Next-Generation Sequencing-Based Monitoring of Circulating Tumor DNA Reveals Clonotypic Heterogeneity in Untreated PTCL
Miloš D. Miljković, Christopher Melani, Stefania Pittaluga, Rahul Lakhotia, Andrea N. Lucas, Allison P. Jacob, Erik Yusko, Elaine S. Jaffe, Wyndham H. Wilson, Mark Roschewski
Abstract
Peripheral T-cell lymphomas (PTCLs) have marked biologic and clinical heterogeneity, which confounds treatment decisions. Advances in circulating tumor DNA (ctDNA) assays using next-generation sequencing (NGS) have improved the detection of molecular relapse and driver mutations in diffuse large B-cell lymphoma and show the potential utility of ctDNA across lymphomas. We investigated NGS-based monitoring of T-cell receptor (TCR) sequences in patients with PTCL undergoing frontline treatment. Of 45 patients, 34 (76%) had tumor-specific clonotypes of the TCRβ or TCRγ genes identified, which included 18 (86%) from baseline tissue and 16 (67%) from baseline serum. Twenty-five (74%) patients had both TCRβ and TCRγ clonotypes, 23 (68%) had more than 1 TCRγ clonotype, and 4 (9%) had multiple TCRβ or TCRγ clonotypes, demonstrating significant intrapatient clonotypic heterogeneity. Among 24 patients with available serial serum samples during treatment, 9 (38%) cleared ctDNA after 2 cycles of therapy, and 11 (46%) had detectable ctDNA at the end of treatment. Patients with detectable ctDNA after therapy showed a trend toward worse survival. Notably, 2 patients with persistently detectable ctDNA after therapy remained in remission with 10 years of follow-up. Clonotypic heterogeneity in tumors and persistence, despite long-term remission, suggests variability in oncological potential. This trial was registered at www.clinicaltrials.gov as #NCT00001337.