Efficacy of Lapatinib in Patients with HER2-Negative Metastatic Breast Cancer and HER2-Positive Circulating Tumor Cells-The DETECT III Clinical Trial

BACKGROUND

The phenotypes of tumor cells change during disease progression, but invasive rebiopsies of metastatic lesions are not always feasible. Here we aimed to determine whether initially HER2-negative metastatic breast cancer (MBC) patients with HER2-positive circulating tumor cells (CTCs) benefit from a HER2-targeted therapy.

METHODS

The open-label, interventional randomized phase III clinical trial (EudraCT Number 2010-024238-46, CliniclTrials.gov Identifier: NCT01619111) recruited from March 2012 until September 2019 with a follow-up duration of 19.5 months. It was a multicenter clinical trial with 94 participating German study centers. A total of 2137 patients with HER2-negative MBC were screened for HER2-positive CTCs with a final modified intention-to-treat population of 101 patients. Eligible patients were randomized to standard therapy with or without lapatinib. Primary study endpoints included CTC clearance (no CTCs at the end of treatment) and secondary endpoints were progression-free survival, overall survival (OS), and safety.

RESULTS

In both treatment arms CTC clearance at first follow-up visit-although not being significantly different for both arms at any time point-was significantly associated with improved OS (42.4 vs 14.1 months; P = 0.002). Patients treated additionally with lapatinib had a significantly improved OS over patients receiving standard treatment (20.5 vs 9.1 months, P = 0.009).

CONCLUSIONS

DETECT III is the first clinical study indicating that phenotyping of CTCs might have clinical utility for stratification of MBC cancer patients to HER2-targeting therapies. The OS benefit could be related to lapatinib, but further studies are required to prove this clinical observation. ClinicalTrials.gov Registration Number: NCT01619111.

Post-Neoadjuvant Treatment in HER2-Positive Breast Cancer: Escalation and De-Escalation Strategies

Simple Summary

The response to neoadjuvant treatment is strongly associated with the clinical outcome of breast cancer patients, especially in the HER2-positive subtype of the disease. In HER2-positive patients with a residual tumor burden, an escalation of post-neoadjuvant therapy leads to the improvement of survival, while (post)-neoadjuvant treatment de-escalation is currently being discussed in low-risk settings in order to avoid unnecessary toxicities.

Abstract

Patients with high-risk non-metastatic breast cancer are recommended for chemotherapy, preferably in the neoadjuvant setting. Beyond advantages such as a better operability and an improved assessment of individual prognosis, the preoperative administration of systemic treatment offers the unique possibility of selecting postoperative therapies according to tumor response. In patients with HER2-positive disease, both the escalation of therapy in the case of high-risk features and the de-escalation in patients with a low tumor load are currently discussed. Patients with small node-negative tumors receive primary surgery and, upon confirmation of pathological T1 N0 status, de-escalated adjuvant therapy with paclitaxel and trastuzumab. For those with a large tumor and/or nodal involvement, neoadjuvant polychemotherapy with a dual antibody blockade is recommended. Patients with invasive residual disease benefit from switching postoperative therapy to the antibody-drug-conjugate trastuzumab emtansine (T-DM1). In this review, we discuss current evidence and controversies regarding post-neoadjuvant treatment strategies in HER2-positive breast cancer.

Abstract PD3-12: Efficacy of the tyrosine kinase inhibitor lapatinib in the treatment of patients with HER2-negative metastatic breast cancer and HER2-positive circulating tumor cells - results from the randomized phase III DETECT III trial

Background: It is well-known that tumor biology may change during the course of the disease due to clonal evolution, and such changes might have important implications for response to targeted treatments. Circulating tumor cells (CTCs) could serve as a real-time liquid biopsy to detect changes in tumor biology. It has been demonstrated that patients with HER2-negative metastatic breast cancer (MBC) may have discordant, HER2-positive CTCs in the peripheral blood. However, up to now there is no randomized clinical trial investigating whether treatment decisions based on CTC phenotype provide benefits in terms of improved outcome. The aim of the DETECT III study is to investigate whether patients with initially HER2-negative MBC and HER2-positive CTCs benefit from HER2-targeted therapy with the tyrosine kinase inhibitor lapatinib. In addition, the significance of CTCs as an early predictive marker for response to therapy will be analyzed. Methods: The randomized phase III DETECT III trial (NCT01619111) compares lapatinib in combination with standard therapy versus standard therapy alone in patients with initially HER2-negative MBC and HER2-positive CTCs. Efficacy of lapatinib treatment is evaluated by CTC clearance rate, progression-free survival (PFS) and overall survival (OS). In addition, we investigate the association between CTC results and both PFS and OS to assess the utility of CTCs as an early predictive marker for treatment response. CTC enumeration and phenotyping was performed using the CellSearch® technology (Menarini Silicon Biosystems; Bologna, Italy). Survival data are analyzed using log rank tests, univariable and adjusted multivariable cox regressions. Results: First results on CTC clearance rates, PFS and OS of 105 prospectively randomized patients will be presented. Conclusion: This first randomized clinical trial in breast cancer patients with treatment decisions being based on the phenotype of CTCs will show whether patients with HER2 negative MBC and HER2 positive CTCs benefit from additional HER2-targeted therapy with lapatinib. This finding might be increasingly important as novel HER2-targeted drugs become available.

Citation Format: Tanja Fehm, Volkmar Mueller, Maggie Banys-Paluchowski, Peter A Fasching, Thomas WP Friedl, Andreas Hartkopf, Jens Huober, Christian Loehberg, Brigitte Rack, Sabine Riethdorf, Andreas Schneeweiss, Diethelm Wallwiener, Franziska Meier-Stiegen, Oliver Hoffmann, Lothar Müller, Pauline Wimberger, Eugen Ruckhaeberle, Jens Blohmer, Wolfgang Janni. Efficacy of the tyrosine kinase inhibitor lapatinib in the treatment of patients with HER2-negative metastatic breast cancer and HER2-positive circulating tumor cells - results from the randomized phase III DETECT III trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD3-12.

Recent advances in radiotherapy of breast cancer

Radiation therapy is an integral part of the multidisciplinary management of breast cancer. Regional lymph node irradiation in younger trials seems to provide superior target coverage as well as a reduction in long-term toxicity resulting in a small benefit in the overall survival rate. For partial breast irradiation there are now two large trials available which support the role of partial breast irradiation in low risk breast cancer patients. Multiple randomized trials have established that a sequentially applied dose to the tumor bed improves local control with the cost of worse cosmetic results.

Label-Free Enrichment and Molecular Characterization of Viable Circulating Tumor Cells from Diagnostic Leukapheresis Products

INTRODUCTION

Circulating tumor cells (CTCs) may be used to improve cancer diagnosis, prognosis, and treatment. However, because knowledge regarding CTC biology is limited and the numbers of CTCs and CTC-positive cancer patients are low, progress in this field is slow. We addressed this limitation by combining diagnostic leukapheresis (DLA) and microfluidic enrichment to obtain large numbers of viable CTCs from metastasized breast cancer patients.

METHODS

DLA was applied to 9 patients, and 7.5 mL of peripheral blood was drawn. CTCs were enriched with the Parsortix™ system. The quality of CTCs from fresh and cryopreserved DLA products was tested, and CTCs were cultured in vitro. Single uncultured and cultured CTCs were isolated by micromanipulation to determine different parameters, such as genomic aberrations and mutation profiles of selected tumor-associated genes. Expression levels of estrogen receptor and HER2/neu were monitored during in vitro culture.

RESULTS

Viable CTCs from peripheral blood and fresh or frozen DLA products could be enriched. DLA increased the likelihood of successful CTC culture. Cryopreserved DLA products could be stored with minimal CTC loss and no overt reduction in the tumor cell quality and viability during an observation period of up to 3 years. The analyzed parameters did not change during in vitro culture. DLA samples with high CTC numbers and lower ratios of apoptotic CTCs were more likely to grow in culture.

CONCLUSIONS

The increased CTC numbers from fresh or cryopreserved DLA products facilitate multiple functional and molecular analyses and, thus, could improve our knowledge of their biology.

Abstract P3-01-12: Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients

Introduction: The enumeration of circulating tumor cells (CTCs) has been shown to be of prognostic relevance for neoadjuvant, adjuvant and metastatic setting of breast cancer in multiple clinical trials. Moreover, the serial determination of CTCs enables therapy monitoring in the metastatic setting. One major caveat is the low number of CTCs detected by established methods which limits the possibility for further evaluation including phenotyping and genotyping. Therefore, the clinical use of CTCs as liquid biopsy for making therapy decisions is still under discussion. Diagnostic leukapheresis (DLA) has been previously established by our research group and implemented in the workflow for isolation and detection of CTCs enabling a reliable detection of CTCs at high frequency. The aim of this clinical study was to assess the safety of leukapheresis in 39 patients with primary and metastatic breast cancer.

Methods: DLA was performed at least 1d before surgery or chemotherapy. A median blood volume of 2.7 L (range, 1.0 L–5.3 L) was processed. Citrate dextrose solution A was used for anticoagulation with ratios ranging from 11:1 to 24:1. Complete blood count as well as measuring blood pressure and heart rate was performed before start of DLA and immediately after DLA. CTCs were enumerated using the CellSearch system. DLA products containing a median number of 1,8x108 MNCs were processed.

Results: 41 patients were eligible for DLA. Only in two patients DLA could not be performed due to technical problems. Thirty-nine patients underwent leukapheresis. Twenty-six patients had non metastatic breast cancer. Thirteen patients were diagnosed with metastatic breast cancer. Severe adverse events including hypotension, nauseas, tingling e.g. resulting in interruption of apheresis were not observed. The DLA did not interfere with the start of chemotherapy or surgery. Complete blood count before and after DLA showed statistic significant but clinically irrelevant decrease in numbers of leukocytes, thrombocytes, hemoglobin and the percentage of hematocrit. In 11/21 DLA samples (52%) of patients with primary breast cancer CTCs were detected. Number of CTCs ranged from 1 to 51. In 11/13 DLA samples (85%) of patients with MBC CTCs were detected. Number of CTCs ranged from 1 to 2913.

Conclusion: Establishing a routine DLA protocol we demonstrated that this procedure is clinically safe and can be implemented into the clinical workflow of breast cancer patient care.

Citation Format: Fehm T, Meier-Stiegen F, Jaeger B, Reinhardt F, Naskou J, Franken A, Neubauer H, Driemel C, Ruckhaeberle E, Niederacher D, Fischer J, Stoecklein N. Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-12.

Prognostic Relevance of Circulating Tumor Cells in Molecular Subtypes of Breast Cancer

Circulating tumor cells (CTCs) can be detected in the peripheral blood of breast cancer patients with early and metastatic disease. Recent data suggest that immune pathologic characteristics between the primary tumor, metastatic colonies and CTCs are discordant and that CTCs possess an independent phenotype that is associated with prognosis and treatment efficacy. Large scale gene expression analysis has provided the possibility to stratify breast cancer according to the gene expression fingerprint of primary tumor tissue into five intrinsic molecular subtypes which can be associated with different clinical outcome. As a consequence of the different prognostic power of primary tumors' characteristics and CTCs several groups have started to investigate if CTCs might be disseminated differentially within these breast cancer subtypes. They determined the CTC number in immunohistochemical subtypes to validate if CTCs may provide differential and more specific prognostic information within each subtype. This review provides an overview of the outcome of some recently published data gathered from early and metastatic breast cancer.

Recommendations from an international consensus conference on the current status and future of neoadjuvant systemic therapy in primary breast cancer

The use of neoadjuvant systemic therapy (NST) for the treatment of primary breast cancer has constantly increased, especially in trials of new therapeutic regimens. In the 1980 s, NST was shown to substantially improve breast-conserving surgery rates and was first typically used for patients with inoperable locally advanced or inflammatory breast cancer. Investigators have since also used NST as an in vivo test for chemosensitivity by assessing pathologic complete response. Today, by using pathologic response and other biomarkers as intermediate end points, results from trials of new regimens and therapies that use NST are aimed to precede and anticipate the results from larger adjuvant trials. In 2003, a panel of representatives from various breast cancer clinical research groups was first convened in Biedenkopf to formulate recommendations on the use of NST. The obtained consensus was updated in two subsequent meetings in 2004 and 2006. The most recent conference on recommendations on the use of NST took place in 2010 and forms the basis of this report.

P3-01-12: Prognostic Impact of RANK, RANKL and OPG Gene Expression in ER Positive Primary Breast Cancer

Background

The cell surface receptor RANK (receptor activator of NFκB), its ligand (RANKL) and the decoy receptor of RANKL osteoprotegerin (OPG) play an important functional role in bone physiology and in bone metastasis by regulating osteoclasts. Just recently it was shown that tumor-infiltrating lymphocytes can stimulate breast cancer metastases through RANK-RANKL signalling.

Material and methods: We analyzed gene expression of RANK, RANKL and OPG in a combined Affymetrix dataset of 307 ER positive breast cancers from our institutions which were either untreated of treated with chemotherapy. Kaplan Meier analysis of disease free survival and Cox regression analysis was applied to examine the prognostic value of the different markers.

Results: We observed no significant difference in survival when samples were analyzed according to either RANK or RANKL mRNA expression. In contrast when samples were stratified in quartiles of OPG expression a positive linear relationship of survival with the expression of OPG was observed. Moreover since OPG demonstrated a bimodal type of expression a cutoff value can be derived from the expression data. Using this cutoff value a hazard ration of 2.14 (95% CI 1.27−3.61; P=0.004 for low OPG expression was detected. OPG expression correlated with lower proportion of grade 3 tumors (15.7% vs 27%; P=0.022) and a higher proportion of PgR positive samples (86.2% vs 71.4%; P=0.002). No significant differences were observed for lymph node status, age, tumor size and HER2 status. In multivariate analysis only lymph node status remained significant while OPG, Ki67, age, grade, and PgR only displayed a trend towards significance.

Conclusion: Expression of osteoprotegerin seems to correlate with good prognosis in ER postive breast cancer. These data are in line with in vitro studies demonstration that OPG inhibits RANKL induced migration of tumor cells.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-01-12.

P2-12-11: Clinical Relevance of a IL-8/B-Cell Gene Signature Identified from Triple Negative Breast Cancer (TNBC) in Intrinsic Breast Cancer Subtypes

Background: As presented recently (SABCS 2010, #S5-5) a ratio of high B-cell and low IL-8 metagenes using gene expression analysis identified 32 % of triple negative breast cancers with good prognosis and was the only significant predictor in multivariate analysis including routine clinicopathological variables.

However, the clinical relevance of this signature within the intrinsic breast cancer subtypes still remains unclear and is analyzed here.

Methods: Affymetrix gene expression data from n=2417 breast cancer patients have been assembled. We performed an unsupervised analysis to define metagenes that distinguish molecular subsets within TNBC (SABCS 2010, #S5-5). A high expression of B- cell metagenes was associated with good and high expression of IL-8-related metagenes were associated with poor prognosis.

To identify intrinsic subtypes we used the method previously described by Hu et al. (2006) and the prognostic value within those subtypes was assessed by analyzing the event free survival of patients as function of high and low B-cell/IL-8 metagene ratio.

Results: Comparing ER positive with ER negative patients the B-ceh7LL-8 ratio showed only in ER negative breast cancer a significant prognostic value (log rank p-value <.0001).

Within the entire cohort 37.8 % of patients could be assigend to luminal A, 35.2 % to luminal B, 7,4 % to erbB2 and 19.6 % to basal-like subtypes. Event free survival of patients with good or poor B-cell/IL-8 ratio showed only in basal-like breast cancer patients a statistical significant difference (p<.0001). However, we could not observe any difference in prognosis in luminal A and B, as well as erbB2 tumors. No difference in the expression of the proliferation metagene was observed when samples of the intrinsic subtypes were stratified according to the prognostic predictor based on high expression of the B-Cell metagene and low expression of the IL-8 metagene.

Conclusion: The B-cell/IL-8 ratio is highly prognostic in basal-like/TNBC and shows no association with proliferation status.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-12-11.

A clinically relevant gene signature in triple negative and basal-like breast cancer

INTRODUCTION

Current prognostic gene expression profiles for breast cancer mainly reflect proliferation status and are most useful in ER-positive cancers. Triple negative breast cancers (TNBC) are clinically heterogeneous and prognostic markers and biology-based therapies are needed to better treat this disease.

METHODS

We assembled Affymetrix gene expression data for 579 TNBC and performed unsupervised analysis to define metagenes that distinguish molecular subsets within TNBC. We used n = 394 cases for discovery and n = 185 cases for validation. Sixteen metagenes emerged that identified basal-like, apocrine and claudin-low molecular subtypes, or reflected various non-neoplastic cell populations, including immune cells, blood, adipocytes, stroma, angiogenesis and inflammation within the cancer. The expressions of these metagenes were correlated with survival and multivariate analysis was performed, including routine clinical and pathological variables.

RESULTS

Seventy-three percent of TNBC displayed basal-like molecular subtype that correlated with high histological grade and younger age. Survival of basal-like TNBC was not different from non basal-like TNBC. High expression of immune cell metagenes was associated with good and high expression of inflammation and angiogenesis-related metagenes were associated with poor prognosis. A ratio of high B-cell and low IL-8 metagenes identified 32% of TNBC with good prognosis (hazard ratio (HR) 0.37, 95% CI 0.22 to 0.61; P < 0.001) and was the only significant predictor in multivariate analysis including routine clinicopathological variables.

CONCLUSIONS

We describe a ratio of high B-cell presence and low IL-8 activity as a powerful new prognostic marker for TNBC. Inhibition of the IL-8 pathway also represents an attractive novel therapeutic target for this disease.

The Luminal B Marker NHERF1 Predicts Endocrine Resistance

Background:Tumors of the luminal B subtype of ER postive breast cancer are characterized by high proliferation as compared to the luminal A subtype. The luminal B have a worse prognosis. We aimed to identify genes specifically expressed in the luminal B subtype of breast cancers and analyze the prognostic impact of these genes and their relationship to endocrine therapy.Methods:121 genes overexpressed in LumB tumors were identified in a test set of 171 Breast cancer samples and reproducibly obtained in four independent validation datasets. The scaffold protein NHERF1 was analyzed in a large scale meta-analysis of microarray datasets encompassing n=3030 breast cancer samples.Results:NHERF1 is an ER regulated gene located on chromosome 17 coding for a scaffold protein involved in growth factor signal transduction. NHERF1 expression among ER positive tumors is associated with larger tumor size, higher histolocigal grading, and HER2 expression. A prognostic value of NHERF1 was observed among ER positive tumors (univariate HR 1.49, 95% CI 1.23-1.80, P&lt;0.001) but not among ER negative samples. NHERF1 remained significant in multivariate analysis (HR 1.37, 95% CI 1.05-1.79, P=0.020) and is not a surrogate marker for high proliferation. A benefit of endocrine treatment seems to be restricted to NHERF1 negative tumors.Conclusions:Markers like NHERF1 specific for the luminal B subtype of breast cancer correlate with poor prognosis and seem to be predictive for endocrine treatment response.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3164.

Clinical relevance of the putative stem cell marker p63 in breast cancer

P63 is a member of the p53 family. This protein is crucial for the maintenance of a stem cell population in the human epithelium and necessary for the normal development of all epithelial tissues including mammary glands. In normal breast tissue, the p63 seems to be a specific myoepithelial cell marker. P63 expression has been described in highly aggressive ER negative basal-like breast tumors. The value of p63 expression in ER positive disease is less clear. The expression levels of p63 mRNA by Affymetrix microarray analysis in a combined cohort of 2,158 ER positive breast cancers and its prognostic and predictive impact were analyzed. Tumor samples containing large amounts of benign breast tissue, which will interfere with p63 measurement, were excluded prior to the analysis. Survival analysis revealed a better prognosis of ER positive breast cancer expressing p63 (n = 410; P < 0.036). No correlation of p63 with standard parameters was observed. In a subgroup analysis, endocrine-treated patients with high p63 expression showed a better prognosis than low p63 expression (P = 0.06; n = 186). In untreated patients, this effect was less clear (n = 148; P = 0.5). P63 is a positive prognostic factor in endocrine-treated ER positive breast cancer and might influence responsiveness to endocrine treatment. Thus, p63 could be helpful as a predictive factor for endocrine therapy.

Use of microarray analysis of differentially expressed genes in luminal B subtype of breast cancers to evaluate NHERF1 as a marker of endocrine resistance

11015

Background: In vitro and in vivo data demonstrate that the expression of estrogen receptor (ER) in breast cancer is mainly associated with low proliferation. Gene expression profiling has recently been used to identify a group of high proliferating estrogen receptor positive breast cancers (the luminal B subtype), which are associated with a prognosis that is even worse than that of high proliferating estrogen receptor negative tumors. The analysis of those tumors might provide valuable information about breast cancer biology and could be helpful for adjuvant or neoadjuvant treatment decisions.Methods and Results: We analyzed microarray data from breast cancer specimens to gain insight into genes which play a role in estrogen receptor signalling. Genes were identified showing strong expression in high proliferating ER-positive tumors but no expression in either Ki67-/ER+ or Ki67+/ER- samples. Among these genes the Na+/H+ exchanger regulatory factor NHERF1 was found. We assessed the clinical relevance of NHERF1 transcript levels using a total of 2469 breast cancers. Analysis indicates that enhanced NHERF1 expression is associated with metastatic progression and poor prognosis of breast cancer patients. We found no correlation between NHERF1 and the nodal status as well as age, but positive correlations for tumor size (P<0.001), grade (P<0.001) and erbb2 (P=0.033). Weak NHERF1 expression correlated with longer disease free survival (DFS) in grade 1 and 2 tumors, but not in grade 3 breast cancers. Since NHERF1 expression is strongly linked to the presence of ER, the predictive value for endocrine treatment was analyzed. For samples with weak or none NHERF1 expression a treatment benefit was observed (P=0.007). While untreated patients display a 10 yr DFS rate of 67.2 ± 3.8%, endocrine treatment resulted in 80.1 ± 4.0%. In contrast no differences in disease free survival were found for corresponding NHERF1 expressing breast cancers. Conclusions: Our data indicate that expression of NHERF1 defines a state of differentiation, where breast cancer cells are refractory to endocrine treatment.

No significant financial relationships to disclose.

T-cell metagene predicts a favorable prognosis in estrogen receptor-negative and HER2-positive breast cancers

INTRODUCTION

Lymphocyte infiltration (LI) is often seen in breast cancer but its importance remains controversial. A positive correlation of human epidermal growth factor receptor 2 (HER2) amplification and LI has been described, which was associated with a more favorable outcome. However, specific lymphocytes might also promote tumor progression by shifting the cytokine milieu in the tumor.

METHODS

Affymetrix HG-U133A microarray data of 1,781 primary breast cancer samples from 12 datasets were included. The correlation of immune system-related metagenes with different immune cells, clinical parameters, and survival was analyzed.

RESULTS

A large cluster of nearly 600 genes with functions in immune cells was consistently obtained in all datasets. Seven robust metagenes from this cluster can act as surrogate markers for the amount of different immune cell types in the breast cancer sample. An IgG metagene as a marker for B cells had no significant prognostic value. In contrast, a strong positive prognostic value for the T-cell surrogate marker (lymphocyte-specific kinase (LCK) metagene) was observed among all estrogen receptor (ER)-negative tumors and those ER-positive tumors with a HER2 overexpression. Moreover ER-negative tumors with high expression of both IgG and LCK metagenes seem to respond better to neoadjuvant chemotherapy.

CONCLUSIONS

Precise definitions of the specific subtypes of immune cells in the tumor can be accomplished from microarray data. These surrogate markers define subgroups of tumors with different prognosis. Importantly, all known prognostic gene signatures uniformly assign poor prognosis to all ER-negative tumors. In contrast, the LCK metagene actually separates the ER-negative group into better or worse prognosis.

T cell marker metagene predicts a favourable prognosis in estrogen receptor negative and Her2 positive breast cancers

Abstract #1048

Background: Lymphocyte infiltration (LI) is often seen in breast cancer and has been suggested as a marker of host antitumor immune response but its importance remains controversial. A positive correlation of Her2 amplification/overexpression and LI has been described which was associated with a more favorable outcome. In rapidly proliferating tumors LI is a good prognostic indicator correlating with lymph node negativity, smaller tumor size, lower grade. However the impact of monocytes, B- and T-lymphocytes on prognosis are still a matter of debate.&#x2028; Material and Methods: A database of 2110 primary invasive breast cancer samples from 14 microarray datasets was established. Only Affymetrix HG-U133A microarrays were included for full comparability. Feature reduction was achieved by generating metagenes from genes with strong correlation in unsupervised clustering. The relationship of the five major metagenes with different cell types in the sample as well as differentiation programs/pathways associated with specific expression profiles was analyzed.&#x2028; Results: A large cluster of approximately 600 genes with functions in immune cells was consistently obtained in all datasets. The redundant information from several ProbeSets allowed the construction of robust metagenes which can be used as surrogate markers for the amount of different immune cell types in the breast cancer sample. However, rather complex relationships of these immunological metagenes with standard parameters of the tumors were observed. When different subgroups of tumors were analyzed for disease free survival the IgG metagene as a surrogate marker for B cells had no significant prognostic value. In contrast high expression of the T cell surrogate marker (LCK metagene) was beneficial among all subgroups of ER-negative tumors. Moreover a positive prognostic value of LCK metagene expression was also revealed for those ER-positive tumors with a Her2 overexpression. In addition a trend for a better response to neoadjuvant chemotherapy was detected for those ER negative tumors associated with lymphocyte infiltration as deduced from high expression of both IgG and LCK metagenes.&#x2028; Conclusions: Tumor associated lymphocytes could represent an anti tumor response but on the other hand they might promote tumor progression by shifting the cytokine milieu toward angiogenic factors, inflammatory cytokines and matrix metallo-proteinases. Thus it is crucial to precisely define the specific subtypes of immune cells which are associated with the tumor. Our results demonstrate that this task can be accomplished by a detailed analysis of the expression of metagenes. These surrogate markers define subgroups of tumors with different prognosis.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1048.