Safety and Short-Term Efficacy of CART Cells in Treatment of Diffuse Large B-Cell Lymphoma with Follicular Transformation

Background：Tissue transformation to Diffuse large B-cell lymphoma(DLBCL) occurs in some patients with follicular cell lymphoma(FL), and these patients have a poor prognosis, and some patients do not respond well to chemotherapy, relapse or disease progression. In recent years, many clinical trials have found that CART cells are have a relatively good effect on relapsed and refractory DLBCL, but what about the effect on DLBCL transformed by FL?

Methods：A total of 13 patients with diffuse large B-cell lymphoma transformed from follicular cell lymphoma who received CART cell therapy in our hospital from January 2020 to January 2021 were observed. All patients had stage III/IV disease (7 patients with stage III and 6 patients with stage IV). Among them, 10 were germinal centers and 3 were non-germinal centers. There were 8 males and 5 females, with a median age of 44 years (33-70 years old), who had undergone more than 2 chemotherapy cycles before admission to our hospital, and the median chemotherapy cycle was 10 cycles (7-19 years old). Among them, 3 had previously undergone other clinical drug trials, 1 had undergone CD20 CART cell immunotherapy, and 1 had undergone radiotherapy. At admission, ECOG was 0-3, and all patients had measurable lesions with a median size of 5cm (1.4cm-12.0cm). After preconditioning, CART cells were reinjected, 12 cases were reinjected with murine anti-CD19-CART, and 1 case was reinjected with humanized anti-CD19-CART. Median volume 3.07×10^6/kg (0.46×10^6/kg -5.43×10^6/kg). The cytokine release syndrome(CRS) and the therapeutic effect of 3 months/6 months after reinfusion were observed, and the endpoint was disease progression or death.

Results：The main treatment related adverse reaction was cytokine release syndrome. Among them, there were 12 I CRS, 1 II CRS, and no treatment-related deaths. The short-term efficacy of 3 months after treatment: 4/13CR（30.8%）, 7/13PR（53.8%）, 2/13 SD/PD(15.4%) and ORR was 11/13 (84.6%). The efficacy of 6 months after treatment: 10/13CR（76.9%）, 0/13PR（0%）and ORR was 10/13 (76.9%). One patient with 3-months CR developed disease at 11 months and died at 12 months, and one patient with 3- months PR developed disease at 5 months and died at 8 months. The remaining 6patients with 3- PR have now achieved CR。the median follow-up time was 10 months (6-19months). Of the 2 patients who did not respond to treatment have achieved PR after subsequent treatment.

Conclusions: It can be seen from this study that CART cells have obvious efficacy and good safety in the treatment of DLBCL transformed by FL. It should be noted that 7 patients had PR status at 3 months after treatment, 6 patients had CR at 6 months after treatment, and 1 patient had disease progression. Efficacy evaluation of patients with DLBCL with potential transformation from FL after CART cell therapy should be appropriately delayed, except that 6 months may be the best time to evaluate the efficacy. At present, the observation time is short, PFS and OS have not been observed, and long-term observation with a larger sample is under way.