LOS ANGELES – A newer blood test (GeneStrat from Biodesix) identified genetic mutations in lung tumors in about 24 hours, allowing for an early start of mutation-specific chemotherapy, in an investigation from Gundersen Health System in La Crosse, Wis.
Interventional pulmonologists drew blood samples when they performed biopsies on 84 patients with highly suspicious lung nodules and submitted both blood and tissue for mutation analysis. The blood was analyzed by Biodesix, the maker of GeneStrat, a commercially available digital droplet polymerase change reaction assay launched in 2015. The company sent the results back in an average of 24.1 hours, and all within 72 hours. The mutation results from tissue analysis took 2-3 weeks.
Fifteen patients (18%) had actionable epidermal growth factor receptor, anaplastic lymphoma kinase, or K-Ras protein gene mutations, and were candidates for targeted therapy. Compared with tissue testing, the blood assay had a sensitivity of 88% and a specificity of 99%. The tissue testing picked up two mutations missed by blood testing. One of the two mutations is rare and was not included in the blood assay. Meanwhile, the assay caught a mutation missed on tissue analysis.
M. Alexander Otto/Frontline Medical News
Dr. Jennifer Mattingley
She and her colleagues are now routinely using GeneStrat to guide initial lung cancer therapy. “The turnaround time is fantastic. It allows us to have [the mutation status] when oncologists meet with patients for the very first time,” she said.
It “definitely” makes a difference. “If you have an actionable mutation and there’s a targeted chemotherapy” – such as erlotinib (Tarceva) for epidermal growth factor receptor mutation patients – it can be started right out of the gate. “Time to treatment is very important,” not just psychologically for patients but also for them to have the best chance against the tumor. The sooner “we can start a targeted therapy,” the better outcomes are likely to be, Dr. Mattingley said.
When mutation status is delayed, patients might be started “on the wrong therapy upfront, and it’s really hard to back up and start over again,” she said.
“Once we give patients a diagnosis of lung cancer, the next thing they should hear right away is how we are going to attack it. We felt strongly [that there was a] need to look at this to see if we could truly expedite the time from diagnosis to treatment. We believe our patients should have no sleepless nights,” Dr. Mattingley said.
There’s also usually not much tissue left after genetic work-up to send into a clinical trial. Using blood to identify mutations “may allow us to conserve our tissue block for future trials, but still get the genetic information we need to start treatment plans for our patients,” she said.
There was no company funding for the work, but Dr. Mattingley is a speaker for GeneStrat’s maker, Biodesix.