Non-invasive detection of somatic mutations using next-generation sequencing in primary central nervous system lymphoma

// Maxime Fontanilles 1, 2 , Florent Marguet 3, 4 , Elodie Bohers 2 , Pierre-Julien Viailly 2 , Sydney Dubois 2 , Philippe Bertrand 2 , Vincent Camus 1, 2 , Sylvain Mareschal 2 , Philippe Ruminy 2 , Catherine Maingonnat 2 , Stephane Lepretre 1 , Elena-Liana Veresezan 5 , Stephane Derrey 6 , Herve Tilly 1, 2 , Jean-Michel Picquenot 5 , Annie Laquerriere 3, 4 and Fabrice Jardin 1, 2 1 Department of Hematology, Cancer Center Henri Becquerel, 76000 Rouen, France 2 INSERM U1245, Cancer Center Henri Becquerel, Institute of Research and Innovation in Biomedicine (IRIB), University of Normandy, UNIVROUEN, 76000 Rouen, France 3 INSERM U1245 and Hopital Charles Nicolle, NeoVasc Team, University of Normandy, UNIVROUEN, CHU-Hopitaux de Rouen, 76031 Rouen, France 4 Department of Neuropathology, Hopital Charles Nicolle, Normandy Center for Genomic and Personalized Medicine, CHU-Hopitaux de Rouen, 76031 Rouen, France 5 Department of Pathology, Cancer Center Henri Becquerel, 76000 Rouen, France 6 Department of Neurosurgery, Hopital Charles Nicolle, CHU-Hopitaux de Rouen, 76031 Rouen, France Correspondence to: Fabrice Jardin, email: fabrice.jardin@chb.unicancer.fr Keywords: primary central nervous system lymphoma, circulating cell-free tumor DNA, somatic mutation, liquid biopsy, next-generation sequencing Received: March 08, 2017     Accepted: May 03, 2017     Published: June 01, 2017 ABSTRACT Purpose: Primary central nervous system lymphomas (PCNSL) have recurrent genomic alterations. The main objective of our study was to demonstrate that targeted sequencing of circulating cell-free DNA (cfDNA) released by PCNSL at the time of diagnosis could identify somatic mutations by next-generation sequencing (NGS). Patients and Methods: PlasmacfDNA and matched tumor DNA (tDNA) from 25 PCNSL patients were sequenced using an Ion Torrent Personal Genome Machine (Life Technologies ® ). First, patient-specific targeted sequencing of identified somatic mutations in tDNA was performed. Then, a second sequencing targeting MYD88 c.T778C was performed and compared to plasma samples from 25 age-matched control patients suffering from other types of cancer. Results: According to the patient-specific targeted sequencing, eight patients (32% [95% CI 15-54%]) had detectable somatic mutations in cfDNA. Considering MYD88 sequencing, six patients had the specific c.T778C alteration detected in plasma. Using a control group, the sensitivity was 24% [9-45%] and the specificity was 100%. Tumor volume or deep brain structure involvement did not influence the detection of somatic mutations in plasma. Conclusion: This pilot study provided evidence that somatic mutations can be detected by NGS in the cfDNA of a subset of patients suffering from PCNSL.