ANGLE plc , the specialist medtech company, has announced that the results of the University of Southern California (USC) Norris Comprehensive Cancer Center’s ongoing work with ANGLE’s Parsortix system have demonstrated the potential for the use of Parsortix as a liquid biopsy for metastatic breast cancer.

USC head to head patient data will be presented at AACR 2016 (the American Association for Cancer Research Annual Meeting 2016), which demonstrates a statistically significant correlation in metastatic breast cancer between analysis of CTCs (circulating tumor cells) harvested from a simple blood test using Parsortix with similar analysis of tissue obtained from invasive biopsy of a secondary cancer site. The directors believe that the data demonstrates the potential for the Parsortix liquid biopsy (simple blood test) to replace the invasive biopsy.

Metastasis is responsible for the vast majority of breast cancer related deaths. Initial treatment recommendations for breast cancer are based on primary tumour biology from the initial solid biopsy at patient presentation. However, the recently updated ASCO (American Society of Clinical Oncology) guidelines call for biopsy of a metastatic site to guide the decision making for treatment as it is known that cancers change their status as disease progresses. Access to the secondary cancer site to obtain this tissue biopsy is challenging and requires the patient to undergo an invasive procedure, which causes trauma and delays treatment until they have recovered from the procedure. Furthermore the surgical intervention takes time to arrange, is expensive and diverts resources from care for the patient.

A liquid biopsy to obtain cancer cells for analysis from a simple blood test has major advantages, including:

In the USC study, the tissue from the invasive biopsy and the CTCs from the Parsortix liquid biopsy harvest were both subjected to Illumina’s whole-transcriptome analysis using total RNA sequencing (RNA-Seq). RNA-Seq can accurately measure gene and transcript abundance, and identify known and novel features of the transcriptome. RNA-Seq analysis has been completed on three sample types covering metastatic tissue biopsy, Parsortix harvested CTCs and, as a control, peripheral blood for each of eight patients. This strategy enables measurement of thousands of genes at once in order to generate a comprehensive picture of cellular function.

For every one of these patients, CTCs were successfully harvested and RNA-Seq analysis successfully completed. This analysis demonstrated a statistically significant correlation between the expression signature of 192 genes in the Parsortix harvested CTCs with similar analysis of tissue obtained from an invasive biopsy of a secondary cancer site.

The metastatic biopsy material was sourced from a wide range of metastatic sites including skin, pleural effusion (fluid around the lung), pericardial effusion (fluid around the heart), breast, cerebrospinal fluid (fluid found in the brain and spine) and bone tissue. For all of these different metastatic sites, the Parsortix CTCs provided similar gene expression compared to the metastatic biopsy, allowing for the potential examination of known and novel genes related to breast cancer.

These results suggest that by using Parsortix the same clinically relevant information may be obtained from a patient blood test as from an invasive metastatic biopsy regardless of its location in the patient.

Breast cancer is the most common cancer in women and the second most common overall. More than 1.7 million cases of breast cancer were recorded in 2012, accounting for around 12 per cent of all new cancer cases and 25 per cent in women. There are 6.3 million women living with breast cancer, according to World Cancer Research Fund International. It is estimated that 20 per cent to 30 per cent of all breast cancer cases will become metastatic, according to Metastatic Breast Cancer Network.

Replacement of the metastatic biopsy for breast cancer with a Parsortix blood test would be non-invasive, cheaper and faster, and could be repeated more frequently, thereby providing “real-time” information for therapy selection reflecting disease progression.

ANGLE now intends to work with USC and other leading cancer centres to develop and implement clinical studies to validate the use of the Parsortix system as a clinical application for the routine biopsy of metastatic breast cancer patients. The multi-centre clinical studies need to be specified but would be expected to take at least 18 months to complete.

“As a breast cancer surgeon, I am very enthusiastic about the potential of liquid biopsy to gain information to guide the treatment of breast cancer patients based on the specific tumour biology for each patient. Our pilot data shows that potentially the same information can be obtained from a simple blood test using Parsortix as from an invasive tissue biopsy and indeed may be advantageous over invasive tissue biopsies in regards to the diverse sites of metastatic disease, thus providing a compelling rationale for use in clinical practice after further validation.”