Determination of the biodistribution of chimeric antigen receptor-modified T cells against CD19 in NSG mice.

Along with the rising of the development of CAR-T therapy, the biodistribution and in vivo proliferation of CAR-T cells which are the basis of their effectiveness and safety, have aroused much attention. For IND application, the biodistribution characteristics of CAR-T cells are required to be determined using at least two methods (both quantitative and qualitative evaluation could be applicable) for a comprehensively understanding of their potential target organs/tissues. This chapter takes the CD19 targeted CAR-T cell as an example, to introduce the most commonly used experimental procedure and technical points of using tumor-bearing NSG mice to perform biodistribution research based on in vivo optical imaging, flow cytometry, histopathology/immunochemistry and real-time quantitative PCR. Although these protocols are not fully standardized and could be further optimized, the data obtained from these approaches has been accepted by U.S. Food and Drug Administration and China Food and Drug Administration.

Preclinical efficacy and safety evaluation of interleukin-6-knockdown CAR-T cells targeting at CD19.

BACKGROUND: ssCART-19 cells with shRNA-IL-6 gene knockdown were subjected to a comprehensive safety evaluation, including efficacy, toxicity and biodistribution studies in NSG (PrkdcscidIL2rgtm1 /Bcgen) mice. METHODS: NSG mice were administered Raji-Luc and then singly dosed with ssCART-19 cells via intravenous infusion. ssCART-19 DNA fragments were quantified in different tissues by qPCR, and the optical intensity of Raji-Luc was determined for evaluate the efficacy of regular CAR-T and ssCART-19 cells. In toxicity study, clinical symptoms observation, body weight measurements, serum biochemical analysis, human cytokine detection, lymphocytes subsets quantification, necropsy and histopathological examination were performed. RESULTS: The ssCART-19 DNA was mainly concentrated in the liver within 3 hours, and was widely distributed in most of the organs/tissues for 4 weeks after administration. Chimeric antigen receptor gene modified T cells (CAR-Ts) were detected in the peripheral blood with a significant increase in number beginning at approximately 3 weeks. ssCART-19 administration resulted in increased of interferon-gamma (IFN-γ), tumor necrosis factor (TNF), interleukin-2 (IL-2), and IL-17A and decreased IL-10 and IL-6 levels. ssCART-19 inhibited the proliferation of Raji-Luc cells in tumor-bearing NSG mice, and reduced the incidence of lymphomas in the liver, kidneys and spleen. It alleviated clinical symptoms caused by tumor cell proliferation in treated animals. CONCLUSIONS: ssCART-19 prolongs the survival time of tumor-bearing mice without obvious risks of immunotoxicity and tumorigenicity. ssCART-19 DNA was found in the brains of treated animals, however no significant central nervous system toxicity was observed. These data were used to support an investigational new drug (IND) application of ssCART-19 for clinical trial in China.

Preclinical safety evaluation of chimeric antigen receptor-modified T cells against CD19 in NSG mice.

BACKGROUND: With the increase of chimeric antigen receptor-modified T (CAR-T) cell therapy, serious complications initiated by CAR-T cells have garnered wide attention. We have previously developed a 4-1BB/CD3-ζ-costimulated CAR-T cells against CD19 (CART19) for adult acute lymphoblastic leukemia (ALL). In this study, a preclinical safety assessment of CART19 was performed on NSG mice, to evaluate the preclinical toxicity along with its efficacy and tissue distribution. METHODS: A total of 120 NSG mice were used for a combined pharmacodynamics and toxicity study for 56 days. Ninety-six mice of which were single dosed with Raji-Luc (5×105 per animal, i.p.) and different concentrations of CART19 (0.2×107, 0.6×107 and 1.8×107 per animal, i.v.), while the rest were assigned to the Untreated group. Optical intensity of Raji-Luc in mice, clinical symptoms, body mass, hematological analysis, humanized cytokine, lymphocyte subset counting, necropsy and histopathological examinations were performed. In addition, a single dose of 0.6×107 CART19 was intravenously administered to 48 NSG mice, and the distribution of CART19 in different tissues was analyzed using quantitative PCR. RESULTS: CART19 is widely distributed in organs well-perfused with blood, including the lungs, blood, bone marrow, liver and spleen. Significant proliferation of CART19 was also found in the blood by through recognition using humanized CD3+ for T lymphocytes. The survival rate and leukemia related clinical symptoms in mice administered CART19 were markedly ameliorated, and the proliferation of Raji cells in mice was effectively inhibited. However, CART19 had no obvious effects on either the mean body mass or the blood cell counts, and no cytokine release syndrome and graft versus host disease were observed. CONCLUSIONS: NSG mice given CART19 treatment demonstrated a longer survival period without significant immunotoxicity, suggesting encouraging clinical prospects for CART19 in patients with R/R ALL. Our study shed light on evaluation and supervision strategies for CAR-T products for the treatment of hematological diseases or leukemia.

Some limit theorems for weighted negative quadrant dependent random variables with infinite mean.

In the present paper, we will investigate weak laws of large numbers for weighted pairwise NQD random variables with infinite mean. The almost sure upper and lower bounds for a particular normalized weighted sum of pairwise NQD nonnegative random variables are established also.