Humanized CD19-Targeted Chimeric Antigen Receptor (CAR) T Cells in CAR-Naive and CAR-Exposed Children and Young Adults With Relapsed or Refractory Acute Lymphoblastic Leukemia.

PURPOSE: CD19-targeted chimeric antigen receptor (CAR)-modified T cells demonstrate unprecedented responses in B-cell acute lymphoblastic leukemia (B-ALL); however, relapse remains a substantial challenge. Short CAR T-cell persistence contributes to this risk; therefore, strategies to improve persistence are needed. METHODS: We conducted a pilot clinical trial of a humanized CD19 CAR T-cell product (huCART19) in children and young adults with relapsed or refractory B-ALL (n = 72) or B-lymphoblastic lymphoma (n = 2), treated in two cohorts: with (retreatment, n = 33) or without (CAR-naive, n = 41) prior CAR exposure. Patients were monitored for toxicity, response, and persistence of huCART19. RESULTS: Seventy-four patients 1-29 years of age received huCART19. Cytokine release syndrome developed in 62 (84%) patients and was grade 4 in five (6.8%). Neurologic toxicities were reported in 29 (39%), three (4%) grade 3 or 4, and fully resolved in all cases. The overall response rate at 1 month after infusion was 98% (100% in B-ALL) in the CAR-naive cohort and 64% in the retreatment cohort. At 6 months, the probability of losing huCART19 persistence was 27% (95% CI, 14 to 41) for CAR-naive and 48% (95% CI, 30 to 64) for retreatment patients, whereas the incidence of B-cell recovery was 15% (95% CI, 6 to 28) and 58% (95% CI, 33 to 77), respectively. Relapse-free survival at 12 and 24 months, respectively, was 84% (95% CI, 72 to 97) and 74% (95% CI, 60 to 90) in CAR-naive and 74% (95% CI, 56 to 97) and 58% (95% CI, 37 to 90) in retreatment cohorts. CONCLUSION: HuCART19 achieved durable remissions with long-term persistence in children and young adults with relapsed or refractory B-ALL, including after failure of prior CAR T-cell therapy.

Autologous CD4 T Lymphocytes Modified with a Tat-Dependent, Virus-Specific Endoribonuclease Gene in HIV-Infected Individuals.

MazF is an Escherichia coli-derived endoribonuclease that selectively cleaves ACA sequences of mRNA prevalent in HIV. We administered a single infusion of autologous CD4 T lymphocytes modified to express a Tat-dependent MazF transgene to 10 HIV-infected individuals (six remaining on antiretroviral therapy [ART]; four undergoing treatment interruption post-infusion) in order to provide a population of HIV-resistant immune cells. In participants who remained on ART, increases in CD4 and CD8 T cell counts of ~200 cells/mm3 each occurred within 2 weeks of infusion and persisted for at least 6 months. Modified cells were detectable for several months in the blood and trafficked to gastrointestinal lymph tissue. HIV-1 Tat introduced ex vivo to the modified CD4+ T cells induced MazF expression in both pre- and post-infusion samples, and MazF expression was detected in vivo post-viral-rebound during ATI. One participant experienced mild cytokine release syndrome. In sum, this study of a single infusion of MazF-modified CD4 T lymphocytes demonstrated safety of these cells, distribution to lymph tissue and maintenance of Tat-inducible MazF endoribonuclease activity, as well as sustained elevation of blood CD4 and CD8 T cell counts. Future studies to assess effects on viremia and latent proviral reservoir are warranted.