MRD-Adapted Low-Dose Radiation Therapy During Frontline Chemoimmunotherapy for Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is commonly treated with frontline chemoimmunotherapy regimens such as R-CHOP or related combinations. Early response assessment using positron emission tomography (PET) imaging provides prognostic information but may not fully capture minimal residual disease. Circulating tumor DNA (ctDNA)-based MRD assays allow for sensitive detection of molecular residual disease during treatment. This study evaluates an MRD-adapted treatment strategy that integrates interim PET imaging and ctDNA MRD testing during frontline therapy for DLBCL. Patients receiving standard-of-care chemoimmunotherapy undergo MRD testing and PET imaging after cycle 2 of treatment. Patients with detectable MRD may receive low-dose radiation therapy (LDRT) directed at residual PET-avid disease sites, while patients with undetectable MRD continue standard therapy without radiation.