The clinical study on treatment of CD19-directed chimeric antigen receptor-modified T cells in a case of refractory Richter syndrome

Richter syndrome (RS) indicates the transformation of chronic lymphocytic leukemia (CLL) into an aggressive lymphoma (mostly DLBCL). Richter syndrome is a rare complication with an aggressive clinical course, bearing an unfavorable prognosis. Currently, there is no effective treatment for it. As a novel cellular-based immune therapy, chimeric antigen receptor-modified T (CART) cells treatment is gradually used in treating hematological malignancies, especially in CD19⁺ B-cell malignancy. Therefore, CD19-directed chimeric antigen receptor-modified T cells (CART-19) treatment is promising to be used as a new method for RS patients. In our study, one RS patient expressing high level of CD19 molecule was enrolled in clinical trial; he has received a series of treatments but did not achieve a satisfactory therapeutic effect. The patient totally received 3.55 × 10⁸ autologous CART-19 cells infusion. After CART-19 infusion, the mainly clinical side effect was repeated fever. The maximal duration period was 24 days and the highest temperature was 40.1°C. Pancytopenia and significantly serum cytokines level rise were observed, including IFN-γ, IL-6, and IL-10. Before discharge, the level of cytokines reduced to normal levels. In addition, we detected the serum biochemical indices as like K⁺ , Ca²⁺ , creatinine, and glutamic-pyruvic transaminase, all of these indices were normal. This showed that there was no tumor necrosis syndrome after treatment. The proportion of B cells in patient's peripheral blood decreased from 72% to 40.2% after infusion, co-occurring with reduction in lymph nodes and hematopoietic reconstitution. Based on the recent revolution in the therapeutic landscape for hematological malignancies including B-cell lymphomas, CART-CD19 cell therapy as a new therapeutic option for RS might be available in the coming years. It aims to reduce patient's tumor burden, prolong their survival time, and provide opportunities for other sequential therapy such as chemotherapy and bone marrow transplantation.