In a Chinese single-institution phase I study reported in the Journal of Clinical Oncology, Pan et al found that donor-derived CD7 chimeric antigen receptor (CAR) T-cell therapy produced a high complete remission rate in patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL).
Twenty patients from Beijing Boren Hospital were enrolled into the trial between July and December 2020. They received anti-CD7 CAR T cells manufactured from either previous stem cell transplantation donors or new donors in single infusions of 5 x 105 or 1 x 106 cells/kg.
No dose-limiting toxicities were observed. All patients (100%) had cytokine-release syndrome, which was grade 3 or 4 in 10%; grade 3 or 4 cytopenias also occurred in all patients (100%). Neurotoxicity occurred in 15%, graft-vs-host disease in 60%, and viral activation in 20%, with all these events being grade 1 or 2. Adverse events led to death in one patient (due to pulmonary hemorrhage related to fungal pneumonia at 5.5 months postinfusion).
Response was observed in 19 patients (95%), with complete remission in 18 (90%), including 17 (85%) with minimal residual disease–negative complete remission by day 15 postinfusion. A total of seven patients underwent stem cell transplantation. At a median follow-up of 6.3 months (range = 4.0–9.2 months), 15 patients remained in remission, including 6 of 7 who underwent stem cell transplantation and 9 of 11 who received no additional treatment for their leukemia.
CAR T cells were detectable in each of the five patients evaluated at 6 months postinfusion. Infusion resulted in rapid depletion of CD7-positive normal lymphocytes—including T cells—within 15 days, with a dramatic increase in CD7-negative T cells observed in all patients. T cells exhibited an effector or effector memory phenotype with a minimal naive fraction. The investigators noted that the expansion of CD7-negative T cells may have alleviated treatment-related T-cell immunodeficiency.
The investigators concluded, “Among 20 patients with relapsed or refractory T-ALL enrolled in this trial, donor-derived CD7 CAR T cells exhibited efficient expansion and achieved a high complete remission rate with [a] manageable safety profile. A multicenter, phase II trial of donor-derived CD7 CAR T cells is in progress.”
Jing Pan, MD, of Boren Clinical Translational Center, Beijing Boren Hospital, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the National Key R&D Program of China, Non-Profit Central Research Institute Fund of Chinese Academy of Medical Sciences, and others. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.