Researchers have developed a blood test that they believe could lead to more personalized treatments for non-small cell lung cancer.
The new test was created by Gary A. Pestano, Ph.D., and colleagues from Biodesix, Inc., a molecular diagnostic company based in Boulder, CO.
Piston and team recently described the accuracy of their new test in The Journal of Molecular Diagnostics.
Lung cancer is one of the most common cancers in the United States. This year, it is estimated that around 222,500 new cases of lung cancer will be diagnosed, and more than 155,000 people will die from the disease.
Non-small cell lung cancer (NSCLC) accounts for around 80-85 percent of lung cancers.
NSCLC is named as such due to the types of cells that it affects in the lungs. The most common subtypes of NSCLC are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
At present, the type of treatment provided for NSCLC is usually determined using a lung biopsy, which involves removing a sample of tissue or fluid from the lungs for analysis. However, Pestano and colleagues note that this procedure is invasive and is not always necessary or accurate.
"For instance, approximately one fourth of patients with NSCLC are either not candidates for biopsy or have insufficient tissue samples recovered from the initial biopsy," note Pestano and colleagues. "This can limit the treating physicians' ability to fully diagnose the cancer genotype."
"Importantly as well, results from tissue-based testing can take weeks to obtain and can delay time to treatment," they add.
Genetic testing and NSCLC
Patients with NSCLC may possess certain gene mutations. For example, EGFR gene mutations are present in around 10 percent of NSCLC patients, while KRAS gene mutations affect around 25 percent of patients with the disease.
Additionally, almost 5 percent of patients with non-small cell lung tumors possess abnormalities in the ALK gene. Most commonly, this involves ALK binding to a gene called EML4, resulting in a mutant gene called EML4-ALK.
Studies have suggested that genetic testing may aid personalized treatment for NSCLC, given that the presence of certain genetic mutations can be used to predict a patient's response to certain cancer therapies.
Patients with EGFR gene mutations, for instance, are more likely to respond to medications called EGFR tyrosine kinase inhibitors, such as erlotinib, while patients with the EML4-ALK gene are less likely to respond to these drugs.
In their study, Pestano and colleagues describe the development of a blood test that identified genetic mutations in blood samples of NSCLC patients with high accuracy, and the results of the test were available in under 72 hours.
Genetic mutations identified with high accuracy
According to the researchers, the new test utilizes a technique called Droplet Digital PCR, or ddPCR, which is a "highly sensitive gene mutation detection method that is based on the partitioning of DNA into droplets."
The technique is able to identify specific DNA mutations and RNA variants from tumors that are circulating in the blood.
The team used the test to analyze more than 1,600 blood samples taken from patients with early-stage NSCLC. Most of these patients were under the care of doctors in community settings, the researchers note.
The test identified EGFR mutations sensitive to tyrosine kinase inhibitors in 10.5 percent of samples, while 18.8 percent of samples had EGFR mutations resistant to tyrosine kinase inhibitors. KRAS gene mutations were identified in 13.2 percent of samples, and 2 percent of samples possessed the EML4-ALK gene.
For the detection of each gene mutation, the blood test demonstrated 80 percent sensitivity and 100 percent specificity, making it almost as accurate as tissue biopsies.
Additionally, 94 percent of the blood test results were available within 72 hours of the blood samples being taken, which is significantly faster than the results from tissue biopsies.
Based on these findings, Pestano and team say that their blood test could improve outcomes for patients with NSCLC by enabling clinicians to make faster, personalized treatment recommendations.
"This study is critical because it is the first to demonstrate the uptake of blood-based testing for actionable mutations in the non-hospital (community) setting. Physicians and patients in a community setting may not have easy access to a large hospital or other diagnosis/treatment facility. This assay provides results within 72 hours from sample receipt."
Gary A. Pestano, Ph.D.