Long-Term Follow-Up of Patients With Follicular Lymphoma Using Next Generation Sequencing to Detect Minimal Residual...

Follicular lymphoma (FL) is a highly treatable, indolent non-Hodgkin lymphoma. Although FL is considered incurable, a patient without progression of disease by 24 months after treatment is predicted to have a survival consistent with persons without lymphoma. Using a sensitive assessment of minimal residual disease (MRD), we tested the hypothesis that MRD monitoring can predict long term remissions.

Unselected patients who were in a clinical remission for at least 24 months after their last treatment were enrolled and monitored prospectively for MRD detectability using a sensitive next-generation sequencing assay (clonoSEQ, Adaptive Biotechnologies, Seattle, WA).

Forty-seven consecutive patients were monitored. We evaluated the MRD thresholds 10^-4, 10^-5, and 10^-6 for the ability to predict long-term remissions in this cohort and determined that undetectable disease at 10^-6 was the best predictor with a specificity and negative predictive value (NPV) of 70% and 100%, respectively. While 3 patients exhibited clinical disease progression during the course of the study, none of the 31 patients with persistent MRD undetectability at 10^-6 experienced relapse.

A significant proportion (31/47; 66.0%) of FL patients in clinical remission after ≥24 months following last therapy were undetectable at 10^-6 by a sensitive assay of MRD. The threshold of sensitivity was 100%, specificity 70%, with a PPV of 19%, but a NPV of 100%. Although longer follow-up is needed for confirmation, many of these patients may continue to have durable complete remissions.