Chimeric antigen receptor (CAR) T cell immunotherapy has achieved complete remission and durable response in highly refractory patients. However, logistical complexity and high costs of manufacturing autologous viral products limit CAR T cell availability.
We reported the early results of a phase I/II trial in B-cell acute lymphoblastic leukemia (B-ALL) patients relapsed after allogeneic hematopoietic stem cell transplantation (HSCT) using donor-derived CD19 CAR T cells generated with the Sleeping Beauty (SB) transposon and differentiated into cytokine induced killer cells (CIK).
The cellular product was produced successfully for all patients from the donor peripheral blood (PB) and consisted mostly of CD3+ lymphocytes with 43% CAR expression. Four pediatric and 9 adult patients were infused with a single dose of CAR T cells. Toxicities reported were two grade I and a grade II cytokine release syndrome (CRS) cases at the highest dose, in the absence of graft-versus-host disease (GvHD), neurotoxicity, or dose-limiting toxicities. Six out of 7 patients, receiving the highest doses, achieved CR and CRi at day 28. Five out of 6 patients in CR were also minimal residual disease (MRD)-negative. Robust expansion was achieved in the majority of the patients. CAR T cells were measurable by transgene copy PCR up to 10 months. Integration site analysis showed a positive safety profile and highly polyclonal repertoire in vitro and at early time points after infusion.
SB-engineered CAR T cells expand and persist in pediatric and adult B-ALL patients relapsed after HSCT. Anti-leukemic activity was achieved without severe toxicities.
This study was supported by grants from AIRC; CRUK; FC AECC; Ministero della salute; FRRB.