Anti-CD19 Chimeric Antigen Receptor T Cell Treatment of Relapsed /Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Resistant to Bruton's Tyrosine Kinase (BTK) Inhibitor
Authors: Chen Weihong , Du Xin , Zhou Wenyujing , Luo Changru , LI Xiaoqing 
Published: November 2020

CASE PRESENTATION: A 68-year-old male was diagnosed with CLL/SLL in November 2007. Bone marrow asp/bx: 36.5% lymphocytes, 78% CD19, 65% ATM (11q22 deleted) positive cells, 13.5% D13S25 (13q14.3 deleted). On December 10, 2009, the patient took FCR scheme for five cycles, followed by FR scheme for one cycle, and then a month of Chlorambucil. On September 5, 2013, the patient took BR scheme for four cycles with no effect. From March 2015 to Feb 2016, 420 mg of Ibrutinib was administered daily. On January 15, 2016, the patient developed swollen lymph nodes in his right neck with intermittent lumps, fever and nausea. He was admitted into the hospital at Feb 2, 2016. Test results: multiple swollen superficial lymph nodes over the body, with the biggest measuring 60×30mm on the right neck, with no tenderness. Supplementary tests: peripheral white blood cells (WBC) 11.94×10E9/L, lymphocyte 7.5×10E9/L, CD19 cells 6.73×10E9/L, bone marrow lymphocyte 62%, peripheral blood lymphocyte 52%. Immunophenotype: CD5, CD19, CD20dim, CD23, CD11b dim, HLA-DR expression, visible CD5+CD19+ cell clusters, and visible immunoglobulin cKappa with restricted expression.
On March 10, 2016, peripheral blood platelet 60 × 10E9/L, CD19 cells 1.94×10E9/L, lactate dehydrogenase 460U/L, FER 115.6ng/ml, hepatitis B virus carrier. Diagnosis: CLL/SLL IV stage, ATM (11q22) deletion, D13S25 (13q14. 3) positive, CD19 positive. Relapse of CLL/SLL occurred again after four months and at this stage the patient was considered for therapy in a clinical trial of CD19-specific chimeric antigen receptor (CAR-) T cell therapy. Ethical approval and informed consent were obtained for anti-CD19 CAR T Cell treatment of ibrutinib resistance in relapsed/refractory CLL/SLL. We infused autologous T cells transduced with a CAR T 19 retroviral vector with CLL/SLL at doses of 3.3 × 10E8 CART19 cells on Mar. 16 2016. Patients were monitored for responses, toxic effects, and the expansion and persistence of circulating CART19 cells. After CART19 cells were infused, the patient experienced chills, fever, headache, weak, anorexia, nausea, shortness of breath, chest tightness, heart palpitation, hypotension and shock for 9 days. The serum levels of IFN-Υ were at their highest at day 7 after CAR T cells infusion. Serum interleukin 6 (IL-6) was at 680pg/ml and CD3+ cells were 97.5%, CD8+ cells 72.8% (18.7-32.8%), FER was 1529.5ng/ml (Normal No. 22-322ng/ml) 14 days after CAR-T cell infusion. The serum levels of IL-6 were at their highest at day14. The patient was diagnosed as having cytokine release syndrome. After the patient took the anti-IL-6R antibody and anti-TNF antibody, he began to recover gradually. Enlarge lymph nodes shrunk after being infused with CART19 cells for 7 days. The peripheral blood CD19 B lymphocytes were 0 on day 14 after infused with CAR T19 cells. Q-PCR was used to detect the amount of the peripheral blood CART19 cells, which stood at 5485 copies/μl, 924 copies/μl, 191 copies/μl respectively 2 weeks, 6 weeks and 3 months after infusing with CART19 cells.
The peripheral blood CART 19 cells were not detectable 4 months after infusing with CART19 cells until present. The lymphadenopathy was decreased gradually after 14 days of infusion. The MRI test showed that lymphadenopathy reduced markedly or disappeared after 6 months of infusion. ATM (11q22 deleted) negative, D13S25 (13q14.3 deleted) negative. After treatment with CAR T 19 cell therapy for 53 months, the patient remained disease-free, the patient's lymph nodes, lymphocytes and I mmunoglobulins were normal.
CONCLUSIONS : Cancer immunotherapy as a method of cancer treatment is the most effective after conventional treatments such as radiotherapy, chemotherapy, and surgery. For BTK Inhibitor resistance in relapsed and refractory CD19+ CLL/SLL, CD19 is a favorable target, because the expression of CD19 is limited to B cells and not present in other tissues or cells. Currently, the efficacy of this treatment in treating CLL/SLL remains to be seen. The effects of chemotherapy on the patient's B cell lymphoma are negligible, due to the fact that his CLL/SLL have become relapsed and refractory. As a result we chose the CAR T19 cell therapy genetic engineering technique as a method of treatment, to which the patient has responded well. Therefor, CAR T cell technology overcome the limitations of existing cancer therapies and has great potential for development and application.

Disclosures
No relevant conflicts of interest to declare.