Trent Breaks Down Mutation Testing and ctDNA Monitoring in GIST

Welcome to OncLive On Air^®! I’m your host today, Caroline Seymour.

OncLive On Air^® is a podcast from OncLive^®, which provides oncology professionals with the resources and information they need to provide the best patient care. In both digital and print formats, OncLive^® covers every angle of oncology practice, from new technology to treatment advances to important regulatory decisions.

In today’s episode, sponsored by Deciphera Pharmaceuticals, we had the pleasure of speaking with Jonathan C. Trent, MD, PhD, about the accuracy and sensitivity of circulating tumor (ct)DNA in gastrointestinal stromal tumor (GIST). Trent is a professor and associate director for Clinical Research at the Sylvester Comprehensive Cancer Center, part of the University of Miami Health System in Florida.

Treatment for patients with GIST is directed by KIT, PDGFRA, and other genomic alterations, which are typically detected with tissue-based next-generation sequencing (NGS) analysis. However, ctDNA-based NGS may be a rapid, noninvasive alternative.

In a study published in JCO Precision Oncology in 2020, Trent and colleagues showed that ctDNA can be used to evaluate mutations with 100% positive predictive value to tissue-based NGS in patients with metastatic GIST. In the analysis, investigators retrospectively evaluated 43 single-institution patients, revealing 16 (35%) KIT exon 11 mutations, 3 (6%) KIT exon 9 mutations, and 1 (2%) PDGFRA mutation via ctDNA. Resistance mutations were identified in KIT exon 17 (n = 8), exon 13 (n = 3), and in both (n = 3).

In part 2 of our exclusive two-part interview, Dr Trent discussed the need for improved awareness around mutation testing in GIST, the limitations of current clinical trial criteria, and the potential for ctDNA to become a longitudinal cancer monitoring tool, helping to prevent invasive means of measuring disease progression.

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