Prognostic relevance of the HER2 status of circulating tumor cells in metastatic breast cancer patients screened for participation in the DETECT study program

BACKGROUND

Circulating tumor cells (CTCs) have been reported to predict clinical outcome in metastatic breast cancer (MBC). Biology of CTCs may differ from that of the primary tumor and HER2-positive CTCs are found in some patients with HER2-negative tumors.

PATIENTS AND METHODS

Patients with HER2-negative MBC were screened for participation in DETECT III and IV trials before the initiation of a new line of therapy. Blood samples were analyzed using CELLSEARCH. CTCs were labeled with an anti-HER2 antibody and classified according to staining intensity (negative, weak, moderate, or strong staining).

RESULTS

Screening blood samples were analyzed in 1933 patients with HER2-negative MBC. As many as 1217 out of the 1933 screened patients (63.0%) had ≥1 CTC per 7.5 ml blood; ≥5 CTCs were detected in 735 patients (38.0%; range 1-35 078 CTCs, median 8 CTCs). HER2 status of CTCs was assessed in 1159 CTC-positive patients; ≥1 CTC with strong HER2 staining was found in 174 (15.0%) patients. The proportion of CTCs with strong HER2 staining among all CTCs of an individual patient ranged between 0.06% and 100% (mean 15.8%). Patients with estrogen receptor (ER)- and progesterone receptor (PR)-positive tumors were more likely to harbor ≥1 CTC with strong HER2 staining. CTC status was significantly associated with overall survival (OS). Detection of ≥1 CTC with strong HER2 staining was associated with shorter OS [9.7 (7.1-12.3) versus 16.5 (14.9-18.1) months in patients with CTCs with negative-to-moderate HER2 staining only, P = 0.013]. In multivariate analysis, age, ER status, PR status, Eastern Cooperative Oncology Group performance status, therapy line, and CTC status independently predicted OS.

CONCLUSION

CTC detection in patients with HER2-negative disease is a strong prognostic factor. Presence of ≥1 CTC with strong HER2 staining was associated with shorter OS, supporting a biological role of HER2 expression on CTCs.

Abstract P3-01-04: DETECT V – Expression analysis of human epidermal growth factor receptor 2 and estrogen receptor on circulating tumor cells of metastatic breast cancer patients

Introduction: The prognostic relevance of Circulating Tumor Cells (CTCs) in patients with metastatic breast cancer (MBC) has been shown in multiple clinical trials. Beside their quantification it is of particular interest to analyze the predictive value of these cells and investigate if therapeutic decisions can be based on the phenotype of CTCs. The DETECT study concept evaluates this possible implication of CTCs. The DETECT V study compares endocrine therapy vs. chemotherapy, both combined with Trastuzumab and Pertuzumab in MBC patients with a HER2-positive (Human Epidermal Growth Factor Receptor 2), hormone receptor-positive tumor. Translational projects to identify potential predictive markers are associated to the study program. The expression of predictive markers HER2 and estrogen receptor (ER) on CTCs is analyzed to establish and validate an “Endocrine Responsiveness Score” (ERS). The ERS is aiming to estimate the potential benefit of endocrine therapy.

Methods: Quantification and characterization of CTCs was performed using Cell Search® CXC Kit. The staining protocol was validated using cell lines with known expression of ER and HER2. CTCs were quantified at randomization, after six weeks and at the end of treatment in two samples. Staining intensities of both markers were specified.

Results: Staining was successfully established. ER staining intensity was specified as negative or positive; HER2 staining intensity as negative, weak, moderate or strong. Detection and characterization of CTCs was analyzed for the first 30 patients. At time of randomization 17 of 26 samples were CTC positive with ≥1 CTC in one sample (HER2 and ER), 6/25 in both samples. After six weeks 8 of 26 patients contained ≥1 CTC in one sample and 5 of 26 in both samples. 11 of 15 CTC positive patients at time of randomization were CTC negative in the subsequent sample after six weeks. The cumulative frequency of ER- and HER2-positivity regarding CTCs detected in all samples was analyzed. 13% of all CTCs detected were ER positive (14/115). The percentage of HER2 3+ CTCs decreased from 27% at time of randomization (25/92) to 0% after six weeks (0/87). Analyzing the distribution of the expression of ER and HER2 in all CTCs of one sample, 10 of 19 samples containing ≥2 CTC showed heterogenic intensity of HER2-specific immunofluorescence. 8 of 14 samples containing ≥2 CTC showed heterogenic intensity of ER-specific immunofluorescence, respectively.

Conclusion: The implementation of “Endocrine Responsiveness Score” ERS aims to predict the potential benefit of endocrine therapy in patients with a HER2-positive, hormone receptor-positive tumor. Descriptive analysis of first patient samples has shown to detect heterogenic expression of HER2 and ER in CTCs of patients participating in the DETECT V study.

Citation Format: Fehm T, Meier-Stiegen F, Riethdorf S, Rack B, Taran F-A, Pantel K, Müller V, Janni W, Huober J. DETECT V – Expression analysis of human epidermal growth factor receptor 2 and estrogen receptor on circulating tumor cells of metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-04.

Abstract OT2-07-01: DETECT V/CHEVENDO – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in addition with CDK4/6 inhibition in patients with HER2-positive and hormone-receptor positive metastatic breast cancer

Background:

Metastatic breast cancer (MBC) is usually an incurable disease and maintenance of quality of life (QoL) is one of the main aims of therapy. In patients with HER2-positive MBC taxane-based chemotherapy in combination with dual HER2 targeted therapy with trastuzumab and pertuzumab,is the standard of care. Adverse events are well-known side effects of any cytostatic treatment and can seriously impact the patients' QoL. The synergistic combination of dual HER2-targeted therapy with trastuzumab and pertuzumab plus endocrine therapy might offer a better treatment option for these patients. First clinical trials suggest an additional benefit when a CDK4/6 inhibitor is added to the combination of endocrine therapy and anti HER2 treatment. DETECT V is a randomized phase III study comparing the safety and efficacy of trastuzumab plus pertuzumab and the CDK 4/6 inhibitor ribociclib in combination with either endocrine therapy or chemotherapy.

Trial design:

Patients with HER2 positive and hormone-receptor positive MBC are 1:1 randomized to receive trastuzumab and pertuzumab combined with endocrine therapy and ribociclib or to chemotherapy with trastuzumab and pertuzumab followed by maintenance therapy with trastuzumab, pertuzumab, endocrine therapy and ribociclib. Chemotherapy and the endocrine agents can be chosen from a variety of available regimens according to the physicians discretion.

Specific aims:

The primary objective of this study is to compare safety and tolerability in both arms, as assessed by the occurrence of AEs during the treatment period. Secondary endpoints are progression free survival, overall survival, quality-adjusted survival using the quality-adjusted time without symptoms and toxicity (Q-TWiST) method. A translational program is included investigating detection and phenotyping of circulating tumor cells (CTC)-and the assessment of marker expression on CTCs in order to validate an endocrine responsiveness score.

Present accrual and target accrual:

The DETECT V trial started 2015 in the Dept. of Gynecology, University of Ulm and at the up to 120 sites in Germany. Until June 2018 97 patients with HER2-positive, hormone-receptor positive metastatic breast cancer have been enrolled. A sample size of 270 patients is planned.

Contact information:

Jens Huober, University of Ulm, Dept of Gynecology, Breast Center, jens.huober@uniklinik-ulm.de

Sabrina Krause, University of Ulm, Dept of Gynecology, sabrina.krause@uniklinik-ulm.de

Citation Format: Krause S, Friedl T, Fehm T, Romashova T, Fasching PA, Schneeweiss A, Müller V, Taran F-A, Polasik A, Tzschaschel M, De Gregorio A, Meier-Stiegen F, Janni W, Huober J. DETECT V/CHEVENDO – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in addition with CDK4/6 inhibition in patients with HER2-positive and hormone-receptor positive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-07-01.

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

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

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

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

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

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

Abstract OT1-03-05: The DETECT V-Study – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in addition with CDK4/6 inhibition in patients with HER2-positive and hormone-receptor positive metastatic breast cancer

Background:Metastatic breast cancer (MBC) is usually an incurable disease and maintenance of quality of life (QoL) is one of the main aims of therapy. In patients with HER2-positive MBC taxane-based chemotherapy in combination with dual HER2 targeted therapy with trastuzumab and pertuzumab, has shown significantly increased progression free survival and overall survival. Adverse events are well-known side effects of any cytostatic treatment and can seriously impact the patients' QoL.

The synergistic combination of dual HER2-targeted therapy with trastuzumab and pertuzumab plus endocrine therapy might offer a better treatment option for these patients. Preclinical data and first clinical trial results suggest an additional benefit when a CDK4/6 inhibitor is added to the combination of endocrine therapy and anti HER2 treatment. DETECT V is a randomized phase III study comparing the safety and efficacy of trastuzumab plus pertuzumab in combination with either endocrine therapy or chemotherapy. In both treatment arms the CDK4/6 inhibitor ribociclib will be added.

Trial design and eligibility criteria: Patients are 1:1 randomized to receive dual HER2-targeted therapy with trastuzumab and pertuzumab combined with endocrine therapy and ribociclib or to chemotherapy with trastuzumab and pertuzumab followed by maintenance therapy with trastuzumab, pertuzumab, endocrine therapy and ribociclib when chemotherapy has stopped.

The sample size calculations are based on the assumption that the probability of having an adverse event as defined by the modified adverse event score for patients with HER2 positive metastatic breast cancer in the chemotherapy arm is 86.3%. Based on this assumption, a minimum of 121 patients per treatment arm is required to detect a 25% decreased risk of having an adverse event as defined by the modified adverse event score (i.e. a relative risk ratio of 0.75) for patients treated with dual HER2-targeted plus endocrine therapy and ribociclib as compared to patients treated with dual HER2-targeted plus chemotherapy with the combination of endocrine therapy and ribociclib as maintenance treatment (90% power, two-sided test, α = 0.05).

Specific aims: The primary objective of this study is to assess the tolerability of both treatment strategies, as assessed by the occurrence of AEs during the treatment period. Modified adverse event score was developed 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.

The DETECT V trial comes along with a comprehensive translational program focusing on detection and phenotyping of circulating tumor cell (CTC)-and the assessment of marker expression on CTCs in order to calculate an endocrine responsiveness score.

Citation Format: Romashova T, Polasik A, Friedl TWP, Rack B, Tzschaschel M, Fasching PA, Taran F-A, Hartkopf A, Schneeweiss A, Mueller V, Bahriye A, Pantel K, Meier-Stiegen F, Wimberger P, Janni W, Fehm T, Huober J. The DETECT V-Study – Comparison of dual HER2-targeted therapy with trastuzumab plus pertuzumab in combination with chemo- or endocrine therapy in addition with CDK4/6 inhibition in patients with HER2-positive and hormone-receptor positive metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-03-05.

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 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 P1-01-15: DETECT V - Detection of the expression of estrogen receptor and human epidermal growth factor receptor 2 on circulating tumor cells from metastatic breast cancer patients

Background: The prognostic relevance of circulating tumor cells (CTCs) in metastatic breast cancer (MBC) has constantly been shown in several clinical studies. Nevertheless, the predictive value of CTCs still remains unclear. The DETECT study concept evaluates the impact of CTCs on therapeutic decisions. Patients with hormone-receptor positive, HER2-positive MBC participating in DETECT V are randomized to a dual HER2 targeted therapy (Trastuzumab and Pertuzumab) combined with either endocrine therapy or chemotherapy. Based on the expression of Estrogen Receptor (ER) and Human Epidermal Growth Factor Receptor 2 (HER2) on detected CTCs, an “Endocrine Responsiveness Score (ERS)” is calculated for prediction of endocrine treatment response. Aim of this project was the optimization of staining procedures using immunofluorescence.

Methods: CTCs are enumerated and characterized using CELLSEARCH® CXC Kit which is based on the immunomagnetic enrichment of EPCAM-positive cells and immunofluorescent characterization of these cells. Comparison of staining intensities in different cell lines with known expression of ER and HER2 was used to validate the staining protocol. To validate ER-staining, staining intensities of the following cell lines were compared: SKBR-3 (negative control), MCF-7 (positive control) and T47D (intermediate expression). HER2-staining was validated comparing staining intensities of SKBR3 (positive control), MDA-MB 453 (intermediate expression) as well as MCF-7 (negative control).

Results: Staining intensities were divided into the following categories: negative, weak, moderate and strong. Signal intensities using CELLSEARCH® system correlated with the known expression of HER2 and ER in the different cell lines. No expression of ER could be shown in SKBR3 cells, T47D cells showed weak expression of ER. MCF-7 cells showed moderate to strong expression of ER but no expression of HER2. MDA-MB 453 and SKBR3 showed moderate to strong and strong expression of HER2, respectively. Expression of HER2 and ER could be depicted accurately using CELLSEARCH® CXC Kit. Results were validated in a ring test in all participating laboratories. First patient samples are currently analyzed.

Conclusion: Establishment and validation of the ERS by characterizing CTCs within the framework of the DETECT V study pursues the objective of assessing the potential benefit of endocrine therapy. Validation results and first patient results will be shown.

Citation Format: Fehm T, Meier-Stiegen F, Riethdorf S, Schramm A, Polasik A, Niederacher D, Rack B, Taran F-A, Müller V, Janni W, Huober J. DETECT V - Detection of the expression of estrogen receptor and human epidermal growth factor receptor 2 on circulating tumor cells from metastatic breast cancer patients [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 P1-01-15.

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 (<=50/>50-65/>65 years), metastasis-free intervals (0/>0-3/>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.

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

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

Abstract PD6-5: Pooled analysis of circulating tumor cells in metastatic breast cancer: Findings from 1944 individual patients data

Background: Clinical validity of CTCs (CellSearch®) in metastatic breast cancer (MBC) patients has previously been assessed in studies with limited statistical power. We aimed to pool all European studies to obtain high-level evidence on the prognostic value of CTCs, to investigate their effects across different clinico-pathological characteristics and therapies and to further validate the MD Anderson/Institut Curie/Fox Chase CTC-based prognostic nomogram established in first-line treated MBC patients (Giordano et al, Clin Cancer Res 2013).

Material and methods: Methods were predefined in a written protocol. In December 2012, we searched for eligible studies that accrued patients in 2003-2012. We contacted all European laboratories using CellSearch®. We used likelihood ratio tests (LR) in Cox regression models stratified by study to assess the independent prognostic value of CTC when added to a clinicopathological (CP) model for progression-free (PFS) and overall survival (OS). Landmark analyses were used to assess the prognostic effect of early changes in CTC. The CTC-based nomogram (http://cancernomograms.com/CTCOnline.html) score was retrieved for every patient; we calculated C-indices, drew calibration plots and Kaplan-Meier curves according to quintiles of the nomogram score.

Results: We collected individual data of 1944 MBC patients, from 20 different studies (some unpublished), from 17 centers in 7 European countries. We observed 1507 PFS events and 929 deaths. Baseline CTC count was significantly associated with several patient characteristics, such as performance status (PS, p<10-4), synchronous metastasis (p<10- 2) tumor subtype (p<10-4), liver & bone metastases (p<10-4), CEA & CA15-3 levels (p<10-4). The CP model for OS included PS, MBC subtypes, number of previous lines of treatment, patient's age, metastasis-free interval, metastatic sites (p<0.01 for all). In a multivariate analysis containing the CP model parameters and CTC count at baseline, elevated CTC count (≥5) was a significant independent predictor of OS (n = 1444, HR = 2.7, 95%CI [2.2-3.2], LR p<10-4). Baseline serum markers added either no or marginal effect to the CP plus baseline CTC model for OS. In contrast, early changes in CTC status at week 3-5 significantly added prognostic information for OS to the model with CP factors and baseline CTC+ (n = 569, HR = 1.8 [2.2-3.2], LR p<0.001). In the population of interest (MBC treated by first line chemotherapy, n = 402 patients, 176 deaths), the CTC-based nomogram exhibited a good C-index for OS (0.69), was well calibrated and showed clear separation of the survival curves. Additional results, including subgroup analyses by tumor subtype and treatments will be presented at the meeting.

Conclusions: This pooled analysis is the largest study ever reported on CTC in MBC, with a previously unreached statistical power. It provides a clear level-of-evidence 1 on the independent prognostic value of CTCs before and during treatment in MBC. Also, the CTC-based prognostic nomogram is independently validated.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-5.

[Prospective observational studies of the development of type 1 diabetes during childhood and puberty]

The incidence of type 1 diabetes is increasing rapidly. Detecting the mechanisms underlying the autoimmune disease is a main goal of research. Studies investigating the pathogenesis of type 1 diabetes are working on the identification and characterization of exogenous, endogenous and genetic factors which induce or modify autoimmunity. Islet cell autoimmunity can be detected through screening for islet cell autoantibodies. This quantitative analysis allows the stratification of the individual risk for the development of type 1 diabetes. Prospective observational studies are most suitable to assess persons at risk, either because of the occurrence of type 1 diabetes in the family or because of a genotype associated with increased risk. Age-related factors which are analysed in observational studies include nutrition, increase in height and weight, childhood diseases and vaccinations as well as psychosocial aspects. Identification and characterization of these risk factors will serve as a basis for working on new approaches to prevent or to cure type 1 diabetes. Aim of this article is to provide an overview of the most relevant observational studies.