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

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.

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.

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.