RESUMEN
Follicular lymphoma (FL) is a clinically heterogeneous disease. The need for treatment, treatment sequencing, number of treatment lines, and its association with survival have not been described in a population-based setting. We identified all patients diagnosed with FL in the Swedish Lymphoma register from 2007 to 2014, followed until 2020, with detailed data on progression/relapse, transformation, and 2nd and further lines of therapy. During a median follow-up of 6.8 years, 1226 patients (69%) received 1st systemic treatment, 358 patients (20%) were managed with watch-and-wait (WaW) only, and 188 (10%) patients were treated with radiotherapy and did not require additional therapy during the study period. Among patients starting systemic treatment, 496 (40%), 224 (18%), and 88 (7%) received 2nd-, 3rd-, or 4th-line therapy, respectively. The 10-year cause-specific cumulative incidence of transformation was 13%. Among patients managed with 1st line R-single, R-CHOP, or BR, 54%, 33%, and 29% required 2nd line, respectively. The cumulative probability of starting subsequent treatment within 2 years was 26% after 1st line and 35% after 2nd line treatment. Two-year OS following 1st, 2nd, 3rd, and 4th line systemic treatment was 84%, 70%, 52%, and 36%, respectively, and remained similar when excluding transformations. We conclude that a substantial proportion of FL patients can be managed with WaW for a long period of time, while patients who require multiple treatment lines constitute a group with a large clinical unmet need. These results constitute valuable real-world reference data for FL.
RESUMEN
Introduction: Analyzing liquid biopsies for tumor-specific aberrations can facilitate detection of measurable residual disease (MRD) during treatment and at follow-up. In this study, we assessed the clinical potential of using whole-genome sequencing (WGS) of lymphomas at diagnosis to identify patient-specific structural (SVs) and single nucleotide variants (SNVs) to enable longitudinal, multi-targeted droplet digital PCR analysis (ddPCR) of cell-free DNA (cfDNA). Methods: In 9 patients with B-cell lymphoma (diffuse large B-cell lymphoma and follicular lymphoma), comprehensive genomic profiling at diagnosis was performed by 30X WGS of paired tumor and normal specimens. Patient-specific multiplex ddPCR (m-ddPCR) assays were designed for simultaneous detection of multiple SNVs, indels and/or SVs, with a detection sensitivity of 0.0025% for SV assays and 0.02% for SNVs/indel assays. M-ddPCR was applied to analyze cfDNA isolated from serially collected plasma at clinically critical timepoints during primary and/or relapse treatment and at follow-up. Results: A total of 164 SNVs/indels were identified by WGS including 30 variants known to be functionally relevant in lymphoma pathogenesis. The most frequently mutated genes included KMT2D, PIM1, SOCS1 and BCL2. WGS analysis further identified recurrent SVs including t(14;18)(q32;q21) (IGH::BCL2), and t(6;14)(p25;q32) (IGH::IRF4). Plasma analysis at diagnosis showed positive circulating tumor DNA (ctDNA) levels in 88% of patients and the ctDNA burden correlated with baseline clinical parameters (LDH and sedimentation rate, p-value <0.01). While clearance of ctDNA levels after primary treatment cycle 1 was observed in 3/6 patients, all patients analyzed at final evaluation of primary treatment showed negative ctDNA, hence correlating with PET-CT imaging. One patient with positive ctDNA at interim also displayed detectable ctDNA (average variant allele frequency (VAF) 6.9%) in the follow-up plasma sample collected 2 years after final evaluation of primary treatment and 25 weeks before clinical manifestation of relapse. Conclusion: In summary, we demonstrate that multi-targeted cfDNA analysis, using a combination of SNVs/indels and SVs candidates identified by WGS analysis, provides a sensitive tool for MRD monitoring and can detect lymphoma relapse earlier than clinical manifestation.