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Research indicates that positive PD-L1 detected by CIRCULOGENE liquid biopsy can have favorable outcomes for cancer patients

Research indicates that positive PD-L1 detected by CIRCULOGENE liquid biopsy can have favorable outcomes for cancer patients

Based on a 3-year, real-world study of patients with metastatic NSCLC, plasma cfRNA PD-L1 expression was as effective as tissue PD-L1 expression for informing ICI treatment benefit, and could identify additional patients who would otherwise be missed by tissue PD-L1 protein testing alone

BIRMINGHAM, Ala. and Pensacola, Fla. (June 9, 2023) – CIRCULOGENE is an innovative diagnostic company transforming precision medicine through the rapid delivery of actionable results. CIRCULOGENE’s blood-based test for PD-L1 expression continues to be at the forefront of cancer research, challenging the preeminence of tissue biopsy in informing patient treatment plans.

Research led by Dr. Paul Walker and a team of scientists from Brody School of Medicine at East Carolina University was recently published in the Journal of Clinical Oncology as part of the 2023 annual meeting proceedings for the American Society of Clinical Oncology (ASCO). This retrospective, observational study included patients with pathologically confirmed, advanced non-small-cell lung cancer (aNSCLC) treated with first-line immune checkpoint inhibitor (ICI)-based therapy and measured 3-year overall survival outcomes for patients.

Although PD-L1 protein expression is predictive of ICI-based treatment benefits in advanced aNSCLC, tissue PD-L1 has some limitations, including challenges in sample acquisition, tumor heterogeneity, and absence of dynamic monitoring. Plasma cell-free RNA (cfRNA) PD-L1 expression assessed with a liquid biopsy potentially overcomes these limitations and could identify additional patients likely to benefit from ICI therapy.

For this study, patients treated with first-line ICI-based treatment meeting the inclusion criteria and with PD-L1 results were placed in three cohorts: (1) patients testing positive for plasma cfRNA PD-L1, (2) patients testing positive for tissue PD-L1 protein, and (3) patients testing negative for PD-L1 in both plasma cfRNA and tissue protein. The cfRNA PD-L1 expression testing was performed at CIRCULOGENE’s CAP/CLIA accredited laboratory using its cfRNA PD-L1 Gene Expression assay which is a real-time exosome-free polymerase chain reaction (PCR) assay with PD-L1 specific PCR primers.

Comparison of plasma cfRNA PD-L1 positive and tissue PD-L1 protein positive patients showed identical overall survival outcomes. For patients receiving comparable treatments, overall survival outcomes were superior for those with positive plasma PD-L1 expression versus patients negative for PD-L1 expression, regardless of tissue or liquid biopsy. Further, in patients with positive PD-L1 expression, there was no difference in overall survival outcome whether the tissue PD-L1 was positive or negative. This suggests that liquid biopsy might identify additional patients who could benefit from ICI-based therapy.

“Improving predictive immune biomarker assays is vital to better predict ICI treatment benefit and extend that benefit to more patients,” said Dr. Walker, Chief Medical Officer of CIRCULOGENE and lead researcher for this study. “Since tissue-only biomarkers can be limited by tissue acquisition, sampling heterogeneity, and inherent static assessment, use of liquid biopsy in conjunction with tissue for PD-L1 testing, can have a significant impact on patient outcome. This real-world data with prolonged follow-up provides a framework of potential clinical utility of plasma cfRNA PD-L1 guiding immunotherapy treatment.”

Dr. Paul Walker is the former Director of Thoracic Oncology at East Carolina University and has been the past Program Director and Chief of Hematology/Oncology for the Brody School of Medicine as well as the Medical Director for the Clinical Trials Office. Dr. Walker has multiple medical journal publications and has been the principal investigator on multiple clinical trials, including immune therapy, immune modulating and boosting therapies.

CIRCULOGENE provides comprehensive biomarker testing for a broad range of cancers allowing physicians to match patient results with specific therapies in just one week. Their sequencing and qPCR methods can provide a full genomic load analysis to help clinicians select targeted therapies, monitor efficacy, and assess recurrence for cancer patients. Applying their liquid biopsy for cfDNA and cfRNA, including PD-L1 and MSI detection, CIRCULOGENE can detect circulating germline and somatic mutations and RNA fusions.

CIRCULOGENE is a Clinical Laboratory Improvement Amendments (CLIA) and College of American Pathologists (CAP) certified laboratory and a Verified Vendor for the federal System for Award Management. For more information, email, or call us at 855-614-7083. Clinicians interested in ordering tests may also visit our contact page at


Scott Rezek

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