[Metastatic castration-resistant prostate cancer : Use of cabazitaxel taking into consideration current data]

BACKGROUND

At the 2016 ASCO annual meeting, new data from two randomized phase III studies concerning taxane-based chemotherapy as a treatment option for patients with metastatic castration-resistant prostate cancer (mCRPC) were presented.

OBJECTIVES

The focus is on the clinical impact of these data.

MATERIALS AND METHODS

A group of German experts in the field of urogenital-oncologic expertise discussed the clinical impact with respect to the current data.

RESULTS

The study results support the current clinical data. They confirm the efficacy and safety of cabazitaxel beyond first-line therapy with docetaxel for patients with mCRPC.

CONCLUSIONS

Cabazitaxel is an important treatment option after docetaxel progression. With respect to the performance status of a patient, it is adequate to reduce the dosage to 20 mg/m² cabazitaxel.

Mast cells decrease efficacy of anti-angiogenic therapy by secreting matrix-degrading granzyme B

Resistance towards VEGF-centered anti-angiogenic therapy still represents a substantial clinical challenge. We report here that mast cells alter the proliferative and organizational state of endothelial cells which reduces the efficacy of anti-angiogenic therapy. Consequently, absence of mast cells sensitizes tumor vessels for anti-angiogenic therapy in different tumor models. Mechanistically, anti-angiogenic therapy only initially reduces tumor vessel proliferation, however, this treatment effect was abrogated over time as a result of mast cell-mediated restimulation of angiogenesis. We show that mast cells secrete increased amounts of granzyme b upon therapy, which mobilizes pro-angiogenic laminin- and vitronectin-bound FGF-1 and GM-CSF from the tumor matrix. In addition, mast cells also diminish efficacy of anti-angiogenic therapy by secretion of FGF-2. These pro-angiogenic factors act beside the targeted VEGFA–VEGFR2-axis and reinduce endothelial cell proliferation and angiogenesis despite the presence of anti-angiogenic therapy. Importantly, inhibition of mast cell degranulation with cromolyn is able to improve efficacy of anti-angiogenic therapy. Thus, concomitant mast cell-targeting might lead to improved efficacy of anti-angiogenic therapy.

Resistance towards VEGF-centered anti-angiogenic therapy is an important clinical challenge. Here, the authors show that mast cells mediate resistance to anti-angiogenetic inhibitors by altering the proliferative and organizational state of endothelial cells through mobilization of FGF-1 and GM-CSF from the tumor matrix and secretion of FGF-2.

Abel E, Heinrich G, Schueller K, Schneeweiss A, Fasching P, Beckmann MW, Scholz C, Friedl TWP, Friese K, Pantel K, Fehm T, Janni W, Rack B. The HER2 phenotype of circulating tumor cells in HER2-positive early breast cancer: A translational research project of a prospective randomized phase III trial

BACKGROUND

HER2 is one of the predominant therapeutic targets in breast cancer. The metastatic selection process may lead to discrepancies between the HER2 status of the primary tumor and circulating tumor cells (CTCs). This study analyzed the HER2 status of CTCs in patients with HER2-positive primary breast cancer at the time of diagnosis. Aim of the study was to assess potential discordance of HER2 status between primary tumor and CTCs, as this may have important implications for the use of HER2-targeted therapy.

METHODS

The number and HER2 status of CTCs out of 30ml peripheral blood were assessed in 642 patients using the CellSearch System (Janssen Diagnostics, USA). The cutoff for CTC positivity was the presence of at least 1 CTC, and the cutoff for HER2 positivity of CTCs was the presence of at least 1 CTC with a strong HER2 staining.

RESULTS

258 (40.2%) of the 642 patients were positive for CTCs (median 2; range 1-1,689). 149 (57.8%) of these 258 patients had at least 1 CTC with strong HER2 staining. The presence of HER2-positive CTCs was not associated with tumor size (p = 0.335), histopathological grading (p = 0.976), hormone receptor status (ER: p = 0.626, PR: p = 0.263) or axillary lymph node involvement (p = 0.430). Overall, 83 (32.2%) of the CTC-positive patients exclusively had CTCs with strong HER2 staining, whereas 31 (12.0%) had only CTCs with negative HER2 staining. Within-sample variation in the HER2 status of CTCs was found in 86 (57.8%) of the 149 patients with more than 1 CTC.

CONCLUSION

This study demonstrated that discordance between the HER2 expression of CTCs and that of the primary tumor frequently occurs in early breast cancer. Future follow-up evaluation will assess whether this discrepancy may contribute to trastuzumab resistance.

Abstract OT1-02-04: The DETECT V-study – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in patients with HER2-positive and hormone-receptor positive metastatic breast cancer

Background: Maintenance of quality of life (QoL) is one of the main aims of treatment of incurable diseases such as metastatic breast cancer (MBC). In patients with HER2-positive MBC, taxan-based chemotherapy in combination with dual HER2 targeted therapy with trastuzumab and pertuzumab has shown promising efficacy results in terms of prolonged survival. However, cytostatic treatment is often accompanied by adverse events of grade 3 or higher, seriously impacting the patients' QoL. In patients with HER2-positive and hormone-receptor positive MBC, the combination of trastuzumab with aromatase inhibitors was shown to be a safe and effective treatment option. The synergistic combination of dual HER2-targeted therapy with trastuzumab and pertuzumab plus endocrine therapy might offer an even better treatment option for these patients. DETECT V is the first prospective randomized phase III clinical trial comparing the safety and efficacy of the dual HER2-targeted therapy in combination with either endocrine therapy or chemotherapy.

Trial design and eligibility criteria: Women with HER2-positive and hormone-receptor positive MBC with first to third line therapy are 1:1 randomized either to a dual HER2-targeted therapy with Pertuzumab and Trastuzumab plus endocrine therapy or to the dual HER2-targeted therapy plus chemotherapy.

Specific aims: The primary objective of this study is to compare the safety and QoL in both arms, as assessed by the occurrence of AEs during the treatment period. We developed a modified adverse event score - including all adverse events grade 3 or higher, except neutropenia, which is included only if rated grade 4, and alopecia, rash, hand-foot-syndrome and peripheral neuropathy which are included if rated grade 2 or higher – in order to better reflect the clinical, physiological and psychological impact of AEs on patients' QoL. Key secondary endpoint, besides the efficacy endpoints progression free survival (PFS) and overall survival, is to compare quality-adjusted survival (QAS), as measured using the quality-adjusted time without symptoms and toxicity (Q-TWiST) method, between both treatment arms. QAS as measured using the Q-TWiST method provides a single metric value that is a composite measure of quantity of survival time and quality of survival as assessed by the patients themselves. Q-TWiST analyses account for possible trade-offs between quantity and quality of life (e.g. prolonged time to progression at the cost of higher toxicity, which adversely affects QoL), and provide an excellent tool to evaluate whether two treatment options differ with regard to the overall perceived value to the patients.

Translational research projects focus on Circulating Tumor Cell(CTC)-enumeration (the presence of CTCs is not obligatory in DETECT V), prognostic role of CTC dynamics, and the assessment of marker expression on CTCs in order to calculate an endocrine responsiveness score which will be evaluated regarding its suitability to predict treatment success.

Contact: For further information on the DETECT V study please contact www.detect-studien.de or studienzentrale.ufk@uniklinik-ulm.de.

Citation Format: Polasik A, Schramm A, Friedl TWP, Rack B, Trapp E, Tzschaschel M, Fasching PA, Taran F-A, Hartkopf A, Schneeweiss A, Müller V, Aktas B, Pantel K, Meier-Stiegen F, Wimberger P, Janni W, Fehm T. The DETECT V-study – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in patients with HER2-positive and hormone-receptor positive metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-02-04.

Abstract P2-05-02: Active surveillance with a combination of tumor marker CA27.29 and detection of circulating tumor cells two year after primary diagnosis strongly predicts subsequent prognosis

Introduction

The prognosis of patients with early breast cancer is commonly estimated by prognostic factors obtained at the time of the initial diagnosis. However, patients and physicians alike are seeking for factors evaluating the prognosis years thereafter during follow-up. The identification of a patient group with an unfavourable prognosis could lead to secondary treatment intervention, potentially improving outcome. Aim of the study was to assess the added prognostic value of circulating tumor cells (CTCs) and CA27.29 beyond established predictors.

Materials and Methods

Patients of the phase III SUCCESS-A study were included into this analysis (n=1005). SUCCESS-A is a chemotherapy study for high risk patients with a comprehensive translational research program, which included the determination of CTCs and CA27.29 two years after the initial diagnosis. A Cox regression model with disease-free survival (DFS) as outcome and well-established predictors (age, BMI, pT, pN, histology, grading, ER, PR, Her2neu) was compared with an extended Cox model with the well-established predictors and additionally CTC (>0 versus 0) two years after randomization, and CA27.29 (in U/mL) measured after chemotherapy and again two years after randomization using a likelihood ratio test. In case of significance, the extended model was applied to predict for each patient the risk of disease recurrence within the next 12 months (0 to 100%). Cross-validated AUC, sensitivity and specificity values were determined to assess clinical usefulness of risk prediction.

Results

The markers CA27.29 and CTC were both significantly associated with subsequent prognosis (p < 0.000001). The detection of CTCs increased the risk of subsequent DFS events (HR=2.14, 95%CI: 1.31-3.48), while CA27.29 after two years increased the risk for DFS events with a HR of 1.12 per U/mL increase (95%CI: 1.09-1.15). The combination of the two markers significantly empowered the prognostic relevance, with a HR of 6.64 for patients with CTCs and an elevated CA27.29 by 10 U/mL compared to patients without CTCs and without CA27.29 elevation. The mean risk of disease recurrence in the third year after randomization was 2.38%. Discrimination of patients with and without disease recurrence based on risk prediction from the extended Cox model (AUC: 0.80) was better than discrimination based on the clinical model without the markers CTC and CA27.29 (AUC: 0.64). Sensitivity with regard to decision thresholds 1%, 2%, 3%, and 4% predicted risk was 0.89, 0.77, 0.65, and 0.55, respectively. The corresponding specificity was 0.42, 0.69, 0.81, and 0.88.

Discussion

Both CTCs and CA29.27 values determined 2 years after primary diagnosis are clinically relevant predictors of subsequent prognosis for those patients. This study extends evidence for active surveillance of breast cancer survivors. Identifying a group of women with a high recurrence risk after two years could be the basis for the development of secondary adjuvant treatment.

Citation Format: Janni W, Rack B, Häberle L, Friedl TWP, Tesch H, Lorenz R, Jäger B, Fehm T, Müller V, Schneeweiß A, Lichtenegger W, Blohmer J, Beckmann MW, Scholz C, Pantel K, Trapp E, Fasching PA. Active surveillance with a combination of tumor marker CA27.29 and detection of circulating tumor cells two year after primary diagnosis strongly predicts subsequent prognosis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-02.

Abstract OT3-04-02: DETECT III and IV – Individualized CTC-based therapy of metastatic breast cancer

Background: Circulating tumor cells (CTCs) are found in patients with early and metastatic breast cancer (MBC), and both their prognostic and predictive value has been described already. There is growing evidence that CTC phenotype may differ from the primary tumor. However, CTC targeted therapy is not used in clinical routine, and treatment decisions often still are based on the primary tumor's phenotype without considering CTC-characteristics. The aim of the DETECT studies is to investigate and evaluate the role of presence and phenotype of CTC for guiding therapeutic decisions in women with HER2-negative MBC.

Trial design and eligibility criteria: In a joint screening for DETECT III and IV, women with HER2-negative MBC are tested for CTCs and their HER2-phenotype. CTC detection is performed by the FDA-approved CellSearch System® (Janssen Diagnostics, Raritan, USA).

Patients with HER2-positive CTCs are randomized in the multicenter Phase III study DETECT III to a physician's choice chemo- or endocrine therapy with or without additional HER2-targeted treatment with lapatinib.

Women with only HER2-negative CTCs are recruited to the multicenter open-label phase II study DETECT IV. Postmenopausal women with hormone-receptor positive MBC are treated with everolimus and a physician's choice endocrine therapy in DETECT IVa. Patients with hormone-receptor positive MBC and an indication for chemotherapy and patients with triple-negative MBC receive mono-chemotherapy with eribulin in DETECT IVb.

Treatment efficacy will be evaluated based on the early available CTC clearance rate (in DETECT III and DETECT IVa) and progression-free survival (in DETECT IVb) respectively, as the primary endpoint; secondary objectives will be to estimate disease control rate, progression-free (DETECT III and IVa) and overall survival, toxicity and tolerability of treatments with lapatinib, everolimus and eribulin, and quality of life.

Specific aims: Changes in CTC-dynamics during therapy and their HER2-phenotype may influence following therapy decisions. The DETECT studies evaluate the prognostic and predictive role of CTCs as well as the efficacy of CTC based therapy to enable the establishment of a more personalized therapy for patients with MBC that might lead to prolonged progressive free survival and/or improved quality of life. The accompanying translational research programs investigate various markers for molecular characterization of CTCs and prediction of therapy response.

Present accrual and target accrual: More than 1550 patients with HER2-negative MBC have already been screened within the DETECT study program. Thus, it is the worldwide largest study concept with therapy decisions resulting from CTC-testing and CTC-phenotypization.

Contact: For further information on the DETECT study program please contact www.detect-studien.de or studienzentrale.ufk@uniklinik-ulm.de.

Citation Format: Polasik A, Schramm A, Friedl TWP, Rack B, Trapp E, Fasching PA, Taran F-A, Hartkopf A, Schneeweiss A, Müller V, Aktas B, Pantel K, Meier-Stiegen F, Wimberger P, Janni W, Fehm T. DETECT III and IV – Individualized CTC-based therapy of metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-04-02.

Abstract P1-01-03: Dynamics of circulating tumor cells during the course of chemotherapy and prognostic relevance across molecular subtypes in high-risk early breast cancer patients – Results from the adjuvant SUCCESS A trial

Background: The presence of circulating tumor cells (CTCs) before chemotherapy is known to be associated with reduced disease free survival (DFS) and overall survival (OS) in early breast cancer (EBC). In addition, recent findings suggest that CTCs persisting after adjuvant chemotherapy indicate poor prognosis. In an explorative analysis of the SUCCESS A trial, we evaluated the prognostic relevance of changes in CTC counts during the course of adjuvant chemotherapy across molecular subtypes to assess whether the prognostic role of persisting CTCs varies according to tumor biology.

Methods: The SUCCESS A trial is a phase III study, where patients with high-risk EBC (stage pN1-3 or pT2-4 or grade 3 or age ≤ 35 or hormone-receptor negative) were randomized to adjuvant chemotherapy with 3 cycles of epirubicin-fluorouracil-cyclophosphamide followed by either 3 cycles of docetaxel or 3 cycles of gemcitabine-docetaxel. CTC enumeration was performed before and after chemotherapy using the FDA-approved CellSearch® System (Janssen Diagnostics, LLC), and CTC positivity was defined as ≥ 1 CTC in 23 ml blood. Molecular subtypes were defined as luminal A like (hormone-receptor positive, grading 1 or 2), luminal B like (hormone-receptor positive, grading 3), triple-negative or HER2-positive. Patient outcome in terms of DFS and OS was analyzed using univariate log-rank tests and Cox regression models (median follow-up time 65.2 months).

Results: Data on both molecular subtypes and CTC status before and after chemotherapy were available for 1485 (39.6%) of 3754 patients randomized. This cohort contained 577 (38.9%) luminal A like, 236 (15.9%) luminal B like, 379 (25.5%) HER2-positive and 293 (19.7%) triple negative tumors. Overall, 917 (61.8%) patients were CTC negative before and after chemotherapy (neg/neg), 260 (17.5%) patients had a negative CTC status before and a positive CTC status after chemotherapy (neg/pos), 229 (15.4%) patients converted from positive to negative CTC status (pos/neg), and 79 (5.3%) patients were positive for CTCs at both time points (pos/pos). There were significant differences in DFS and OS among these four groups in patients with luminal A like tumors (log rank test, both p < 0.003) and patients with luminal B like tumors (log rank test, both p < 0.001). In both patients with luminal A like or luminal B like tumors, persistently CTC positive patients had the worst outcome (relative to persistently CTC-negative patients) in terms of DFS and OS. In contrast to luminal-like tumors, no significant differences with regard to DFS or OS were found among the four groups (neg/neg, neg/pos, pos/neg, pos/pos) in patients with HER2-positive or triple-negative tumors (log rank test, all p > 0.13).

Conclusion: The presence of CTCs both before and after adjuvant chemotherapy was associated with poor survival in luminal A like and luminal B like tumors, but not in HER2-positive or triple-negative tumors. Further research is needed to evaluate the effect of chemotherapy on CTC prevalence in different molecular subtypes of EBC.

Citation Format: Tzschaschel MLJ, Rack B, Andergassen U, Friedl TWP, Schneeweiss A, Mueller V, Tanja F, Pantel K, Gade J, Lorenz R, Rezai M, Tesch H, Soeling U, Polasik A, Alunni-Fabbroni M, Trapp EK, Mahner S, Schindlbeck C, Lichtenegger W, Beckmann MW, Fasching PA, Janni W. Dynamics of circulating tumor cells during the course of chemotherapy and prognostic relevance across molecular subtypes in high-risk early breast cancer patients – Results from the adjuvant SUCCESS A trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-01-03.

Diverse prognostic value of the GTn promoter polymorphism in squamous cell and adeno carcinoma of the oesophagus

The basal transcription of heme oxygenase-1 (HO-1) regulation is dependent upon a GT repeat germ line polymorphism (GTn) in the promoter of the HO-1 gene. We determined the prognostic value of HO-1 promoter polymorphism on the natural postoperative course of complete resected oesophageal cancer. Genomic DNA from 297 patients was amplified by polymerase chain reaction and sequenced. The results were correlated with clinicopathological parameters, disseminated tumour cells in bone marrow (DTC) and clinical outcome. Depending on short allele with <25 and long allele with ≥25, GTn repeats three genotypes (SS, SL and LL) were defined. A diverse role of GTn was evident in squamous cell carcinoma (SCC) and adenocarcinoma (AC). In SCC, the SS genotype presented less advanced tumours with lower rate DTC in bone marrow and relapse compared with L-allele carriers. In contrast, AC patients with the SS genotype displayed a complete opposing tumour characteristic. The disease-free (DFS) and overall survival (OS) in SCC patients was markedly reduced in LL genotypes (p < 0.001). In AC contrarily the SS genotype patients displayed the worst DFS and OS (p < 0.001). GTn is a strong prognostic factor with diverse prognostic value for recurrence and survival in AC and SCC.

A novel microfluidic platform for size and deformability based separation and the subsequent molecular characterization of viable circulating tumor cells

Circulating tumor cells (CTCs) were introduced as biomarkers more than 10 years ago, but capture of viable CTCs at high purity from peripheral blood of cancer patients is still a major technical challenge. Here, we report a novel microfluidic platform designed for marker independent capture of CTCs. The Parsortix™ cell separation system provides size and deformability-based enrichment with automated staining for cell identification, and subsequent recovery (harvesting) of cells from the device. Using the Parsortix™ system, average cell capture inside the device ranged between 42% and 70%. Subsequent harvest of cells from the device ranged between 54% and 69% of cells captured. Most importantly, 99% of the isolated tumor cells were viable after processing in spiking experiments as well as after harvesting from patient samples and still functional for downstream molecular analysis as demonstrated by mRNA characterization and array-based comparative genomic hybridization. Analyzing clinical blood samples from metastatic (n = 20) and nonmetastatic (n = 6) cancer patients in parallel with CellSearch(®) system, we found that there was no statistically significant difference between the quantitative behavior of the two systems in this set of twenty six paired separations. In conclusion, the epitope independent Parsortix™ system enables the isolation of viable CTCs at a very high purity. Using this system, viable tumor cells are easily accessible and ready for molecular and functional analysis. The system's ability for enumeration and molecular characterization of EpCAM-negative CTCs will help to broaden research into the mechanisms of cancer as well as facilitating the use of CTCs as "liquid biopsies."

Abstract P2-02-06: Impact of apoptotic circulating tumor cells in metastatic breast cancer

Background

Circulating tumor cells (CTC) are a heterogeneous cell population and an independent negative prognostic factor for progression-free (PFS) and overall survival (OS) in patients with metastatic breast cancer (MBC). The study aimed to prospectively assess CTC status for the subtypes apoptotic CTC (aCTC) and intact CTC (iCTC) at baseline (CTCBL) and after one cycle of a new line of systemic therapy (CTC1C). Changes from CTCBL to CTC1C (CTC kinetics, CTCKIN) were evaluated for their utility in predicting response, progression-free (PFS) and overall survival (OS).

Methods

423 MBC patients were included in a prospective trial prior to a new regimen of treatment. Intact and apoptotic CTC were analyzed at baseline (CTCBL) and after one cycle of systemic therapy (CTC1C) using CellSearch™ (Veridex) and morphologic criteria. Samples with ≥5 CTC/7.5ml blood were regarded as positive. Therapy response was assessed using the RECIST-criteria on three-monthly radiological controls. CTCKIN were characterized by ≥25% change from CTCBL to CTC1C to differentiate stable, increased and decreased CTC kinetic.

Results

35% of patients were iCTCBL-positive and 28% aCTCBL-positive at baseline (CTCBL). PFS and OS differ significantly between the iCTCBL-positive and the iCTCBL-negative group (PFS 4.5 vs. 8.0; OS 12.5 vs. 27.2 (months)). Positive aCTC in conjunction with positive iCTCBL at baseline has worst prognostic impact (PFS 6.3; OS 8.7).

Regarding the CTCKIN (BL to 1C), aCTC-decrease (≥25%) is a positive prognostic factor compared to aCTC-stable and aCTC-increase (PFS 7.6 vs. 3.7; 3.3 and OS 21.0 vs. 4.8; 5.7). Decreasing aCTCKIN shows favorable prognostic impact versus decreasing iCTCKIN (PFS 7.6 vs. 5.9 and OS 21.0 vs 16.4).

Conclusion

Elevated aCTC levels at baseline have an unfavorable prognostic impact on both OS and PFS in conjunction with elevated iCTC. Additionally, the decrease of aCTC is a relevant prognostic value for systemic therapy response. aCTCKIN allows better differentiation for therapy response in patients with positive CTC-status at baseline. Differentiated enumeration of intact and apoptotic CTC should be considered in clinical application.

Citation Format: Wallwiener M, Deutsch TM, Riethdorf S, Hartkopf AD, Taran F-A, Trumpp A, Brucker S, Schütz F, Rom J, Pantel K, Schneeweiss A. Impact of apoptotic circulating tumor cells in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-06.

Abstract P2-02-02: Predictors for discordance in HER2 phenotype between primary tumor and circulating tumor cells in women with metastatic breast cancer

Aim: The DETECT study program evaluates whether treatment efficacy in women with metastatic breast cancer (MBC) is increased by taking into account the molecular characteristics of circulating tumor cells (CTCs). Here, we present data on both prevalence and HER2 phenotype of CTCs in patients with HER2 negative MBC screened within the DETECT program. The aim of this study is to evaluate the rate of discordance in HER2 phenotype between primary tumor and CTCs and to analyze whether primary tumor and/or patient characteristics can predict discordance in HER2-status.

Methods: The number of CTCs in 7.5 ml of peripheral blood (using the FDA-cleared CellSearch® System; Janssen Diagnostics, LLC) and their HER2 status were evaluated. Patients were defined as having a positive HER2-status on CTCs if at least 1 CTC with a strong (+++) immunocytochemical HER2 staining intensity was found. To assess which factors predict discordance of HER2 phenotype between primary tumor and CTCs, we used a multivariate binary logistic regression model with backward selection procedure. Patient and primary tumor characteristics included as independent factors were patient age, time since primary diagnosis, tumor stage, nodal stage, grading, histological type, and hormone receptor status (HRS).

Results: 1123 women with HER2-negative MBC were screened for CTCs. Based on a cutoff of ≥ 1 CTC, 711 (63.3%) of 1123 screened patients were positive for CTCs, while 412 (36.7%) of the 1123 screened patients were categorized as CTC positive if a cutoff of ≥ 5 CTCs was used.

At least one HER2-positive CTC was found in 134 of the 711 HER2-negative MBC patients with one or more CTCs (median 2 HER2-positive CTCs, range 1 – 80), indicating a discordance between primary tumor and CTCs with regard to HER2-status in 18.8% of patients. If the analysis was restricted to the 412 patients with 5 or more CTCs, at least one HER2-positive CTC was found in 121 patients, resulting in 29.4% discordance rate.

A multivariate logistic regression with discordance in HER2 phenotype (yes/no) as binary response variable, including number of CTCs (1 – 4 CTCs vs. 5 or more CTCs) to account for the difference in discordance rate observed at different cutoff values for CTC positivity, showed that histological type (lobular vs. ductal, odds ratio OR 2.66, 95% confidence interval CI 1.62 – 4.37, p &lt; 0.001), HRS (positive vs. negative, OR 2.89, 95% CI 1.16 – 7.19, p = 0.022) and CTC number (5 or more CTCs vs. 1 – 4 CTCs, OR 7.57, 95% CI 3.93 – 14.89, p &lt; 0.001) significantly predicted discordance in HER2 phenotype between primary tumor and CTCs.

Conclusion: Our data revealed discordance in HER2 status between primary tumor and CTCs in 19% to 29% of patients with HER2 negative MBC. Discordance in HER2 status was predicted by histological type and HRS of the primary tumor, as well as by the number of CTCs detected. Individualized breast cancer treatment based on CTC phenotype is currently investigated in Phase III trials and not part of clinical routine yet. However, the knowledge of factors associated with discordance in HER2 status may be incorporated in today's clinical practice by guiding the decision process for performing a biopsy to characterize a metastatic relapse.

Citation Format: Janni W, Schramm A, Friedl TWP, Schochter F, Huober J, Rack B, Alunni-Fabbroni M, Fasching PA, Taran F-A, Hartkopf A, Schneeweiss A, Müller V, Aktas B, Krawczyk N, Pantel K, Fehm T. Predictors for discordance in HER2 phenotype between primary tumor and circulating tumor cells in women with metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-02.

Abstract P2-08-08: Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis

Background: The European Pooled Analysis of CTC (EPAC) in metastatic breast cancer, based on 1,944 individual data from patients with various tumor types and clinical settings (Bidard et al, Lancet Oncol 2014), has established CTC count (CellSearch) at baseline and during therapy as a level of evidence 1 independent prognostic biomarker and demonstrated its superiority over serum blood markers. As part of the study pre-planned objectives, we sought to establish nomograms allowing accurate individual survival predictions.

Methods: Using individual data from 17 centers, we built simplified multivariate prognostic models taking into account the independent prognostic clinico-pathological (CP) characteristics including CTC count, dichotomized using the 5CTC/7.5ml threshold, at baseline and at 3-5 weeks after the start of a new treatment regimen, and derived nomograms for progression-free survival (PFS) and overall survival (OS) prediction at baseline and after 3-5 weeks of treatment. We report here the internal validation of these nomograms. Discrimination of the models was assessed using the c-index estimated by a jackknife procedure and the calibration was visually assessed through 10-fold crossvalidated calibration plots at 1,2,3 years for OS and 1,2 years for PFS.

Results: Multivariate models at baseline for PFS and OS were fitted on 1501 and 568 individual patient data with CTC count at baseline and CTC count at baseline and after 3-5 weeks, respectively. Models include tumor subtype, the number of previous chemotherapy lines (0/1/≥2), PS, age (&lt;=50/&gt;50-65/&gt;65 years), metastasis-free intervals (0/&gt;0-3/&gt;3 years), metastatic sites (liver and CNS) and CTC count at baseline and eventually at 3-5 weeks of treatment. The C-index increased from 0.722 to 0.755 (increase in C-index:0.033, 95% CI [0.019;0.045]) when adding baseline CTC to the CP only model for OS (n=1501). For those patients with CTC values at 3-5 weeks (n=568), there was an additional increase in the C-index when adding CTC at 3-5 weeks to a model with already CP and baseline CTC from 0.731 to 0.743 (increase in C-index 0.013, 95% CI [-0.004;0.025]). The model with CP and baseline CTC counts showed a good calibration for OS at 1,2,3 years and the model with CP, baseline CTC and CTC count at 3-5 weeks a moderately good calibration. Similar results were obtained for PFS.

Conclusion: From the largest database with individual CTC data, we were able to build PFS and OS survival nomograms, with satisfactory discrimination and calibration. Our planned next step is to validate the nomogram in an additional cohort.

Citation Format: Bidard F-C, Peeters D, Fehm T, Nole F, Gisbert-Criado R, Mavroudis D, Grisanti S, Generali D, Garcia-Saenz JA, Stebbing J, Caldas C, Gazzaniga P, Manso L, Zamarchi R, Fernandez de Lascoiti A, de Mattos-Arruda L, Ignatiadis M, van Laere SJ, Meier-Stiegen F, Sandri M-T, Vidal-Martinez J, Politaki E, Consoli F, Bottini A, Diaz-Rubio E, Krell J, Dawson S-J, Raimondi C, Rutten A, Janni W, Munzone E, Carañana V, Agelaki S, Almici C, Dirix L, Solomayer E, Zorzino L, Reis-Filho JS, Squifflet P, Pantel K, Beije N, Sleijfers S, Pierga J-Y, Michiels S. Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-08.

Abstract OT1-02-02: The DETECT study program – Personalized treatment in metastatic breast cancer based on circulating tumor cells

Circulating tumor cells (CTCs) are found in patients with primary and metastatic breast cancer (MBC), respectively, and discordance in HER2 and hormone-receptor status between primary tumor, metastases and CTCs is well described. Treatment decisions are still based on the expression profile of solid tumor samples whereas CTCs are thought to cause tumor progression by blood-derived metastases. Nevertheless, targeted therapy based on expression profile of CTCs is not established in clinical routine. Individualized treatment decisions based on presence and phenotype of CTCs will be analyzed within the DETECT study program.

Metastatic breast cancer patients with HER2-negative MBC are screened in DETECT III and IV for presence of CTCs by using the CellSearch System (Janssen Diagnostics) which is FDA approved for enumeration of CTCs. Patients are enrolled into the different cohorts according to HER2-phenotype of CTCs. Since February 2012, women with HER2-negative MBC and HER2-positive CTCs are treated in the multicenter randomized Phase III study DETECT III with standard therapy with or without additional HER2-targeted therapy with Lapatinib. For standard therapy, physicians can choose between exemestane, letrozole and anastrozole for endocrine therapy, or docetaxel, paclitaxel, capecitabine, vinorelbine and non-pegylated liposomal doxorubicin for chemotherapy. Efficacy of CTC-based anti-HER2 treatment is evaluated by analyzing CTC-clearance rate after treatment.

Patients with only HER2-negative CTCs are recruited for the multicenter open-label phase II study DETECT IV. Since December 2013, women with hormone-receptor positive MBC receive endocrine therapy (tamoxifen, exemestane, letrozole or anastrozole) plus everolimus in DETECT IVa. In February 2015, DETECT IV was extended by the eribulin-cohort which offers a cytotoxic treatment with eribulin for women with triple-negative or hormone-receptor positive, chemotherapy demanding MBC (DETECT IVb). Progression free survival is used for assessment of clinical efficacy with overall survival and disease control rate as secondary objectives.

DETECT V, a multicenter open-label phase III study starting in summer 2015, randomizes patients with hormone-receptor positive, HER2-positive MBC to a dual HER2 targeted therapy (Trastuzumab and Pertuzumab) combined with either endocrine therapy or cytotoxic treatment. Quality of life determined by occurrence of adverse events is compared between both treatment arms. For prediction of endocrine treatment response, an "Endocrine Responsiveness Score" is calculated based on expression of estrogen-receptor and HER2 on detected CTCs.

More than 1200 patients are already screened in the DETECT study concept. Thus, it is the worldwide largest study concept with therapy decisions resulting from CTC-testing and CTC-phenotypization. The accompanying translational research programs evaluates further markers for molecular characterization of CTCs and prediction of therapy response.

Conclusion and Contact

The value of CTC phenotypes for making decisions on therapy interventions and predicting treatment responses in patients with MBC is tested in the DETECT study concept. The findings will help to move a step forward towards a more personalized anti-cancer therapy.

Citation Format: Schramm A, Friedl TWP, Huober J, Jäger B, Rack B, Trapp E, Fasching PA, Taran F-A, Hartkopf A, Schneeweiss A, Müller V, Aktas B, Pantel K, Meier-Stiegen F, Wimberger P, Kümmel S, Gebauer G, Müller L, Janni W, Fehm T. The DETECT study program – Personalized treatment in metastatic breast cancer based on circulating tumor cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-02-02.

The biology of circulating tumor cells

Metastasis is a biologically complex process consisting of numerous stochastic events which may tremendously differ across various cancer types. Circulating tumor cells (CTCs) are cells that are shed from primary tumors and metastatic deposits into the blood stream. CTCs bear a tremendous potential to improve our understanding of steps involved in the metastatic cascade, starting from intravasation of tumor cells into the circulation until the formation of clinically detectable metastasis. These efforts were propelled by novel high-resolution approaches to dissect the genomes and transcriptomes of CTCs. Furthermore, capturing of viable CTCs has paved the way for innovative culturing technologies to study fundamental characteristics of CTCs such as invasiveness, their kinetics and responses to selection barriers, such as given therapies. Hence the study of CTCs is not only instrumental as a basic research tool, but also allows the serial monitoring of tumor genotypes and may therefore provide predictive and prognostic biomarkers for clinicians. Here, we review how CTCs have contributed to significant insights into the metastatic process and how they may be utilized in clinical practice.