Grail presented long-awaited data from its Circulating Cell-free Genome Atlas (CCGA) project, which aims to establish the company’s ability to detect traces of early-stage cancers floating through the bloodstream.
Samples from lung cancer patients were evaluated using three of the company’s prototype genome-sequencing assays. At 98% specificity, detection rates ranged from 38% to 51% in participants with early-stage lung cancer, demonstrating early support for the concept.
“These initial data from CCGA are exciting because they suggest it is possible to detect lung cancer through DNA signals in the blood at earlier stages when survival rates may be higher,” said Geoffrey Oxnard, M.D., an associate professor of medicine at Dana-Farber Cancer Institute and Harvard Medical School, who discussed the results in an oral presentation at the annual meeting of the American Society of Clinical Oncology in Chicago.
In the first phase of the substudy, blood samples from 1,627 participants with and without cancer were sequenced, including 20 cancer types across all stages.
In 127 lung cancer patients, the prototype assays sequenced paired cell-free DNA and white blood cells to detect mutations such as single nucleotide variants, small insertions and deletions; somatic copy number changes; and abnormal cfDNA methylation patterns.
Detection rates ranged from 59% to 92% across all stages in patients with adenocarcinoma, squamous cell and small cell lung cancers, with false positive rates under 2%.
Targeted sequencing for small mutations and variations detected 51% of stages I-IIIA lung cancers, while whole-genome assays of somatic changes and methylation patterns identified 38% and 41%, respectively. The three tests performed about the same in later stages of disease, detecting 87% to 89% of cases.
“We are encouraged by these initial results and believe a highly specific blood test for lung cancer could help improve early detection rates for this deadly disease,” Anne-Renee Hartman, M.D., Grail’s VP of clinical development, said in a statement. While the five-year survival rate for early-stage lung cancer is 56%, only 16% of lung cancers are diagnosed at that time, the company said.
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The five-year longitudinal CCGA study plans to enroll more than 15,000 participants across 142 sites in the U.S. and Canada, with about 70% of participants being either newly diagnosed with cancer or yet to receive treatment at the time of enrollment. The study’s group of participants without cancer includes individuals with conditions known to increase cfDNA signals, such as inflammatory or autoimmune diseases.
Grail has raised huge sums of money to fund the massive clinical evaluation of its blood testing initiative: CCGA and a second observational study focused on breast cancer, STRIVE, aim to enroll at least 135,000 participants. The Menlo Park, California-based company has held three venture capital funding rounds, each gathering north of $100 million, for a total of $1.5 billion in financing, plus plans for a future IPO listing in Hong Kong.