Humanized CD19 CAR-T cells in relapsed/refractory B-ALL patients who relapsed after or failed murine CD19 CAR-T therapy

Abstract

Background For CD19-positive relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL) after treatment with murine CD19 (mCD19) CAR-T, the reinfusion of mCD19 CAR-T cells may be ineffective due to anti-mouse single-chain variable fragment (scFv) antibody caused by mCD19 CAR. To overcome this immunogenicity, we applied humanized CD19 (hCD19) CAR-T cells to treat r/r B-ALL patients with prior mCD19 CAR-T therapy. Methods Nineteen pediatric and adult patients were included, 16 relapsed after and 3 were primarily resistant to mCD19 CAR-T. All patients presented with more than 5% blasts in bone marrow and/or extramedullary disease, and still showed CD19 antigen expression. Humanized CD19-CARs were lentiviral vectors carrying a second generation CAR with 4–1-BB co-stimulatory and CD3ζ signaling domains. Patient-derived cells were collected for producing CAR-T cells, the median dose of infused hCD19 CAR-T cells was 2.4 × 105/kg (range, 1.0–18.0 × 105/kg). Results hCD19 CAR-T resulted in a complete remission (CR) rate of 68% (13/19). Among 13 remission patients, 11 underwent allogeneic hematopoietic cell transplantation (allo-HCT) (3 were second HCT) and 10 remained in CR; the event-free survival rates at 12–18 months were 91% in 11 patients received following allo-HCT and 69% in all CR patients. Six cases had no response to hCD19 CAR-T, 3 died of disease progression; another 3 received salvage second transplantation, of them, 2 relapsed again (one died). Cytokine release syndrome (CRS) occurred in 95% (18/19) of patients, most CRS events were grade 1 and grade 2 (n = 17), there was only one grade 4 CRS. Two cases experienced grade 1 neurotoxicity. Conclusions Humanized CD19 CAR-T cell therapy could be a treatment option for CD19-positive B-ALL patients who relapsed after or resisted prior murine CD19 CAR-T, hCD19 CAR-T followed by allo-HCT provided a longer remission in CR patients. Nevertheless, the prognosis of non-responders to hCD19 CAR-T remained dismal. Trial registration Chinese Clinical Trial Registry/WHO International Clinical Trial Registry (ChiCTR1900024456, URL: www.chictr.org.cn); registered on July 12, 2019.

Safety and efficacy of autologous and allogeneic humanized CD19-targeted CAR-T cell therapy for patients with relapsed/refractory B-ALL

“…It was manufactured as described before. 13 Briefly, autologous peripheral blood mononuclear cells (PBMCs) or allogeneic PBMCs apheresed directly from the allo-HSCT donors were stimulated with magnetic beads coated with anti-CD3/CD28 antibodies (Thermo Fisher Scientific) overnight. The next day, transduction via a lentiviral vector was performed at a multiplicity of infection 1:10 ratio.…”

Safety and efficacy of co-administration of CD19 and CD22 CAR-T cells in children with B-ALL relapse after CD19 CAR-T therapy

“…Myers et al used humanized CD19 CAR-T to treat patients who relapsed after murine-derived CAR-T therapy and reported a 1-month ORR of 64% [ 41 ]. Similarly, An et al observed a CR rate of 68% in their cohort [ 42 ]. Further investigation is needed to determine whether the recurrence in pt01 after CART2 was attributable to anti-murine CAR immunogenicity.…”

Characterization of the input material quality for the production of tisagenlecleucel by multiparameter flow cytometry and its relation to the clinical outcome

“…Thus, a combination of these factors might severely impair the treatment outcome among patients with primary refractory DLBCL. Any solution to these problems would be complicated − for example, such patients could be considered for clinical trials with enhanced next-generation CAR-T cell products, which can be rapidly manufactured from the original apheresis for commercial CAR-T cell products ( 16 ). Hence, patients with primary refractory DLBCL without detectable CAR-T cell expansion would be such candidates.…”