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Background: Gene expression (GEX) signatures in breast cancer provide prognostic information, but little is known about their predictive value for tamoxifen treatment. We examined the tamoxifen-predictive value and prognostic effects of different GEX signatures in premenopausal women with early breast cancer., Methods: RNA from formalin-fixed paraffin-embedded tumor tissue from premenopausal women randomized between two years of tamoxifen treatment and no systemic treatment was extracted and successfully subjected to GEX profiling (n = 437, NanoString Breast Cancer 360™ panel). The median follow-up periods for a recurrence-free interval (RFi) and overall survival (OS) were 28 and 33 years, respectively. Associations between GEX signatures and tamoxifen effect were assessed in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+ /HER2-) tumors using Kaplan-Meier estimates and Cox regression. The prognostic effects of GEX signatures were studied in the entire cohort. False discovery rate adjustments (q-values) were applied to account for multiple hypothesis testing., Results: In patients with ER+/HER2- tumors, FOXA1 expression below the median was associated with an improved effect of tamoxifen after 10 years with regard to RFi (hazard ratio [HR] FOXA1(high)  = 1.04, 95% CI = 0.61-1.76, HR FOXA1(low)  = 0.30, 95% CI = 0.14-0.67, q interaction  = 0.0013), and a resembling trend was observed for AR (HR AR(high)  = 1.15, 95% CI = 0.60-2.20, HR AR(low)  = 0.42, 95% CI = 0.24-0.75, q interaction  = 0.87). Similar patterns were observed for OS. Tamoxifen was in the same subgroup most beneficial for RFi in patients with low ESR1 expression (HR RFi ESR1(high)  = 0.76, 95% CI = 0.43-1.35, HR RFi, ESR1(low)  = 0.56, 95% CI = 0.29-1.06, q interaction  = 0.37). Irrespective of molecular subtype, higher levels of ESR1, Mast cells, and PGR on a continuous scale were correlated with improved 10 years RFi (HR ESR1  = 0.80, 95% CI = 0.69-0.92, q = 0.005; HR Mast cells  = 0.74, 95% CI = 0.65-0.85, q < 0.0001; and HR PGR  = 0.78, 95% CI = 0.68-0.89, q = 0.002). For BC proliferation and Hypoxia, higher scores associated with worse outcomes (HR BCproliferation  = 1.54, 95% CI = 1.33-1.79, q < 0.0001; HR Hypoxia  = 1.38, 95% CI = 1.20-1.58, q < 0.0001). The results were similar for OS., Conclusions: Expression of FOXA1 is a promising predictive biomarker for tamoxifen effect in ER+/HER2- premenopausal breast cancer. In addition, each of the signatures BC proliferation, Hypoxia, Mast cells, and the GEX of AR, ESR1, and PGR had prognostic value, also after adjusting for established prognostic factors. Trial registration This trial was retrospectively registered in the ISRCTN database the 6th of December 2019, trial ID: https://clinicaltrials.gov/ct2/show/ISRCTN12474687 ., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Background: Tumour-infiltrating lymphocytes (TILs) are of important prognostic and predictive value in human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) and triple-negative breast cancer (TNBC), but their clinical relevance in oestrogen receptor-positive/HER2-negative (ER+/HER2-) remains unknown. The primary study aim was to analyse the prognostic effect of TILs on the BC-free interval (BCFi) in premenopausal patients stratified by BC subtypes. The secondary aim was to investigate if TILs are predictive of tamoxifen (TAM) benefit., Methods: Archival tissues from primary breast tumours were collected from patients from the SBII:2pre trial, in which 564 premenopausal women were randomised to 2 years of adjuvant TAM or no systemic treatment, regardless of hormone receptor status. TILs were scored on whole tissue sections from 447 patients with available ER status. Tumours were divided into ER+/HER2-, HER2+ and TNBC subtypes by immunohistochemistry and in situ hybridisation. The prognostic value of TILs was analysed in systemically untreated patients (n = 221); the predictive information was investigated in the ER+ subgroup (n = 321) by cumulative incidence curves and Cox regression analyses. The median follow-up was 28 years., Results: High (≥ 50%) infiltration of TILs was a favourable prognostic factor in terms of BCFi (univariable analysis: hazard ratio BCFi (HR BCFi ) 0.40; 95% confidence interval (CI) 0.22-0.71; P = 0.002). Similar effects were observed across all BC subtypes. The effect of adjuvant TAM was stronger in patients with ER+ tumours and TILs < 50% (HR BCFi 0.63; 95% CI 0.47-0.84; P = 0.002) than in patients with high immune infiltration (≥ 50%) (HR BCFi 0.84; 95% CI (0.24-2.86); P = 0.77). However, evidence for differential effects of TAM in categories of TILs, i.e. interaction, was weak., Conclusions: We demonstrate a long-term favourable prognostic value of high infiltration of TILs in a cohort of premenopausal BC patients and the positive prognostic effect was extended to the ER+/HER2- subgroup. A beneficial effect of TAM in ER+ patients was observed in patients with tumours of low TIL infiltration, but evidence for a treatment predictive effect was weak., Trial Registration: This trial is registered in the ISRCTN database, trial ID: ISRCTN12474687 .

Introduction: mTOR and its downstream effectors the 4E-binding protein 1 (4EBP1) and the p70 ribosomal S6 kinases (S6K1 and S6K2) are frequently upregulated in breast cancer, and assumed to be driving forces in tumourigenesis, in close connection with oestrogen receptor (ER) networks. Here, we investigated these factors as clinical markers in five different cohorts of breast cancer patients., Methods: The prognostic significance of 4EBP1, S6K1 and S6K2 mRNA expression was assessed with real-time PCR in 93 tumours from the treatment randomised Stockholm trials, encompassing postmenopausal patients enrolled between 1976 and 1990. Three publicly available breast cancer cohorts were used to confirm the results. Furthermore, the predictive values of 4EBP1 and p4EBP1&#95;S65 protein expression for both prognosis and endocrine treatment benefit were assessed by immunohistochemical analysis of 912 node-negative breast cancers from the Stockholm trials., Results: S6K2 and 4EBP1 mRNA expression levels showed significant correlation and were associated with a poor outcome in all cohorts investigated. 4EBP1 protein was confirmed as an independent prognostic factor, especially in progesterone receptor (PgR)-expressing cancers. 4EBP1 protein expression was also associated with a poor response to endocrine treatment in the ER/PgR positive group. Cross-talk to genomic as well as non-genomic ER/PgR signalling may be involved and the results further support a combination of ER and mTOR signalling targeted therapies., Conclusion: This study suggests S6K2 and 4EBP1 as important factors for breast tumourigenesis, interplaying with hormone receptor signalling. We propose S6K2 and 4EBP1 as new potential clinical markers for prognosis and endocrine therapy response in breast cancer.

Introduction: The HOXB13:IL17BR index has been identified to predict clinical outcome in the setting of adjuvant tamoxifen monotherapy of breast cancer. Further studies have shown that HOXB13 in particular can indicate benefit of prolonged tamoxifen treatment. Patients with high-expressing tumors did not benefit from prolonged treatment, suggesting that HOXB13 might be involved in tamoxifen resistance. No studies have been made regarding the HOXB13 protein levels in breast cancer. The aim of our study was to investigate whether tamoxifen benefit can be correlated to different levels of HOXB13 protein expression., Methods: We used immunohistochemistry to analyze protein levels of HOXB13 in tumor samples from 912 postmenopausal node-negative breast cancer patients randomized to adjuvant tamoxifen therapy or no endocrine treatment., Results: Tamoxifen-treated patients with estrogen receptor-positive tumors expressing none or low levels of HOXB13 had a clear benefit from tamoxifen in terms of longer distant recurrence-free survival (DRFS) (hazard ratio = 0.38, 95% confidence interval = 0.23 to 0.60, P = 0.000048). However, for patients with a high or intermediate HOXB13 tumor expression, tamoxifen did not prolong the DRFS compared with the untreated patients (hazard ratio = 0.88, 95% confidence interval = 0.47 to 1.65, P = 0.69). Interaction between HOXB13 expression and benefit from tamoxifen was statistically significant for DRFS (P = 0.035). No prognostic value could be ascribed to HOXB13 among systemically untreated patients., Conclusions: A high HOXB13 expression was associated with decreased benefit from tamoxifen, which indicates that HOXB13 protein level may be used as a predictive marker for tamoxifen treatment.

Introduction: Some patients with breast cancer develop local recurrence after breast-conservation surgery despite postoperative radiotherapy, whereas others remain free of local recurrence even in the absence of radiotherapy. As clinical parameters are insufficient for identifying these two groups of patients, we investigated whether gene expression profiling would add further information., Methods: We performed gene expression analysis (oligonucleotide arrays, 26,824 reporters) on 143 patients with lymph node-negative disease and tumor-free margins. A support vector machine was employed to build classifiers using leave-one-out cross-validation., Results: Within the estrogen receptor-positive (ER+) subgroup, the gene expression profile clearly distinguished patients with local recurrence after radiotherapy (n = 20) from those without local recurrence (n = 80 with or without radiotherapy). The receiver operating characteristic (ROC) area was 0.91, and 5,237 of 26,824 reporters had a P value of less than 0.001 (false discovery rate = 0.005). This gene expression profile provides substantially added value to conventional clinical markers (for example, age, histological grade, and tumor size) in predicting local recurrence despite radiotherapy. Within the ER- subgroup, a weaker, but still significant, signal was found (ROC area = 0.74). The ROC area for distinguishing patients who develop local recurrence from those who remain local recurrence-free in the absence of radiotherapy was 0.66 (combined ER+/ER-)., Conclusion: A highly distinct gene expression profile for patients developing local recurrence after breast-conservation surgery despite radiotherapy has been identified. If verified in further studies, this profile might be a most important tool in the decision making for surgery and adjuvant therapy.

Introduction: The amplification event occurring at chromosome locus 11q13, reported in several different cancers, includes a number of potential oncogenes. We have previously reported amplification of one such oncogene, namely CCND1, to be correlated with an adverse effect of tamoxifen in premenopausal breast cancer patients. Over-expression of cyclin D1 protein, however, confers tamoxifen resistance but not a tamoxifen-induced adverse effect. Potentially, co-amplification of an additional 11q13 gene, with a resulting protein over-expression, is required to cause an agonistic effect. Moreover, during 11q13 amplification a deletion of the distal 11q region has been described. In order to assess the potential impact of the deletion we examined a selected marker for this event., Method: Array comparative genomic hybridization analysis was employed to identify and confirm changes in the gene expression of a number of different genes mapping to the 11q chromosomal region, associated with CCND1 amplification. The subsequent protein expression of these candidate genes was then examined in a clinical material of 500 primary breast cancers from premenopausal patients who were randomly assigned to either tamoxifen or no adjuvant treatment. The protein expression was also compared with gene expression data in a subset of 56 breast cancer samples., Results: Cortactin and FADD (Fas-associated death domain) over-expression was linked to CCND1 amplification, determined by fluorescence in situ hybridization, but was not associated with a diminished effect of tamoxifen. However, deletion of distal chromosome 11q, defined as downregulation of the marker Chk1 (checkpoint kinase 1), was associated with an impaired tamoxifen response, and interestingly with low proliferative breast cancer of low grade. For Pak1 (p21-activated kinase 1) and cyclin D1 the protein expression corresponded to the gene expression data., Conclusions: The results indicate that many 11q13 associated gene products are over-expressed in conjunction with cyclin D1 but not linked to an agonistic effect of tamoxifen. Finally, the deletion of distal 11q, linked to 11q13 amplification, might be an important event affecting breast cancer outcome and tamoxifen response.

Introduction: Tamoxifen therapy reduces the risk of recurrence and prolongs the survival of oestrogen-receptor-positive patients with breast cancer. Even if most patients benefit from tamoxifen, many breast tumours either fail to respond or become resistant. Because tamoxifen is extensively metabolised by polymorphic enzymes, one proposed mechanism underlying the resistance is altered metabolism. In the present study we investigated the prognostic and/or predictive value of functional polymorphisms in cytochrome P450 3A5 CYP3A5 (*3), CYP2D6 (*4), sulphotransferase 1A1 (SULT1A1; *2) and UDP-glucuronosyltransferase 2B15 (UGT2B15; *2) in tamoxifen-treated patients with breast cancer., Methods: In all, 677 tamoxifen-treated postmenopausal patients with breast cancer, of whom 238 were randomised to either 2 or 5 years of tamoxifen, were genotyped by using PCR with restriction fragment length polymorphism or PCR with denaturing high-performance liquid chromatography., Results: The prognostic evaluation performed in the total population revealed a significantly better disease-free survival in patients homozygous for CYP2D6*4. For CYP3A5, SULT1A1 and UGT2B15 no prognostic significance was observed. In the randomised group we found that for CYP3A5, homozygous carriers of the *3 allele tended to have an increased risk of recurrence when treated for 2 years with tamoxifen, although this was not statistically significant (hazard ratio (HR) = 2.84, 95% confidence interval (CI) = 0.68 to 11.99, P = 0.15). In the group randomised to 5 years' tamoxifen the survival pattern shifted towards a significantly improved recurrence-free survival (RFS) among CYP3A5*3-homozygous patients (HR = 0.20, 95% CI = 0.07 to 0.55, P = 0.002). No reliable differences could be seen between treatment duration and the genotypes of CYP2D6, SULT1A1 or UGT2B15. The significantly improved RFS with prolonged tamoxifen treatment in CYP3A5*3 homozygotes was also seen in a multivariate Cox model (HR = 0.13, CI = 0.02 to 0.86, P = 0.03), whereas no differences could be seen for CYP2D6, SULT1A1 and UGT2B15., Conclusion: The metabolism of tamoxifen is complex and the mechanisms responsible for the resistance are unlikely to be explained by a single polymorphism; instead it is a combination of several mechanisms. However, the present data suggest that genetic variation in CYP3A5 may predict response to tamoxifen therapy.

Background: Tamoxifen is widely used as endocrine therapy for oestrogen-receptor-positive breast cancer. However, many of these patients experience recurrence despite tamoxifen therapy by incompletely understood mechanisms. In the present report we propose that tamoxifen resistance may be due to differences in activity of metabolic enzymes as a result of genetic polymorphism. Cytochrome P450 2D6 (CYP2D6) and sulfotransferase 1A1 (SULT1A1) are polymorphic and are involved in the metabolism of tamoxifen. The CYP2D6*4 and SULT1A1*2 genotypes result in decreased enzyme activity. We therefore investigated the genotypes of CYP2D6 and SULT1A1 in 226 breast cancer patients participating in a trial of adjuvant tamoxifen treatment in order to validate the benefit from the therapy., Methods: The patients were genotyped using PCR followed by cleavage with restriction enzymes., Results: Carriers of the CYP2D6*4 allele demonstrated a decreased risk of recurrence when treated with tamoxifen (relative risk = 0.28, 95% confidence interval = 0.11-0.74, P = 0.0089). A similar pattern was seen among the SULT1A1*1 homozygotes (relative risk = 0.48, 95% confidence interval = 0.21-1.12, P = 0.074). The combination of CYP2D6*4 and/or SULT1A1*1/*1 genotypes comprised 60% of the patients and showed a 62% decreased risk of distant recurrence with tamoxifen (relative risk = 0.38, 95% confidence interval = 0.19-0.74, P = 0.0041)., Conclusion: The present study suggests that genotype of metabolic enzymes might be useful as a guide for adjuvant endocrine treatment of postmenopausal breast cancer patients. However, results are in contradiction to prior hypotheses and the present sample size is relatively small. Findings therefore need to be confirmed in a larger cohort.

Background: The serine/threonine kinase Akt, or protein kinase B, has recently been a focus of interest because of its activity to inhibit apoptosis. It mediates cell survival by acting as a transducer of signals from growth factor receptors that activate phosphatidylinositol 3-kinase., Methods: We analysed the expression of the isoforms Akt1 and Akt2 as well as phosphorylated Akt (pAkt) by immunohistochemistry in frozen tumour samples from 280 postmenopausal patients who participated in a randomised trial comparing cyclophosphamide-methotrexate-5-fluorouracil chemotherapy and postoperative radiotherapy. The patients were simultaneously randomised to tamoxifen or to no endocrine treatment., Results: Marked staining was found in 24% of the tumours for Akt1, but in only 4% for Akt2. A low frequency of Akt2-positive cells (1-10%) was observed in another 26% of the tumours. pAkt was significantly associated with both Akt1 and Akt2 expression. Overexpression of erbB2 correlated significantly with pAkt (P = 0.0028). The benefit from tamoxifen was analysed in oestrogen receptor (ER)-positive patients. Patients with a negative status of Akt (no overexpression of Akt1, Akt2 or pAkt) showed significant benefit from tamoxifen. The relative rate of distant recurrence, with versus without tamoxifen, was 0.44 (95% confidence interval [CI], 0.25-0.79) for ER+/Akt1- patients, while it was 0.72 (95% CI, 0.34-1.53) for ER+/Akt1+ patients. The difference in rate ratio did not reach statistical significance. The rate of locoregional recurrence was significantly decreased with radiotherapy versus chemotherapy for Akt-negative patients (rate ratio, 0.23; 95% CI, 0.08-0.67; P = 0.0074), while no benefit was evident for the Akt-positive subgroup (rate ratio, 0.77; 95% CI, 0.31-1.9; P = 0.58). The interaction between Akt and the efficacy of radiotherapy was significant in multivariate analysis (P = 0.042)., Conclusion: Activation of the Akt pathway is correlated with erbB2 overexpression in breast cancer. The results suggest that Akt may predict the local control benefit from radiotherapy.