Serum HER2 Extracellular Domain Research Articles

Abstract PO4-14-06: Impact of Serum HER2 Extracellular Domain in Metastatic Breast Cancer Patients Treated with Trastuzumab Deruxtecan (T-DXd)

Abstract Background: Trastuzumab deruxtecan (T-DXd) is a standard of care as 2nd line and after prior chemotherapy for HER2 positive and low metastatic breast cancer (MBC), respectively, based on Destiny Breast03 and 04 results. However, biopsies over time during treatment have shown that HER2 expression is variable. The predictive factors of trastuzumab deruxtecan (T-DXd) for MBC with HER2 positive and low are unclear. The HER2 extracellular domain (HER2-ECD) has been confirmed as a prognosis marker and predictive marker of treatment for HER2-positive MBC. Especially, HER2-ECD is considered a promising biomarker in cases where HER2 expression in metastases is unconfirmed. We hypothesized that HER2-ECD could serve as a biomarker for T-DXd. Patients and methods: A retrospective study of consecutively treated patients in a single center between 2019-2023 with HER2-low and HER2-positive MBC was performed using chart review. HER2 status was diagnosed according to 2020 ASCO-CAP guidelines. HER2-ECD high was defined as >15.0 ng/ml. HER2-ECD was collected prior to T-DXd treatment. We compared overall response (ORR), progression-free survival (OFS), overall survival (OS), and disease control rate (DCR) at HER2-ECD high and low groups. Cox regression analyses were performed to assess the ORR. We used the Kaplan-Meier method to estimate the PFS and OS and the log-rank test to compare each treatment group. Results: A total of 41 MBC patients were included in this study. Patients with HER-positive and HER2-low were 34 and 7, respectively. Among HER2 positive (n=34), HER2-ECD high and low are 14 (41%) and 20 (59%) patients, respectively. Among HER2 low (n=7), HER2-ECD high and low are 3 (43%) and 4 (57%) patients, respectively. Twenty-six patients received T-DM1 prior to T-DXd treatment for MBC with HER2 positive, but no patients received CPT-11 before T-DXd for MBC with HER2 positive and low. The ORR of T-DXd was 89% and 52% in the HER2-ECD high and low groups, respectively (p< 0.001). All 6 cases with CR were HER2-ECD high. Among HER2 low group (n=7), ORR of T-DXd was 67% (2/3) and 25% (1/4) in HER2-ECD high and low groups, respectively. The median PFS in the HER2-ECD high group showed longer than the HER2-ECD low group, 21.8 vs. 8.0 months (HR 0.31; 95%CI, 0.13-0.78, p=0.012). Although there were no significant differences in OS, HER2 ECD high group tended to show longer OS (HR 0.23; 95%CI, 0.04-1.16, p=0.07). The DCR was 100% in the HER2 ECD high group and 87% in the low group. Conclusion: T-DXd showed significantly better response and prolonged PFS in the group with high HER2-ECD. HER2-ECD has the potential to become a biomarker for T-DXd. Further study is warranted to assess the HER2-ECD as a biomarker, especially for HER2 low MBC patients treated with T-DXd. Table. Association between the response and the HER2 status or HER2-ECD status Citation Format: Kazuki Nozawa, Maho Kusudo, Nari Kureyama, Akira Nakakami, Rie Komaki, Yuka Endo, Ayumi Kataoka, Haruru Kotani, Akiyo Yoshimura, Masaya Hattori, Masataka Sawaki, Hiroji Iwata. Impact of Serum HER2 Extracellular Domain in Metastatic Breast Cancer Patients Treated with Trastuzumab Deruxtecan (T-DXd) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-14-06.

Exploratory analysis of serum HER2 extracellular domain for HER2 positive gastric cancer treated with SOX plus trastuzumab.

The aim of this study was to explore the clinical utility of serum HER2 extracellular domain (sHER2 ECD) using data from a clinical trial evaluating trastuzumab combined S-1 plus oxaliplatin (SOX) in HER2 positive gastric cancer. sHER2 ECD were prospectively measured at baseline and subsequent treatment courses. Based on each quantile point of baseline sHER2 ECD levels and its early changes, patients were divided into two groups and compared clinical outcomes. 43 patients were enrolled, and 17 patients (39.5%) were positive for baseline sHER2 ECD. Higher baseline sHER2 ECD levels tended to have lower hazard ratios (HRs). When divided into two groups by baseline sHER2 ECD of 19.1ng/ml, median progression-free survival (PFS) and overall survival (OS) was longer in the higher group (mPFS: 16.8 vs 8.7months, p = 0.359. mOS: 35.5 vs 20.6months, p = 0.270), respectively. After initiation of treatment, sHER2 ECD significantly decreased up until the third cycle. Higher reduction rates of sHER2 ECD within 3 cycles also tended to have lower HRs. When divided into two groups by reduction rate of 42.5%, mPFS and mOS was longer in the higher reduced group (mPFS: 17.2 vs 8.7months, p = 0.095. mOS: 65.0 vs 17.8months, p = 0.047), respectively. Furthermore, higher reduction rates could surrogate higher objective response rates (ORR) (ORR: 90% vs 63.2% for 29.5%, p = 0.065. 100% vs 70% for 42.5%, p = 0.085), respectively. Baseline sHER2 ECD levels and its early decline may be useful biomarkers for SOX plus trastuzumab efficacy in HER2 positive gastric cancer.

Prognostic Value of the Serum HER2 Extracellular Domain Level in Breast Cancer: A Systematic Review and Meta-Analysis.

Simple SummaryWe performed a systematic review and meta-analysis evaluating the predictive value of the serum HER2 extracellular domain (sHER2 ECD) for breast cancer prognosis. Our review investigated 40 studies (12,229 patients) that assessed the impact of the sHER2 ECD levels on breast cancer prognosis and explored the clinical significance of sHER2 ECD levels in different treatment modalities. Our findings indicated that an elevated sHER2 was an unfavorable prognostic factor in breast cancer. More interestingly, sHER2 ECD was found to be a promising biomarker for predicting adverse clinical outcomes of trastuzumab-based treatment but did not affect the efficacy of tyrosine kinase inhibitors. In addition, the baseline cutoff value of sHER2 ECD in different treatment stages of breast cancer remains to be further explored. Overall, our study suggested that sHER2 ECD levels have important prognostic value in breast cancer and may be helpful for clinicians to select the appropriate anti-HER2 therapy for HER2-positive breast cancer, providing more evidence for guiding clinical practice.An elevated serum HER2 extracellular domain is associated with poor prognosis in breast cancer, but the relationship between sHER2 and the efficacy of different modalities remains controversial. Herein, we aimed to evaluate the prognostic value of serum HER2 extracellular domain (sHER2 ECD) in breast cancer and to identify its correlation with the efficacy of different treatment regimens. A systematic search of the PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases was conducted to identify studies exploring the association between HER2 ECD level and clinical outcomes among patients with breast cancer. Using the random effects models, pooled hazard ratios (HRs), and odds ratios (ORs) with 95% confidence intervals (CI), were calculated for progression-free survival (PFS), overall survival (OS), disease-free survival (DFS), and the objective response rate (ORR). Heterogeneity was further evaluated by subgroup and sensitivity analysis. Overall, 40 studies comprising 12,229 patients were included in this systematic review and meta-analysis. Elevated HER2 ECD levels were associated with worse PFS (HR 1.74, 95% CI 1.40–2.17; p < 0.001), and this effect was observed in patients treated with chemotherapy (HR 1.81, 95% CI 1.37–2.39; p < 0.001), endocrine therapy (HR 1.91, 95% CI 1.57–2.32; p < 0.001), and trastuzumab (HR 1.74, 95% CI 1.31–2.30; p < 0.001). However, this association was not present in patients treated with tyrosine kinase inhibitors (TKIs) (HR 1.44, 95% CI 0.85–2.43, p = 0.17). The HRs/ORs for an elevated HER2 ECD level for DFS, OS, and ORR were 2.73 (95% CI 2.17–3.42; p < 0.001), 2.13 (95% CI 1.77–2.57; p < 0.001), and 0.80 (95% CI 0.49–1.31; p = 0.381), respectively. An elevated sHER2 ECD was an unfavorable prognostic factor in breast cancer but did not affect the efficacy of tyrosine kinase inhibitors such as lapatinib. Detection of sHER2 ECD may be helpful for clinicians selecting the appropriate anti-HER2 therapy for patients with HER2-positive breast cancer.

Abstract OT1-02-02: A global, phase 2 study of ARX788 in patients with HER2-positive metastatic breast cancer whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens

Abstract Background: The HER2 receptor is a cancer driver which is overexpressed on 15-20% of breast cancers. Though historically survival is poor with this disease subtype, HER2+ targeted therapy has improved survival in both early and advanced disease. In spite of this, most patients in the metastatic setting will eventually experience disease progression and death. Therefore, new therapeutic options and innovative treatments are needed for patients with recurrent or refractory disease. ARX788 is a next-generation antibody–drug conjugates (ADC) using a technology platform whereby a HER2 specific monoclonal antibody is conjugated with Amberstatin269, a potent cytotoxic tubulin inhibitor. Site-specific, high homogenous, and stable covalent conjugation in ARX788 leads to slow release and prolonged peak of serum pAF-AS269, which may contribute to the lower systemic toxicity, increased targeted delivery of payload to tumor cells, and lower effective dose compared to other HER2 ADCs.Methods: ACE-Breast-03 (NCT04829604) is a global, single arm, phase 2 study designed to assess anticancer activity and safety of ARX788 in patients with metastatic HER2 positive breast cancer. Patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens are eligible. Patients must have adequate organ function and any brain metastasis must demonstrate radiographic stability and lack of steroid dependence. Approximately 200 subjects with advanced HER2-positive breast cancer will be enrolled. ARX788 will be administered as an intravenous (IV) infusion at 1.5 mg/kg as the initial dose on Day 1 of the first 4-week cycle and followed by 1.3 mg/kg at every subsequent 4-week cycle. Efficacy will be assessed using Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1 via imaging every 8 weeks (±7 days) on study and endpoints include objective response rate (ORR), duration of response (DOR), time to response (TTR), best overall response (BOR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The safety and tolerability profile will be assessed. Blood samples will be collected at specified time points to determine serum concentrations of ARX788 (intact ADC), total antibody, and metabolite pAF-AS269. Biomarkers (e.g., cell-free DNA, serum HER2 extracellular domain, and circulating tumor cells) at baseline and on-treatment will be analyzed for exploratory research. Descriptive statistics will be used to evaluate anticancer activity, safety, and tolerability. The study is currently recruiting patients. Please contact breast03trialinquiry@ambrx.com for additional information. Citation Format: Janice Lu, Kevin M Kalinsky, Debu Tripathy, George W Sledge, William Gradishar, Ruth O’Regan, Joyce O’Shaughnessy, Shanu Modi, Joshua Drago, Haeseong Park, Amelia McCartney, Sophia Frentzas, Catherine Shannon, Katharine Cuff, Richard Eek, Miguel Idzwan Martin, Giuseppe Curigliano, Guy Jerusalem, Chiun-Sheng Huang, Michael Press, Matt Li, Dong Xu, Cynthia Song, Richard Huhn, Jinchun Yan, Sara Hurvitz. A global, phase 2 study of ARX788 in patients with HER2-positive metastatic breast cancer whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-02-02.

Clinical Relevance of Tissue and Serum Human Epidermal Growth Factor Receptor 2 Expression in Patients With Esophageal Squamous Cell Carcinoma

Serum and tissue human epidermal growth factor receptor 2 (HER2) levels were evaluated in resected esophageal squamous cell carcinoma (SCC) specimens to assess the relationship between HER2 expression and long-term prognosis. We included 95 patients who underwent esophagectomy for esophageal SCC. The serum HER2-extracellular domain (sHER2-ECD) levels were measured using an ELISA kit. A time-dependent receiver operating characteristics curve for censored survival outcomes was constructed to estimate the optimal cut-off value of sHER2-ECD (set at 4211 pg/mL). Immunohistochemical (IHC) staining was performed for HER2, and specimens were classified based on low (0 or 1+) or high HER2-IHC expression (2+ or 3+). Patients with low sHER2-ECD levels showed poorly differentiated tumors, nodal involvement, and larger tumor size more frequently compared to patients with high sHER2-ECD levels. There were no differences in clinicopathological features based on HER2-IHC expression. Between patients with high and low HER2-IHC expression, the former group showed significantly higher sHER2-ECD levels. Patients with high sHER2-ECD levels had significantly favorable relapse-free survival (RFS) and overall survival (OS) compared to those with low sHER2-ECD levels. Conversely, patients with high HER2-IHC expression had significantly poorer RFS than did patients with low HER2-IHC expression, although no difference was observed in OS. Additionally, patients with high sHER2-ECD levels and low HER2-IHC expression had the highest OS and RFS among the patients studied. The correlation among sHER2-ECD levels, HER2-IHC expression, and prognosis was demonstrated. Prospective studies are required to validate the impact of serum and tissue HER2 expression in esophageal SCC prognosis.

386O Exploratory biomarker analysis of DESTINY-CRC01, a phase II, multicenter, open-label study of trastuzumab deruxtecan (T-DXd, DS-8201) in patients (pts) with HER2-expressing metastatic colorectal cancer (mCRC)

T-DXd is an antibody–drug conjugate consisting of an anti-HER2 antibody, a cleavable linker, and a topoisomerase I inhibitor. In primary analyses of DESTINY-CRC01 (NCT03384940), T-DXd showed antitumor activity and a manageable safety profile in HER2+ mCRC pts (Siena ASCO 2020). We present exploratory biomarker data and its relation to response in HER2+ mCRC. Pts with centrally confirmed HER2-expressing, RAS wildtype mCRC that progressed after ≥2 prior regimens received 6.4 mg/kg of T-DXd Q3W in 3 cohorts (A: HER2+, IHC3+, or IHC2+/ISH+, n = 53; B: IHC2+/ISH−, n = 15; C: IHC1+, n = 18). Circulating tumor DNA (ctDNA) samples at baseline (BL), cycle 4, day 1, and end of treatment, along with BL serum HER2 extracellular domain (HER2ECD) were analyzed as exploratory biomarkers. To correct for variation in plasma tumor fraction between samples, adjusted plasma ERBB2 copy number (ApCN) was calculated based on the maximum variant allele fraction (Siravegna CCR 2019). Exploratory cutoff values for ApCN in ctDNA and HER2ECD were defined as those with the maximum value of the Youden index for ORR. In cohort A, higher clinical response to T-DXd was observed with higher tumor or plasma HER2 expression (Table). Antitumor activity of T-DXd was seen in pts with or without ctDNA-detected activating RAS or PIK3CA mutations and was lower in pts with blood TMB high vs low (Table). In paired ctDNA samples collected at BL and disease progression from 30 pts, acquired alterations were observed in several genes, but none was common across pts (n = 12).Table: 386OORR by BL Biomarker GroupBiomarker GroupN = 53ORR, % (95% CI)Tumor HER2 ExpressionHER2+5345.3 (31.6-59.6)IHC3+4057.5 (40.9-73.0)IHC2+/ISH+137.7 (0.2-36.0)Blood biomarkersERBB2 ApCN≥30.92462.5 (40.6-81.2)<30.9 or not detected2832.1 (15.9-52.4)ERBB2 plasma amplificationFocal3655.6 (38.1-72.1)Aneuploidy or not detected1625.0 (7.3-52.4)HER2ECD≥23.5 ng/mL2263.6 (40.7-82.8)<23.5 ng/mL2729.6 (13.8-50.2)NRAS/KRAS mutationActivating633.3a (4.3-77.7)WT or other4647.8 (32.9-63.1)PIK3CA mutationActivating633.3 (4.3-77.7)WT or other4647.8 (32.9-63.1)TMBHigh (≥20 mut/Mb)1323.1 (5.0-53.8)Low (<20 mut/Mb)3953.8 (37.2-69.9)aResponders had KRAS mutations. Open table in a new tab aResponders had KRAS mutations. This exploratory analysis of biomarker data in HER2+ mCRC pts administered T-DXd indicates that antitumor activity appears to be correlated with BL HER2 expression or amplification in tumor and liquid biopsy. Further investigations into potential mechanisms of resistance to and patient selection for T-DXd in HER2+ mCRC are warranted.

Shed HER2 surrogacy evaluation in primary breast cancer patients: a study assessing tumor tissue HER2 expression at both extracellular and intracellular levels

The aim of the present study was to investigate serum HER2 extracellular domain (ECD) as a putative surrogate marker of the shedding phenomenon of HER2 receptor from the tumor tissue of primary breast cancer (BC) patients. A pilot retrospective study was conducted on 100 matched serum and tissue samples from patients with node-positive primary BC, stage II/III. Analysis of association and concordance between serum HER2 ECD levels (measured by chemiluminescence immunoassay) and the expression in matched tumor tissue of HER2 ECD and intracellular receptor domain (ICD) (determined by immunohistochemistry) were performed. The median serum HER2 ECD level was 9.4 ng/ml and cutoff values were set at 15.2 ng/ml or 13.0 ng/ml. HER2 ICD and ECD were overexpressed in tumor tissue of 19.8% and 6.9% of patients, respectively. Statistically significant associations were found between serum HER2 ECD levels and tissue expression of both HER2 ICD and ECD (p < .001; Fisher analysis). Moreover, strong concordances were found between serum HER2 ECD levels and tissue expression of HER2 ICD or ECD (cutoff 15.2 ng/ml: 80 and 92.5%, respectively). Our findings support a role for serum HER2 ECD as a surrogate marker of tissue HER2 status in primary BC, both for HER2 ICD or ECD expression.

Portable detection of serum HER-2 in breast cancer by a pressure-based platform.

A high serum HER-2 extracellular domain (sHER-2 ECD) level has a reverse association with tumor behaviors. In this study, a portable platform for the disease biomarker sHER-2 ECD detection has been established using a pressure-based bioassay. The pressure bioassay consists of a monoclonal antibody immobilized on an eight-well strip, the analyte HER-2, and another monoclonal antibody labeled with the Pt nanoparticles (PtNPs), which have the catalytic ability to decompose H2O2 into H2O and O2(g). The increased pressure due to O2(g) generation is measured by a hand-held pressure meter. A total of 34 serum samples were collected to validate the performance of the pressure bioassay. The results showed that the pressure bioassay platform of HER-2 had a dynamic range from 2 to 50ng/mL with a limit of detection (LOD) of 2ng/mL, which was consistent with the ELISA result. In the real serum samples, there was a significant correlation between sHER-2 ECD level and several clinicopathological parameters, especially tissue HER-2 status. Furthermore, the sHER-2 ECD level was found to decrease after targeted therapy in a patient with tHER-2 positive. Overall, this bioassay can facilitate breast cancer diagnosis and prognosis in clinical scenarios and resource-limited areas.

Aptamer based fluorescent probe for serum HER2-ECD detection: The clinical utility in breast cancer

The transmembrane protein HER2 is overexpressed in approximately 30% of breast cancer patients. HER2-positive breast cancers tend to spread more aggressively, which result in increased mortality in women. Nowadays, the real-time monitoring of HER2 status is important in clinical diagnosis and treatment for HER2-positive patients. Although IHC and FISH assay are standard methods to evaluate the tissue HER2 status, both approaches which required high quality tissue samples and are not suitable for monitoring the status of HER2 in real time. Since extracellular domain (ECD) of the HER2 receptor can be shed into the circulation, the serum test of HER2 ECD has been developed as an additional approach to probe HER2 overexpression. The serum test will be able to monitor the dynamic changes of HER2 status. In this paper, we detected serum HER2 ECD using Cy5-labeled HB5 aptamer as a result of its specific binding ability to HER2 ECD. This aptamer-based fluorescent probe is easily synthesized and modified and as sensitive as anti-HER2 antibodies. We believe that Cy5-HB5 may have application potentials in serum HER2 test for clinical utility of breast cancer, such as recurrence and metastases.

Serum HER-2 extracellular domain for breast cancer patients

Serum HER-2 extracellular domain for breast cancer patients

Biomarker analysis of the NeoSphere study: pertuzumab, trastuzumab, and docetaxel versus trastuzumab plus docetaxel, pertuzumab plus trastuzumab, or pertuzumab plus docetaxel for the neoadjuvant treatment of HER2-positive breast cancer

BackgroundNeoSphere showed significantly higher pathologic complete response (pCR) with neoadjuvant pertuzumab, trastuzumab, and docetaxel compared with trastuzumab plus docetaxel, pertuzumab plus trastuzumab, or pertuzumab plus docetaxel. We assessed associations between human epidermal growth factor receptor 2 (HER2) pathway-related biomarkers and clinical outcome in response to these regimens.MethodsTumor, serum, and whole blood samples were collected at baseline and post neoadjuvant treatment before surgery. Associations between biomarkers and pCR, and between biomarkers and clinical variables were assessed in the overall and estrogen receptor (ER)-positive and ER-negative populations. Changes in serum marker levels between baseline and post-neoadjuvant treatment were examined.ResultsNo markers were associated with pCR across all groups; however, significant associations were observed for two markers in individual groups. High HER2 was significantly associated with higher pCR rates (P = 0.001) and a significant treatment interaction (P = 0.0236) with pertuzumab, trastuzumab, and docetaxel (odds ratio 2.07, P = 0.01). Low serum transforming growth factor alpha (TGFα) was associated with higher pCR rates with pertuzumab plus trastuzumab (P = 0.04) without a significant treatment interaction. Presence of truncated HER2 did not affect pCR. A non-significant decreased pCR benefit was observed consistently across groups in patients with mutated PIK3CA while the treatment benefit from pertuzumab was maintained when comparing the trastuzumab plus docetaxel and pertuzumab, trastuzumab, and docetaxel groups. Notably, PIK3CA exon 9 mutations were associated with residual disease (pooled groups), which was not found for exon 20 mutations. Serum HER2 extracellular domain levels were significantly increased between baseline and post-neoadjuvant treatment in the non-trastuzumab-treated group, and decreased in the trastuzumab-containing groups (likely due to trastuzumab’s mechanism of action). Differences in biomarker profiles according to ER status were observed.ConclusionsThe observed associations of HER2 protein levels with sensitivity to pertuzumab, and of PIK3CA exon 9 mutation to lack of sensitivity to HER2-targeted monoclonal antibody treatment, warrant further investigation. Previously reported findings of truncated forms of HER2 as resistance markers to HER2-targeted treatment could not be confirmed in NeoSphere. Conventional HER2 assessment should continue and HER2 remains the only biomarker suitable for patient selection in this population.Trial registrationClinicaltrials.gov, NCT00545688. Registered on 16 October 2007.

Serum HER2 as a predictive biomarker for tissue HER2 status and prognosis in patients with gastric cancer.

AIMTo investigate the association between serum human epidermal growth factor receptor 2 (HER2) extracellular domain (ECD) and tissue HER2 status, and the prognostic value of serum HER2 ECD in patients with gastric cancer.METHODSA total of 239 patients with gastric cancer were enrolled from December 2012 to June 2013. Serum HER2 ECD was determined by chemiluminescent assay, and tissue HER2 status was evaluated by immunohistochemistry and fluorescence in situ hybridization assay. A receiver operating characteristic (ROC) curve was plotted to identify the optimal cut-off value for serum HER2 ECD assay for predicting survival in gastric cancer patients.RESULTSSerum HER2 ECD was significantly correlated with tissue HER2 status (P < 0.001), tumor size (P < 0.001), and intestinal type of gastric cancer (P = 0.021). Serum HER2 ECD levels differed significantly between patients with HER2-positive tissue expression and those with HER2-negative tissue expression. ROC analysis yielded an area under the curve value of 0.79 (95%CI: 0.71-0.87, P < 0.001), with a sensitivity and specificity of 0.54 (95%CI: 0.37-0.70) and 0.93 (95%CI: 0.88-0.96), respectively. With a cut-off value of 24.75 ng/mL, high serum HER2 ECD had a negative impact on overall survival of the patients (HR: 1.93, 95%CI: 1.32-4.38, P = 0.006).CONCLUSIONSerum HER2 ECD could be a highly specific surrogate biomarker for tissue HER2 status in gastric cancer. Optimal cut-off criteria for predicting survival should be established.

O3-7-4 - Analysis of biomarkers in a pilot study of pertuzumab, trastuzumab and eribulin for advanced HER2 positive breast cancer

Introduction: We reported the efficacy, safety and QOL of the pilot study of pertuzumab, trastuzumab and eribulin (PTE) for advanced HER2 positive breast cancer (UMIN000012018) at the San Antonio Breast Cancer Symposium in 2015. We analyzed patient's samples to explore prognostic and predictive factors. Materials and Methods: Tumor samples from the primary or metastatic lesions and serum samples before the first dose of the drug and 3 months after were collected. Of the 10 enrolled patients, 8 tumor samples and 8 serum samples were available. We investigated PIK3CA mutations (E542K, E545K, H1047R) and MAGE antigen, one of the Cancer-Testis antigens, expression of tumor tissue, serum trastuzumab concentration and serum HER2 extracellular domain (sHER) value. Serum trastuzumab concentration was measured by sandwich ELISA. MCV-1, an antibody for MAGE-A2, A4 or A12 antigen (Clin Cancer Res. 2015; 21: 2268-77), was used for immunohistological staining. Results: Serum trastuzumab concentration at 3 months had a strong negative correlation with sHER2 before the first dose, but not with time to progression (TTP). Tumor samples from 3 patients with >10 months TTP had MAGE antigen expression, but others did not. Maximum response of 4 cases with PIK3CA mutation was SD, but 1 had more than 2 years TTP. Discussion: PTE therapy seems to be effective for HER2 positive breast cancer, both PIK3CA wild and mutation. Expression of the MAGE antigen may be a prognostic factor. Further studies are required to confirm this.

A prospective study to assess the clinical utility of serum HER2 extracellular domain in breast cancer with HER2 overexpression.

PurposeWe explored the clinical utility of human epidermal growth factor receptor-2 extracellular domain (HER2/ECD) in patients treated for an invasive breast cancer with HER2 overexpression.MethodsWe prospectively studied HER2/ECD levels in the sera of 334 women included between 2007 and 2014, all treated with trastuzumab. HER2/ECD levels were measured at diagnosis, during treatments, and along the follow-up. We investigated the relationship of HER2/ECD with other clinicopathological parameters at diagnosis, its prognosis value, and its utility during the monitoring of a neoadjuvant treatment and the follow-up.ResultsElevated HER2/ECD at diagnosis correlated positively with parameters associated with tumor aggressiveness. Disease-free survival of non-metastatic patients was significantly shorter in patients with high HER2/ECD at diagnosis (HR = 13.6, 95 % CI 1.6–113.6, P < 0.0001). Progression-free survival of metastatic patients was better for patients with low HER2/ECD (HR = 2.6, 95 % CI 1.2–5.3, P = 0.033). A multivariate analysis revealed that HER2/ECD level at diagnosis was an independent prognosis factor. During neoadjuvant therapy, a significant decrease in HER2/ECD was reported only for the complete histological response group (P = 0.031). During the follow-up, HER2/ECD helped predict relapse, disease progression, and metastases before imaging in 18.6 % cases of the studied cohort.ConclusionsHER2/ECD is a prognosis factor that is valuable in evaluating the neoadjuvant treatment efficiency. HER2/ECD also appears to be a helpful surveillance biomarker for the early diagnosis of relapses and to predict the fate of metastases. This study brings evidences to support the use of HER2/ECD in the management of HER2-positive breast cancer.

Serum NSE, MMP-9 and HER2 extracellular domain are associated with brain metastases in metastatic breast cancer patients: predictive biomarkers for brain metastases?

Breast cancer (BC) is the second most common cause of brain metastases (BM). Predictive factors for BM have been widely studied in metastatic BC; however, there is no known serum tumor marker to accurately predict BM. Elevated serum S100ß protein and neuron-specific enolase (NSE) could reflect the brain damages induced by BM. Matrix metalloproteinase 9 (MMP-9) is involved in tumor invasion and metastatic dissemination, including BM. Also, HER2-amplified BC were shown to have a particular tropism for central nervous system (CNS). This study evaluated the correlation of these biomarkers with the presence of BM in metastatic BC patients. In this case-control study, 88 consecutive metastatic BC patients with BM (BM group) treated in our institution (2008-2015) were retrospectively selected, based on the availability of frozen serum samples for tumor marker determination. Patients were matched by age, tumor biology and number of previous metastatic chemotherapy lines to 162 metastatic BC patients without CNS involvement (control group). Serum NSE, MMP-9 and HER2 extracellular domain (ECD) levels were significantly higher in the BM group (p = 0.0051, p = 0.0062 and p = 0.0057, respectively). In multivariate analysis, serum HER2 and MMP-9 levels accurately discriminated patients with BM: odds ratios 4.4 (p < 0.001; 95%CI: 1.9-9.6) for HER2 ECD and 3.5 (p = 0.005; 95%CI: 1.5-8.4) for MMP-9. In multivariate analysis, HER2 ECD and NSE serum levels were independent prognostic factors in patients with BM. Serum HER2 ECD and MMP-9 appear to be associated with BM in metastatic BC patients. Their predictive value for BM still needs to be evaluated in further prospective studies.

Serum HER2 extra-cellular domain, S100ß and CA 15-3 levels are independent prognostic factors in metastatic breast cancer patients.

BackgroundMetastatic breast cancer (MBC) prognosis is highly variable, depending on various factors such as the biological subtype, the performance status, disease extension…. A better evaluation of a patient’s prognostic factors could allow for a more accurate choice of treatments. The role of serum tumor markers remains, however, unclear in this population. Considering the recent interest in phenotypic changes and tumor heterogeneity during breast cancer progression, additional tumor markers could be interesting in this setting.MethodsTwo hundred fifty MBC patients treated at the Montpellier Cancer Institute (2008–2015) were retrospectively selected, based on the availability of frozen serum samples. The usual MBC clinical and pathological variables were collected, altogether with Cancer Antigen 15-3 (CA15-3), Carcinoembryonic Antigen (CEA), HER2 extra-cellular domain (ECD), Neuron Specific Enolase (NSE), S100ß protein and Matrix Metalloproteinase 9 (MMP-9) serum levels in order to determine their prognostic value.ResultsWith a median follow-up of 40.8 months, median overall survival was 16.2 months (95 % CI 12.4–20.6). In multivariate analysis, the performance status, brain or subcutaneous metastases, the number of previous metastatic chemotherapy lines and the tumor biological subtype were independent prognostic factors. Elevated CA 15-3 (HR = 1.95, IC 95 % 1.31–2.93, p = 0.001), HER2 ECD (regardless of tumor HER2 status, HR = 2.51, IC 95 % 1.53–4.12, p < 0.001) and S100ß (HR = 1.93, IC 95 % 1.05–3.54, p = 0.033) serum levels were independently associated with a poor outcome.ConclusionsSerum CA 15-3, HER2 ECD and S100ß could represent useful independent prognostic factors in MBC. Of particular interest is the independent value of serum HER2 ECD levels, regardless of the tumor HER2 status, possibly linked to metastatic tumor heterogeneity.

Serum HER2 extracellular domain levels and HER2 circulating tumor cell status in patients with metastatic breast cancer.

To shed light on the clinical role of HER2 status in serum as extracellular domain (ECD) and corresponding circulating tumor cells (CTCs) in metastatic breast cancer patients. 68 patients were analyzed. Serum HER2 was determined by ADVIA Centaur(®) Serum HER2 test. CellSearch System was performed for CTC quantification. HER2 was overexpressed in 21 primary tumors. In total, 19 patients had ECD >15 ng/ml (the cut-off used), 48 patients had at least one CTC. ECD positivity was associated with CTC number (p = 0.01), HER2-positive CTC (p = 0.01) and the ratio HER2-positive CTC/total CTC (p = 0.02). ECD was not associated with survival. ECD in combination with HER2 CTC status would deserve further investigation in larger series for addressing its putative prognostic relevance.

Meaningful interpretation of serum HER2 ECD levels requires clear patient clinical background, and serves several functions in the efficient management of breast cancer patients

BackgroundThis study was initiated to evaluate the clinical significant of HER2 extracellular domain (ECD) in the real-time management of breast cancer patients. MethodsFive-hundred forty-six eligible breast cancer patients were divided according to their clinical background. The correlation between ECD, tissue HER2, and clinical outcome of the patients were analyzed. ResultsReceiver operating characteristic analysis revealed that ECD measured before receiving neoadjuvant therapy yielded the highest area under the curve (0.9185; P<0.0001), indicating that ECD and tissue HER2 levels are consistent in untreated tumor-bearing patients. At cut-off of 15.0ng/ml, the prognostic value of ECD was demonstrated using univariate (HR=1.664, P<0.0001) and multivariate (HR=1.547, P=0.011) Cox regression analysis. Kaplan-Meier survival curves revealed that patients with elevated ECD had shorter progression-free survival (PFS) (4.0 vs. 6.1months, P<0.0001). Elevated ECD was also an adverse predictor for PFS in response to anti-HER2 therapy (4.3 vs. 10.2months, P=0.0155). In contrast, ≥20%, decreased ECD was associated with longer PFS in patients who received anti-HER2 therapy (10.9 vs. 2.4months, P=0.0164) and overall (10.7 vs. 2.8months, P=0.0034). ConclusionsA patient's clinical history can help determine whether ECD could provide added value for breast cancer management.

P1-5-61 - Characterization of serum HER2 extracellular domain (ECD) level in patients with metastatic colorectal cancer

Background: Overexpression of human epidermal growth factor receptor (HER) 2 occurs in approximately 20% of breast or gastric, and 5% of colorectal cancers. Moreover,activation of the HER2 pathway has been reported to be one of the mechanisms of primary or acquired resistace to anti-EGFR antibodies in RAS wild-type metastatic colorectal cancer (mCRC). The serum level of the HER2 extracellular domain (ECD) is used as a tumor marker or surrogate marker of the HER2 status in gastric and breast cancers. However, little is known about HER2-ECD levels and its characterization in mCRC patients (pts).Methods: We prospectively analyzed consecutive mCRC pts receiving palliative chemotherapy in our hospital. HER2-ECD level was measured in blood serum, and its positivity was defined as a serum HER2 level> 15.2 ng/ml, based on the manufacturers' recommended cutoff value.Results: A total of 145 pts were enrolled in this study. Pt characteristics were as follows: males/females (55%/45%), median age (range); 64 (24- 93) years, primary site; colon/rectum (52%/48%), RAS status; wild/RAS mutant/BRAF mutant/ unknown (57%/31%/5%/8%). The positive rate of HER2 ECD, CEA, and CA19-9 were 27.6, 80.0 and 51.7%, respectively. HER2 ECD showed a linear relationship with CEA level (correlation coefficient of 0.677). Regarding the association with the RAS status, serum levels of HER2 ECD in RAS wild type pts were higher than those in RAS mutant pts (positive rate of 33 vs. 20%, respectively). Moreover, in RAS wild type pts, pts resistant to anti-EGFR antibody within 1 year showed a higher positive rate of HER2 ECD than the others (55 vs. 28%,respectively; p = 0.0311).Conclusions: A Non negligible number of mCRC pts were positive for serum levels of HER2 ECD. HER2 ECD may be associated with tumor burden and acquired resistance to anti-EGFR therapy, but further studies are necessary to determine clinical utility of HER2 ECD. Background: Overexpression of human epidermal growth factor receptor (HER) 2 occurs in approximately 20% of breast or gastric, and 5% of colorectal cancers. Moreover,activation of the HER2 pathway has been reported to be one of the mechanisms of primary or acquired resistace to anti-EGFR antibodies in RAS wild-type metastatic colorectal cancer (mCRC). The serum level of the HER2 extracellular domain (ECD) is used as a tumor marker or surrogate marker of the HER2 status in gastric and breast cancers. However, little is known about HER2-ECD levels and its characterization in mCRC patients (pts). Methods: We prospectively analyzed consecutive mCRC pts receiving palliative chemotherapy in our hospital. HER2-ECD level was measured in blood serum, and its positivity was defined as a serum HER2 level> 15.2 ng/ml, based on the manufacturers' recommended cutoff value. Results: A total of 145 pts were enrolled in this study. Pt characteristics were as follows: males/females (55%/45%), median age (range); 64 (24- 93) years, primary site; colon/rectum (52%/48%), RAS status; wild/RAS mutant/BRAF mutant/ unknown (57%/31%/5%/8%). The positive rate of HER2 ECD, CEA, and CA19-9 were 27.6, 80.0 and 51.7%, respectively. HER2 ECD showed a linear relationship with CEA level (correlation coefficient of 0.677). Regarding the association with the RAS status, serum levels of HER2 ECD in RAS wild type pts were higher than those in RAS mutant pts (positive rate of 33 vs. 20%, respectively). Moreover, in RAS wild type pts, pts resistant to anti-EGFR antibody within 1 year showed a higher positive rate of HER2 ECD than the others (55 vs. 28%,respectively; p = 0.0311). Conclusions: A Non negligible number of mCRC pts were positive for serum levels of HER2 ECD. HER2 ECD may be associated with tumor burden and acquired resistance to anti-EGFR therapy, but further studies are necessary to determine clinical utility of HER2 ECD.

P053 Serum HER2 extracellular domain before surgery compared with HER2 in breast cancer

P053 Serum HER2 extracellular domain before surgery compared with HER2 in breast cancer