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]

Abstract P4-16-02: A survival benefit from locoregional radiotherapy for node-positive and CMF treated breast cancer is most significant in Luminal A tumors

Background: Between 1978–1986, 318 premenopausal women treated with mastectomy for lymph node positive breast cancer, were randomized to CMF chemotherapy alone vs. CMF chemotherapy and adjuvant radiotherapy (RT) to the chest wall and regional lymph nodes. After 15 years of follow-up, post-mastectomy RT was associated with a statistically significant 29% relative risk reduction in mortality. Recent evidence suggests that Luminal A tumors, identified using hormone receptors and Ki67, have a particularly favorable prognosis. We retrospectively identified the Luminal A tumors from this clinical trial cohort to determine if the response to postmastectomy RT differed among Luminal A and non-Luminal A tumors.

Methods: 203 archival breast tumor samples from this study were used to construct a tissue microarray. Luminal A tumors were identified using an immunopanel consisting of: estrogen receptor, progestorone receptor, Her2, and Ki67. Luminal A tumors were defined as either ER or PR positive, Her2 negative, and Ki67 < 14%. Kaplan-Meier estimates and the log-rank test were used to test the differences in locoregional relapse free survival (LRFS) and breast cancer specific survival (BCSS). Interaction between treatment and Luminal A/Non-luminal A were tested using Cox regression analysis.

Results: The intrinsic subtype was successfully determined in 144 breast tumors, and 49 were classified as Luminal A (34%). Survival outcomes at 10 years are summarized in Table 1:

Abstract P3-06-03: Association between PAM50 breast cancer intrinsic subtypes and effect of gemcitabine in advanced breast cancer patients

Background: Breast cancer can be subclassified into luminal A and B, basal-like and HER2-enriched subtypes, each with distinct biology, prognosis and response to therapy. Pre-clinical studies have suggested that a basal-like subtype is associated with responsiveness to gemcitabine. Additional data suggest that patients with highly proliferating tumors (non-luminal A) might be particularly responsive to gemcitabine. We examined these hypotheses on SBG0102, a randomized trial comparing gemcitabine plus docetaxel (GD) to single agent docetaxel (D) in patients with advanced breast cancer. Secondarily, we analyzed prognosis by PAM50 subtype, which has not previously been addressed in a metastatic setting.

Patients and Methods: RNA was isolated from archival formalin-fixed, paraffin-embedded primary breast tumor tissue from patients randomly assigned to GD or D, and analyzed with NanoString Technologies' nCounter system and PAM50 intrinsic subtyping algorithm. Using time to progression (TTP) as primary endpoint, overall survival (OS) and response rate (RR) as secondary endpoints, relationships between subtypes and outcome after chemotherapy were analyzed by methods prespecified in writing as a formal prospective-retrospective clinical trial correlative study. Data analysis was performed independently by the DBCG statistical core.

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 significantly associated with TTP (P = .0006) and OS (P = .0083) by Kaplan-Meier analysis. In the adjusted Cox model PAM50 remained independently prognostic. RR was not significantly different by subtype, and PAM50 was not a significant predictor of TTP by treatment arm. PAM50 was however a highly significant predictor of OS following GD compared to D (Pinteraction=.0016). The 43 patients with a basal-like subtype had a significant reduction in OS events (hazard ratio (HR)=0.29; 95% CI 0.15–0.57; Pinteraction=.0006), although TTP events were not significant by interaction test (HR = 0.39; 95% CI 0.19–0.82; Pinteraction=.22). Kaplan-Meier estimates revealed a gain in median OS of 10 months in the doublet arm compared to the monotherapy arm (18.7 (95% CI, 12.4–23.0) v 8.5 (95% CI, 4.2–11.8) months).

Conclusion: A significantly improved and clinical important prolongation of survival was seen from the addition of gemcitabine to docetaxel in advanced basal-like breast cancer patients. However, we could not show a similar significant reduction in TTP events. These results need validation in a second similar trial or a prospective study stratified for basal-like breast cancer to obtain convincing evidence that identification of a basal-like profile may be used to direct the use of gemcitabine in combination with docetaxel.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-03.

Prognostic significance of progesterone receptor-positive tumor cells within immunohistochemically defined luminal A breast cancer

PURPOSE

Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes.

PATIENTS AND METHODS

Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) -positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance.

RESULTS

Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) -positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa.

CONCLUSION

Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A tumors is HR positive/HER2 negative/Ki-67 less than 14%, and PR more than 20%.

Concordance among gene expression-based predictors for ER-positive breast cancer treated with adjuvant tamoxifen

BACKGROUND

ER-positive (ER+) breast cancer includes all of the intrinsic molecular subtypes, although the luminal A and B subtypes predominate. In this study, we evaluated the ability of six clinically relevant genomic signatures to predict relapse in patients with ER+ tumors treated with adjuvant tamoxifen only.

METHODS

Four microarray datasets were combined and research-based versions of PAM50 intrinsic subtyping and risk of relapse (PAM50-ROR) score, 21-gene recurrence score (OncotypeDX), Mammaprint, Rotterdam 76 gene, index of sensitivity to endocrine therapy (SET) and an estrogen-induced gene set were evaluated. Distant relapse-free survival (DRFS) was estimated by Kaplan-Meier and log-rank tests, and multivariable analyses were done using Cox regression analysis. Harrell's C-index was also used to estimate performance.

RESULTS

All signatures were prognostic in patients with ER+ node-negative tumors, whereas most were prognostic in ER+ node-positive disease. Among the signatures evaluated, PAM50-ROR, OncotypeDX, Mammaprint and SET were consistently found to be independent predictors of relapse. A combination of all signatures significantly increased the performance prediction. Importantly, low-risk tumors (>90% DRFS at 8.5 years) were identified by the majority of signatures only within node-negative disease, and these tumors were mostly luminal A (78%-100%).

CONCLUSIONS

Most established genomic signatures were successful in outcome predictions in ER+ breast cancer and provided statistically independent information. From a clinical perspective, multiple signatures combined together most accurately predicted outcome, but a common finding was that each signature identified a subset of luminal A patients with node-negative disease who might be considered suitable candidates for adjuvant endocrine therapy alone.

PAM50 breast cancer subtyping by RT-qPCR and concordance with standard clinical molecular markers

Background

Many methodologies have been used in research to identify the “intrinsic” subtypes of breast cancer commonly known as Luminal A, Luminal B, HER2-Enriched (HER2-E) and Basal-like. The PAM50 gene set is often used for gene expression-based subtyping; however, surrogate subtyping using panels of immunohistochemical (IHC) markers are still widely used clinically. Discrepancies between these methods may lead to different treatment decisions.

Methods

We used the PAM50 RT-qPCR assay to expression profile 814 tumors from the GEICAM/9906 phase III clinical trial that enrolled women with locally advanced primary invasive breast cancer. All samples were scored at a single site by IHC for estrogen receptor (ER), progesterone receptor (PR), and Her2/neu (HER2) protein expression. Equivocal HER2 cases were confirmed by chromogenic in situ hybridization (CISH). Single gene scores by IHC/CISH were compared with RT-qPCR continuous gene expression values and “intrinsic” subtype assignment by the PAM50. High, medium, and low expression for ESR1, PGR, ERBB2, and proliferation were selected using quartile cut-points from the continuous RT-qPCR data across the PAM50 subtype assignments.

Results

ESR1, PGR, and ERBB2 gene expression had high agreement with established binary IHC cut-points (area under the curve (AUC) ≥ 0.9). Estrogen receptor positivity by IHC was strongly associated with Luminal (A and B) subtypes (92%), but only 75% of ER negative tumors were classified into the HER2-E and Basal-like subtypes. Luminal A tumors more frequently expressed PR than Luminal B (94% vs 74%) and Luminal A tumors were less likely to have high proliferation (11% vs 77%). Seventy-seven percent (30/39) of ER-/HER2+ tumors by IHC were classified as the HER2-E subtype. Triple negative tumors were mainly comprised of Basal-like (57%) and HER2-E (30%) subtypes. Single gene scoring for ESR1, PGR, and ERBB2 was more prognostic than the corresponding IHC markers as shown in a multivariate analysis.

Conclusions

The standard immunohistochemical panel for breast cancer (ER, PR, and HER2) does not adequately identify the PAM50 gene expression subtypes. Although there is high agreement between biomarker scoring by protein immunohistochemistry and gene expression, the gene expression determinations for ESR1 and ERBB2 status was more prognostic.

SS18-SSX2 and the mitochondrial apoptosis pathway in mouse and human synovial sarcomas

Synovial sarcoma is a deadly malignancy with limited sensitivity to traditional cytotoxic chemotherapy. SS18-SSX fusion oncogene expression characterizes human synovial sarcomas and drives oncogenesis in a mouse model. Elevated expression of BCL2 is considered a consistent feature of the synovial sarcoma expression profile. Our objective was to evaluate the expression of apoptotic pathway members in synovial sarcomas and interrogate the impact of modulating SS18-SSX expression on this pathway. We show in human and murine synovial sarcoma cells that SS18-SSX increases BCL2 expression, but represses other anti-apoptotic genes, including MCL1 and BCL2A1. This repression is achieved by directly suppressing expression via binding through activating transcription factor 2 (ATF2) to the cyclic adenosine monophosphate (AMP) response element (CRE) in the promoters of these genes and recruiting TLE1/Groucho. The suppression of these two anti-apoptotic pathways silences the typical routes by which other tumors evade BH3-domain peptidomimetic pharmacotherapy. We show that mouse and human synovial sarcoma cells are sensitive in vitro to ABT-263, a BH3-peptidomimetic, much more than the other tested cancer cell lines. ABT-263 also enhances the sensitivity of these cells to doxorubicin, a traditional cytotoxic chemotherapy used for synovial sarcoma. We also demonstrate the capacity of ABT-263 to stunt synovial sarcomagenesis in vivo in a genetic mouse model. These data recommend pursuit of BH3-peptidomimetic pharmacotherapy in human synovial sarcomas.

A 50-gene intrinsic subtype classifier for prognosis and prediction of benefit from adjuvant tamoxifen

PURPOSE

Gene expression profiling classifies breast cancer into intrinsic subtypes based on the biology of the underlying disease pathways. We have used material from a prospective randomized trial of tamoxifen versus placebo in premenopausal women with primary breast cancer (NCIC CTG MA.12) to evaluate the prognostic and predictive significance of intrinsic subtypes identified by both the PAM50 gene set and by immunohistochemistry.

EXPERIMENTAL DESIGN

Total RNA from 398 of 672 (59%) patients was available for intrinsic subtyping with a quantitative reverse transcriptase PCR (qRT-PCR) 50-gene predictor (PAM50) for luminal A, luminal B, HER-2-enriched, and basal-like subtypes. A tissue microarray was also constructed from 492 of 672 (73%) of the study population to assess a panel of six immunohistochemical IHC antibodies to define the same intrinsic subtypes.

RESULTS

Classification into intrinsic subtypes by the PAM50 assay was prognostic for both disease-free survival (DFS; P = 0.0003) and overall survival (OS; P = 0.0002), whereas classification by the IHC panel was not. Luminal subtype by PAM50 was predictive of tamoxifen benefit [DFS: HR, 0.52; 95% confidence interval (CI), 0.32-0.86 vs. HR, 0.80; 95% CI, 0.50-1.29 for nonluminal subtypes], although the interaction test was not significant (P = 0.24), whereas neither subtyping by central immunohistochemistry nor by local estrogen receptor (ER) or progesterone receptor (PR) status were predictive. Risk of relapse (ROR) modeling with the PAM50 assay produced a continuous risk score in both node-negative and node-positive disease.

CONCLUSIONS

In the MA.12 study, intrinsic subtype classification by qRT-PCR with the PAM50 assay was superior to IHC profiling for both prognosis and prediction of benefit from adjuvant tamoxifen.

Quantitative hormone receptors, triple-negative breast cancer (TNBC), and molecular subtypes: A collaborative effort of the BIG-NCI NABCG

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Background: Most TNBC trials focusing on biology of the basal-like subtype (BLBC) allow borderline (1-10% staining) estrogen receptor (ER) and progesterone receptor (PgR) expression by immunohistochemistry (IHC); however the optimal ER and PgR cut points to enrich for non-luminal subtypes has not been studied. In this study,we compared quantitative ER/PgR status with gene expression-based intrinsic subtype in order to determine if borderline cases should be included in TNBC trials. Methods: ER, PgR, and HER2 status was determined by central review of tumors collected from three phase III randomized trials: GEICAM 9906 (n=820), NCIC CTG MA.5 (n=476) and MA.12 (n=398). PAM50 intrinsic subtyping (BLBC, HER2-enriched, Luminal A, Luminal B and Normal-like) was performed using the qRT-PCR-based assay. Quantitative ER/PgR expression by IHC and subtype was tested using ANOVA and Fisher’s exact test. Results: Of 1,694 tumors, 15% were BLBC, 21% HER2-Enriched, 33% Luminal A, 25% Luminal B and 4% Normal-like. BLBC subtypes were significantly associated with low expression of ER and PgR (median = 0.05%) compared to other subtypes (p < 0.001). The vast majority of BLBC (96%) did not express any ER or PgR protein by IHC. BLBC represented 73% of TNBC (borderline cases not included) and significantly more than the additional TNBC with borderline ER/PgR (p < 0.001). Within borderline ER/PgR and HER2-negative cases only, 17% were BLBC and 46% were luminal subtypes (Table). Conclusions: BLBC rarely express ER or PgR by IHC. The majority of borderline TNBC (1-10% ER/PgR) are not BLBC; half of them are categorized as luminal categories that may be endocrine sensitive. TNBC trials seeking to target BLBC tumor biology should use the ASCO/CAP guidelines of 0% as the cutoffs for ER and PgR negativity. [Table: see text]

Systematic analysis of breast cancer morphology uncovers stromal features associated with survival

The morphological interpretation of histologic sections forms the basis of diagnosis and prognostication for cancer. In the diagnosis of carcinomas, pathologists perform a semiquantitative analysis of a small set of morphological features to determine the cancer's histologic grade. Physicians use histologic grade to inform their assessment of a carcinoma's aggressiveness and a patient's prognosis. Nevertheless, the determination of grade in breast cancer examines only a small set of morphological features of breast cancer epithelial cells, which has been largely unchanged since the 1920s. A comprehensive analysis of automatically quantitated morphological features could identify characteristics of prognostic relevance and provide an accurate and reproducible means for assessing prognosis from microscopic image data. We developed the C-Path (Computational Pathologist) system to measure a rich quantitative feature set from the breast cancer epithelium and stroma (6642 features), including both standard morphometric descriptors of image objects and higher-level contextual, relational, and global image features. These measurements were used to construct a prognostic model. We applied the C-Path system to microscopic images from two independent cohorts of breast cancer patients [from the Netherlands Cancer Institute (NKI) cohort, n = 248, and the Vancouver General Hospital (VGH) cohort, n = 328]. The prognostic model score generated by our system was strongly associated with overall survival in both the NKI and the VGH cohorts (both log-rank P ≤ 0.001). This association was independent of clinical, pathological, and molecular factors. Three stromal features were significantly associated with survival, and this association was stronger than the association of survival with epithelial characteristics in the model. These findings implicate stromal morphologic structure as a previously unrecognized prognostic determinant for breast cancer.

Deconstruction of the SS18-SSX fusion oncoprotein complex: insights into disease etiology and therapeutics

Synovial sarcoma is a translocation-associated sarcoma where the underlying chromosomal event generates SS18-SSX fusion transcripts. In vitro and in vivo studies have shown that the SS18-SSX fusion oncoprotein is both necessary and sufficient to support tumorigenesis; however, its mechanism of action remains poorly defined. We have purified a core SS18-SSX complex and discovered that SS18-SSX serves as a bridge between activating transcription factor 2 (ATF2) and transducin-like enhancer of split 1 (TLE1), resulting in repression of ATF2 target genes. Disruption of these components by siRNA knockdown or treatment with HDAC inhibitors rescues target gene expression, leading to growth suppression and apoptosis. Together, these studies define a fundamental role for aberrant ATF2 transcriptional dysregulation in the etiology of synovial sarcoma.

Responsiveness of intrinsic subtypes to adjuvant anthracycline substitution in the NCIC.CTG MA.5 randomized trial

PURPOSE

Recent studies suggest that intrinsic breast cancer subtypes may differ in their responsiveness to specific chemotherapy regimens. We examined this hypothesis on NCIC.CTG MA.5, a clinical trial randomizing premenopausal women with node-positive breast cancer to adjuvant CMF (cyclophosphamide-methotrexate-fluorouracil) versus CEF (cyclophosphamide-epirubicin-fluorouracil) chemotherapy.

EXPERIMENTAL DESIGN

Intrinsic subtype was determined for 476 tumors using the quantitative reverse transcriptase PCR PAM50 gene expression test. Luminal A, luminal B, HER2-enriched (HER2-E), and basal-like subtypes were correlated with relapse-free survival (RFS) and overall survival (OS), estimated using Kaplan-Meier plots and log-rank testing. Multivariable Cox regression analyses determined significance of interaction between treatment and intrinsic subtypes.

RESULTS

Intrinsic subtypes were associated with RFS (P = 0.0005) and OS (P < 0.0001) on the combined cohort. The HER2-E showed the greatest benefit from CEF versus CMF, with absolute 5-year RFS and OS differences exceeding 20%, whereas there was a less than 2% difference for non-HER2-E tumors (interaction test P = 0.03 for RFS and 0.03 for OS). Within clinically defined Her2(+) tumors, 79% (72 of 91) were classified as the HER2-E subtype by gene expression and this subset was strongly associated with better response to CEF versus CMF (62% vs. 22%, P = 0.0006). There was no significant difference in benefit between CEF and CMF in basal-like tumors [n = 94; HR, 1.1; 95% confidence interval (CI), 0.6-2.1 for RFS and HR, 1.3; 95% CI, 0.7-2.5 for OS].

CONCLUSION

HER2-E strongly predicted anthracycline sensitivity. The chemotherapy-sensitive basal-like tumors showed no added benefit for CEF over CMF, suggesting that nonanthracycline regimens may be adequate in this subtype although further investigation is required.

Histone deacetylase 1 and 2 in mesenchymal tumors

Histone deacetylases (HDACs) have a critical role in epigenetic gene silencing, rendering a compact chromatin structure by removing acetyl groups from lysine residues within the tails of core histones, thereby repressing gene expression. Epigenetic transcriptional dysregulation is an important oncogenic mechanism in some sarcomas associated with translocations, for which antitumor activity by HDAC inhibitors has been shown in preclinical studies. Nevertheless, the expression of the protein targets of these drugs has not yet been broadly surveyed in this neoplasia. In this study, we assess the expression of HDAC1 and 2 by immunohistochemistry in a tissue microarray series of 1332 cases, representing 44 categories of malignant and borderline mesenchymal tumors. HDAC2 was the more highly expressed isoform, and was more strongly expressed in translocation-associated sarcomas than in other mesenchymal tumors or normal tissues. HDAC1, in contrast, displayed lower expression in translocation-associated sarcomas than in other mesenchymal tumors or in normal tissues. These results indicate that HDAC1 and HDAC2 are differentially expressed in mesenchymal neoplasms, and suggest that HDAC2 is the isoform more likely contributing to the pathogenesis of many translocation-associated sarcomas and to their response to HDAC inhibitors.

P1-06-07: TIMP-1 in Combination with HER2 and TOP2A for Prediction of Benefit from Adjuvant Anthracyclines in High Risk Breast Cancer Patients

Purpose: HER2 amplification, TOP2A aberrations and absence of TIMP-1 (Tissue Inhibitor of Metalloproteinase-1) expression in breast carcinomas have been associated with incremental benefit from anthracycline-containing adjuvant chemotherapy in several reports. In the DBCG 89D trial, we demonstrated that the predictive value of these markers improved when they were combined in a profile and the present study was undertaken to validate these findings in NCIC CTG MA.5, a similar but independent clinical trial.

Design: TIMP-1 was examined by immunohistochemistry in archival tumor tissue from 403 of 716 premenopausal high-risk patients with known HER2 and TOP2A status who were randomized to CEF or CMF in the MA.5 trial. Patients were classified according to 2 predefined marker profiles — the HT profile (HER2, TIMP-1) and the 2T profile (TOP2A, TIMP-1) and the statistical analyses were performed as closely as possible to the analytical approach used previously in the MA.5 trial and when analysing the biomarker profiles in the DBCG 89D trial.

Results: 98 (24%) patients had no TIMP-1 staining of tumor cells, 27% were HER2 amplified, and 18% were TOP2A aberrant. 44% of patients were classified as HT responsive (HER2-positive and/or TIMP-1 negative) and 37% as 2T responsive (TOP2A aberrant and/or TIMP-1 negative). There was no heterogeneity in treatment effect of CEF versus CMF according to TIMP-1. In HT responsive patients, CEF was superior to CMF with improved RFS (adjusted HR, 0.64; 95% CI, 0.42 to 0.98) and a borderline-significant improvement in OS (adjusted HR, 0.66; 95% CI, 0.42 to 1.04). A significant HT profile versus treatment interaction was detected for OS (P=0.03). In 2T responsive patients, CEF was superior to CMF with borderline significant improvement in RFS (adjusted HR, 0.67; 95% CI, 0.43 to 1.03), and with improvement in OS (adjusted HR, 0.58; 95% CI, 0.36 to 0.93). A significant 2T profile versus treatment interaction was detected for OS (P=0.01).

Conclusion: In the MA.5 trial, we have validated the HT and 2T profiles as predictors of incremental benefit from anthracycline-containing chemotherapy. The proportion of patients categorized as anthracycline responsive increases from 18–27% using individual markers to 37–44% when combining TIMP-1 with either HER2 or TOP2A. Patients with responsive profiles had a 34–42% relative reduction in mortality when treated with CEF. In contrast, patients with non-responsive profiles (56-63% of patients) had no incremental benefit from CEF compared with CMF. All 3 biomarkers are easily applied in the pathology lab and as such could be used in daily clinical practice to select patients for anthracycline or non-anthracycline containing adjuvant chemotherapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-06-07.

TIMP-1 in combination with HER2 and TOP2A for prediction of benefit from adjuvant anthracyclines in high-risk breast cancer patients

HER2 amplification, TOP2A aberrations, and absence of tissue inhibitor of metalloproteinase (TIMP-1) expression in breast carcinomas have been shown to be associated with incremental benefit from anthracycline-containing adjuvant chemotherapy, and this study was undertaken to validate these findings in a similar, but independent, randomized clinical trial. TIMP-1 was examined by immunohistochemistry in archival tumor tissue from 403 of 716 premenopausal high-risk patients with known HER2 and TOP2A status who were randomized to cyclophosphamide, epirubicin, and fluorouracil (CEF) or cyclophosphamide, methotrexate, and fluorouracil (CMF) in the MA.5 trial. Ninety-eight (24%) patients had no TIMP-1 staining of tumor cells, 27% were HER2 amplified, and 18% were TOP2A aberrant. Forty-four percentage was classified as HT responsive (HER2 amplified and/or TIMP-1 negative) and 37% as 2T responsive (TOP2A aberrant and/or TIMP-1 negative). There was no heterogeneity in treatment effect of CEF versus CMF according to TIMP-1. In HT-responsive patients, CEF was superior to CMF with an improved RFS (adjusted HR, 0.64; 95% CI, 0.42-0.97), but this was not significant for OS (adjusted HR, 0.66; 95% CI, 0.42-1.04). A significant HT profile versus treatment interaction was detected for OS (P = 0.03). In 2T-responsive patients, CEF seemed to improve RFS compared to CMF (adjusted HR, 0.67; 95% CI, 0.43-1.03) and improved OS (adjusted HR, 0.58; 95% CI, 0.36-0.93). A significant 2T profile versus treatment interaction was detected for OS (P = 0.01). With this study, we validate a more substantial reduction in mortality by CEF compared to CMF in patients with an HT- or 2T-responsive profile; however, we could not show a similarly significant reduction in RFS events, where a benefit of CEF over CMF was found irrespective of TIMP-1 status. Further studies are necessary before the HT and 2T profiles may be used to direct the use of anthracyclines.

Assessment of Ki67 in breast cancer: recommendations from the International Ki67 in Breast Cancer working group

Uncontrolled proliferation is a hallmark of cancer. In breast cancer, immunohistochemical assessment of the proportion of cells staining for the nuclear antigen Ki67 has become the most widely used method for comparing proliferation between tumor samples. Potential uses include prognosis, prediction of relative responsiveness or resistance to chemotherapy or endocrine therapy, estimation of residual risk in patients on standard therapy and as a dynamic biomarker of treatment efficacy in samples taken before, during, and after neoadjuvant therapy, particularly neoadjuvant endocrine therapy. Increasingly, Ki67 is measured in these scenarios for clinical research, including as a primary efficacy endpoint for clinical trials, and sometimes for clinical management. At present, the enormous variation in analytical practice markedly limits the value of Ki67 in each of these contexts. On March 12, 2010, an international panel of investigators with substantial expertise in the assessment of Ki67 and in the development of biomarker guidelines was convened in London by the co-chairs of the Breast International Group and North American Breast Cancer Group Biomarker Working Party to consider evidence for potential applications. Comprehensive recommendations on preanalytical and analytical assessment, and interpretation and scoring of Ki67 were formulated based on current evidence. These recommendations are geared toward achieving a harmonized methodology, create greater between-laboratory and between-study comparability, and allow earlier valid applications of this marker in clinical practice.

Kaposi sarcoma of the adrenal gland resembling epithelioid angiosarcoma: a case report

Patients with human immunodeficiency virus infection are known to have increased risk of various neoplasms, including Kaposi sarcoma, which classically involves the skin and mucosal locations. The anaplastic variant of Kaposi sarcoma is rare and poorly documented in the literature. It is characterised clinically by a more aggressive behaviour and increased metastatic potential, and histologically by increased cellularity, mitotic rate, and rarely by epithelioid angiosarcoma-like morphology. We report herein a 64-year-old man with a long-standing history of human immunodeficiency virus infection who developed a right adrenal tumor with a high-grade anaplastic angiosarcoma-like morphology. Immunohistochemistry for human herpes virus-8 was strongly positive in the tumor cells. To the best of our knowledge, this is the first report of an anaplastic Kaposi sarcoma in the adrenal gland.

deFuse: an algorithm for gene fusion discovery in tumor RNA-Seq data

Gene fusions created by somatic genomic rearrangements are known to play an important role in the onset and development of some cancers, such as lymphomas and sarcomas. RNA-Seq (whole transcriptome shotgun sequencing) is proving to be a useful tool for the discovery of novel gene fusions in cancer transcriptomes. However, algorithmic methods for the discovery of gene fusions using RNA-Seq data remain underdeveloped. We have developed deFuse, a novel computational method for fusion discovery in tumor RNA-Seq data. Unlike existing methods that use only unique best-hit alignments and consider only fusion boundaries at the ends of known exons, deFuse considers all alignments and all possible locations for fusion boundaries. As a result, deFuse is able to identify fusion sequences with demonstrably better sensitivity than previous approaches. To increase the specificity of our approach, we curated a list of 60 true positive and 61 true negative fusion sequences (as confirmed by RT-PCR), and have trained an adaboost classifier on 11 novel features of the sequence data. The resulting classifier has an estimated value of 0.91 for the area under the ROC curve. We have used deFuse to discover gene fusions in 40 ovarian tumor samples, one ovarian cancer cell line, and three sarcoma samples. We report herein the first gene fusions discovered in ovarian cancer. We conclude that gene fusions are not infrequent events in ovarian cancer and that these events have the potential to substantially alter the expression patterns of the genes involved; gene fusions should therefore be considered in efforts to comprehensively characterize the mutational profiles of ovarian cancer transcriptomes.

Cancer and Leukemia Group B Pathology Committee guidelines for tissue microarray construction representing multicenter prospective clinical trial tissues

Practice-changing evidence requires confirmation, preferably in multi-institutional clinical trials. The collection of tissue within such trials has enabled biomarker studies and evaluation of companion diagnostic tests. Tissue microarrays (TMAs) have become a standard approach in many cooperative oncology groups. A principal goal is to maximize the number of assays with this precious tissue. However, production strategies for these arrays have not been standardized, possibly decreasing the value of the study. In this article, members of the Cancer and Leukemia Group B Pathology Committee relay our experiences as array facility directors and propose guidelines regarding the production of high-quality TMAs for cooperative group studies. We also discuss statistical issues arising from having a proportion of patients available for TMAs and the possibility that patients with TMAs fail to represent the greater study population.

Discovery research to clinical trial: a ten year journey

Clinician-scientists have the training and motivation to translate basic science into tools for improved clinical care, but the road to achieve this is hardly straight forward, particularly for large scale genomic datasets. This year's Joe Doupe Young Investigator award winner, Dr. Torsten Nielsen, details successful examples of new scientific insights, diagnostics and clinical trials that have resulted from microarray-based gene expression profiling of sarcomas: TLE1 as a biomarker for synovial sarcoma, histone deacetylase inhibitor therapy for translocation-associated sarcomas of young adults, and CSF1 pathway inhibitors for tenosynovial giant cell tumors. Results from exciting, emerging next generation sequencing technologies will need to undergo similar validation and preclinical studies before they can be expected to impact patient care.

A comparison of PAM50 intrinsic subtyping with immunohistochemistry and clinical prognostic factors in tamoxifen-treated estrogen receptor-positive breast cancer

PURPOSE

To compare clinical, immunohistochemical (IHC), and gene expression models of prognosis applicable to formalin-fixed, paraffin-embedded blocks in a large series of estrogen receptor (ER)-positive breast cancers from patients uniformly treated with adjuvant tamoxifen.

EXPERIMENTAL DESIGN

Quantitative real-time reverse transcription-PCR (qRT-PCR) assays for 50 genes identifying intrinsic breast cancer subtypes were completed on 786 specimens linked to clinical (median follow-up, 11.7 years) and IHC [ER, progesterone receptor (PR), HER2, and Ki67] data. Performance of predefined intrinsic subtype and risk-of-relapse scores was assessed using multivariable Cox models and Kaplan-Meier analysis. Harrell's C-index was used to compare fixed models trained in independent data sets, including proliferation signatures.

RESULTS

Despite clinical ER positivity, 10% of cases were assigned to nonluminal subtypes. qRT-PCR signatures for proliferation genes gave more prognostic information than clinical assays for hormone receptors or Ki67. In Cox models incorporating standard prognostic variables, hazard ratios for breast cancer disease-specific survival over the first 5 years of follow-up, relative to the most common luminal A subtype, are 1.99 [95% confidence interval (CI), 1.09-3.64] for luminal B, 3.65 (95% CI, 1.64-8.16) for HER2-enriched subtype, and 17.71 (95% CI, 1.71-183.33) for the basal-like subtype. For node-negative disease, PAM50 qRT-PCR-based risk assignment weighted for tumor size and proliferation identifies a group with >95% 10-year survival without chemotherapy. In node-positive disease, PAM50-based prognostic models were also superior.

CONCLUSION

The PAM50 gene expression test for intrinsic biological subtype can be applied to large series of formalin-fixed, paraffin-embedded breast cancers, and gives more prognostic information than clinical factors and IHC using standard cut points.