ANGLE PLC (AIM:AGL, OTCQX:ANPCY) has announced the presentation of two posters at the San Antonio Breast Cancer Symposium (SABCS), in San Antonio, Texas, United States, between 6-10 December 2022 which demonstrated the successful isolation and subsequent analysis of circulating tumour cells (CTCs) from Metastatic Breast Cancer (MBC) patient blood samples using its Parsortix PC1 Clinical System.
The world-leading liquid biopsy company said the first poster, presented by ANGLE, outlines the utility of the Parsortix PC1 Clinical System in capturing and harvesting CTCs from a significantly larger proportion of MBC patients, compared to healthy donor samples. The ANG-008 study evaluated 75 MBC patient blood samples and 71 healthy volunteer blood samples.
Firstly, the harvested CTCs were deposited onto glass slides for staining using cytocentrifugation, a method which has been shown to lose a significant proportion of cells. The cells retained on the cytology slides were stained using an immunofluorescence (IF) assay, and CTCs were characterized as nucleated cells that were positive for CK and/or EpCAM and negative for blood markers. The IF-stained slides were subsequently restained using Wright-Giemsa reagents and CTCs identified by a qualified pathologist. CTCs were observed in 45.3% and 42.9% of MBC patients following IF and Wright-Giemsa evaluation, respectively.
Of the CTC-positive MBC patient samples, 70.6% had CK positive and EpCAM negative cells only. This high proportion of EpCAM negativity highlights the limitations of using EpCAM-based approaches to capture CTCs and the advantages of using the epitope-independent Parsortix PC1 Clinical System.
The second poster, presented by The University of Texas MD Anderson Cancer Center, showed results from the ANG-002 HOMING study, a prospective clinical trial that highlights the use of the Parsortix PC1 Clinical System for the isolation and harvest of CTCs from patients with MBC and its ability to perform multiple subsequent downstream analyses on the harvested CTCs.
The research evaluated 207 MBC patients, including newly diagnosed, recurrent and progressive MBC patients, and 204 healthy volunteers. Similarly, this study identified CTCs using Wright-Giemsa staining confirmed by a qualified pathologist. Furthermore, as proof of concept, CTCs harvested from a second blood sample were evaluated using one of three additional subsequent evaluation techniques, including molecular profiling by real-time quantitative reverse transcription PCR (qRT-PCR) or RNA sequencing, or analysis of HER2 amplification by fluorescence in situ hybridisation (FISH).
The cytologic evaluation, which used the same cytocentrifugation method to deposit the harvested cells onto glass slides for staining, identified CTCs in 48.5% of all evaluable MBC patient sample independent of tumour subtype. Molecular profiling demonstrated (i) a higher expression of CTC related genes in MBC patients compared to healthy volunteers, (ii) a correlation of CTC-related gene expression with CTC count and (iii) genes from a specific cancer pathway (KEGG) were differentially expressed in MBC patients when compared to healthy volunteers. Furthermore, the HER2 status, analysed by FISH, of the harvested CTCs was successfully evaluated, with amplification being observed in a single CTC from an MBC patient sample.
Data generated from both studies was used to support the De Novo classification of the Parsortix PC1 Clinical System as a Class II device, which was granted by the US Food and Drug Administration (FDA) on 24 May 2022.
Overall, ANGLE said, the research presented at the SABCS highlights the successful use of the Parsortix PC1 Clinical System for CTC enrichment in blood from patients with MBC, allowing for a variety of possible downstream analyses, including IF and Wright-Giemsa staining and molecular profiling evaluation.
In a statement, ANGLE founder and chief executive, Andrew Newland, commented: "We are pleased to announce ANGLE's contributions and attendance at the San Antonio Breast Cancer Symposium this year. The two posters presented showcase the utility of the Parsortix PC1 Clinical System for the isolation and harvest of CTCs for use in multiple subsequent downstream analyses.
"We continue to show the valuable use of the instrument to identify EpCAM-negative CTCs, which is not possible with alternative antibody-based approaches. The data from these two studies contributed to the ground-breaking success of a De Novo FDA regulatory clearance for the Parsortix PC1 Clinical System, which we believe will drive future commercial success."
The research is available online at https://angleplc.com/library/publications/.