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Biodesix Blood-Based Diagnostic Testing Approach To PD-L1 Detection Shows Concordance with Immunohistochemistry

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Biodesix presented preliminary data evaluating a blood-based PD-L1 assay to identify patients who may benefit from cancer immunotherapies. The data were presented last week at the AACR-NCI-EORTC conference. The study was conducted in collaboration with Dr. Michael Pritchett, from FirstHealth Moore Regional Hospital, Pinehurst Medical Clinic, and Dr. Jiaxin Niu, from Banner MD Anderson Cancer Center.

“Measurement of PD-L1 is challenging not only when tissue is lacking, but due to the inherent complexity of immunohistochemistry. The testing approach demonstrated in this study shows promise as a method of assessing PD-L1 in plasma,” said Michael Pritchett, DO, MPH. “A more objective measure of PD-L1 status could offer a path to better patient care decisions in the treatment of non-small cell lung cancer.”

Programmed cell death ligand 1 (PD-L1) has been detected in up to 50% of all human cancers, and has become a major focus of therapeutic and biomarker research.1 Patients with cancers expressing the PD-L1 protein are more likely to respond to certain immuno-oncology therapeutics, and several PD-L1-related immuno-oncology therapies have received FDA approval.

The study, “Concordance of IHC and a new blood-based expression assay for the detection of PD-L1 in patients diagnosed with non-small cell lung cancer,” refers to an assay under development at Biodesix that uses multiplexed droplet digital PCR (ddPCR) detection of circulating mRNA; PD-L1 levels were also measured by QPCR. The data demonstrated a strong correlation between the two technologies.

The investigational methodology incorporates CK19 expression to identify PD-L1 derived from activated immune cells and or/tumor cells. In the study, preliminary thresholds were identified for the developmental PD-L1 assay based on 1% and 50% cut-offs with the PharmDx 22c3 IHC assay. Although concordance with a 50% positive IHC cut-off was not significant, when a variable threshold was used based on a logistic regression score for the blood assay along with the 1% cut-off, concordance of up to 80% was observed between the two assays.

“80% correlation between blood-based and tissue-based PD-L1 results is impressive, and clinically meaningful,” said Dr. Niu, MD, PhD. “If confirmed prospectively with simultaneously collected samples, it would be very convincing and have significant clinical implications.”

Source: GlobeNewswire