Hypo-fractionated radiotherapy combined with PD-1 inhibitor for relapsed/refractory B-cell lymphoma after failure to CD19 CAR-T therapy.

B-cell lymphoma relapsed after chimeric antigen receptor (CAR) T-cell therapy lacks effective standard treatment options and generally has a poor prognosis, largely due to mechanisms such as immune escape and tumor heterogeneity. Radiotherapy combined with immune checkpoint inhibitors (ICIs) may exert synergistic effects, including local tumor control through radiation-induced DNA damage and systemic immune activation via modulation of the tumor immune microenvironment. This case report describes a patient with relapsed/refractory (R/R) B-cell lymphoma who experienced multiple relapses and treatment failures, including CD19 CAR-T therapy. Almost 7 years after CAR-T treatment, the patient developed disease relapse and was diagnosed with follicular lymphoma (FL). The patient received a personalized treatment strategy combining hypo-fractionated radiotherapy (30 Gy/5 fractions) and the Programmed Death-1 (PD-1) inhibitor camrelizumab, achieving complete remission (CR) and remaining disease-free for over 43 months. This case highlights the potential efficacy of this combination strategy in R/R lymphoma, particularly in patients with limited treatment options.