Molecular Characterization of Circulating Tumor DNA in Pediatric Rhabdomyosarcoma: A Feasibility Study
Olivia Ruhen, Nathalie S.M. Lak, Janine Stutterheim, Sara G. Danielli, Mathieu Chicard, Yasmine Iddir, Alexandra Saint‐Charles, Virginia Di Paolo, Lucia Tombolan, Susanne A. Gatz, Ewa Aładowicz, Paula Proszek, Sabri Jamal, Reda Stankunaite, Deborah Hughes, Paul Carter, Elisa Izquierdo, Ajla Wasti, Julia Chisholm, Sally L. George, Erika Pace, Louis Chesler, Isabelle Aerts, Gaëlle Pierron, Sakina Zaïdi, Olivier Delattre, Didier Surdez, Anna Kelsey, Michael Hubank, Paolo Bonvini, Gianni Bisogno, Angela Di Giannatale, Gudrun Schleiermacher, Beat W. Schäfer, Godelieve A.M. Tytgat, Janet Shipley
Abstract
PURPOSE: Rhabdomyosarcomas (RMS) are rare neoplasms affecting children and young adults. Efforts to improve patient survival have been undermined by a lack of suitable disease markers. Plasma circulating tumor DNA (ctDNA) has shown promise as a potential minimally invasive biomarker and monitoring tool in other cancers; however, it remains underexplored in RMS. We aimed to determine the feasibility of identifying and quantifying ctDNA in plasma as a marker of disease burden and/or treatment response using blood samples from RMS mouse models and patients. METHODS: gene fusions were identified in the RMS samples collected at diagnosis. Patient-matched plasma samples collected from 28 patients with RMS before, during, and after treatment were analyzed for the presence of ctDNA via ddPCR, panel sequencing, and/or whole-exome sequencing. RESULTS: Human tumor-derived DNA was detectable in plasma samples from mouse models of RMS and correlated with tumor burden. In patients, ctDNA was detected in 14/18 pretreatment plasma samples with ddPCR and 7/7 cases assessed by sequencing. Levels of ctDNA at diagnosis were significantly higher in patients with unfavorable tumor sites, positive nodal status, and metastasis. In patients with serial plasma samples (n = 18), fluctuations in ctDNA levels corresponded to treatment response. CONCLUSION: Comprehensive ctDNA analysis combining high sensitivity and throughput can identify key molecular drivers in RMS models and patients, suggesting potential as a minimally invasive biomarker. Preclinical assessment of treatments using mouse models and further patient testing through prospective clinical trials are now warranted.