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
Authors: 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 
Published: May 2019

Abstract
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.