of this study was to compare the prognostic potential for Ki67 hot spot scoring and global scoring using different digital image analysis (DIA) platforms.

METHODS

An ER+/HER2- breast cancer cohort (n = 139) with whole slide images of sequential sections stained for hematoxylin-eosin, pancytokeratin and Ki67, was analyzed using two DIA platforms. For hot spot analysis virtual dual staining was applied, aligning pancytokeratin and Ki67 images and 22 hot spot algorithms with different features were designed. For global Ki67 scoring an automated QuPath algorithm was applied on Ki67-stained whole slide images. Clinicopathological data included overall survival (OS) and recurrence-free survival (RFS) along with PAM50 molecular subtypes.

RESULTS

We show significant variations in Ki67 hot spot scoring depending on number of included tumor cells, hot spot size, shape and location. The higher the number of scored tumor cells, the higher the reproducibility of Ki67 proliferation values. Hot spot scoring had greater prognostic potential for RFS in high versus low Ki67 subgroups (hazard ratio (HR) 6.88, CI 2.07-22.87, p = 0.002), compared to global scoring (HR 3.13, CI 1.41-6.96, p = 0.005). Regarding OS, global scoring (HR 7.46, CI 2.46-22.58, p < 0.001) was slightly better than hot spot scoring (HR 6.93, CI 1.61-29.91, p = 0.009). In adjusted multivariate analysis, only global scoring was an independent prognostic marker for both RFS and OS. In addition, global Ki67-based surrogate subtypes reached higher concordance with PAM50 molecular subtype for luminal A and B tumors (66.3% concordance rate, κ = 0.345), than using hot spot scoring (55.8% concordance rate, κ = 0.250).

CONCLUSIONS

We conclude that the automated global Ki67 scoring is feasible and shows clinical validity, which, however, needs to be confirmed in a larger cohort before clinical implementation.

The generalisability of randomised clinical trials: an interim external validity analysis of the ongoing SENOMAC trial in sentinel lymph node-positive breast cancer

Purpose

None of the key randomised trials on the omission of axillary lymph node dissection (ALND) in sentinel lymph-positive breast cancer have reported external validity, even though results indicate selection bias. Our aim was to assess the external validity of the ongoing randomised SENOMAC trial by comparing characteristics of Swedish SENOMAC trial participants with non-included eligible patients registered in the Swedish National Breast Cancer Register (NKBC).

Methods

In the ongoing non-inferiority European SENOMAC trial, clinically node-negative cT1–T3 breast cancer patients with up to two sentinel lymph node macrometastases are randomised to undergo completion ALND or not. Both breast-conserving surgery and mastectomy are eligible interventions. Data from NKBC were extracted for the years 2016 and 2017, and patient and tumour characteristics compared with Swedish trial participants from the same years.

Results

Overall, 306 NKBC cases from non-participating and 847 NKBC cases from participating sites (excluding SENOMAC participants) were compared with 463 SENOMAC trial participants. Patients belonging to the middle age groups (p = 0.015), with smaller tumours (p = 0.013) treated by breast-conserving therapy (50.3 versus 47.1 versus 65.2%, p < 0.001) and less nodal tumour burden (only 1 macrometastasis in 78.8 versus 79.9 versus 87.3%, p = 0.001) were over-represented in the trial population. Time trends indicated, however, that differences may be mitigated over time.

Conclusions

This interim external validity analysis specifically addresses selection mechanisms during an ongoing trial, potentially increasing generalisability by the time full accrual is reached. Similar validity checks should be an integral part of prospective clinical trials.

Trial registration: NCT 02240472, retrospective registration date September 14, 2015 after trial initiation on January 31, 2015

Re-testing of predictive biomarkers on surgical breast cancer specimens is clinically relevant

PURPOSE

The accuracy of predictive and prognostic biomarker assessment in breast cancer is paramount since these guide therapy decisions. The aim was to investigate the concordance of biomarkers and immunohistochemical (IHC)-based surrogate tumor subtypes between core needle biopsies (CNB) and consecutive paired breast cancer surgical resections.

METHODS

This retrospective study comprised two cohorts of patients with primary breast cancer diagnosed between 2016 and 2017: one treated with primary surgery (n = 526) and one with neoadjuvant chemotherapy (NAC) (n = 216). The agreement between preoperative CNB and paired tumor specimens regarding the assessment of biomarkers and surrogate tumor subtypes was evaluated in both cohorts.

RESULTS

In the primary surgery cohort, the concordance rates and kappa values for estrogen receptor (ER), progesterone receptor (PR) and Ki67 were 98.6% (κ = 0.917), 89.3% (κ = 0.725) and 78.8% (κ = 0.529), respectively. Importantly, human epidermal growth factor receptor 2 (HER2) IHC assessment showed only moderate agreement (κ = 0.462). HER2 status combining IHC and in situ hybridization was discordant in 3.6% of cases, potentially impacting on indications for HER2-targeted therapy. The concordance rate for IHC-based surrogate tumor subtypes was only 73.2-78.3%. Generally lower concordance rates for ER, PR and HER2 were observed in the NAC cohort. Here, HER2 status was discordant in 7.4%.

CONCLUSIONS

The agreement of HER2 and Ki67 between CNB and paired surgical specimen in primary breast cancer is insufficient. Limited agreement of surrogate tumor subtypes indicates a significant clinical value of biomarker re-testing on surgical specimens.