Expert Weighs in on Use of Cell-Free DNA Testing in NSCLC

Genomic sequencing to help guide treatment for patients with non-small cell lung cancer (NSCLC) has become not only a much talked about topic in cancer care but a vital part of many patient’s treatment plans. This is why the question of whether to use cell-free(cf) DNA testing or traditional tissue testing has become key in the NSCLC space.

At the 2019 World Conference on Lung Cancer (WCLC) in Barcelona, Spain, OncLive^®, a sister publication to Oncology Nursing News, had the chance to sit down with Hai Tran, MD, associate professor at The University of Texas MD Anderson Cancer Center, and discuss the results of a study for advanced NSCLC patients treated with a first-line EGFR-TKI based on mutation detection from tissue or cfDNA-based genomic sequencing.

OncLive^®: Can you discuss the rationale for this study?

Tran: We started initiating using the cfDNA testing in 2015 and initiation of that was there were more and more patients beginning to ask the questions of an alternative to tissue biopsies for genomic testing. So, we started this in 2015 and over that time period with the initial news of the test there were a lot of questions about the validity of the data used to treat our patients.

Then as the test went on through the next 2-and-a-half years, our clinicians began to use more and more of their testing not only on the front-line but also following the patients during their time on therapy to monitor them, rather than to potentially look for response to therapy, but more importantly to look for when the patient does progress and when they could potentially develop a mechanism of resistance.

Can you discuss the study design and results?

With this particular subset of data, what we have is looking at the clinical outcome in comparing tissue base prior to initiation that we use self-DNA testing, and then, in a similar fashion in the same group of patients, in matching 38 patients in each group in the frontline for TKI where the patients are being treated based on tissue or genomic testing results or with the cfDNA testing. With those patients in each cohort, the progression-free survival (PFS) is similar in both populations, there were no statistical differences in their PFS.

What will it take to have a wider adoption of cfDNA-based genomic sequencing for advanced NSCLC?

I think the adoption is slowly growing with a lot of the publications as well as at various meetings such as the 2019 ASCO annual meeting, over the last year. Additional data has been very supportive in the use of cfDNA in conjunction with tissue testing or in replacements. The very exciting news is that in our data set, both the clinical outcome for the frontline EGFR therapy and the concordance, that is comparing the results of the tissue (that being the gold standard) compared to cfDNA, the sensitivity, specificity, and the predicted value is very high. Over 90% accuracy for the cfDNA to match with the tissue.

I also think acceptance is slowly gaining momentum in academia, as well as, in the community practice. That, in conjunction with the simplicity in getting the blood to be collected and shipped, and the rapidity of the results enhances the use of cfDNA testing.

Are there any ongoing challenges with the use of cfDNA?

I think there's going to be a growing body of data to show the use of cfDNA, the question is whether or not it can be used to replace the tissue for genomic testing. I believe it's going to be an amalgam of both tissue and cfDNA blood-based testing in the near future. And I think the most exciting part of it is some of the newer data sets from cfDNA, regarding some of the early patient populations, are using it as a tool to identify patients who are at risk of developing lung cancer as a biomarker for detecting lung cancer.

Secondly, for patients who have lower stage lung cancer who have a surgical receptacle or actually have no disease after initial therapy, they can find these patients a potential marker for recurrence of lung cancer. Ultimately, there's a lot of interest in the data for cfDNA for not only genomic testing in the treatment but also in the early stage and for the patients who are post-surgical being monitored for early recurrences.