Identification of a Low-Risk Luminal A Breast Cancer Cohort That May Not Benefit From Breast Radiotherapy

PURPOSE

To determine the prognostic and predictive value of intrinsic subtyping by using immunohistochemical (IHC) biomarkers for ipsilateral breast relapse (IBR) in participants in an early breast cancer randomized trial of tamoxifen with or without breast radiotherapy (RT).

PATIENTS AND METHODS

IHC analysis of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 (HER2), cytokeratin 5/6, epidermal growth factor receptor, and Ki-67 was conducted on 501 of 769 available blocks. Patients were classified as luminal A (n = 265), luminal B (n = 165), or high-risk subtype (luminal HER2, n = 22; HER2 enriched, n = 13; basal like, n = 30; or triple-negative nonbasal, n = 6). Median follow-up was 10 years.

RESULTS

Classification by subtype was prognostic for IBR (10-year estimates: luminal A, 5.2%; luminal B, 10.5%; high-risk subtypes, 21.3%; P < .001). Luminal subtypes seemed to derive less benefit from RT (luminal A hazard ratio [HR], 0.40; luminal B HR, 0.51) than high-risk subtypes (HR, 0.13); however, the overall subtype-treatment interaction term was not significant (P = .26). In an exploratory analysis of women with clinical low-risk (age older than 60 years, T1, grade 1 or 2) luminal A tumors (n = 151), 10-year IBR was 3.1% versus 11.8% for the high-risk cohort (n = 341; P = .0063). Clinical low-risk luminal A patients had a 10-year IBR of 1.3% with tamoxifen versus 5.0% with tamoxifen plus RT (P = .42). Multivariable analysis showed that RT (HR, 0.31; P < .001), clinical risk group (HR, 2.2; P = .025), and luminal A subtype (HR, 0.25; P < .001) were significantly associated with IBR.

CONCLUSION

IHC subtyping was prognostic for IBR but was not predictive of benefit from RT. Further studies may validate the exploratory finding of a low-risk luminal A group who may be spared breast RT.

Abstract S1-02: Prognostic effects of gene mutation in estrogen receptor positive breast cancer

Background: Relationships between recurrent somatic mutations and outcome in estrogen receptor positive (ER+) breast cancer has not been extensively studied as the original discovery efforts were from either heterogeneously treated patients or follow up was too brief. Targeted massively parallel sequencing (MPS) analysis was therefore conducted on DNA extracted from archived formalin-fixed breast primaries from a cohort of over 600 patents from British Columbia treated with five years of adjuvant tamoxifen monotherapy and followed for over 10 years (Nielsen et al CCR 16:5222, 2010).

Methods: Genes were selected for targeted sequencing by meta-analysis of five large-scale breast cancer sequencing studies and manual review of breast cancer literature. In total 83 genes were identified and 3286 probes were designed to tile across all known exons. Minimum starting input DNA was 50ng (mean=189.1ng). Illumina sequencing libraries were constructed, indexed, pooled, and enriched for target sequences by hybrid-capture followed by paired-end 100bp reads. The Genome Modeling System was used to perform single-tumor somatic variant prediction. Variant calls were filtered to include only targeted regions and exclude variants with global mutant allele frequencies greater than 0.1% in 1000 genomes or NHLBI exome datasets. Kaplan-Meier analysis and multivariable analysis (clinical features and intrinsic subtype by qPCR) was performed for breast-cancer-specific and relapse free survival.

Results: A total of 638 samples met minimum quality controls of 80% targeted space covered at 20X or greater. On average each sample had 332M of aligned bases and a mean coverage of 134.3X. In total 7,159 variants were identified including 3,696 missense, 494 nonsense, and 1,047 frameshift insertions or deletions. Preliminary results indicate significant associations between mutation status and improved survival for PIK3CA, ARID1B, ERBB3, MAP3K1 and GATA3 or worse survival for PTEN, DDR1, TP53 and JAK2. Five Y537N/C, two E380Q and 5 potentially novel ligand-binding-domain mutations were identified in ESR1. Such mutations were recently reported to be associated with resistance to hormone therapy but were discovered here in as much as 1.9% of pre-treatment samples. Analysis will be presented regarding the use of relapse events to differentiate passenger from driver mutations.

Conclusion. Multiple recurrently mutated genes have both positive and negative associations with prognosis in tamoxifen montherapy treated breast cancer populations. Associations with poor outcome suggest that PTEN, DDR1, and JAK2 are high priorities for pharmacological interventions.

Table 1: Mutations and survival in ER+ breast cancerGeneP-ValueHazard RatioPTEN0.0022.11PIK3CA0.0070.69DDR10.0082.41ARID1B0.010.57ERBB30.020.36MAP3K10.010.5TP530.041.48GATA30.040.44JAK20.052.1

Citation Format: Obi L Griffith, Malachi Griffith, Jingqin Luo, Jasreet Hundall, Christopher A Miller, David E Larson, Robert Fulton, Richard K Wilson, Shuzhen Liu, Samuel Leung, Torsten O Nielsen, Elaine R Mardis, Matthew J Ellis. Prognostic effects of gene mutation in estrogen receptor positive breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S1-02.

Defining breast cancer intrinsic subtypes by quantitative receptor expression

PURPOSE

To determine intrinsic breast cancer subtypes represented within categories defined by quantitative hormone receptor (HR) and HER2 expression.

METHODS

We merged 1,557 cases from three randomized phase III trials into a single data set. These breast tumors were centrally reviewed in each trial for quantitative ER, PR, and HER2 expression by immunohistochemistry (IHC) stain and by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), with intrinsic subtyping by research-based PAM50 RT-qPCR assay.

RESULTS

Among 283 HER2-negative tumors with <1% HR expression by IHC, 207 (73%) were basal-like; other subtypes, particularly HER2-enriched (48, 17%), were present. Among the 1,298 HER2-negative tumors, borderline HR (1%-9% staining) was uncommon (n = 39), and these tumors were heterogeneous: 17 (44%) luminal A/B, 12 (31%) HER2-enriched, and only 7 (18%) basal-like. Including them in the definition of triple-negative breast cancer significantly diminished enrichment for basal-like cancer (p < .05). Among 106 HER2-positive tumors with <1% HR expression by IHC, the HER2-enriched subtype was the most frequent (87, 82%), whereas among 127 HER2-positive tumors with strong HR (>10%) expression, only 69 (54%) were HER2-enriched and 55 (43%) were luminal (39 luminal B, 16 luminal A). Quantitative HR expression by RT-qPCR gave similar results. Regardless of methodology, basal-like cases seldom expressed ER/ESR1 or PR/PGR and were associated with the lowest expression level of HER2/ERBB2 relative to other subtypes.

CONCLUSION

Significant discordance remains between clinical assay-defined subsets and intrinsic subtype. For identifying basal-like breast cancer, the optimal HR IHC cut point was <1%, matching the American Society of Clinical Oncology and College of American Pathologists guidelines. Tumors with borderline HR staining are molecularly diverse and may require additional assays to clarify underlying biology.

Abstract P4-11-06: TLE3 is not a predictive biomarker for taxane sensitivity in the NCIC CTG MA.21 clinical trial

Background: TLE3, a nuclear transcriptional repressor downstream of the WNT signaling pathway, has been identified as a candidate predictive biomarker of taxane benefit in early breast cancer. However, robust clinical evidence is required before implementing novel diagnostic biomarkers. We tested the hypothesis that TLE3 predicts for benefit from taxane containing polychemotherapy in the NCIC CTG MA.21 clinical trial.

Methods: MA.21 accrued 2104 patients [701 each to cyclophosphamide, epirubicin, and 5 fluorouracil (CEF) and epirubicin and cyclophosphamide with filgrastim and epoetin alfa followed by paclitaxel (EC/T), 702 to doxorubicin and cyclophosphamide followed by paclitaxel (AC/T)] who were followed median 8 years by the final analysis. EC/T and CEF were not significantly different (p= 0.69) while AC/T was inferior to both EC/T and CEF (respectively, p=0.001 and p=0004). Tissue microarrays were constructed from 1097 of the 2104 patients. Patient characteristics were well balanced between those included in the TLE3 analysis and the full trial population. Up to four 0.6 mm tumor cores were stained for TLE3 expression by immunohistochemistry using a previously validated methodology. Continuous visual TLE3 score was the average % positive stain across all cores, while continuous automated score was sum of cells with positive stain/ total cells assessed in all cores. The primary objective used the EC/T (taxane-containing) and CEF (non-taxane; similar dose-density) arms for a test of predictive effect of TLE3 on relapse free survival. TLE3 was positive if &gt;30% of cells stained, the established cut-point, with data available from at least 1 core/tumor. We also examined quartile cut-points, multivariate effects of TLE3, and compared AC/T and CEF.

Results: MA.21 patients had 83.2% TLE3+ tumors by visual score and 80.6% TLE3+ by automated image analysis greater than the predicted rate of TLE3 positivity (58.6%) based on prior series and adjusting for clinicopathological features. TLE3 expression was significantly positively associated with ER expression (91.2% of ER+ were TLE3+; p&lt;0.0001). There was no evidence of a predictive effect of TLE3 expression with respect to taxane benefit using the established 30% cut-point, nor quartile cut-points. The treatment and TLE3 interaction term for the EC/T by CEF comparison was not significant (stratified p=0.68, for manual TLE3; p=0.44, for automated TLE3).

Conclusions: MA.21 patients had a much higher proportion of TLE3+ tumors than anticipated. Multiple assessments of TLE3 cut-points yielded no evidence that it was predictive of taxane benefit.

In our trial TLE3 expression was not a biomarker for taxane benefit (EC/T vs CEF) when using either previously established or common quartile cut-offs for expression in breast cancer.

Citation Format: John MS Bartlett, Torsten O Nielsen, Dongxia Gao, Karen A Gelmon, Mary Anne Quintayo, Jane Starczynski, Lei Han, Margot J Burnell, Mark N Levine, Lois E Shepherd, Judy-Anne W Chapman. TLE3 is not a predictive biomarker for taxane sensitivity in the NCIC CTG MA.21 clinical trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-11-06.

A phase II study of SB939, a novel pan-histone deacetylase inhibitor, in patients with translocation-associated recurrent/metastatic sarcomas-NCIC-CTG IND 200†

BACKGROUND

A subgroup of sarcomas is characterized by defining chromosomal translocations, creating fusion transcription factor oncogenes. Resultant fusion oncoproteins associate with chromatin-modifying complexes containing histone deacetylases (HDAC), and lead to epigenetic transcriptional dysregulation. HDAC inhibitors were shown to be effective in vitro, reversing gene repression by these complexes, restoring PTEN expression and apoptosis via the PI3K/Akt/mTOR pathway.

PATIENTS AND METHODS

SB939 is an oral inhibitor of classes 1 and 2 HDAC. Eligible patients with recurrent or metastatic translocation-associated sarcoma (TAS) by local pathology were treated with 60 mg/day every other day for 3 of 4 weeks. Central pathology review was conducted with fusion oncogenes characterized, and HDAC2 expression correlated with efficacy in pre-specified methods.

RESULTS

Twenty-two patients were treated with a median of 2 cycles. Fourteen patients were assessable for response with confirmed specific chromosomal translocations; 8 had a best response of stable disease (SD) (median duration 5.4 months) with no confirmed objective responses. The 3-month progression-free survival (PFS) rate was 49%. Among those with HDAC2 score ≥5, 7/10 had SD, versus 0/3 with HDAC2 score <5. SB939 was considered as well tolerated with <10% patients experienced ≥grade 3 toxicity.

CONCLUSION

This study was stopped prematurely due to prolonged unavailability of SB939. No objective responses were seen. Although the observed SD in HDAC2 high patients was interesting, due to the small sample size, no definitive conclusion can be drawn about the efficacy of SB939 in this patient population.

CLINICAL TRIAL

NCT01112384.

Synovial sarcoma: recent discoveries as a roadmap to new avenues for therapy

Oncogenesis in synovial sarcoma is driven by the chromosomal translocation t(X,18; p11,q11), which generates an in-frame fusion of the SWI/SNF subunit SS18 to the C-terminal repression domains of SSX1 or SSX2. Proteomic studies have identified an integral role of SS18-SSX in the SWI/SNF complex, and provide new evidence for mistargeting of polycomb repression in synovial sarcoma. Two recent in vivo studies are highlighted, providing additional support for the importance of WNT signaling in synovial sarcoma: One used a conditional mouse model in which knockout of β-catenin prevents tumor formation, and the other used a small-molecule inhibitor of β-catenin in xenograft models.

SIGNIFICANCE

Synovial sarcoma appears to arise from still poorly characterized immature mesenchymal progenitor cells through the action of its primary oncogenic driver, the SS18-SSX fusion gene, which encodes a multifaceted disruptor of epigenetic control. The effects of SS18-SSX on polycomb-mediated gene repression and SWI/SNF chromatin remodeling have recently come into focus and may offer new insights into the basic function of these processes. A central role for deregulation of WNT-β-catenin signaling in synovial sarcoma has also been strengthened by recent in vivo studies. These new insights into the the biology of synovial sarcoma are guiding novel preclinical and clinical studies in this aggressive cancer.

Effect of continuous statistically standardized measures of estrogen and progesterone receptors on disease-free survival in NCIC CTG MA.12 Trial and BC Cohort

INTRODUCTION

We hypothesized improved inter-laboratory comparability of estrogen receptor (ER) and progesterone receptor (PgR) across different assay methodologies with adjunctive statistical standardization, akin to bone mineral density (BMD) z-scores. We examined statistical standardization in MA.12, a placebo-controlled pre-menopausal trial of adjuvant tamoxifen with locally assessed hormone receptor +/- tumours, and in a cohort of post-menopausal British Columbia (BC) tamoxifen-treated patients.

METHODS

ER and PgR were centrally assessed for both patient groups with real time quantitative reverse transcription polymerase chain reaction (qPCR) and immunohistochemistry (IHC). Effects on disease-free survival (DFS) were investigated separately for 345 MA.12 and 673 BC patients who had both qPCR and IHC assessments. Comparisons utilized continuous laboratory units and statistically standardized z-scores. Univariate categorization of ER/PgR was by number of standard deviations (SD) above or below the mean (z-score ≥1.0 SD below mean; z-score <1.0 SD below mean; z-score ≤1.0 SD above mean; z-score >1.0 SD above mean). Exploratory multivariate examinations utilized step-wise Cox regression.

RESULTS

Median follow-up for MA.12 was 9.7 years; for BC patients, 11.8 years. For MA.12, 101 of 345 (29%) patients were IHC ER-PgR-. ER was not univariately associated with DFS (qPCR, P = 0.19; IHC, P = 0.08), while PgR was (qPCR, P = 0.09; IHC, P = 0.04). For BC patients, neither receptor was univariately associated with DFS: for ER, PCR, P = 0.36, IHC, P = 0.24; while for PgR, qPCR, P = 0.17, IHC, P = 0.31. Multivariately, MA.12 patients randomized to tamoxifen had significantly better DFS (P = 0.002 to 0.005) than placebo. Meanwhile, jointly ER and PgR were not associated with DFS whether assessed by qPCR or by IHC in all patients, or in the subgroup of patients with IHC positive stain, for pooled or separate treatment arms. Different results by type of continuous unit supported the concept of ER level being relevant for medical decision-making. For postmenopausal BC tamoxifen patients, higher qPCR PgR was weakly associated with better DFS (P = 0.06).

CONCLUSIONS

MA.12 pre-menopausal patients in a placebo-controlled tamoxifen trial had similar multivariate prognostic effects with statistically standardized hormone receptors when tumours were assayed by qPCR or IHC, for hormone receptor +/- and + tumours. The BC post-menopausal tamoxifen cohort did not exhibit a significant prognostic association of ER or PgR with DFS. Adjunctive statistical standardization is currently under investigation in other NCIC CTG endocrine trials.

Prognostic significance of FOXP3+ tumor-infiltrating lymphocytes in breast cancer depends on estrogen receptor and human epidermal growth factor receptor-2 expression status and concurrent cytotoxic T-cell infiltration

Introduction

The infiltration of FOXP3⁺ regulatory T cells into invasive tumors has been reported to be associated with survival in a variety of cancers. The prognostic significance of FOXP3⁺ tumor-infiltrating lymphocytes (TILs) in breast cancer, however, remains controversial.

Methods

FOXP3⁺ TILs were assessed by immunohistochemistry on tissue microarrays constructed from a well-defined cohort of 3,992 breast cancer patients linked to detailed demographic, biomarker, treatment and outcome data. Survival analyses were performed using the Kaplan-Meier function and Cox proportional hazards regression models to evaluate the association of FOXP3⁺ TILs with breast cancer-specific survival, stratified by intrinsic subtype and cytotoxic T-cell infiltration status (as defined by CD8 immunohistochemistry).

Results

The presence of high numbers of FOXP3⁺ TILs was significantly associated with young age, high grade, estrogen receptor (ER) negativity, concurrent CD8⁺ cytotoxic T-cell infiltration, and human epidermal growth factor receptor-2 positive (HER2⁺)/ER⁺ and core basal subtypes. On multivariate survival analysis, a high level of FOXP3⁺ TILs was significantly associated with poor survival in ER⁺ breast cancers that lacked CD8⁺ T-cell infiltrates (hazard ratio (HR) = 1.30, 95% confidence interval (CI) = 1.02 to 1.66). However, in ER⁺ breast cancers, FOXP3⁺ TILs were strongly associated with improved survival in the HER2⁺/ER⁺ subgroup, particularly in those with co-existent CD8⁺ T-cell infiltrates (HR = 0.48, 95% CI = 0.23 to 0.98), for which the presence of high levels of FOXP3⁺ TILs was independent of standard clinical prognostic factors.

Conclusions

FOXP3⁺ regulatory TILs are a poor prognostic indicator in ER⁺ breast cancer, but a favorable prognostic factor in the HER2⁺/ER⁺ subtype. The prognostic value of FOXP3⁺ TILs in breast cancer differs depending on ER and HER2 expression status and CD8⁺ T-cell infiltration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0432-8) contains supplementary material, which is available to authorized users.

Association between CD8+ T-cell infiltration and breast cancer survival in 12,439 patients

BACKGROUND

T-cell infiltration in estrogen receptor (ER)-negative breast tumours has been associated with longer survival. To investigate this association and the potential of tumour T-cell infiltration as a prognostic and predictive marker, we have conducted the largest study of T cells in breast cancer to date.

PATIENTS AND METHODS

Four studies totalling 12 439 patients were used for this work. Cytotoxic (CD8+) and regulatory (forkhead box protein 3, FOXP3+) T cells were quantified using immunohistochemistry (IHC). IHC for CD8 was conducted using available material from all four studies (8978 samples) and for FOXP3 from three studies (5239 samples)-multiple imputation was used to resolve missing data from the remaining patients. Cox regression was used to test for associations with breast cancer-specific survival.

RESULTS

In ER-negative tumours [triple-negative breast cancer and human epidermal growth factor receptor 2 (human epidermal growth factor receptor 2 (HER2) positive)], presence of CD8+ T cells within the tumour was associated with a 28% [95% confidence interval (CI) 16% to 38%] reduction in the hazard of breast cancer-specific mortality, and CD8+ T cells within the stroma with a 21% (95% CI 7% to 33%) reduction in hazard. In ER-positive HER2-positive tumours, CD8+ T cells within the tumour were associated with a 27% (95% CI 4% to 44%) reduction in hazard. In ER-negative disease, there was evidence for greater benefit from anthracyclines in the National Epirubicin Adjuvant Trial in patients with CD8+ tumours [hazard ratio (HR) = 0.54; 95% CI 0.37-0.79] versus CD8-negative tumours (HR = 0.87; 95% CI 0.55-1.38). The difference in effect between these subgroups was significant when limited to cases with complete data (P heterogeneity = 0.04) and approached significance in imputed data (P heterogeneity = 0.1).

CONCLUSIONS

The presence of CD8+ T cells in breast cancer is associated with a significant reduction in the relative risk of death from disease in both the ER-negative [supplementary Figure S1, available at Annals of Oncology online] and the ER-positive HER2-positive subtypes. Tumour lymphocytic infiltration may improve risk stratification in breast cancer patients classified into these subtypes. NEAT ClinicalTrials.gov: NCT00003577.

Developing a new generation of breast cancer clinical gene expression tests

When treatment decisions are based purely on clinicopathological factors, many women with estrogen receptor-positive/human epidermal growth factor receptor 2-negative cancers are overtreated. Gene expression profiles are valuable clinical tools that stratify the recurrence risk to identify patients most likely to benefit from adjuvant systemic therapies. Building upon greater understanding of tumor biology and more rigorous approaches to validation (including independent studies with a high level of evidence), several second-generation multigene tests have been developed. In the previous issue, Martin and colleagues report the third clinical validation study for EndoPredict, a distributed assay to assess risk of distant recurrences in estrogen receptor-positive/human epidermal growth factor receptor 2-negative women. The authors confirm the assay's independent prognostic value in premenopausal and postmenopausal, node-positive women treated with contemporary chemotherapy followed by endocrine therapy. EndoPredict did not, however, predict benefit from adding paclitaxel. Predictive signatures for selecting among chemotherapy regimens remain an area needing further development.

PAM50 breast cancer intrinsic subtypes and effect of gemcitabine in advanced breast cancer patients

BACKGROUND

In vitro studies suggest basal breast cancers are more sensitive to gemcitabine relative to other intrinsic subtypes. The main objective of this study was to use specimens from a randomized clinical trial to evaluate whether the basal-like subtype identifies patients with advanced breast cancer who benefit from gemcitabine plus docetaxel (GD) compared to single agent docetaxel (D).

MATERIAL AND METHODS

From patients randomly assigned to GD or D, RNA was isolated from archival formalin-fixed, paraffin-embedded primary breast tumor tissue and used for PAM50 intrinsic subtyping by NanoString nCounter. Statistical analyses were prespecified as a formal prospective-retrospective clinical trial correlative study. Using time to progression (TTP) as primary endpoint, overall survival (OS) and response rate as secondary endpoints, relationships between subtypes and outcome after chemotherapy were analyzed by the Kaplan-Meier method, and Cox proportional hazards regression models. Data analysis was performed independently by the Danish Breast Cancer Cooperative Group (DBCG) statistical core and all statistical tests were two-sided.

RESULTS

RNA from 270 patients was evaluable; 84 patients (31%) were classified as luminal A, 97 (36%) luminal B, 43 (16%) basal-like, and 46 (17%) as HER2-enriched. PAM50 intrinsic subtype was a significant independent prognostic factor for both TTP (p=0.014) and OS (p=0.0003). Response rate was not different by subtype, and PAM50 was not a predictor of TTP by treatment arm. PAM50 was however a highly significant predictor of OS following GD compared to D (pinteraction=0.0016). Patients with a basal-like subtype had a significant reduction in OS events [hazard ratio (HR)=0.29, 95% confidence interval (CI)=0.15-0.57; pinteraction=0.0006].

CONCLUSION

A significantly improved and clinically important prolongation of survival was seen from the addition of gemcitabine to docetaxel in advanced basal-like breast cancer patients.

Diagnostic value of next-generation sequencing in an unusual sphenoid tumor

Extraordinary advancements in sequencing technology have made what was once a decade-long multi-institutional endeavor into a methodology with the potential for practical use in a clinical setting. We therefore set out to examine the clinical value of next-generation sequencing by enrolling patients with incurable or ambiguous tumors into the Personalized OncoGenomics initiative at the British Columbia Cancer Agency whereby whole genome and transcriptome analyses of tumor/normal tissue pairs are completed with the ultimate goal of directing therapeutics. First, we established that the sequencing, analysis, and communication with oncologists could be completed in less than 5 weeks. Second, we found that cancer diagnostics is an area that can greatly benefit from the comprehensiveness of a whole genome analysis. Here, we present a scenario in which a metastasized sphenoid mass, which was initially thought of as an undifferentiated squamous cell carcinoma, was rediagnosed as an SMARCB1-negative rhabdoid tumor based on the newly acquired finding of homozygous SMARCB1 deletion. The new diagnosis led to a change in chemotherapy and a complete nodal response in the patient. This study also provides additional insight into the mutational landscape of an adult SMARCB1-negative tumor that has not been explored at a whole genome and transcriptome level.

The PAM50 risk-of-recurrence score predicts risk for late distant recurrence after endocrine therapy in postmenopausal women with endocrine-responsive early breast cancer

PURPOSE

To assess the prognostic value of the PAM50 risk-of-recurrence (ROR) score on late distant recurrence (beyond 5 years after diagnosis and treatment) in a large cohort of postmenopausal, endocrine-responsive breast cancer patients.

EXPERIMENTAL DESIGN

The PAM50 assay was performed on formalin-fixed paraffin-embedded whole-tumor sections of patients who had been enrolled in the Austrian Breast and Colorectal Cancer Study Group Trial 8 (ABCSG-8). RNA expression levels of the PAM50 genes were determined centrally using the nCounter Dx Analysis System. Late distant recurrence-free survival (DRFS) was analyzed using Cox models adjusted for clinical and pathologic parameters.

RESULTS

PAM50 analysis was successfully performed in 1,246 ABCSG-8 patients. PAM50 ROR score and ROR-based risk groups provided significant additional prognostic information with respect to late DRFS compared with a combined score of clinical factors alone (ROR score: ΔLRχ(2) 15.32, P < 0.001; ROR-based risk groups: ΔLRχ(2) 14.83, P < 0.001). Between years 5 and 15, we observed an absolute risk of distant recurrence of 2.4% in the low ROR-based risk group, as compared with 17.5% in the high ROR-based risk group. The DRFS differences according to the PAM50 ROR score were observed for both node-positive and node-negative disease.

CONCLUSION

PAM50 ROR score and ROR-based risk groups can differentiate patients with breast cancer with respect to their risk for late distant recurrence beyond what can be achieved with established clinicopathologic risk factors.

An international Ki67 reproducibility study

BACKGROUND

In breast cancer, immunohistochemical assessment of proliferation using the marker Ki67 has potential use in both research and clinical management. However, lack of consistency across laboratories has limited Ki67's value. A working group was assembled to devise a strategy to harmonize Ki67 analysis and increase scoring concordance. Toward that goal, we conducted a Ki67 reproducibility study.

METHODS

Eight laboratories received 100 breast cancer cases arranged into 1-mm core tissue microarrays-one set stained by the participating laboratory and one set stained by the central laboratory, both using antibody MIB-1. Each laboratory scored Ki67 as percentage of positively stained invasive tumor cells using its own method. Six laboratories repeated scoring of 50 locally stained cases on 3 different days. Sources of variation were analyzed using random effects models with log2-transformed measurements. Reproducibility was quantified by intraclass correlation coefficient (ICC), and the approximate two-sided 95% confidence intervals (CIs) for the true intraclass correlation coefficients in these experiments were provided.

RESULTS

Intralaboratory reproducibility was high (ICC = 0.94; 95% CI = 0.93 to 0.97). Interlaboratory reproducibility was only moderate (central staining: ICC = 0.71, 95% CI = 0.47 to 0.78; local staining: ICC = 0.59, 95% CI = 0.37 to 0.68). Geometric mean of Ki67 values for each laboratory across the 100 cases ranged 7.1% to 23.9% with central staining and 6.1% to 30.1% with local staining. Factors contributing to interlaboratory discordance included tumor region selection, counting method, and subjective assessment of staining positivity. Formal counting methods gave more consistent results than visual estimation.

CONCLUSIONS

Substantial variability in Ki67 scoring was observed among some of the world's most experienced laboratories. Ki67 values and cutoffs for clinical decision-making cannot be transferred between laboratories without standardizing scoring methodology because analytical validity is limited.

Predicting distant recurrence in receptor-positive breast cancer patients with limited clinicopathological risk: using the PAM50 Risk of Recurrence score in 1478 postmenopausal patients of the ABCSG-8 trial treated with adjuvant endocrine therapy alone

BACKGROUND

PAM50 is a 50-gene test that is designed to identify intrinsic breast cancer subtypes and generate a Risk of Recurrence (ROR) score. It has been developed to be carried out in qualified routine hospital pathology laboratories.

PATIENTS AND METHODS

One thousand four hundred seventy-eight postmenopausal women with estrogen receptor (ER)+ early breast cancer (EBC) treated with tamoxifen or tamoxifen followed by anastrozole from the prospective randomized ABCSG-8 trial were entered into this study. Patients did not receive adjuvant chemotherapy. RNA was extracted from paraffin blocks and analyzed using the PAM50 test. Both intrinsic subtype (luminal A/B, HER2-enriched, basal-like) and ROR score were calculated. The primary analysis was designed to test whether the continuous ROR score adds prognostic value in predicting distant recurrence (DR) over and above standard clinical variables.

RESULTS

In all tested subgroups, ROR score significantly adds prognostic information to the clinical predictor (P<0.0001). PAM50 assigns an intrinsic subtype to all cases, and the luminal A cohort had a significantly lower ROR at 10 years compared with Luminal B (P<0.0001). Significant and clinically relevant discrimination between low- and high-risk groups occurred also within all tested subgroups.

CONCLUSION(S)

The results of the primary analysis, in combination with recently published results from the ATAC trial, constitute Level 1 evidence for clinical validity of the PAM50 test for predicting the risk of DR in postmenopausal women with ER+ EBC. A 10-year metastasis risk of <3.5% in the ROR low category makes it unlikely that additional chemotherapy would improve this outcome-this finding could help to avoid unwarranted overtreatment.

CLINICAL TRIAL NUMBER

ABCSG 8: NCT00291759.

Abstract S2-07: An international Ki67 reproducibility study: Harmonizing scoring methodology

Introduction: Ki67 is an important biomarker for breast cancer but lack of scoring standardization has limited its clinical use. A previous International Ki67 in Breast Cancer Working Group reproducibility study (phase 1) found problematic inter-laboratory variability when labs employed their own scoring methods. This follow-up study (phase 2) devised and tested strategies to harmonize Ki67 scoring.

Methods:

Web-based Calibration: 17 labs were sent simple instructions prescribing a scoring pattern with supporting sample images and asked to score web images of 9 “training” and 9 “test” breast cancer cases representing a range of Ki67 values. Cases were selected from centrally MIB-1 stained TMA cores used in phase 1. Labs yielding consistent scores served as reference labs. Software tracked object selection and scoring. After scoring the training cases, labs were asked to learn from discrepancies by comparing their scored images with scored reference images. “Passing” the training was required for proceeding to testing. The study allowed multiple attempts in training but only 1 attempt on the test cases. Statistical criteria for success, reflecting deviation from reference scores (RMSE &lt; 0.6, MAXDEV &lt; 1.0), were pre-specified.

Phase 2 on glass: Scoring instructions similar to those used in the calibration were provided to 16 of the calibration study labs. They were asked to apply the same standardized method to glass TMA slides (50 cases from the phase 1 TMA, none used in the calibration). Three sections from the TMA were circulated among 3 groups. Labs’ Ki67 scores were log2-transformed to approximate a normal distribution. Sources of variation (e.g., patient, lab) were analyzed using 2-way crossed random effects models with quantification of reproducibility via intraclass correlation coefficient (ICC; range of 0-1, 1 = highest agreement). The pre-specified benchmark of success was a scoring ICC consistent with a true value of 0.9 and significantly greater than the observed overall ICC from phase 1 (0.7).

Results:

Web-based Calibration: Lab performance through the calibration exercise, from training to testing, showed trends of improvement (average across labs: RMSE decreased from 0.6 to 0.4, MAXDEV decreased from 1.6 to 0.9), although not statistically significant, possibly due to limited number of labs (paired t-test: p = 0.07 for RMSE, 0.06 for MAXDEV).

Phase 2 on glass: Whereas inter-laboratory reproducibility in phase 1 was only moderate overall, standardizing the scoring method resulted in achieving a scoring ICC of 0.92 (0.79-0.95), 0.96 (0.78-0.97), and 0.94 (0.77-0.97) in phase 2 for the three groups receiving a given section of the TMA, respectively. Substantial discrepancies persisted among labs on some cases, however, including in the range of clinically relevant cutoffs.

Conclusions: Previous evidence showed that absolute values and cutoffs for Ki67 cannot be transferred between labs without careful standardization of scoring methodology. Use of a common scoring method after training with a web-based calibration tool achieves high inter-laboratory reproducibility in Ki67 scoring on centrally-stained glass TMA slides. Future research should extend this approach to unstained biopsies and whole sections, and link to outcomes, particularly for cases around cutoffs.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S2-07.

Activating transcription factor 2 in mesenchymal tumors

Activating transcription factor 2 (ATF2) is a member of activator protein 1 superfamily, which can heterodimerize with other transcription factors regulating cell differentiation and survival. ATF2 assembles into a complex with the synovial sarcoma translocation, chromosome 18 (SS18)-synovial sarcoma, X breakpoint (SSX) fusion oncoprotein, and the transducin-like enhancer of split 1 (TLE1) corepressor, driving oncogenesis in synovial sarcoma. The fusion oncoproteins in many other translocation-associated sarcomas incorporate transcription factors from the ATF/cAMP response element binding or E26 families, which potentially form heterodimers with ATF2 to regulate transcription. ATF2 may therefore play an important role in the oncogenesis of many mesenchymal tumors, but as yet, little is known about its protein expression in patient specimens. Herein we perform immunohistochemical analyses using a validated specific antibody for ATF2 expression and intracellular localization on a cohort of 594 malignant and 207 benign mesenchymal tumors representing 47 diagnostic entities. Melanoma served as a positive control for nuclear and cytoplasmic staining. High nuclear ATF2 expression was mainly observed in translocation-associated and/or spindle cell sarcomas including synovial sarcoma, desmoplastic small round cell tumor, endometrial stromal sarcoma, gastrointestinal stromal tumor, malignant peripheral nerve sheath tumor, and solitary fibrous tumor. Cytoplasmic ATF2 expression was less frequently seen than nuclear expression in malignant mesenchymal tumors. Benign mesenchymal tumors mostly showed much lower nuclear and cytoplasmic ATF2 expression.

Myxoid liposarcoma in a 91-year-old patient

Background

Myxoid liposarcoma is a mesenchymal malignancy most commonly presenting in young adults. This tumor is known for its characteristic chromosomal rearrangement at the DDIT3 locus.

Results

We report a case of myxoid liposarcoma in a 91-year-old, the oldest known patient with this disease-entity. FISH analysis of the DDIT3 and FUS loci demonstrate the pathognomonic chromosomal alteration in the setting of predominantly round cell histology on biopsy, confirmed by RT-PCR.

Conclusion

Myxoid liposarcoma affects mostly young adults but can be seen in the elderly population. Molecular and cytogenetic assays are helpful auxiliaries to histology in the setting of unusual histology and clinical presentation.

A survey of immunohistochemical biomarkers for basal-like breast cancer against a gene expression profile gold standard

Gene expression profiling of breast cancer delineates a particularly aggressive subtype referred to as 'basal-like', which comprises ∼15% of all breast cancers, afflicts younger women and is refractory to endocrine and anti-HER2 therapies. Immunohistochemical surrogate definitions for basal-like breast cancer, such as the clinical ER/PR/HER2 triple-negative phenotype and models incorporating positive expression for CK5 (CK5/6) and/or EGFR are heavily cited. However, many additional biomarkers for basal-like breast cancer have been described in the literature. A parallel comparison of 46 proposed immunohistochemical biomarkers of basal-like breast cancer was performed against a gene expression profile gold standard on a tissue microarray containing 42 basal-like and 80 non-basal-like breast cancer cases. Ki67 and PPH3 were the most sensitive biomarkers (both 92%) positively expressed in the basal-like subtype, whereas CK14, IMP3 and NGFR were the most specific (100%). Among biomarkers surveyed, loss of INPP4B (a negative regulator of phosphatidylinositol signaling) was 61% sensitive and 99% specific with the highest odds ratio (OR) at 108, indicating the strongest association with basal-like breast cancer. Expression of nestin, a common marker of neural progenitor cells that is also associated with the triple-negative/basal-like phenotype and poor breast cancer prognosis, possessed the second highest OR at 29 among the 46 biomarkers surveyed, as well as 54% sensitivity and 96% specificity. As a positively expressed biomarker, nestin possesses technical advantages over INPP4B that make it a more ideal biomarker for identification of basal-like breast cancer. The comprehensive immunohistochemical biomarker survey presented in this study is a necessary step for determining an optimized surrogate immunopanel that best defines basal-like breast cancer in a practical and clinically accessible way.

Identifying clinically relevant prognostic subgroups in node-positive postmenopausal HR+ early breast cancer patients treated with endocrine therapy: A combined analysis of 2,485 patients from ABCSG-8 and ATAC using the PAM50 risk of recurrence (ROR) score and intrinsic subtype

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Background: Most postmenopausal women with node positive HR+ EBC receive adjuvant chemotherapy. We hypothesized that a molecular-based characterization of residual risk after endocrine therapy using the ROR score and IS may identify node-positive patient subgroups with limited long-term recurrence risk after endocrine therapy better than clinical-pathological risk assessment by clinical treatment score (CTS) alone. Methods: Long-term follow-up and tissue samples were obtained from 2,485 postmenopausal HR+ patients from the ABCSG-8 (N=1,478) and transATAC (N=1,007) trials. The PAM50 test was conducted on RNA extracted from paraffin blocks using the NanoString nCounter Analysis system. The ability of ROR, IS and ROR-defined risk groups (ROR-RG) to add prognostic information to CTS was assessed by the likelihood ratio test in a prospectively defined analysis plan. Results: Patients in the combined data set were grouped by the number of positive nodes into 1 (N1), 2 (N2), or 2 or 3 (N2-3),Baseline hazards for these subgroups were similar in the two trials. ROR score, IS and ROR-RG added statistically significant prognostic information (10-year distant recurrence risk) beyond CTS in all groups. In patients with one positive node, the absolute 10-year risk of distant recurrence was 6.6% [95% CI: 3.3%-12.8%] in the PAM-50-low risk group (40% of patients) and 8.4 % [5.3%-13.3%] in the Luminal A subgroup (69% of patients). Conclusions: The results of this combined analysis demonstrate that a significant proportion of N1 EBC patients have very limited long term recurrence risk and suggest the same for some N2 patients. The PAM50 ROR score, IS and ROR-RG reliably provide additional prognostic information beyond CTS and may be useful in deciding which women with node-positive HR+ EBC can be spared adjuvant chemotherapy. [Table: see text]