ANGLE PLC (AIM:AGL, OTCQX:ANPCY) said pilot data from a study in ovarian cancer patients showed its Parsortix system could be used to select patients for clinical trials who are likely to respond better to immunotherapy treatments.
Andrew Newland, chief executive of ANGLE, said the data showcased the utility of the Parsortix system for the unbiased isolation of multiple subsets of circulating tumour cells (CTCs) in ovarian cancer patients.
He said while circulating tumour DNA (ctDNA) is increasingly used for the stratification of cancer patients, “it is unable to provide insight into PD-L1 status”, referring to the Programmed death-ligand 1 protein that is a common marker of immune tolerance and is considered useful for immunotherapy by immune checkpoint inhibitors.
“In contrast, CTCs can provide PD-L1 status. ANGLE is currently in the process of validating a PD-L1 assay in its clinical laboratories as a key part of its pharma services offering for clinical trials,” he said.
Currently, the proportion of patients that respond to PD-L1 or PD-1 inhibitors is low, at around 13% to 50%, which ANGLE said was an indication of “a clear need for improved patient selection as non-responders do not benefit from treatment but risk developing hyper-progressive disease and drug toxicity with immune-related adverse events”.
The study was carried out by Edith Cowan University in Perth, Australia, with results demonstrating the ability to evaluate the expression of both epithelial and mesenchymal markers, as well as PD-L1 status, of CTCs isolated using the Parsortix system, to help to predict whether patients will respond to immunotherapy drugs.
The Parsortix system was selected by researchers for the study due to its ability for unbiased CTC enrichment, enabling the isolation of both epithelial and mesenchymal cancer cells and those in transition (EMTing-CTCs), ANGLE said.
“This is clinically relevant because, although the transition to a mesenchymal phenotype is associated with increased metastatic potential and worse prognosis, many CTC isolation methods, including the leading antibody-based system, only capture epithelial cells and miss mesenchymal and EMTing cells,” the company explained.
In the study, blood from 16 ovarian cancer patients was collected and processed using the Parsortix system, with isolated CTCs stained with multiple markers to determine their their PD-L1 status and whether they were epithelial, EMTing or mesenchymal.
CTCs were identified in 63% of patients and, of these CTCs, 61% were exclusively epithelial, 26% exclusively mesenchymal and 11% were positive for both epithelial and mesenchymal markers (EMTing-CTCs).
Half of the patients with detectable CTCs were PD-L1 positive. PD-L1 positive CTCs were more common amongst EMTing-CTCs, accounting for 76% of the EMTing-CTCs observed, with a significant association between the two when compared to epithelial and mesenchymal CTCs, the survey found.