Abstract P3-01-02: Detection of circulating tumor cells (CTC) in blood and disseminated tumor cells (DTC) in bone marrow at surgery identifies breast cancer patients (pts) with long-term risk of distant recurrence and breast cancer-specific death

We examined the prognostic impact of CTCs and DTCs detected at the time of definitive surgery in pts diagnosed with early breast cancer (EBC).

Methods: Blood and bone marrow samples from 742 treatment-naïve EBC pts, not eligible for neoadjuvant therapy, were collected immediately prior to surgery. 87% were hormone receptor (HR)-positive, and 71% were node-negative. DTCs (n=584) were enumerated using an EPCAM-based method involving immunomagnetic enrichment and flow cytometry (IE/FC). CTCs were enumerated either by IE/FC (n=288) or CellSearch (n=380). Optimal cutoffs for CTC-/DTC-positivity were selected using Monte-Carlo cross validation. Multivariate Cox regression analysis was performed to determine correlation between levels of CTCs/DTCs vs. distant recurrence-free survival (DRFS) and breast cancer-specific survival (BCSS). The overall median follow-up was 7.1 years for DRFS and and 9.1 years for BCSS, but extended up to 13.3 years in subset analyses (Table 1).

Results: CTC-positivity by CellSearch was associated with HER2-positivity (Fisher p=0.01). Using optimized cutoffs in multivariate analyses, we found that CTC-positive pts by CellSearch had a statistically significant increased risk of distant recurrence (HR 4.93, p=0.0067). Moreover, pts who were CTC-positive by IE/FC had a statistically significant increased risk of breast cancer-specific death (HR=3.54, p=0.0138). DTC status, by itself, was not prognostic; however, when combined with CTC status by IE/FC (n=273), positive detection for both (CTC+DTC+) was significantly associated with increased risk of distant recurrence (HR=3.09, p=0.0270) and breast cancer-specific death (HR=4.55, p=0.0205).

Table 1.Multivariate analysis to determine the prognostic significance of CTCs and DTCs detected at the time of surgery in treatment naive early breast cancer patients. Adjusted for age at diagnosis, tumor size, pathologic stage, HR and HER2 status, node status and grade.  DRFS  BCSS  Variable and Method% positiveHR [95% CI]Wald p-valueMedian f/u [range] Years*HR [95% CI]Wald p-valueMedian f/u [range] Years*CTC+ vs. CTC- by CellSearch94.93[1.56-15.6]0.00676.4 [0.16-13.8]4.50[0.76-26.5]0.09627.5 [0.71-15.0]CTC+ vs. CTC- by IE/FC401.92[0.93-3.95]0.07599.8 [0.09-18.5]3.54[1.29-9.72]0.013813.3 [1.93-18.5]DTC+ vs. DTC- by IE/FC181.46[0.75-2.81]0.26317.5 [0.09-18.5]1.48[0.64-3.42]0.35429.8 [1.55-18.5]CTC+DTC+ vs. CTC-DTC- by IE/FC8**3.09[1.14-8.40]0.02709.8 [0.09-18.5]4.55[1.26-16.39]0.020513.3 [1.93-18.5]*f/u - follow-up; **double positive

Conclusions: We demonstrate the impact of quantitative evaluation of CTCs and DTCs by IE/FC. Our large single institution dataset, in which CTCs and DTCs have been contemporaneously quantitated, has the longest patient follow-up. Simultaneous detection of CTCs and DTCs at the time of definitive surgery in treatment naïve EBC pts is an independent prognostic factor associated with increased long-term risk of distant recurrence and death due to breast cancer. Given the lack of early endpoints for low-risk patients, liquid biopsy may be an important consideration for future studies.

Citation Format: Magbanua MJM, Yau C, Wolf D, Lee JS, Chattopadhyay A, Scott JH, Yoder E, Hwang S, Alvarado M, Ewing CA, Delson AL, van't Veer L, Esserman L, Park JW. Detection of circulating tumor cells (CTC) in blood and disseminated tumor cells (DTC) in bone marrow at surgery identifies breast cancer patients (pts) with long-term risk of distant recurrence and breast cancer-specific death [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 P3-01-02.

Abstract P4-01-12: Low peripheral blood CD4/CD8 ratio at the time of surgery is a negative long-term prognostic factor in women with early stage breast cancer

It is hypothesized that cancer prognosis may be related to the functional status of the immune system. We examined the correlation between peripheral blood CD4/CD8 ratio measured at the time of surgery and clinical outcome in patients diagnosed with early stage breast cancer.

Patient and Methods

Peripheral blood from 57 treatment-naïve early breast cancer patients, not eligible for neoadjuvant chemotherapy, was collected on the day of definitive surgery. CD4+ and CD8+ T cells were enumerated using flow cytometry and the ratio between the two immune cell populations was calculated. Cox regression analyses were performed to determine the relationship between CD4/CD8 ratio vs. distant disease-free survival (DRFS), breast cancer-specific survival (BCSS) and overall survival (OS). The median follow-up times were 10.1 years (range: 0.4-17.5) and 15.0 (range: 1.0-18.5) for DRFS and BCSS/OS, respectively.

Results

The patients' mean age at diagnosis was 54 years old (range: 31-78). 82% were hormone receptor-positive, 21% HER2-positive, and 61% node-negative. The median CD4/CD8 ratio was 2; and a ratio ≤ 2 was considered low. CD4/CD8 ratio was not associated with any of the clinicopathologic variable examined. Multivariate analysis using a survival model that adjusted for potential confounding factors (age, tumor size, grade, stage, hormone receptor, HER2, lymph-node status) revealed that patients with low CD4/CD8 ratio have statistically significant increased risk of distant recurrence (DRFS HR 5.3, Wald p=0.0381) and death (OS HR 3.8 Wald p=0.0271).

Conclusions

Immune dysfunction at the time surgery is correlated with long-term increased risk for metastatic recurrence and death. Larger clinical studies are warranted to confirm the results of this study.

Citation Format: Magbanua MJM, Yau C, Scott JH, van't Veer L, Park JW, Esserman L, Campbell M. Low peripheral blood CD4/CD8 ratio at the time of surgery is a negative long-term prognostic factor in women with early stage 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 P4-01-12.

Abstract PD6-8: Prognostic value of disseminated tumor cells according to ER/PR and HER2 status in non-metastatic breast cancer

Background: Disseminated tumor cells (DTCs) in the bone marrow from breast cancer patients have been reported as a prognostic factor. We evaluated prognostic value of DTCs in non-metastatic breast cancer according to ER/PR and HER2 status.

Methods: Bone marrow aspirates were obtained from 607 non-metastatic breast cancer patients at the time of primary surgery between 1999 and 2012. DTCs were identified via immunomagnetic enrichment followed by flow cytometry (IE/FC) using anti-EpCAM monoclonal antibody (mAb). The relation between high DTC count and clinical outcome was analyzed with ER/PR and HER2 status. Patients whose DTC count is in the above 80th percentile were considered as higher DTCs.

Results: Median and mean DTC count were 7.2 and 24.5 cells/mL and 80th percentile was 18.5 cells/mL. Higher DTC group (> = 18.5 cells/mL) showed impaired disease free survival (DFS; P = .019, log-rank) after median follow-up of 59 months. This poorer outcome in higher DTC group was observed mainly in ER(-) patients and triple negative patients with lower DFS (P = .002 and 018) and overall survival (OS; P = .004 and .012). There was no significant survival difference in ER(+), HER2(+), or ER(+)/HER2(-) patients.

Conclusion: High DTCs in non-metastatic breast cancer is associated with poor clinical outcome, especially in ER(-) or triple negative patients. However, DTCs is not related with prognosis in other ER/HER2 status groups.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-8.

A phase 1 trial of imatinib, bevacizumab, and metronomic cyclophosphamide in advanced colorectal cancer

Background:

This phase 1 clinical trial was conducted to determine the safety, maximum-tolerated dose (MTD), and pharmacokinetics of imatinib, bevacizumab, and metronomic cyclophosphamide in patients with advanced colorectal cancer (CRC).

Methods:

Patients with refractory stage IV CRC were treated with bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks (fixed dose) plus oral cyclophosphamide q.d. and imatinib q.d. or b.i.d. in 28-day cycles with 3+3 dose escalation. Response was assessed every two cycles. Pharmacokinetics of imatinib and cyclophosphamide and circulating tumour, endothelial, and immune cell subsets were measured.

Results:

Thirty-five patients were enrolled. Maximum-tolerated doses were cyclophosphamide 50 mg q.d., imatinib 400 mg q.d., and bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks. Dose-limiting toxicities (DLTs) included nausea/vomiting, neutropaenia, hyponatraemia, fistula, and haematuria. The DLT window required expansion to 42 days (1.5 cycles) to capture delayed toxicities. Imatinib exposure increased insignificantly after adding cyclophosphamide. Seven patients (20%) experienced stable disease for >6 months. Circulating tumour, endothelial, or immune cells were not associated with progression-free survival.

Conclusion:

The combination of metronomic cyclophosphamide, imatinib, and bevacizumab is safe and tolerable without significant drug interactions. A subset of patients experienced prolonged stable disease independent of dose level.

Abstract P2-01-05: Parallel DNA and RNA profiling of EpCAM-positive cells in blood of metastatic breast cancer (MBC) patients confirm their malignant nature

Background: Molecular studies of EpCAM-positive cells found in the blood of cancer patients have been limited to immuno-enriched samples containing a high background of leukocytes. We developed a process to isolate rare EpCAM-positive cells and subjected them to DNA and RNA profiling.

Methods: Blood was subjected to immunomagnetic enrichment using EpCAM beads followed by fluorescence activated cell sorting (IE/FACS) to isolate EpCAM-positive cells away from leukocytes (CD45+). Duplicate samples of 20 cells were isolated from the same enriched blood from 53 MBC patients and then subjected to DNA and RNA profiling in parallel. For DNA profiling, sorted cells were subjected to BAC array comparative genomic hybridization analysis following whole genome amplification. For RNA profiling, QPCR analysis was performed on sixty four (64) cancer-related genes using Taqman® low density arrays. For non-tumor controls, RNA profiling was performed on matched leukocytes (CD45+) isolated from the same enriched blood samples from 44 of the 53 patients.

Results: Differential gene expression analysis between EpCAM-positive cells and matched leukocytes confirmed the up-regulation of EPCAM and other genes including MUC1 and KRT19 (adjusted p <0.05). In addition, EpCAM-positive cells showed a significant down-regulation of the leukocyte-specific marker PTPRC (encodes CD45) as well as CD44 and VIM, markers associated with stem cellness and epithelial to mesenchymal transition, respectively. Unsupervised hierarchical clustering analysis of RNA profiles showed that EpCAM-positive cells clustered away from the leukocytes. Genome-wide copy number analysis of EpCAM-expressing cells revealed gains (e.g. 1q and 8q), losses (e.g. 8p and 16q), and focal amplifications (e.g. on 8q and 11q including CCND1) frequently seen in primary breast cancers.

Discussion: We demonstrate the feasibility of isolation and molecular analysis of highly pure EpCAM-positive cells in the blood. Our results strongly suggest that epithelial cells captured from blood of MBC patients are malignant in nature and are therefore circulating tumor cells. This approach can serve as a non-invasive source of highly pure metastatic tumor tissue for further molecular characterization. This study was supported by CALGB and BCRF.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-05.

Genome-wide copy number analysis of circulating tumor cells from patients (pts) with metastatic breast cancer (MBC)

9

Background: We developed a novel approach to isolate circulating tumor cells (CTCs) via immunomagnetic enrichment followed by fluorescence activated cell sorting (IE/FACS) and examined copy number alterations in these cells.

Methods: Magnetic beads coated with EpCAM mAb were added to blood to enrich for tumor cells. Enriched samples were then subjected to FACS analysis using differentially labeled mAbs to distinguish tumor cells (EpCAM+) from leukocytes (CD45+) during sorting. DNA from isolated tumor cells was subjected to whole genome amplification (WGA) and copy number analysis via array comparative genomic hybridization (aCGH). The assay was evaluated in CTCs from 5 MBC pts with matched archival primary tumors and later extended to an additional 176 MBC pts, 97 of which were successfully profiled.

Results: Comparison of CTCs with matched archival primary tumors confirmed shared lineage with notable divergence. In addition, serial testing of CTCs confirmed reproducibility, and indicated genomic change over time. Genomic profiling of CTCs from 102 MBC pts revealed a wide range of copy number alterations including those previously reported in breast cancer. Comparison with a published aCGH dataset of primary breast tumors revealed similar frequencies of recurrent genomic copy number aberrations.

Conclusions: It is feasible to isolate CTCs away from hematopoietic cells with high purity via IE/FACS and profile them via aCGH analysis following WGA. Our approach may be utilized to explore genomic events involved in cancer progression and to monitor therapeutic efficacy of targeted therapies in clinical trials in a relatively non-invasive manner. This work was supported by grants from the CALGB, BCRF, TBCRC (Avon, Komen), EDRN and U54.

Abstract PD04-10: Genome-Wide Copy Number Analysis of Circulating Tumor Cells (CTCs) from Metastatic Breast Cancer Patients

Background: Clinical studies have demonstrated the prognostic and predictive value of the number of CTCs in metastatic breast cancer. However, it is the molecular characterization of CTCs that offers insight into the biology of these tumor cells in the context of personalized treatment.

Methods: Ten to twenty mLs of blood from 32 metastatic breast cancer patients with poor prognosis (≥5 CTCs in 7.5mLs blood) were subjected to immunomagnetic enrichment. Pools of ∼20 CTCs [EpCAM+, CD45-, nucleated] were isolated via fluorescence activated cell sorting, FACS. Genomic DNA was subjected to whole genome amplification followed by array comparative genomic hybridization (CGH) analysis. Serial genomic profiling was performed in three patients. Genomic profiles from archival primary tumor available from 4 patients were compared to matched CTCs. Copy number analysis was performed using the Nexus® Copy Number. Genomic alterations with p ≥0.05 were considered significant. Results: Genomic profiling of CTCs revealed significant recurrent (≥35%) genomic alterations including gains in 8q12.1, 8q24 and losses in 1p36, 4p16, 5q21, 10q22, 11q24-25, and 13q34. Good concordance of CGH profiles obtained from CTCs isolated from serial blood samples attested to the reproducibility of the assay. Furthermore, comparisons of CTCs with matched archival primary tumors confirmed shared lineage with some divergence.

Conclusions: Copy number analysis revealed common genomic alterations in CTCs as well as shared aberrations with matched primary tumor. In addition, we demonstrated the feasibility of serial genomic profiling of CTCs. Future work will determine associations between genomic aberrations in CTCs and clinicopathological parameters. Uncovering genomic alterations in CTCs may lead to the discovery of therapeutic biomarkers to specifically target these cells in breast cancer patients who respond poorly to current aggressive therapies.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD04-10.