[Pseudoprogression after CAR-T cell therapy: friend or foe?.]

Introduction: Pseudoprogression is a complication observed following CAR-T therapy that can mimic disease progression; however, its incidence is not well defined. This phenomenon is driven by a robust inflammatory response due to the recognition of CAR-T cells targeting the lymphoma. Misinterpreting pseudoprogression as true disease progression could result in unnecessary alterations to the treatment regimen.

Clinical case: Here, we present a case of a 69-year-old patient with diffuse large B-cell lymphoma (DLBCL) who received axicabtagene ciloleucel as fourth line therapy and exhibited pseudoprogression on Pet scans at 3 and 9 months after treatment. Two biopsies performed to investigate these findings were negative for lymphoma recurrence. The patient has been in complete metabolic remission for three years following the infusion.

Conclusions: Biopsy is crucial for distinguishing between pseudoprogression and disease progression in patients with DLBCL after CAR-T therapy. However, obtaining a biopsy may be challenging when lesions are closed to vital organs or major blood vessels, complicating the procedure and increasing the risk of complications.