Results of a long-term follow-up study show that chimeric antigen receptor T-cell (CAR-T) therapy in adults with acute lymphoblastic leukemia (ALL) may produce durable responses, especially in those with low disease burden.
The study was published in The New England Journal of Medicine (February 2018;378:449-459).
Previous studies have shown that CD-19 specific CAR-T therapy induces high rates of initial response among patients with relapsed B-cell ALL as well as long-term remission in a subgroup of patients. However, long-term safety and efficacy data are lacking.
Jae Park, MD, Memorial Sloan Kettering Cancer Center (New York, NY), and colleagues conducted a phase I study involving 53 adult patients with relapsed B-cell ALL who received an infusion of autologous T cells expressing the 19-28z CAR. Researchers assessed for safety and long-term outcomes, as well as their associations with demographic, clinical, and disease characteristics. All patients received infusion at Memorial Sloan Kettering Cancer Center.
Researchers noted that after infusion, severe cytokine release syndrome occurred in 26% of the patients (n = 14; 95% CI, 15-40) and one patient died. A complete remission was observed in 83% of the patients.
After a median follow-up of 29 months, the median event-free survival was 6.1 months (95% CI, 5.0-11.5). The median overall survival was 12.9 months (95% CI, 8.7-23.4).
Additionally, Dr Park and colleagues noted that patients with a low disease burden (< 5% bone marrow blasts) before treatment had significantly enhanced remission duration and survival. Median event-free survival in these patients as 10.6 months (95% CI, 5.9 to not reached) and median overall survival was 20.1 months (95% CI, 8.7 to not reached).
Furthermore, patients with a higher disease burden (≥ 5% bone marrow blasts or extramedullary disease) demonstrated a greater incidence of cytokine release syndrome and neurotoxic events, as well as shorter long-term survival compared with patients with a lower disease burden.
“This study is the longest follow-up study of CAR T-cells published today,” said Dr Park in an interview (January 31, 2018). “It’s allowing us to confirm the durability of the remissions, which is the question on everybody’s mind.”—Zachary Bessette