Study Published by Clinical Cancer Research Shows PGDx’s Liquid Biopsy Predictive of PD-1 Blockade Response

BALTIMORE–(BUSINESS WIRE)–A study published by Clinical Cancer Research, a journal of the American Association for Cancer Research (AACR), shows Personal Genome Diagnostics Inc.’s (PGDx) liquid biopsy technology successfully detected microsatellite instability (MSI) in circulating tumor DNA (ctDNA), and was able to estimate the likelihood of both an immediate and durable response to immune checkpoint blockade in cancer patients with MSI. The study results point to the value of liquid biopsies as a non-invasive approach to genotyping and monitoring in patients diagnosed with advanced forms of cancer. Researchers from PDGx, Johns Hopkins and Memorial Sloan Kettering Cancer Center, among other institutions, contributed to the study.

“Microsatellite instability and high tumor mutation burden (TMB) are promising pan-tumor biomarkers that are used to identify patients who may be candidates for treatment with immune checkpoint blockade,” said John Simmons, PhD, VP of Translational Medicine for PGDx. “Obtaining samples via tumor biopsy can be challenging in people with advanced cancer, so this liquid biopsy test is a tool that can help doctors select the best therapy for their patients.”

Microsatellite instability was the first pan-cancer biomarker approved for determining treatment with the immune checkpoint inhibitor, pembrolizumab. In liquid biopsy testing, MSI status can be determined by evaluating the level of circulating tumor DNA in a patient’s plasma (blood) sample. This study finds ctDNA testing can also help doctors monitor patient response to treatment and identify earlier when a therapy is no longer effective.

“Our study further demonstrates that ctDNA is a more rapid and dynamic method to determine response to therapy, and in particular to immune checkpoint blockade, in comparison with a protein biomarker or radiographic imaging,” said Andrew Georgiadis, Senior Scientist at PGDx and first author of the study.

About the Study Methodology and Key Results
Investigators developed a novel, highly sensitive and specific analytic method to identify MSI in ctDNA. For patients treated with PD-1 blockade, researchers demonstrated that detection of MSI and a high level of TMB in pre-treatment plasma predicted progression-free and overall survival (hazard ratios 0.21 and 0.23, p=0.001 and 0.003, respectively). Additionally, analyzing cfDNA from longitudinally collected plasma samples obtained during therapy identified patients who achieved durable response to PD-1 blockade.

About Liquid Biopsy
PGDx’s commitment to increasing patient access to genomic testing options is centered on development of their elio portfolio, kitted products that integrate optimized chemistry with automated bioinformatics for comprehensive tissue-based and liquid biopsy genomic profiling in molecular laboratories worldwide. Earlier this year, PGDx announced CE registration of PGDx elio plasma resolve, bringing a local, non-invasive testing option to cancer patients in Europe. PGDx has received Breakthrough Device designation from the FDA for elio plasma resolve based on the assay’s ability to detect MSI status in plasma as an aid in selecting patients for certain therapies.

Personal Genome Diagnostics
Personal Genome Diagnostics (PGDx) empowers the fight against cancer by unlocking actionable information from the genome. We are committed to improving clinical insight, speed of results, and healthcare economics by delivering a portfolio of regulated tissue-based and liquid biopsy genomic products for laboratories worldwide. PGDx was established by researchers from Johns Hopkins University who are pioneers in cancer genome sequencing and liquid biopsy technologies. For additional information, visit

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