Abstract 7485: Microfluidic detection of dual positive cells in whole blood of metastatic breast cancer patients

Abstract Background. Dual positive cells (DPCs) that express both epithelial markers and leukocytic markers have been observed in peripheral blood of breast cancer patients. DPCs acquire functional behaviors from both cell types which may drive tumor progression. However, the lack of reliable methods to isolate and identify DPCs has hindered the investigation of their origin and clinical implications in breast cancer patients. While microfluidic devices have been widely used for the detection of circulating tumor cells (CTCs) by liquid biopsy, DPC detection is underexplored in these devices. Herein, we demonstrate rapid onchip isolation and detection of DPCs in whole blood samples from metastatic breast cancer (MBC) patients using an integrated microfluidic device. Methods. Our microfluidic device consists of a unique preconditioning component that concentrates targets in whole blood and a downstream cell immobilization component that captures target cells. We included 7 female patients with MBC, of which 29% are white (2), 57% are African American (4), and 14% are Latina (1). The median age is 50y (34y -75y). All patients were undergoing systemic breast cancer therapy at the time of blood collection. A total of 9 samples (4 mL each) were collected from either an antecubital vein (peripheral vein) or the subcutaneous port catheter (central vein) of these patients. All samples were processed within 5 hours of blood drawn in our novel microfluidic biochip. CTCs (EpCAM+/CK+, CD45-, DAPI+) and DPCs (EpCAM+/CK+, CD45+/CD66b+, DAPI+) were identified by immunofluorescence after cells were fixed. Results. Processing of each sample was completed within 40 minutes using our microfluidic device. Both DPCs and CTCs were detected in all the samples (9/9). The average DPC count was 3 DPCs per 4 mL whole blood with a standard deviation of 1. 9 cells. The average CTC count was 9 with a standard deviation of 5 per 4 mL whole blood. 89% of the samples (8/9) had 5 CTCs after the sample volume is scaled to the standard 7. 5 mL. No correlation was found between DPC count and CTC count (Pearson correlation coefficient r=0. 08). While the blood collection location (central vs peripheral veins) had a significant impact on the CTC count (12. 6 vs 4 on average with p0. 01), there was no statistical difference in DPC counts in the samples collected from central and peripheral veins. Conclusions. Both DPCs and CTCs can be rapidly isolated and detected from MBC patient whole blood in our microfluidic device. Our preliminary results indicate no correlation between DPCs and CTCs, suggesting that DPCs might not originate in blood circulation of MBC patients. More work with a larger patient cohort will be needed to further investigate the clinical implications of DPCs on MBC patients. Citation Format: Jian Zhou, Qiyue Luan, Celine Macaraniag, Arielle B. Guzman, Maria Mantice, Oana Danciu, Kent F. Hoskins, Ian Papautsky. Microfluidic detection of dual positive cells in whole blood of metastatic breast cancer patients abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7485.