Utility of Minimally Invasive Plasma-Based NGS Expands in NSCLC

As the role of targeted therapy continues to gain momentum in non–small cell lung cancer (NSCLC), plasma-based next-generation sequencing (NGS) also continues to offer a minimally invasive, highly specific modality to identify patients with actionable alterations, explained Charu Aggarwal, MD, MPH, in a virtual presentation during the 4th Annual International Congress on Oncology and Pathology^TM.¹

The technology, which has the ability to personalize treatment, could improve outcomes, minimize potential immunotherapy-induced myelosuppression, and lower overall adverse effects for patients with NSCLC, said Aggarwal, who is the Leslye M. Heisler Assistant Professor of Medicine in the Division of Hematology-Oncology at the University of Pennsylvania.

“Based on an improved understanding of the lung cancer biology, we have been able to now dissect lung cancer, especially NSCLC into several distinct buckets, which are increasingly becoming actionable.” said Aggarwal. “We know that lung cancer is complex, and that tremendous progress has been made. We [also] know that it’s important to deliver personalized medicine, [but] how should we go about identifying these patients?”

While the utility of liquid biopsy has remained a widely debated topic in oncology, Aggarwal suggested that in cases of inadequate or unavailable tissue, plasma-based testing could identify actionable targets including mutations, copy-number alterations, gene fusions, and DNA methylation.

Additionally, Aggarwal suggested that concurrent tissue and plasma testing should be considered in patients with newly diagnosed NSCLC for which adequate tissue is available.

Among potentially identifiable markers, multiple FDA-approved agents are available to treat patients who harbor alterations in EGFR, ALK, ROS1, BRAF, MET, RET, and NTRK.

Data to Support Plasma-Based NGS Testing

Findings from a prospective cohort study of which Aggarwal was the lead author on showed that the addition of plasma-based NGS to tissue-based testing led to markedly improved detection of targetable mutations in patients with stage IV NSCLC.² Moreover, as more patients with actionable targets were identified, NGS improved the delivery of molecularly guided therapy.

Of 323 patients, actionable mutations were detected in 20.5% of patients who underwent tissue testing alone. When plasma testing was added, 35.8% of patients had a targetable alteration identified.

Results from the Noninvasive versus Invasive Lung Evaluation (NILE) study demonstrated a similar rate of guideline-recommended biomarker detection but with a faster turn-around time with liquid biopsy compared with tissue biopsy.³

In the study, the addition of the Guardant360 NGS panel to tissue biopsy increased the rate of biomarker detection by 48%. Additionally, the results of the liquid biopsy were delivered within 9 days versus 15 days with tissue biopsy (P <.0001).

In addition to these findings, data from a post-hoc analysis of the phase 3 AURA trial demonstrated similar response rates and progression-free survival for patients with EGFR T790M-positive NSCLC treated with osimertinib (Tagrisso) regardless of whether tumor- or plasma-based testing was implemented.⁴ Moreover, the study suggested that some patients with EGFR T790M-positive NSCLC as determined by a validated plasma-based assay could avoid invasive tumor-based testing.

The study also suggested that upon T790M-negative results, concurrent plasma and tissue testing should be implemented to rule out false negatives.

Limitations of NGS

Although the specificity of tumor biopsy and liquid biopsy are high, the sensitivity of blood-based testing is lower than that of tissue-based testing.

Moreover, as liquid biopsy measures the amount of circulating tumor DNA (ctDNA) in the blood that is shed from the tumor, the modality may not have as much success in low-shedding intrathoracic tumors, for example, or tumors with low tumor burden.

Of particular interest is the fact that allelic fraction does not correlate with response with liquid biopsy. Also, patients who have visceral metastases have a higher rate of ctDNA and therefore a higher rate of detection of targetable mutations, said Aggarwal.

The Future of Plasma-Based Testing

Beyond alteration identification, evidence has shown that ctDNA testing could have utility in monitoring resistance to treatment, measuring minimal residual disease in early-stage NSCLC, predicting potential post-surgery relapses, and detecting tumor mutational burden.

Although more research is needed to flesh out the full utility of plasma-based testing, Aggarwal is certain that the modality is “here to stay.”

“Beyond lung cancer, there are certain applications that are being used that are cancer specific and platform specific that are going to be very useful in the future,” she said.

“Plasma NGS is a powerful tool for targeted therapy. [It] is an easy, fast, and minimally invasive way to rule in a mutation. I suggested an algorithm which I use in my clinic in case of inadequate or unavailable tissue. [This has] truly given us an [alternate testing] option and a way to offer personalized therapy to our patients,” Aggarwal concluded.

References:

1. Aggarwal C. ctDNA and the “Liquid First” Concept. Presented at: 4th Annual International Congress on Oncology and Pathology^T; June 20, 2020; Virtual.
2. Aggarwal C. Thompson JC, Black TA, et al. Clinical implications of plasma-based genotyping with the delivery of personalized therapy in metastatic non–small cell lung cancer. JAMA Oncol. 2019;5(2):173-180. doi:10.1001/jamaoncol.2018.4305
3. Leighl NB, Page RD, Raymond VM, et al. Clinical utility of comprehensive cell-free DNA (cfDNA) analysis to identify genomic biomarkers in newly diagnosed metastatic non-small cell lung cancer (mNSCLC) [published online ahead of print, April 15, 2019]. Clin Cancer Res. doi:10.1158/1078-0432.CCR-19-0624
4. Oxnard GR, Thress KS, Alden RS, et al. Association between plasma genotyping and outcomes of treatment with osimertinib (AZD9291) in advanced non–small cell lung cancer. J Clin Oncol. 2016;34(28):3375-3382. doi:10.1200/JCO.2016.66.7162