Liquid biopsy for disease monitoring after anti-CD19 chimeric antigen receptor T cell in diffuse large B-cell...

Chimeric antigen receptor T cells (CARTs) against CD19 antigen represent an effective therapy for relapsed/refractory diffuse large B-cell lymphoma (rrDLBCL). There is no diagnostic test able to predict which patients with residual disease will relapse from those that will reach a delayed complete response. Positron emission tomography/computed tomography scan (PET-CT) is characterized by a significant number of false positive results after immunotherapy. Circulating tumor DNA (ctDNA) may be a good-useful tool to quantify minimal residual disease and for monitoring disease response.

We present a patient with DLBCL treated with CART cells in which we tested the combined use of ctDNA and PET-CT scan.

Disease reassessment with PET-CT scan showed a partial remission (3 weeks) and a very good partial remission (2 months). A clinical progression at 3 months was confirmed with PET-CT scan. Levels of ctDNA progressively decreased and became undetectable. An initial increase in KMT2D p.E4385G variant allele frequency confirmed disease progression.

Our case shows how the complementary use of ctDNA and PET-CT scan could be a helpful tool in the clinical management of these patients.