The level of regulatory T lymphocyte detected by flow cytometry in chimeric antigen receptor T cell immunotherapy and its clinical significance / 中华检验医学杂志

ABSTRACT

Objective:To investigate the characteristics of changes in peripheral blood regulatory T lymphocyte (Treg) levels in patients with B-cell lymphoma who received chimeric antigen receptor (CAR)-T cell immunotherapy, and the relationship between Treg levels and optimal efficacy and treatment response.Methods:The data of 23 patients with relapsed/refractory B-cell malignancies who received CD19/CD22 CAR-T cell immunotherapy in Wuhan Tongji Hospital from 2019 to 2021 were retrospectively studied. The enrolled patients were divided into complete remission (CR) group (8 cases), partial remission (PR) group (7 cases) and no response(NR) group (8 cases) according to Lugano′s revised lymphoma efficacy evaluation criteria. A total of 16 patients with B-cell lymphoma who did not receive CAR-T cell immunotherapy during the same period in Wuhan Tongji Hospital were collected as the control group.In different periods during CAR-T cell immunotherapy, multicolor flow cytometry(MFC) was used to dynamically detect peripheral blood the proportion of Treg in CD4 +T cells (Treg/CD4 +T), the proportion of lymphocytes (Treg/Lym), the proportion of Treg in white blood cells (Treg/WBC), and the absolute number of Treg (Treg#). The trend of Treg levels over time, as well as the differences in Treg levels in patients with different prognosis groups in different periods were analyzed.According to the proportion of Treg and the median level of absolute number within 1 to 15 days after CAR-T cell infusion, the patients were divided into a low-level group with 11 cases and a high-level group with 12 cases. The statistical differences in the peak value of CAR-T copy, iron protein, and IL-6 were compared between various groups. Independent samples t test, Mann-Whitney U test, Cox-Stuart trend existence test and one-way analysis of variance was used in statistical analysis. Results:In the 23 patients who received CAR-T cell immunotherapy, the mean values of Treg/CD4 +T and Treg/Lym before CAR-T cell infusion were (20.42±7.96)% and (13.61±7.13)%, respectively, which were significantly higher than that of the control group [(7.33±3.61)%, t=5.893, P<0.001; (1.91±0.90)%, t=6.53, P<0.001]. The number of Treg in the meantime was significantly lower [(1.81±1.52)/μl<(13.66±9.89)/μl, t=4.261, P<0.001]. After infusion, Treg/CD4 +T and Treg/Lym all remarkably decreased ( P<0.001),Treg/WBC increased significantly( P=0.01). The mean values of Treg/CD4 +T (12.87±1.93)%, Treg/Lym (6.35±2.84)%, and Treg/WBC (0.05±0.05)% in the patients with CR as the best response group were lower than those in the PR group [(29.68±5.49)%( P<0.01), (21.85±2.1)%( P<0.01), 0.50±0.69( P<0.05)] before CAR-T cell immunotherapy. Patients with lower mean Treg/CD4 +T within 1 to 15 days after reinfusion of CAR-T cells had higher peak CAR-T copy number ( P<0.05). Conclusion:Treg/CD4 +T and Treg/Lym were increased and then decreased during CAR-T treatment in B cell malignancies. The patients with lower proportions of Treg before infusion have favorable treatment efficacy. Besides, patients with lower Treg/CD4 +T after infusion have better CAR-T cell expansion. In the process of CAR-T cell immunotherapy, the use of MFC to dynamically monitor the proportion of Treg has certain clinical significance for the prediction of the optimal efficacy of immunotherapy and the prediction of treatment response.