Real-Time Monitoring of Circulating Tumor DNA and Study of Prognostic Factors in Patients Treated With CAR-T Cells

The main objective is to demonstrate the feasibility of monitoring residual disease in real time by monitoring circulating tumor DNA in patients with relapsed or refractory diffuse large cell B-cell lymphoma treated with anti-CD19 CAR-T (axi-cel, tisa -cel or liso-cel). The primary endpoint of the study is to assess the capacity of our research lab to transmit the result of the molecular characterization of the residual disease (MRD) sampled on Day+7 (+/- 3 days) of the injection of CAR-Ts (MRD evaluated by the quantity of ctDNA by NGS technique) of the patient with DLBCL R/R treated with CAR-T, to the recruiting investigator no later than Day+28 (+ /- 3 days). We will evaluate the proportion between the number of informative evaluable patients (patients with at least one detectable mutation in pre-treatment and having reached the PET-CT evaluation of Day+28) and the total number of informative patients (patients with at least one mutation detectable in pre-treatment). The target will be achieved and real-time MRD assessment will be considered feasible if the proportion is at least 80%. Patients who do not have a detectable mutation in pre-treatment ("non-informative patients for follow-up of residual disease"), as well as patients who do not reach the ctDNA sample by Day+7, and/or do not not reaching the PET-CT by Day+28, will be considered as not evaluable for the primary endpoint, and will be the subject of a separate descriptive analysis and will be evaluable for the secondary objectives. We took this into account when evaluating the number of patients to include. Day0 corresponds to the day of injection of the CAR-Ts, Day+7 corresponds to the 8th day post-injection of the CAR-Ts, and D+28 refers to the planned date of the PET-CT evaluation of Day+28 (this examination being the "gold standard" for the evaluation of the response to treatment with CAR-T).