Inhibition of RANK signaling in breast cancer induces an anti-tumor immune response orchestrated by CD8+ T cells

Most breast cancers exhibit low immune infiltration and are unresponsive to immunotherapy. We hypothesized that inhibition of the receptor activator of nuclear factor-κB (RANK) signaling pathway may enhance immune activation. Here we report that loss of RANK signaling in mouse tumor cells increases leukocytes, lymphocytes, and CD8⁺ T cells, and reduces macrophage and neutrophil infiltration. CD8⁺ T cells mediate the attenuated tumor phenotype observed upon RANK loss, whereas neutrophils, supported by RANK-expressing tumor cells, induce immunosuppression. RANKL inhibition increases the anti-tumor effect of immunotherapies in breast cancer through a tumor cell mediated effect. Comparably, pre-operative single-agent denosumab in premenopausal early-stage breast cancer patients from the Phase-II D-BEYOND clinical trial (NCT01864798) is well tolerated, inhibits RANK pathway and increases tumor infiltrating lymphocytes and CD8⁺ T cells. Higher RANK signaling activation in tumors and serum RANKL levels at baseline predict these immune-modulatory effects. No changes in tumor cell proliferation (primary endpoint) or other secondary endpoints are observed. Overall, our preclinical and clinical findings reveal that tumor cells exploit RANK pathway as a mechanism to evade immune surveillance and support the use of RANK pathway inhibitors to prime luminal breast cancer for immunotherapy.

Receptor activator of nuclear factor-κB (RANK)/RANK-ligand (RANKL) signaling regulates the tumor-immune crosstalk. Here the authors show that systemic RANKL inhibition promotes CD8 + T cell infiltration in patients with early breast cancer and that loss of RANK signaling in tumor cells drives a T cell-dependent anti-tumor response in preclinical models.

Abstract 3853: The anti-tumor immune responses by active and quiescent tertiary lymphoid structures to breast cancer

There is a growing interest in active immune responses generated by tertiary lymphoid structures (TLS) arising in solid tumors; however, their clinical impact in breast cancer (BC) remains unclear. Several studies show that transcription factors contribute to TLS formation via their regulation of cytokine and chemokine production. The Forkhead box (FOX) protein 1 (FOXP1) has been shown to play critical roles in regulating immune cells, including our recent work revealing its effects on TIL migration. These data lead us to further investigate FOXP1 expression in tumor infiltrating lymphocytes (TIL) and TLS. We identify two types of TLS based on FOXP1 expression: 1) those that contain a germinal center (GC+) and those that do not (GC-). Comparative analysis of FOXP1 expression in secondary lymphoid organs, including more immune active tonsils (many GC) and less immune active spleens (primarily without GC) confirm differences in FOXP1 expression associated with GC. In BC, TLS containing tumors were more frequently GC- than GC+ (n=49), with triple-negative tumors having higher numbers of GC+ TLS compared to luminal or HER2+ tumors. Immunofluorescence and multiplex immunohistochemistry was used to closely examine the GC+ and GC- TLS, finding an immune active profile in the former, characterized by T follicular helper cells (PD1+CD4+ T), mature dendritic cells (CD21+ and CD23+), actively proliferating (Ki67+) B cells undergoing immunoglobulin (Ig) class switch recombination (AID+) and a plasma cell presence (CD138+). Analysis of Ig's in the primary tumor supernatants revealed that BC with ≥1 GC+ TLS (n=20) were characterized by increases in total Ig, IgG1, IgG2 and IgA, reflecting active humoral immunity, compared to BC containing only GC- TLS (n=29). Gene expression analysis of individual micro-dissected TLS demonstrated upregulation of Th1, Th2 and Tfh immune genes in the GC+ compared to the GC- TLS, suggesting the former also sustain cell-mediated immune responses. Immune infiltrates in tumors with ≥1 GC+ TLS are specifically characterized by high global TIL, CD3+, CD4+ or CD8+ T cell TIL and CD20+ TIL-B (n=29). Analysis of BC TIL spatial distribution identified increased stromal TIL (all subpopulations) while intratumoral TIL increases were predominantly CD3+ and CD8+ T cell TIL in tumors with GC+ TLS. Overall, our data indicate that GC+ TLS house active immune responses in BC while GC- TLS are quiescent.

Citation Format: Pushpamali De Silva, Soizic Garaud, Cinzia Solinas, Grégory Noël, Mireille Langouo Fontsa, Anaïs Boisson, Alexandre de Wind, Vinu Jose, Gert Van den Eynden, Noemie Thomas, Hugues Duvillier, Céline Naveaux, Ligia Craciun, Dominique Bron, Martine Piccart-Gebhart, Denis Larsimont, Karen Willard-Gallo. The anti-tumor immune responses by active and quiescent tertiary lymphoid structures to breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3853.

Pitfalls in assessing stromal tumor infiltrating lymphocytes (sTILs) in breast cancer

Stromal tumor-infiltrating lymphocytes (sTILs) are important prognostic and predictive biomarkers in triple-negative (TNBC) and HER2-positive breast cancer. Incorporating sTILs into clinical practice necessitates reproducible assessment. Previously developed standardized scoring guidelines have been widely embraced by the clinical and research communities. We evaluated sources of variability in sTIL assessment by pathologists in three previous sTIL ring studies. We identify common challenges and evaluate impact of discrepancies on outcome estimates in early TNBC using a newly-developed prognostic tool. Discordant sTIL assessment is driven by heterogeneity in lymphocyte distribution. Additional factors include: technical slide-related issues; scoring outside the tumor boundary; tumors with minimal assessable stroma; including lymphocytes associated with other structures; and including other inflammatory cells. Small variations in sTIL assessment modestly alter risk estimation in early TNBC but have the potential to affect treatment selection if cutpoints are employed. Scoring and averaging multiple areas, as well as use of reference images, improve consistency of sTIL evaluation. Moreover, to assist in avoiding the pitfalls identified in this analysis, we developed an educational resource available at www.tilsinbreastcancer.org/pitfalls.

Tumor-Infiltrating Lymphocytes in Patients Receiving Trastuzumab/Pertuzumab-Based Chemotherapy: A TRYPHAENA Substudy

Background

There is an urgent requirement to identify biomarkers to tailor treatment in human epidermal growth factor receptor 2 (HER2)-amplified early breast cancer treated with trastuzumab/pertuzumab-based chemotherapy.

Methods

Among the 225 patients randomly assigned to trastuzumab/pertuzumab concurrently or sequentially with an anthracycline-containing regimen or concurrently with an anthracycline-free regimen in the Tryphaena trial, we determined the percentage of tumor-infiltrating lymphocytes (TILs) at baseline in 213 patients, of which 126 demonstrated a pathological complete response (pCR; ypT0/is ypN0), with 28 demonstrating event-free survival (EFS) events. We investigated associations between baseline TIL percentage and either pCR or EFS after adjusting for clinicopathological characteristics using logistic and Cox regression models, respectively. To understand TIL biology, we evaluated associations between baseline TILs and baseline tumor gene expression data (800 gene set by NanoString) in a subset of 173 patients. All statistical tests were two-sided.

Results

Among the patients with measurable TILs at baseline, the median level was 14.1% (interquartile range = 7.1%-32.4%). After adjusting for clinicopathological characteristics, baseline percentage TIL was not associated with pCR (adjusted odds ratio [aOR] for every 10-percentage unit increase in TILs = 1.12, 95% confidence interval [CI] = 0.95 to 1.31, P = .17). At a median follow-up of 4.7 years, for every increase in baseline TILs of 10%, there was a 25% reduction in the hazard for an EFS event (aOR = 0.75, 95% CI = 0.56 to 1.00, P = .05) after adjusting for baseline clinicopathological characteristics and pCR. Additionally, genes associated with epithelial-mesenchymal transition, angiogenesis, and T-cell inhibition such as SNAIL1, ZEB1, NOTCH3, and B7-H3 were statistically significantly inversely correlated with percentage TIL.

Conclusions

Baseline TIL percentage provides independent prognostic information in patients treated with trastuzumab/pertuzumab-based neoadjuvant chemotherapy. However, further validation is required.

Abstract PR10: Active and quiescent tertiary lymphoid structures, differentiated using FOXP1 expression, play a role in immunity to breast cancer

Interest is growing in active immune responses generated by tertiary lymphoid structures (TLS) arising in solid tumors; however, their clinical impact in breast cancer (BC) remains unclear. Several studies show that transcription factors contribute to TLS formation via their regulation of cytokine and chemokine production. The Forkhead box (FOX) protein 1 (FOXP1) has been shown to play critical roles in regulating immune cells, including our recent work revealing its effects on TIL migration. These data lead us to further investigate FOXP1 expression in tumor-infiltrating lymphocytes (TIL) and TLS. We identify two types of TLS based on FOXP1 expression: 1) those that contain a germinal center (GC+) and those that do not (GC-). Comparative analysis of FOXP1 expression in secondary lymphoid organs, including more immune active tonsils (many GC) and less immune active spleens (primarily without GC), confirms differences in FOXP1 expression associated with GC. In BC, TLS-containing tumors were more frequently GC- than GC+ (n=49), with triple-negative tumors having higher numbers of GC+ TLS compared to luminal or HER2+ tumors. Immunofluorescence and multiplex immunohistochemistry was used to closely examine the GC+ and GC- TLS, finding an immune active profile in the former, characterized by T follicular helper cells (PD1+CD4+ T), mature dendritic cells (CD21+ and CD23+), actively proliferating (Ki67+) B cells undergoing immunoglobulin (Ig) class switch recombination (AID+) and a plasma cell presence (CD138+). Analysis of Igs in primary tumor supernatants revealed that BC with ≥1 GC+ TLS (n=20) were characterized by increases in total Ig, IgG1, IgG2, and IgA, reflecting active humoral immunity, compared to BC containing only GC- TLS (n=29). Gene expression analysis of individual microdissected TLS demonstrated upregulation of Th1, Th2, and Tfh immune genes in the GC+ compared to the GC- TLS, suggesting the former also sustain cell-mediated immune responses. Immune infiltrates in tumors with ≥1 GC+ TLS are specifically characterized by high global TIL, CD3+, CD4+ or CD8+ T cell TIL and CD20+ TIL-B (n=29). Analysis of BC TIL spatial distribution identified increased stromal TIL (all subpopulations) while intratumoral TIL increases were predominantly CD3+ and CD8+ T cell TIL in tumors with GC+ TLS. Overall, our data indicate that GC+ TLS house active immune responses in BC while GC- TLS are quiescent.

This abstract is also being presented as Poster B99.

Citation Format: Pushpamali De Silva, Soizic Garaud, Cinzia Solinas, Grégory Noël, Mireille Langouo Fontsa, Anaïs Boisson, Alexandre de Wind, David Venet, Gert Van den Eynden, Hugues Duvillier, Céline Naveaux, Ligia Craciun, Dominique Bron, Martine Piccart-Gebhart, Denis Larsimont, Karen Willard-Gallo. Active and quiescent tertiary lymphoid structures, differentiated using FOXP1 expression, play a role in immunity to breast cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr PR10.

Abstract P5-04-12: Functional CXCR5+CD4+ follicular helper T cells in breast cancer associated tertiary lymphoid structures signal active immune responses at the tumor site

Background: The association between tumor infiltrating lymphocytes (TIL) and positive clinical outcomes in breast cancer (BC) is now commonly recognized. Previous work from our laboratory demonstrated that TIL can organize in tertiary lymphoid structures (TLS) in BC-associated stroma. We further showed that CXCL13, produced by specialized CD4+ T follicular helper (TfhX13) cell, is an important TLS chemoattractant and associated with positive clinical outcomes. The current study investigated how immune cell functionally and regulation in TLS contributes to immune responses in BC.

Methodology: We prospectively collected fresh primary BC tissues and prepared enzyme-free homogenates to produce TIL suspensions and tumor supernatants for flow cytometry and cytokine/chemokine/immunoglobulin (Ig) analysis, respectively. Matching formalin-fixed paraffin-embedded tumor tissues were analyzed using dual immunohistochemistry (IHC) and immunofluorescence (IF) confocal microscopy or multiplex IHC.

Results: We show that CXCR5, the CXCL13 receptor, is expressed on subpopulations of CD4+ (Tfh) and CD8+ T cell TIL as well as the majority of TIL-B, with all CXCR5+ TIL co-localizing in TLS. The functional activities of Tfh TIL, evaluated using an in vitro assay with allogeneic human splenic B cells, reveals that PD-1hiICOS+ Tfh TIL (in some triple negative and HER2+ but not luminal BC) can provide help to TIL-B for Ig production. This observation is strengthened by additional data showing: 1) a correlation between functional (PD-1hiICOS+) Tfh TIL densities and IgG concentrations in primary BC supernatants; 2) a strong correlation between PD-1+ Tfh TIL and Ki67+ TIL-B in BC-associated TLS; and 3) cell-to-cell contact between Tfh TIL and TIL-B in TLS with active germinal centers. PD-1hiICOS+ (functional) and PD-1lo/intICOS− (non-functional) Tfh TIL were sorted for mRNA analysis with functional Tfh TIL expressing higher levels of IL-21, IFNγ and CXCL13. Higher IFNγ expression by PD-1hiICOS+ Tfh TIL suggests their functional Th1 orientation. CXCR5+ T follicular regulatory (Tfr) TIL were also detected in TLS and shown to express, CD25, demethylated FOXP3, and GARP, a marker of active TGFβ. Analyzing the ratio between Tfh and GARP+ Tfr TIL revealed that when the balance favors Tfh TIL, IgG production is increased. This Tfh/Tfr ratio was also correlated with activated CXCR5+CD8+ TIL in TLS. Multiplex IHC identified the positioning of CXCR5+ TIL subpopulations and demonstrated there are important cell-to-cell contacts between these subpopulations in active TLS.

Conclusions: Our data show that Tfh TIL subpopulations play major roles in the functionality of BC-associated TLS. The balance between functionally active and regulatory CXCR5+ Tfh TIL together with active CXCR5+CD8+ TIL and CXCR5+ TIL-B appears to regulate immune activities in the tumor microenvironment. Tumors with functional Tfh TIL are linked to a more robust stromal and intratumoral infiltrate together with a ratio of active TLS >1. Thus, while TIL density scores provide important primary insight on immune activity in BC, their organization and subpopulation balances may offer key information for fine-tuning treatment selection options, particularly for immune-based therapies.

Citation Format: Karen Willard-Gallo, Gregory Noel, Mireille Langouo Fontsa, Soizic Garaud, Alexandre de Wind, Gert Van den Eynden, Roberto Salgado, Anais Boisson, Celine Naveaux, Hugues Duvillier, Ligia Craciun, Martine Piccart-Gebhart, Denis Larsimont. Functional CXCR5+CD4+ follicular helper T cells in breast cancer associated tertiary lymphoid structures signal active immune responses at the tumor site [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-04-12.

Reactive stroma and trastuzumab resistance in HER2-positive early breast cancer

We investigated the value of reactive stroma as a predictor for trastuzumab resistance in patients with early HER2-positive breast cancer receiving adjuvant therapy. The pathological reactive stroma and the mRNA gene signatures that reflect reactive stroma in 209 HER2-positive breast cancer samples from the FinHer adjuvant trial were evaluated. Levels of stromal gene signatures were determined as a continuous parameter, and pathological reactive stromal findings were defined as stromal predominant breast cancer (SPBC; ≥50% stromal) and correlated with distant disease-free survival. Gene signatures associated with reactive stroma in HER2-positive early breast cancer (N = 209) were significantly associated with trastuzumab resistance in estrogen receptor (ER)-negative tumors (hazard ratio [HR] = 1.27 p interaction = 0.014 [DCN], HR = 1.58, p interaction = 0.027 [PLAU], HR = 1.71, p interaction = 0.019 [HER2STROMA, novel HER2 stromal signature]), but not in ER-positive tumors (HR = 0.73 p interaction = 0.47 [DCN], HR = 0.71, p interaction = 0.73 [PLAU], HR = 0.84; p interaction = 0.36 [HER2STROMA]). Pathological evaluation of HER2-positive/ER-negative tumors suggested an association between SPBC and trastuzumab resistance. Reactive stroma did not correlate with tumor-infiltrating lymphocytes (TILs), and the expected benefit from trastuzumab in patients with high levels of TILs was pronounced only in tumors with low stromal reactivity (SPBC <50%). In conclusion, reactive stroma in HER2-positive/ER-negative early breast cancer tumors may predict resistance to adjuvant trastuzumab therapy.

Tumor infiltrating B-cells signal functional humoral immune responses in breast cancer

Tumor-infiltrating B-cells (TIL-B) in breast cancer (BC) have previously been associated with improved clinical outcomes; however, their role(s) in tumor immunity is not currently well known. This study confirms and extends the correlation between higher TIL-B densities and positive outcomes through an analysis of HER2-positive and triple-negative BC patients from the BIG 02-98 clinical trial (10yr mean follow-up). Fresh tissue analyses identify an increase in TIL-B density in untreated primary BC compared to normal breast tissues, which is associated with global, CD4+ and CD8+ TIL, higher tumor grades, higher proliferation and hormone receptor negativity. All B-cell differentiation stages are detectable but significant increases in memory TIL-B are consistently present. BC with higher infiltrates are specifically characterized by germinal center TIL-B, which in turn are correlated with TFH TIL and antibody-secreting TIL-B principally located in tertiary lymphoid structures. Some TIL-B also interact directly with tumor cells. Functional analyses reveal TIL-B are responsive to BCR stimulation ex vivo, express activation markers and produce cytokines and immunoglobulins despite reduced expression of the antigen-presenting molecules HLA-DR and CD40. Overall, these data support the concept that ongoing humoral immune responses are generated by TIL-B and help to generate effective anti-tumor immunity at the tumor site.

Immune Infiltration in Invasive Lobular Breast Cancer

Background

Invasive lobular breast cancer (ILC) is the second most common histological subtype of breast cancer after invasive ductal cancer (IDC). Here, we aimed at evaluating the prevalence, levels, and composition of tumor-infiltrating lymphocytes (TILs) and their association with clinico-pathological and outcome variables in ILC, and to compare them with IDC.

Methods

We considered two patient series with TIL data: a multicentric retrospective series (n = 614) and the BIG 02-98 study (n = 149 ILC and 807 IDC). We compared immune subsets identified by immuno-histochemistry in the ILC (n = 159) and IDC (n = 468) patients from the Nottingham series, as well as the CIBERSORT immune profiling of the ILC (n = 98) and IDC (n = 388) METABRIC and The Cancer Genome Atlas patients. All ILC/IDC comparisons were done in estrogen receptor (ER)–positive/human epidermal growth factor receptor 2 (HER2)–negative tumors. All statistical tests were two-sided.

Results

TIL levels were statistically significantly lower in ILC compared with IDC (fold-change = 0.79, 95% confidence interval = 0.70 to 0.88, P < .001). In ILC, high TIL levels were associated with young age, lymph node involvement, and high proliferative tumors. In the univariate analysis, high TIL levels were associated with worse prognosis in the retrospective and BIG 02-98 lobular series, although they did not reach statistical significance in the latter. The Nottingham series revealed that the levels of intratumoral but not total CD8⁺ were statistically significantly lower in ILC compared with IDC. Comparison of the CIBERSORT profiles highlighted statistically significant differences in terms of immune composition.

Conclusions

This study shows differences between the immune infiltrates of ER-positive/HER2-negative ILC and IDC in terms of prevalence, levels, localization, composition, and clinical associations.

Spatially distinct tumor immune microenvironments stratify triple-negative breast cancers

Understanding the tumor immune microenvironment (TIME) promises to be key for optimal cancer therapy, especially in triple-negative breast cancer (TNBC). Integrating spatial resolution of immune cells with laser capture microdissection gene expression profiles, we defined distinct TIME stratification in TNBC, with implications for current therapies including immune checkpoint blockade. TNBCs with an immunoreactive microenvironment exhibited tumoral infiltration of granzyme B+CD8+ T cells (GzmB+CD8+ T cells), a type 1 IFN signature, and elevated expression of multiple immune inhibitory molecules including indoleamine 2,3-dioxygenase (IDO) and programmed cell death ligand 1 (PD-L1), and resulted in good outcomes. An "immune-cold" microenvironment with an absence of tumoral CD8+ T cells was defined by elevated expression of the immunosuppressive marker B7-H4, signatures of fibrotic stroma, and poor outcomes. A distinct poor-outcome immunomodulatory microenvironment, hitherto poorly characterized, exhibited stromal restriction of CD8+ T cells, stromal expression of PD-L1, and enrichment for signatures of cholesterol biosynthesis. Metasignatures defining these TIME subtypes allowed us to stratify TNBCs, predict outcomes, and identify potential therapeutic targets for TNBC.

BRCA gene mutations do not shape the extent and organization of tumor infiltrating lymphocytes in triple negative breast cancer

This study investigated the prevalence of TIL subpopulations, TLS, PD-1 and PD-L1 in tumors from TNBC patients harboring wild-type or mutated BRCA1 or BRCA2 germline genes. This TNBC cohort included 85% TIL-positive (≥10%) tumors with 21% classified as TIL^hi (≥50%). Interestingly, the BRCA^mut group had a significantly higher incidence of TIL^pos tumors compared to the BRCA^wt group (P = 0.037). T cells were dominant in the infiltrate but no statistically significant differences were detected between BRCA^wt and BRCA^mut for CD3⁺, CD4⁺ and CD8⁺ T cells or CD20⁺ B cells. TLS were detected in 74% of tumors but again no significant differences between the BRCA groups. PD-1 expression was observed in 33% and PD-L1 in 53% (any cell, cut-off ≥1%) tumors for the entire TNBC cohort. PD-1 expression correlated with PD-L1 and both with TIL and TLS but was not associated with BRCA mutational status. Our analyses reveal that BRCA^wt and BRCA^mut TNBC are similar except for a significant increase of TIL^pos tumors in the BRCA^mut group. While BRCA gene mutations may not directly drive immune infiltration, the greater number of TIL^pos tumors could signal greater immunogenicity in this group.

Cell-free DNA profiling of metastatic prostate cancer reveals microsatellite instability, structural rearrangements and clonal hematopoiesis

BACKGROUND

There are multiple existing and emerging therapeutic avenues for metastatic prostate cancer, with a common denominator, which is the need for predictive biomarkers. Circulating tumor DNA (ctDNA) has the potential to cost-efficiently accelerate precision medicine trials to improve clinical efficacy and diminish costs and toxicity. However, comprehensive ctDNA profiling in metastatic prostate cancer to date has been limited.

METHODS

A combination of targeted and low-pass whole genome sequencing was performed on plasma cell-free DNA and matched white blood cell germline DNA in 364 blood samples from 217 metastatic prostate cancer patients.

RESULTS

ctDNA was detected in 85.9% of baseline samples, correlated to line of therapy and was mirrored by circulating tumor cell enumeration of synchronous blood samples. Comprehensive profiling of the androgen receptor (AR) revealed a continuous increase in the fraction of patients with intra-AR structural variation, from 15.4% during first-line metastatic castration-resistant prostate cancer therapy to 45.2% in fourth line, indicating a continuous evolution of AR during the course of the disease. Patients displayed frequent alterations in DNA repair deficiency genes (18.0%). Additionally, the microsatellite instability phenotype was identified in 3.81% of eligible samples (≥ 0.1 ctDNA fraction). Sequencing of non-repetitive intronic and exonic regions of PTEN, RB1, and TP53 detected biallelic inactivation in 47.5%, 20.3%, and 44.1% of samples with ≥ 0.2 ctDNA fraction, respectively. Only one patient carried a clonal high-impact variant without a detectable second hit. Intronic high-impact structural variation was twice as common as exonic mutations in PTEN and RB1. Finally, 14.6% of patients presented false positive variants due to clonal hematopoiesis, commonly ignored in commercially available assays.

CONCLUSIONS

ctDNA profiles appear to mirror the genomic landscape of metastatic prostate cancer tissue and may cost-efficiently provide somatic information in clinical trials designed to identify predictive biomarkers. However, intronic sequencing of the interrogated tumor suppressors challenges the ubiquitous focus on coding regions and is vital, together with profiling of synchronous white blood cells, to minimize erroneous assignments which in turn may confound results and impede true associations in clinical trials.

Abstract CT101: D-BEYOND: A window of opportunity trial evaluating denosumab, a RANK-ligand (RANKL) inhibitor and its biological effects in young pre-menopausal women diagnosed with early breast cancer

Background

Breast cancer (BC) in young women has unique biology and poor prognosis. Previous reports suggest that they often express RANKL, which was also shown to play a role in mammary tumorigenesis and the etiology of BRCA1/2 related BC. Here, we present the primary results of D-BEYOND, a window of opportunity study investigating the biological activity of the RANKL inhibitor; denosumab in pre-menopausal BC patients.

Methods

D-BEYOND is a prospective, phase IIa, single-arm, multicenter study assessing the effect of denosumab on BC biology in premenopausal women with early BC (NCT01864798). Patients received two subcutaneous injections of denosumab (120mg), one week apart, followed by breast surgery. Blood, tumor and normal adjacent breast tissue were collected at baseline and at surgery. The primary endpoint was geometric mean change in tumor Ki67 assessed by immunohistochemistry (IHC) from baseline to surgery. Absolute Ki67 responders were defined as having &lt;2.7% IHC staining in the post-treatment tumor. Serum levels of soluble RANKL (sRANKL), OPG and C-terminal telopeptide (CTX) were assessed by ELISA. Ki67, RANK and RANKL expression were assessed by IHC. The percentage of tumor infiltrating lymphocytes (TILs) were also evaluated. Pre- and post-treatment values were compared using a paired t-test.

Results

A total of 27 patients were enrolled in the study between October 2013 and July 2016. The median age was 45 years (range 35-51 years). Tumors of 21 patients were hormone receptor positive (77.8%), 4 were HER2 positive (14.8%) and 2 were triple negative (7.4%). No serious adverse events were reported, the most frequent non-serious adverse event being arthralgia (14.8%). After treatment, serum levels of CTX and sRANKL decreased in all patients (P &lt; 0.001) whereas serum levels of OPG increased in 76.9% of patients (P = 0.009, 95% CI 0.56-0.91). There was no significant reduction of Ki67 values from baseline (geometric mean change after treatment; 0.98, 95% CI 0.76-1.26; P = 0.90) and there were no absolute Ki67 responders. Twenty-four pre- and post-treatment tumor pairs were available for RANK/L staining and TILs assessment. There was no significant difference in RANKL and RANK H-score in tumors after treatment (P = 0.842, P = 0.142, respectively) but we observed a decrease of RANKL H-score in 3 tumors (12.5%) and an increase of RANK H-score in 5 tumors (20%). Interestingly, there was a significant increase in the percentage of stromal TILs after treatment (geometric mean change of 2.51, 95% CI 1.58-3.97; P = 0.004). There were 10/24 patients (41.7%) with a change in TILs of at least 10%, all of them having an increase in TILs presence (P = 0.002).

Conclusion

Short course of denosumab did not reduce tumor proliferation rate. However, it induced a significant increase in TILs. These findings suggest that denosumab may potentiate immunotherapy efficacy, at least in young BC patients. Additional results including immune cell profiling by multiplex IHC and RNA-sequencing of tumor and normal tissues will be presented at the meeting.

Citation Format: Bastien Nguyen, Marion Maetens, Roberto Salgado, David Venet, Peter Vuylsteke, Laura Polastro, Hans Wieldiers, Philippe Simon, Geoff Lindeman, Denis Larsimont, Gert Van den Eynden, Chloe Velghe, Francoise Rothe, Soizic Garaud, Stefan Michiels, Karen Willard-gallo, Hatem A. Azim, Sherene Loi, Martine Piccart, Christos Sotiriou. D-BEYOND: A window of opportunity trial evaluating denosumab, a RANK-ligand (RANKL) inhibitor and its biological effects in young pre-menopausal women diagnosed with early breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT101.

Abstract 4689: Immune functions and regulation of follicular helper CD4+CXCR5+T cells in human breast cancer

Introduction: High levels of tumor infiltrating lymphocytes (TIL) have been associated with good clinical outcomes in patients with HER2-positive (HER2+) and triple-negative (TN) breast cancer (BC) . Recently, we demonstrated that 60% of BC TIL are organized in tertiary lymphoid structures (TLS) located in the stroma. We further identified a CXCL13-producing CD4+ T follicular helper cell (Tfh) subpopulation and demonstrated that this chemokine, important for TLS formation, is associated with positive clinical outcomes in BC. The aim of the present study was to investigate how conventional CD4+ Tfh cells, expressing the CXCL13 receptor CXCR5, contribute to immune function and regulation in BC-associated TLS.

Methods: We prospectively collected fresh primary BC tissues and prepared enzyme-free homogenates to prepare tumor supernatant and TIL for flow cytometric analysis and sorting. Matching formalin-fixed paraffin-embedded (FFPE) were used for subsequent spatial analysis by dual IHC and confocal microscopy.

Results: Flow cytometric analyses show that ~15% CD4+, ~13% CD8+ and &gt;95% B cell TIL express CXCR5 while confocal microscopy reveals that these CXCR5+ TIL subpopulations co-localize in BC TLS and their presence is tightly correlated. BC Tfh TIL (compared to activated tonsillar Tfh) have a memory phenotype and express ICOS and PD-1 suggesting they are activated, but BCL6 is undetectable and CXCL13 positive cells are rare in only some tumors. RNA analysis detected high expression of IL-21, IL-10 and CXCL13 in Tfh TIL. Investigation into the role of Tfh cells in TLS functionality was accomplished via an in vitro assay where Tfh TIL were activated with allogeneic splenic B cells. These experiments reveal that only ICOS+PD-1+Tfh TIL from TN/HER2+ BC are capable of inducing IgM and IgG secretion by B cells. A comparison of ICOS+PD-1+ with ICOS-PD-1- Tfh TIL confirms an activated, functional nature for the former characterized by high levels of IL-21, IL-10 and CXCL13 mRNA expression. We also found specialized follicular regulatory T cells (Tfr), expressing CXCR5, CD25, demethylated Foxp3 and GARP, localized in TLS. To understand the regulation of Tfh function(s) by Tfr we quantified immunoglobulins in the primary tumor supernatant, finding a correlation between the Tfh/Tfr ratio (fresh tissues) and IgG and IgM production (supernatant) in TN/HER2+ BC. These data suggest that the balance between effector and regulatory Tfh influences B cell differentiation in TLS.

Conclusions: We show that it is possible to isolate functional Tfh TIL from fresh BC tissues, demonstrate their activation and functional state and link a Tfr presence with negative regulation of TLS function. These data begin to shed light on anti-tumor immune responses occurring in TLS at the tumor site, whose functional activities may have important treatment implications, particularly for immunotherapy in BC.

Citation Format: Mireille Langouo, Gregory Noël, Gert Van den Eynden, Alexandre De Wind, Soizic Garaud, Pushpamali De Silva, Cinzia Solinas, Anais Boisson, Celine Naveaux, Hugues Duvillier, Ligia Craciun, Denis Larsimont, Martine Piccart-Gebhart, Karen Willard-Gallo. Immune functions and regulation of follicular helper CD4+CXCR5+T cells in human breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4689.

Abstract 1624: Reliability of immune biomarker assessment in breast cancer: A report on interobserver variability from studies at a single institution

Reproducible evaluation of immune infiltration parameters is needed for the development of reliable biomarkers in the era of cancer immunotherapy. This study investigated inter-observer reproducibility when evaluating tumor-infiltrating lymphocytes (TIL), tertiary lymphoid structures (TLS), PD-1 and PD-L1 positivity on immunohistochemically-stained (IHC) breast cancer (BC) tissues, including detailed analysis of spatial positioning in the tumor microenvironment and expression on individual positive cells. Retrospectively collected archival BC samples (N=441) were dual IHC-stained for CD3 (pan T cells) plus CD20 (pan B cells) for TIL and TLS assessment with a consecutive tissue section dual-IHC stained for PD-1 and PD-L1. The 882 tissue sections were independently read by two immuno-pathologists blinded to the clinical data for specific studies between 2014 and 2017. Five independent study series were used for the current analysis: 1) samples of BC relapses, 2) residual disease in breast after neodjuvant treatment, and 3) three independent series of untreated primary tumors. Intraclass correlation coefficients for evaluations are shown in the table below:

RelapsesResidual diseaseUntreated primary tumorsSeries 1: N=88Series 2: N=20Series 3: N=85Series 4: N=113Series 5: N=135201420142014-201520162017ICCICCICCICCICC%Stromal TIL0.85 [0.76-0.90]0.71 [0.27-0.89]0.79 [0.68-0.87]0.74 [0.62-0.82]0.77 [0.68-0.83]%Intratumoral TIL0.40 [0.09-0.61]0.63 [0.08-0.86]0.73 [0.58-0.82]0.87 [0.81-0.91]0.64 [0.51-0.74]%Global TIL0.87 [0.80-0.92]0.79 [0.47-0.92]0.83 [0.74-0.89]0.80 [0.72-0.86]0.81 [0.73-0.86]%CD30.83 [0.74-0.89]0.71 [0.28-0.89]0.81 [0.70-0.88]0.72 [0.60-0.80]0.73 [0.63-0.81]%CD200.74 [0.62-0.81]0.81 [0.52-0.92]0.76 [0.63-0.84]0.78 [0.68-0.84]0.78 [0.70-0.84]TLS0.80 [0.70-0.87]0.78 [0.45-0.91]0.83 [0.74-0.89]0.95 [0.93-0.97]0.97 [0.96-0.98]%PD-L1 tumor cells0.78 [0.66-0.86]0.56 [-0.12-0.82]0.82 [0.73-0.89]0.62 [0.45-0.74]0.45 [0.25-0.61]%PD-L1 stromal cells0.61 [0.40-0.74]-1.56 [-1.53-0.60]0.43 [0.12-0.63]0.61 [0.44-0.73]0.31 [0.05-0.5]%PD-L1 immune cells0.53 [0.29-0.70]0.94 [0.84-0.97]0.29 [-0.09-0.54]0.38 [0.10-0.57]0.10 [-0.25-0.35]%PD-1 TLS-0.00 [-0.54-0.35]NA0.72 [0.57-0.82]0.57 [0.35-0.72]0.76 [0.62-0.84]

Cohen's κ coefficients reveal poor agreement (κ&lt;0.4) for assessment of the categorical global PD-1 and PD-L1 variables (cut-off &gt;1%). Sporadically, fair agreement (κ&gt;0.4) was observed for PD-L1 expressed by immune and tumor cells. Globally, the inter-observer agreement remained constant overtime. Poor reproducibility for categorical global PD-1 and global PD-L1 assessment was observed. On the contrary, pathologists have excellent reproducibility for assessing global TIL and TLS, good/excellent reproducibility for PD-1 in TLS (primary tumors) and for PD-L1 expression on tumor cells which make these of great interest for clinical use.

Citation Format: Cinzia Solinas, Gert Van den Eynden, Alexandre De Wind, François Richard, Anaïs Boisson, Soizic Garaud, Karen Willard-Gallo. Reliability of immune biomarker assessment in breast cancer: A report on interobserver variability from studies at a single institution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1624.

Circulating tumor cells and survival in abiraterone- and enzalutamide-treated patients with castration-resistant prostate cancer

BACKGROUND

The outcome to treatment administered to patients with metastatic castration-resistant prostate cancer (mCRPC) greatly differs between individuals, underlining the need for biomarkers guiding treatment decision making.

OBJECTIVE

To investigate the prognostic value of circulating tumor cell (CTC) enumeration and dynamics, in the context of second-line endocrine therapies (ie, abiraterone acetate or enzalutamide), irrespective of prior systemic therapies.

DESIGN, SETTINGS, AND PARTICIPANTS

In a prospective, multicentre study blood samples for CTC enumeration were collected from patients with mCRPC at baseline (n = 174). In patients who responded for minimally 10-12 weeks a follow-up sample was collected.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

For baseline analysis, patients were stratified in <5 or ≥5 CTCs/7.5 mL, whereas for the analysis of CTC dynamics at 10-12 weeks, in patients with stable, increasing or decreasing CTC counts. Progression-free survival (PFS), overall survival (OS), and PSA changes at 10-12 weeks were compared between groups.

RESULTS

Patients demonstrating increasing CTCs on therapy had a shorter median PFS (4.03 vs 12.98 vs 13.67 months, HR 3.6, 95%CI 1.9-6.8; P < 0.0001) and OS (11.2 months vs not reached, HR 9.5, 95%CI 3.7-24; P < 0.0001), compared to patients with decreasing or stable CTCs. Multivariable Cox regression showed that prior chemotherapy (HR 4.1, 95%CI 1.9-8.9; P = 0.0003), a high baseline CTC count (HR 1.5, 95%CI 1.2-1.9; P = 0.002) and increasing CTCs at follow-up (HR 3.3, 95%CI 1.4-7.6; P = 0.005) were independent predictors of worse PFS. Previous chemotherapy (HR 7, 95%CI 1.9-25; P = 0.003), high baseline CTC counts (HR 2.2, 95%CI 1.4-3.7; P = 0.002) and increasing CTCs during therapy (HR 4.6, 95%CI 1.4-15; P = 0.01) were independently associated with shorter OS. ≥30% and ≥50% PSA responses less frequently occurred in patients with CTC inclines at 10-12 weeks on therapy (χ² test: P < 0.01).

CONCLUSIONS

CTC dynamics during therapy are associated with PSA response and provide independent clinical prognostication over PSA declines. Hence the study demonstrates the pharmacodynamic properties of CTCs.

p-STAT3 in luminal breast cancer: Integrated RNA-protein pooled analysis and results from the BIG 2-98 phase III trial

In the present study, in order to investigate the role of signal transducer and activator of transcription 3 (STAT3) in estrogen receptor (ER)-positive breast cancer prognosis, we evaluated the phosphorylated STAT3 (p-STAT3) status and investigated its effect on the outcome in a pooled analysis and in a large prospective adjuvant trial. By using the TCGA repository, we developed gene signatures that reflected the level of p-STAT3. Using pooled analysis of the expression data from luminal breast cancer patients, we assessed the effects of the p-STAT3 expression signature on prognosis. We further validated the p-STAT3 prognostic effect using immunohistochemistry (IHC) and immunofluorescence staining of p-STAT3 tissue microarrays from a large randomised prospective trial. Our analysis demonstrated that p-STAT3 expression was elevated in luminal A-type breast cancer (Kruskal-Wallis test, P<10e-10) and was significantly associated with a good prognosis (log-rank, P<10e-10). Notably, the p-STAT3 expression signature identified patients with a good prognosis irrespective of the luminal subtype (log-rank: luminal A, P=0.026; luminal B, P=0.006). p-STAT3 staining by IHC in the stroma or tumour was detected in 174 out of 610 ER-positive samples (28.5%) from the BIG 2-98 randomised trial. With a median follow-up of 10.1 years, p-STAT3 was associated with a reduced risk of recurrence in ER-positive/HER2-negative breast cancer (Cox univariate HR, 0.66; 95% CI, 0.44-0.98; P=0.04). On the whole, our data indicate that p-STAT3 is associated with an improved outcome in ER-positive breast cancer.

Immune Checkpoint Molecules on Tumor-Infiltrating Lymphocytes and Their Association with Tertiary Lymphoid Structures in Human Breast Cancer

There is an exponentially growing interest in targeting immune checkpoint molecules in breast cancer (BC), particularly in the triple-negative subtype where unmet treatment needs remain. This study was designed to analyze the expression, localization, and prognostic role of PD-1, PD-L1, PD-L2, CTLA-4, LAG3, and TIM3 in primary BC. Gene expression analysis using the METABRIC microarray dataset found that all six immune checkpoint molecules are highly expressed in basal-like and HER2-enriched compared to the other BC molecular subtypes. Flow cytometric analysis of fresh tissue homogenates from untreated primary tumors show that PD-1 is principally expressed on CD4⁺ or CD8⁺ T cells and CTLA-4 is expressed on CD4⁺ T cells. The global proportion of PD-L1⁺, PD-L2⁺, LAG3⁺, and TIM3⁺ tumor-infiltrating lymphocytes (TIL) was low and detectable in only a small number of tumors. Immunohistochemically staining fixed tissues from the same tumors was employed to score TIL and tertiary lymphoid structures (TLS). PD-L1⁺, PD-L2⁺, LAG3⁺, and TIM3⁺ cells were detected in some TLS in a pattern that resembles secondary lymphoid organs. This observation suggests that TLS are important sites of immune activation and regulation, particularly in tumors with extensive baseline immune infiltration. Significantly improved overall survival was correlated with PD-1 expression in the HER2-enriched and PD-L1 or CTLA-4 expression in basal-like BC. PD-1 and CTLA-4 proteins were most frequently detected on TIL, which supports the correlations observed between their gene expression and improved long-term outcome in basal-like and HER2-enriched BC. PD-L1 expression by tumor or immune cells is uncommon in BC. Overall, the data presented here distinguish PD-1 as a marker of T cell activity in both the T and B cell areas of BC associated TLS. We found that immune checkpoint molecule expression parallels the extent of TIL and TLS, although there is a noteworthy amount of heterogeneity between tumors even within the same molecular subtype. These data indicate that assessing the levels of immune checkpoint molecule expression in an individual patient has important implications for the success of therapeutically targeting them in BC.

DNA methylation-based immune response signature improves patient diagnosis in multiple cancers

BACKGROUND

The tumor immune response is increasingly associated with better clinical outcomes in breast and other cancers. However, the evaluation of tumor-infiltrating lymphocytes (TILs) relies on histopathological measurements with limited accuracy and reproducibility. Here, we profiled DNA methylation markers to identify a methylation of TIL (MeTIL) signature that recapitulates TIL evaluations and their prognostic value for long-term outcomes in breast cancer (BC).

METHODS

MeTIL signature scores were correlated with clinical endpoints reflecting overall or disease-free survival and a pathologic complete response to preoperative anthracycline therapy in 3 BC cohorts from the Jules Bordet Institute in Brussels and in other cancer types from The Cancer Genome Atlas.

RESULTS

The MeTIL signature measured TIL distributions in a sensitive manner and predicted survival and response to chemotherapy in BC better than did histopathological assessment of TILs or gene expression-based immune markers, respectively. The MeTIL signature also improved the prediction of survival in other malignancies, including melanoma and lung cancer. Furthermore, the MeTIL signature predicted differences in survival for malignancies in which TILs were not known to have a prognostic value. Finally, we showed that MeTIL markers can be determined by bisulfite pyrosequencing of small amounts of DNA from formalin-fixed, paraffin-embedded tumor tissue, supporting clinical applications for this methodology.

CONCLUSIONS

This study highlights the power of DNA methylation to evaluate tumor immune responses and the potential of this approach to improve the diagnosis and treatment of breast and other cancers.

FUNDING

This work was funded by the Fonds National de la Recherche Scientifique (FNRS) and Télévie, the INNOVIRIS Brussels Region BRUBREAST Project, the IUAP P7/03 program, the Belgian "Foundation against Cancer," the Breast Cancer Research Foundation (BCRF), and the Fonds Gaston Ithier.

Abstract 3694: FOXP1 suppresses immune cell migration in breast tumors

Tumor infiltrating lymphocytes (TIL) play an essential role in mediating response to chemotherapy and improving clinical outcomes in breast cancer (BC). Extensive TIL infiltration is characterized by their organized into tertiary lymphoid structures (TLS). TIL infiltration and TLS formation may be regulated, in part, by transcription factors (TF) controlling cytokine/chemokine production within the tumor microenvironment. The forkhead box protein 1 (FOXP1) is a TF shown to be abnormally expressed in a variety of human tumors and play an important role in T cell cytokine production. Therefore we aimed to study FOXP1-mediated regulation of TIL in BC. Investigation of FOXP1 expression in public microarray data from untreated BC patients, BC cell lines [Luminal A (MCF7), HER2+ (BT474) and triple negative (TN; MDA-MB231)] and prospectively collected formalin-fixed paraffin-embedded (FFPE) primary breast tissues showed that FOXP1 is repressed at transcript and protein level in HER2+ or TN breast tumors compared to estrogen receptor positive tumors (Luminal A and B). Moreover HER2+ and TN subtypes, which showed decreased FOXP1 levels, are 2 well known highly infiltrated BC. Based on our hypothesis that FOXP1 could play a role on immune cell infiltration in breast tumors, data analysis of the prospective BC cohort showed that high FOXP1 (FOXP1hi) expression is significantly associated with a lower percentage of TIL and number of TLS compared to FOXP1 low (FOXP1lo) tumors. To investigate the impact on specific cytokines/chemokines involved in TIL recruitment and/or TLS formation, FOXP1 was silenced in MCF7 (FOXP1hi tumor cell line) or upregulated in MDA-MB-231 (FOXP1lo tumor cell line) followed by gene expression analysis using a RT-qPCR based human cytokine/chemokine array. FOXP1 repression upregulated major T and B cell chemoattractant chemokines and overexpression repressed most of these molecules in the cell line experiments. Next we analyzed major chemoattractant molecule expression in FOXP1lo and FOXP1hi prospective breast tumors and found that FOXP1hi tumors having a significant decrease in CXCL9, CXCL10, CXCL11, CXCL13, CX3CL, CCL20, IL2, and IL21. A migration assay (Transwell chambers) done using healthy donor (HD) PBMC showed a significant increase in total lymphocytes migrated towards FOXP1 repressed tumor conditioned media (TCM) of MCF7 compared to the TCM of control or medium alone. Finally analysis of lymphocyte migration to FOXP1lo and FOXP1hi tumor supernatants (SN) from primary tumors that we consistently prepare without enzymatic digestion, showed that there was a significant decrease in number of lymphocytes migrated towards FOXP1hi tumor SN including the migration rates of individual T and B lymphocytes populations compared to FOXP1lo tumor SN. These data suggest that FOXP1 could play a critical role in establishing effective anti-tumor immune responses by negative regulation of TIL via suppression of cytokine/chemokine expression in breast tumors.

Citation Format: Pushpamali De Silva, Soizic Garaud, Roland de Wind, Gert Van den Eynden, Anaïs Boisson, Cinzia Solinas, Edoardo Migliori, Hugues Duvillier, Denis Larsimont, Martine Piccart-Gebhart, Karen Willard-Gallo. FOXP1 suppresses immune cell migration in breast tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3694. doi:10.1158/1538-7445.AM2017-3694

Circulating tumour cells and survival in abiraterone- and enzalutamide-treated patients with castration-resistant prostate cancer

5049

Background: A heterogeneous landscape of patients with metastatic castration-resistant prostate cancer (mCRPC) exists in current clinical practice. We investigated the prognostic value of CTC enumeration and dynamics, in the context of second-line endocrine therapies (i.e. abiraterone or enzalutamide). Methods: In a prospective, multicentre study blood samples were collected from patients with mCRPC at baseline (n = 147) and follow-up (n = 95/147(64.6%)). At baseline, patients were stratified in favourable ( < 5 CTCs/7.5mL) and unfavourable (≥5 CTCs/7.5mL) groups, whereas at follow-up, in those demonstrating a stable, in- or decreasing CTC count. PFS and OS were compared between groups. PSA changes at 10-12 weeks were evaluable in 83 patients. Results: Patients with ≥5 CTCs/7.5 mL (n = 59) at baseline had a shorter PFS (3.9 vs. 11.3 months, p< 0.0001) and OS (9.34 months vs. not reached, p< 0.0001). Patients demonstrating increasing CTCs (n = 21) on therapy had a shorter PFS (4.03 vs. 10.36 vs. 13.08 months, p < 0.0001) and OS (11.2 months vs. not reached, p < 0.0001), compared to patients with decreasing (n = 41) and stable (n = 33) CTCs, respectively. Multivariate Cox regression showed that the number of CTCs (HR (95%CI): 1.0054 (1.0006–1.010), p= 0.0260) and an increasing follow-up CTC count (HR (95%CI): 2.8987 (1.2856–6.536), p= 0.0103) were independent predictors of PFS. CTC increase was the sole independent predictor for OS (HR (95%CI): 7.3512 (1.7953–30.101), p= 0.0055). At 10-12 weeks, a PSA response of ≥30% and ≥50% was achieved in 46/83 (55.4%) and 33/83 (39.8%) patients, respectively, which was statistically different between chemo-naive or -pretreated patients (≥30%: p= 0.0395), patients with increasing, stable or decreasing CTC counts (≥30%: p= 0.0019; ≥50%: p= 0.0032), and patients with increasing or stable/decreasing CTC counts (≥30%: p= 0.0006; ≥50%: p= 0.0014). Conclusions: CTC levels are associated with PFS and OS in mCRPC patients, starting a new line of endocrine therapy. Follow-up CTC enumeration is associated with PSA response and its dynamics is an independent predictor of PFS and OS, thereby demonstrating the pharmacodynamic properties of CTCs.

Prevalence and heterogeneity of androgen receptor splice variants and intra-AR structural variation in patient with castration-resistant prostate cancer

11530

Background: Androgen receptor splice variant 7 (AR-V7) is linked to a priori resistance to abiraterone acetate and enzalutamide. However, AR-V7 negativity does not necessarily indicate responsiveness and up to 20% of AR-V7 positive patients do demonstrate moderate response to these second-line endocrine therapies. Methods: Peripheral blood samples from patients with CRPC (n = 30) starting a new line of systemic therapy were subjected to comprehensive profiling of AR. AR splice variant (ARV) profiling for eight isoforms was performed by targeted RNA-Seq on CellSearch-enriched circulating tumour cells. Low-pass whole-genome and targeted sequencing of the entire AR gene in plasma-derived circulating cell-free DNA allowed the assessment of copy number status and structural rearrangements, respectively. ARV expression, structural variation, copy number alterations and ligand-binding domain mutations were combined and correlated to clinicopathologic parameters. Results: Twenty-five out of 30 patients (83%) demonstrated an aberration in AR. Twenty out of 30 patients (66.7%) demonstrated AR amplifications. Interestingly, 15/30 patients had intra-AR structural variants, of whom 14 expressed ARVs. In the context of endocrine treatment, 15/26 (57.7%) patients were ARV-positive with 13/15 patients having less than 6 months benefit from their therapy (Fisher’s exact test, p = 0.0115). ARV expression was heterogeneous with 10/15 ARV-positive patients expressing several ARV. Notably, AR-V7 was most frequently detected, however AR-V3 was 3.5x more abundant (Wilcox signed rank, p = 0.0029). In 17 patients, a baseline AR profile was available and demonstrated how having any ARV was associated with progression-free survival (HR: 4.53, 95%CI: 1.424–14.41; p = 0.0105). In the poor response group, 6/17 (35.2%) were AR-V7 negative, of whom 4 carried other AR aberrations. Conclusions: Comprehensive AR profiling on liquid biopsies is feasible and provides new insights into the mechanisms driving endocrine resistance. Clinical validation, by means of a non-interventional, prospective and multicentric study, is essential and currently ongoing.

Abstract A62: Investigating the role of follicular helper T cells, B cells and CXCL13 in breast cancer-associated tertiary lymphoid structures

Patient outcomes have been linked to the presence of tumor infiltrating lymphocytes (TIL) in solid tumors. In human breast cancer (BC), higher TIL infiltration is associated with a better prognosis and also predicts relevant responses to pre-operative chemotherapy. TIL are primarily composed of T cells, albeit around 20% of BC patients show significant B cell infiltration, and can organize in tertiary lymphoid structures (TLS) located in the peritumoral stroma 1, which are associated with survival in HER2+ and triple negative BC patients. Further, these studies revealed that CD4+ follicular helper T (Tfh) cells producing CXCL13 were specifically associated with peritumoral TLS. CXCL13 is an important B cell chemoattractant whose function is to recruit B cells to the germinal center (GC) in secondary lymphoid organs and TLS, where they can mature and differentiate into memory or antibody-producing B cells. Our recent efforts have focused on exploring the role of Tfh, B cells and CXCL13 play in the development and/or maintenance of GC-like structures in BC-associated TLS. We first derived a GC-B cell gene signature for integration in our published Tfh cell gene signature 1. The combined gene signature was tested for its ability to sensitively detect BC-associated TLS using a qRT-PCR-based assay and a retrospective series (n=54) of formalin-fixed paraffin-embedded (FFPE) BC tissues. These data revealed a correlation between gene signature expression and the extent of TIL and TLS scored by trained pathologists on dual-immunohistochemistry stained (CD3+CD20 for T and B cells, respectively) FFPE tissue sections. The detection of TLS using our combined GC-B cell/Tfh cell gene signature was subsequently confirmed using tissues from our prospective BC cohort (n=83). In addition, CXCL13 gene expression was well correlated with genes associated with GC-B cells and Tfh, indicating these parameters are closely related, as confirmed by immunofluorescence staining on FFPE tissues.

Further understanding the factors that promote TLS formation in vivo could provide important insight for treatment decisions in BC. CXCL13 expression was originally identified as an important signal associated with TLS that was predictive for patient outcomes 1. Factors capable of inducing CXCL13 expression in CD4+ T cells isolated from peripheral blood were investigated using flow cytometry. TGFβ1 alone or together with several cytokines (IL4, IL12, IL21, IL23 and in particular IL2 blockade) increased CXCL13 expression in activated CD4+ T cells. Similar to our characterization of Tfh TIL in fresh tumor tissues, these CXCL13-producing CD4+ T cells were CXCR5 negative and expressed the Tfh marker ICOS; however, they only had low levels of PD-1 expression compared to PD-1hi Tfh cells. CD8+ T cells were also found to produce CXCL13 albeit at low levels. The currently ongoing identification of critical genes involved in regulating CXCL13 production in treated CD4+T cells will help to elucidate the mechanism(s) underlying chemokine induction. The increased accuracy in TIL and TLS detection in BC together with a better understanding of the role Tfh and CXCL13 play in these structures (and GC) development should help to identify the critical immune components involved in BC TLS formation.

1Gu-Trantien et al. J Clin Invest. 2013

Citation Format: Edoardo Migliori, Chunyan Gu-Trantien, Soizic Garaud, Gert Van den Eynden, Alexandre De Wind, Pushpamali De Silva, Cinzia Solinas, Anais Boisson, Celine Naveaux, Denis Larsimont, Martine Piccart-Gebhart, Karen Willard-Gallo. Investigating the role of follicular helper T cells, B cells and CXCL13 in breast cancer-associated tertiary lymphoid structures. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A62.

Comprehensive Profiling of the Androgen Receptor in Liquid Biopsies from Castration-resistant Prostate Cancer Reveals Novel Intra-AR Structural Variation and Splice Variant Expression Patterns

BACKGROUND

Expression of the androgen receptor splice variant 7 (AR-V7) is associated with poor response to second-line endocrine therapy in castration-resistant prostate cancer (CRPC). However, a large fraction of nonresponding patients are AR-V7-negative.

OBJECTIVE

To investigate if a comprehensive liquid biopsy-based AR profile may improve patient stratification in the context of second-line endocrine therapy.

DESIGN, SETTING, AND PARTICIPANTS

Peripheral blood was collected from patients with CRPC (n=30) before initiation of a new line of systemic therapy. We performed profiling of circulating tumour DNA via low-pass whole-genome sequencing and targeted sequencing of the entire AR gene, including introns. Targeted RNA sequencing was performed on enriched circulating tumour cell fractions to assess the expression levels of seven AR splice variants (ARVs).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Somatic AR variations, including copy-number alterations, structural variations, and point mutations, were combined with ARV expression patterns and correlated to clinicopathologic parameters.

RESULTS AND LIMITATIONS

Collectively, any AR perturbation, including ARV, was detected in 25/30 patients. Surprisingly, intra-AR structural variation was present in 15/30 patients, of whom 14 expressed ARVs. The majority of ARV-positive patients expressed multiple ARVs, with AR-V3 the most abundantly expressed. The presence of any ARV was associated with progression-free survival after second-line endocrine treatment (hazard ratio 4.53, 95% confidence interval 1.424-14.41; p=0.0105). Six out of 17 poor responders were AR-V7-negative, but four carried other AR perturbations.

CONCLUSIONS

Comprehensive AR profiling, which is feasible using liquid biopsies, is necessary to increase our understanding of the mechanisms underpinning resistance to endocrine treatment.

PATIENT SUMMARY

Alterations in the androgen receptor are associated with endocrine treatment outcomes. This study demonstrates that it is possible to identify different types of alterations via simple blood draws. Follow-up studies are needed to determine the effect of such alterations on hormonal therapy.

Tumor-infiltrating lymphocyte composition, organization and PD-1/ PD-L1 expression are linked in breast cancer

The clinical relevance of tumor-infiltrating lymphocytes (TIL) in breast cancer (BC) has been clearly established by their demonstrated correlation with long-term positive outcomes. Nevertheless, the relationship between protective immunity, observed in some patients, and critical features of the infiltrate remains unresolved. This study examined TIL density, composition and organization together with PD-1 and PD-L1 expression in freshly collected and paraffin-embedded tissues from 125 patients with invasive primary BC. Tumor and normal breast tissues were analyzed using both flow cytometry and immunohistochemistry. TIL density distribution is a continuum with 25% of tumors identified as TIL-negative at a TIL density equivalent to normal breast tissues. TIL-positive tumors (75%) were equally divided into TIL-intermediate and TIL-high. Tumors had higher mean frequencies of CD4⁺ T cells and CD19⁺ B cells and a lower mean frequency of CD8⁺ T cells compare with normal tissues, increasing the CD4⁺/CD8⁺ T-cell ratio. Tertiary lymphoid structures (TLS), principally located in the peri-tumoral stroma, were detected in 60% of tumors and correlated with higher TIL infiltration. PD-1 and PD-L1 expression were also associated with higher TIL densities and TLS. TIL density, TLS and PD-L1 expression were correlated with more aggressive tumor characteristics, including higher proliferation and hormone receptor negativity. Our findings reveal an important relationship between PD-1/PD-L1 expression, increased CD4⁺ T and B-cell infiltration, TIL density and TLS, suggesting that evaluating not only the extent but also the nature and location of the immune infiltrate should be considered when evaluating antitumor immunity and the potential for benefit from immunotherapies.

Assays for Qualification and Quality Stratification of Clinical Biospecimens Used in Research: A Technical Report from the ISBER Biospecimen Science Working Group

This technical report presents quality control (QC) assays that can be performed in order to qualify clinical biospecimens that have been biobanked for use in research. Some QC assays are specific to a disease area. Some QC assays are specific to a particular downstream analytical platform. When such a qualification is not possible, QC assays are presented that can be performed to stratify clinical biospecimens according to their biomolecular quality.

A Biospecimen Proficiency Testing Program for Biobank Accreditation: Four Years of Experience

Biobanks produce and distribute biospecimens, ensuring their fitness for purpose and accurately qualifying them before distribution. In their efforts toward professionalization, biobanks can nowadays seek certification or accreditation. One of the requirements of these standards is regular participation in Proficiency Testing (PT) programs. An international PT program has been developed and provided to biobanks and other laboratories that perform specific tests to qualify different types of biospecimens. This PT program includes biospecimen testing schemes, as well as biospecimen processing interlaboratory exercises. This PT program supports the development of biobank quality assurance by providing the possibility to assess biobank laboratory performance and useful insights into biobank laboratory method performance characteristics and thus fulfill the demands from accreditation authorities.

Abstract A124: Tertiary lymphoid structures: Predictors of effective antitumor immunity in human breast cancer?

The clinical relevance of tumor infiltrating lymphocytes (TIL) in breast cancer (BC) is now broadly accepted; however, the relationship between protective immunity, observed in some patients, and critical features of lymphoid subset composition and organization are largely unknown. Our recent work revealed that tertiary lymphoid structures (TLS), principally composed of T and B cells, present in the peri-tumoral regions of BC are associated with increased TIL infiltration in the tumor bed and good clinical outcomes in both the neo-adjuvant and adjuvant settings. To gain insight into the immune components linked with a significant TIL and TLS presence, we initiated a prospective study of T and B cell TIL. Breast tissues from tumors (current n=483) and matched non-adjacent non-tumor tissues (NANT) as well as normal tissue from mammary reductions (n=49) were systematically immunophenotyped by flow cytometry on the day of surgery. Primary tumor supernatants derived from the tissue homogenates (non-enzymatic) and plasma from all patients were stored for cytokine/chemokine and immunoglobulin analysis. TIL organization and spatial distribution was analyzed on paraffin sections using immunohistochemistry (IHC) and immunofluorescence (IF). The fresh tissue analyses revealed that TIL distribution in BC forms a continuum. The infiltration levels detected in normal tissue and NANT were used to define cutoffs that discriminate between TIL positive (TILpos) and negative (TILneg) tumors. TILneg tumors are defined as those with a TIL density &lt;99th percentile of the lymphocyte density in normal breast tissue. TILpos tumors include TIL-high (TILhi) where TIL density is &gt;99th percentile of lymphocyte density in NANT and TIL-intermediate (TILint). Applying these thresholds to the TIL infiltration levels identified approximately 25% of tumors as TILneg with infiltrating lymphocytes similar to normal breast tissue. The TILpos tumors (75%) are subdivided into 36% TILint and 39% TILhi tumors. TILpos tumors are characterized by an increase in CD4+ T cells and CD19+/CD20+ B cells. The median CD4/CD8 ratio was &gt;1 in TILpos compared to &lt;1 in TILneg tumors and NANT. CD4+ and CD8+ T cells were predominantly CD45RO+ memory cells with a significant proportion expressing PD-1. All stages of B cell differentiation were detected in the infiltrate; however, memory B cells were significantly increased in BC (50%) compared to normal tissues (&lt;15%) with the highest levels seen in TILhi tumors. An increase in centroblasts and centrocytes, the germinal center (GC) B cells, was associated with Tfh cells, both resident in peri-tumoral TLS. Their presence was positively correlated with antibody-secreting cells, suggesting local humoral immune responses are generated in TLS, which is supported by the increased immunoglobulin levels detected in tumor supernatants compared to NANT/normal tissue supernatants. Closer examination of Tfh cells infiltrating BC indicates that CXCL13-producing Tfh TIL vary from Tfh cells in secondary lymphoid organs such as tonsils. Tfh TIL express the highest levels of some GC Tfh cell markers (PD-1, CD200 and TIGIT) but intermediate levels of others (ICOS and BCL6) and are essentially negative for CXCR5. Closer examination of Tfh cells in the tumor bed revealed that they directly contact CD20+ B cells, IgG+ and IgA+ plasma cells as well as CXCL13–CD8+ TIL. Taken together, our data suggest that active cross-talk between adaptive immune cells in the tumor microenvironment may be key to establishing immunological memory sufficiently robust to control residual BC over the long term. These data further signify that TLS and/or the presence of GC-associated Tfh and B cells may be important biomarkers that identify effective anti-tumor immunity, which can ultimately be used to independently grade therapeutic responses.

Citation Format: Soizic Garaud, Laurence Buisseret, Chunyan Gu-Trantien, Gert Van den Eynden, Alexandre de Wind, Edoardo Migliori, Roberto Salgado, Denis Larsimont, Martine Piccart, Karen Willard-Gallo. Tertiary lymphoid structures: Predictors of effective antitumor immunity in human breast cancer? [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A124.

Constitutive phosphorylated STAT3-associated gene signature is predictive for trastuzumab resistance in primary HER2-positive breast cancer

BACKGROUND

The likelihood of recurrence in patients with breast cancer who have HER2-positive tumors is relatively high, although trastuzumab is a remarkably effective drug in this setting. Signal transducer and activator of transcription 3 protein (STAT3), a transcription factor that is persistently tyrosine-705 phosphorylated (pSTAT3) in response to numerous oncogenic signaling pathways, activates downstream proliferative and anti-apoptotic pathways. We hypothesized that pSTAT3 expression in HER2-positive breast cancer will confer trastuzumab resistance.

METHODS

We integrated reverse phase protein array (RPPA) and gene expression data from patients with HER2-positive breast cancer treated with trastuzumab in the adjuvant setting.

RESULTS

We show that a pSTAT3-associated gene signature (pSTAT3-GS) is able to predict pSTAT3 status in an independent dataset (TCGA; AUC = 0.77, P = 0.02). This suggests that STAT3 induces a characteristic set of gene expression changes in HER2-positive cancers. Tumors characterized as high pSTAT3-GS were associated with trastuzumab resistance (log rank P = 0.049). These results were confirmed using data from the prospective, randomized controlled FinHer study, where the effect was especially prominent in HER2-positive estrogen receptor (ER)-negative tumors (interaction test P = 0.02). Of interest, constitutively activated pSTAT3 tumors were associated with loss of PTEN, elevated IL6, and stromal reactivation.

CONCLUSIONS

This study provides compelling evidence for a link between pSTAT3 and trastuzumab resistance in HER2-positive primary breast cancers. Our results suggest that it may be valuable to add agents targeting the STAT3 pathway to trastuzumab for treatment of HER2-positive breast cancer.

Abstract P1-07-09: SMAD nuclear staining patterns in inflammatory breast cancer suggest non-canonical TGFβ-signalling establishing collective, sheet-like invasion SMAD nuclear staining patterns in inflammatory breast cancer suggest non-canonical TGFβ-signalling es

Introduction: Inflammatory Breast Cancer (IBC) is an aggressive and highly metastatic form of breast cancer. Recent expression profiling studies revealed IBC-specific modulation of TGFβ-signalling. In the present study, we aim to validate these findings by evaluating nuclear SMAD staining patterns.

Materials and Methods: Immunohistochemistry (IHC) was performed for SMAD2, -3, -4 and -6 on tissue sections from patients with (N=79) and without (N=133) IBC. Protocols for IHC were established on cell blocks from breast cancer cell lines with and without SMAD staining identified by western blotting on nuclear protein extracts. A staining score was assigned by multiplying the percentage of stained cancer cell nuclei by the staining intensity evaluated on a three-scale basis (1=weak, 2=intermediate, 3=strong). Expression data were subjected to unsupervised hierarchical cluster analysis (UHCA) and statistical assessment of staining differences was done using uni- and multivariate models. Additionally, we looked at the correlation between nuclear SMAD expression and gene expression in 11 patients. For each gene, we generated a spearman correlation coefficient, and selected only those genes that were positively correlated with nuclear SMAD expression in 11 patients (p&lt;0.05).

Results: UHCA for SMAD2, -3 and -4 nuclear protein expression data identified two sample clusters downstream of the first bifurcation. IBC samples were significantly (OR=60.34, P&lt;0.001) enriched in the cluster characterized by increased nuclear SMAD2 protein expression and absence of both nuclear SMAD3 and -4 protein expression. Univariate analysis revealed that these staining patterns are significant (all Ps&lt;0.01). Multivariate analysis demonstrated that gain of SMAD2 nuclear expression and loss of SMAD3 nuclear expression in IBC are unrelated observations and independent of histological grade, hormone receptor expression, ErbB2 amplification and tumour stage. SMAD correlation analysis showed us that genes positively correlated with nuclear SMAD2 expression included CD44 and REL, both markers that represent crucial pathways in IBC. Interestingly, nuclear SMAD3 expression was positively correlated with ZEB1.

Discussion: In line with the expectations, our data show that TGFβ-signalling indeed differs between samples from patients with and without IBC. In addition, this study does offer novel insights on IBC biology. First, SMAD2 nuclear staining is gained in IBC in the absence of its canonical binding partners SMAD3 and -4, suggesting non-canonical TGFβ-signalling in IBC. Second, it has been shown that SMAD2 induces an invasive response program in cancer cells without affecting their epithelial morphology, while SMAD3 accounts for invasion by induction of Epithelial-to-Mesenchymal transition (EMT). Thus our results indicate that IBC cell invasion occurs in a collective, sheet-like fashion instead of EMT, which is probably responsible for the invasion of non-IBC cells.

Citation Format: Melike Marsan, Gert Van den Eynden, Patrick Neven, Ignace Vergote, Peter Vermeulen, Luc Dirix, Steven Van Laere. SMAD nuclear staining patterns in inflammatory breast cancer suggest non-canonical TGFβ-signalling establishing collective, sheet-like invasion SMAD nuclear staining patterns in inflammatory breast cancer suggest non-canonical TGFβ-signalling es [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 P1-07-09.

A core invasiveness gene signature reflects epithelial-to-mesenchymal transition but not metastatic potential in breast cancer cell lines and tissue samples

Introduction

Metastases remain the primary cause of cancer-related death. The acquisition of invasive tumour cell behaviour is thought to be a cornerstone of the metastatic cascade. Therefore, gene signatures related to invasiveness could aid in stratifying patients according to their prognostic profile. In the present study we aimed at identifying an invasiveness gene signature and investigated its biological relevance in breast cancer.

Methods & Results

We collected a set of published gene signatures related to cell motility and invasion. Using this collection, we identified 16 genes that were represented at a higher frequency than observed by coincidence, hereafter named the core invasiveness gene signature. Principal component analysis showed that these overrepresented genes were able to segregate invasive and non-invasive breast cancer cell lines, outperforming sets of 16 randomly selected genes (all P<0.001). When applied onto additional data sets, the expression of the core invasiveness gene signature was significantly elevated in cell lines forced to undergo epithelial-mesenchymal transition. The link between core invasiveness gene expression and epithelial-mesenchymal transition was also confirmed in a dataset consisting of 2420 human breast cancer samples. Univariate and multivariate Cox regression analysis demonstrated that CIG expression is not associated with a shorter distant metastasis free survival interval (HR = 0.956, 95%C.I. = 0.896–1.019, P = 0.186).

Discussion

These data demonstrate that we have identified a set of core invasiveness genes, the expression of which is associated with epithelial-mesenchymal transition in breast cancer cell lines and in human tissue samples. Despite the connection between epithelial-mesenchymal transition and invasive tumour cell behaviour, we were unable to demonstrate a link between the core invasiveness gene signature and enhanced metastatic potential.

P-cadherin in adhesion and invasion: opposite roles in colon and bladder carcinoma

Neoexpression or upregulation of placental cadherin (P-cadherin), a member of the classical cadherin family, has previously been described in several carcinomas, such as colorectal and bladder carcinomas. In this study, we combined two different approaches, immunohistochemistry of tumor samples and in vitro knockdown of P-cadherin, to gain a better insight into the role of P-cadherin in these types of cancer. First, we performed immunohistochemistry for P- and E-cadherins in a series of 52 colorectal adenocarcinomas, including well, moderately and poorly differentiated (WD, MD, and PD) tumors. Decrease or loss of P-cadherin neoexpression was significantly associated with a higher tumor grade and could discriminate WD from MD and/or PD tumors (p < 0.001). E-cadherin, on the other hand, was strongly expressed at the membrane of most WD (18 of 19) and MD tumors (15 of 19). Downregulation correlated significantly with the PD phenotype (p ≤ 0.001). In a second approach, we transiently or stably knocked down P-cadherin in HT-29 colon adenocarcinoma cells. This led to decreased intercellular adhesion and to an increased migratory and long-term invasive phenotype compared with control HT-29 cells, suggesting that P-cadherin acts as a proadhesive and anti-invasive/antimigratory molecule in colon carcinoma cells. Contrasting with these results and illustrating the context-specific function of P-cadherin were our results obtained in RT-112 bladder carcinoma cells. Stable knockdown of P-cadherin in RT-112 cells diminished invasion and migration, and promoted intercellular adhesion.

Relapse-free survival in breast cancer patients is associated with a gene expression signature characteristic for inflammatory breast cancer

PURPOSE

We hypothesize that a gene expression profile characteristic for inflammatory breast cancer (IBC), an aggressive form of breast cancer associated with rapid cancer dissemination and poor survival, might be related to tumor aggressiveness in non-IBC (nIBC).

EXPERIMENTAL DESIGN

RNA from 17 IBC samples and 40 nIBC samples was hybridized onto Affymetrix chips. A gene signature predictive of IBC was identified and applied onto 1,157 nIBC samples with survival data of 881 nIBC samples. Samples were classified as IBC-like or nIBC-like. The IBC signature classification was compared with the classifications according to other prognostically relevant gene signatures and clinicopathologic variables. In addition, relapse-free survival (RFS) was compared by the Kaplan-Meyer method.

RESULTS

Classification according to the IBC signature is significantly (P < 0.05) associated with the cell-of-origin subtypes, the wound healing response, the invasive gene signature, the genomic grade index, the fibroblastic neoplasm signature, and the 70-gene prognostic signature. Significant associations (P < 0.01) were found between the IBC signature and tumor grade, estrogen receptor status, ErbB2 status, and patient age at diagnosis. Patients with an IBC-like phenotype show a significantly shorter RFS interval (P < 0.05). Oncomine analysis identified cell motility as an important concept linked with the IBC signature.

CONCLUSIONS

We show that nIBC carcinomas having an IBC-like phenotype have a reduced RFS interval. This suggests that IBC and nIBC show comparable phenotypic traits, for example augmented cell motility, with respect to aggressive tumor cell behavior. This observation lends credit to the use of IBC to study aggressive tumor cell behavior.