Purpose: Anti-CD19 chimeric antigen receptors (CARs) are artificial fusion proteins that cause CD19-specific T-cell activation. Durability of remissions and incidence of long-term adverse events are critical factors determining the utility of anti-CD19 CAR T-cell therapy, but long-term follow-up of patients treated with anti-CD19 CAR T cells is limited. This work provides the longest follow-up of patients in remission after anti-CD19 CAR T-cell therapy.
Methods: Between 2009 and 2015, we administered 46 CAR T-cell treatments to 43 patients (ClinicalTrials.gov identifier: NCT00924326). Patients had relapsed B-cell malignancies of the following types: diffuse large B-cell lymphoma or primary mediastinal B-cell lymphoma (DLBCL/PMBCL; n = 28), low-grade B-cell lymphoma (n = 8), or chronic lymphocytic leukemia (CLL; n = 7). This report focuses on long-term outcomes of these patients. The CAR used was FMC63-28Z; axicabtagene ciloleucel uses the same CAR. Cyclophosphamide plus fludarabine conditioning chemotherapy was administered before CAR T cells.
Results: The percentages of CAR T-cell treatments resulting in a > 3-year duration of response (DOR) were 51% (95% CI, 35% to 67%) for all evaluable treatments, 48% (95% CI, 28% to 69%) for DLBCL/PMBCL, 63% (95% CI, 25% to 92%) for low-grade lymphoma, and 50% (95% CI, 16% to 84%) for CLL. The median event-free survival of all 45 evaluable treatments was 55 months. Long-term adverse effects were rare, except for B-cell depletion and hypogammaglobulinemia. Median peak blood CAR-positive cell levels were higher among patients with a DOR of > 3 years (98/µL; range, 9-1,217/µL) than among patients with a DOR of < 3 years (18/µL; range, 0-308/μL, P = .0051).
Conclusion: Complete remissions of a variety of B-cell malignancies lasting ≥ 3 years occurred after 51% of evaluable anti-CD19 CAR T-cell treatments. Remissions of up to 9 years are ongoing. Late adverse events were rare.