Penn Medicine researchers found long-term persistence of CD19 CAR T cells in a subset of lymphoma patients, with detailed analyses revealing changes in their phenotype, gene expression and clonal composition over time.
Written By: Mayuresh Salvi, PharmD
Reviewed By: Pharmacally Editorial Team
A study published in Nature Medicine has found that CD19-directed chimeric antigen receptor (CAR) T cells can remain detectable for many years after treatment in patients with B-cell non-Hodgkin lymphoma (B-NHL), including beyond five years and up to approximately a decade after infusion.
The study provides a biological follow-up to research from the same Penn Medicine team published in the New England Journal of Medicine in June 2026, which reported 10-year clinical outcomes after a single infusion of tisagenlecleucel in the same 38-patient cohort. That study found no lymphoma relapses beyond 5.4 years and 10-year lymphoma-free survival of 32% in patients with large B-cell lymphoma and 47% in those with follicular lymphoma.
Study Examined Long-Term CAR T-Cell Persistence
The researchers analyzed longitudinal samples from 38 patients with B-NHL enrolled in clinical trial (NCT02030834). The cohort included 24 patients with large B-cell lymphoma and 14 with follicular lymphoma. Patients received 4-1BB-costimulated anti-CD19 CAR T cells, referred to as CART19 in the study and now known as tisagenlecleucel.
Among 12 patients who remained in remission beyond five years, samples suitable for long-term CAR T-cell analysis were available from eight. CAR T cells were detected by quantitative PCR in five of these patients, at time points ranging from 7.0 to 10.1 years after infusion.
The median CAR transgene level among these five patients was 262 copies per microgram of DNA, with levels ranging from 10 to 1,567 copies per microgram. In one patient, flow cytometry clearly detected CAR T cells representing 1.2% of circulating CD3-positive lymphocytes.
Higher levels of persistent CAR T cells were associated with sustained B-cell aplasia. All three patients with more than 200 transgene copies per microgram of DNA had persistent B-cell aplasia, while patients with lower-level persistence showed B-cell reconstitution.
Long-Term CAR T Cells Showed Distinct Biological Features
The most detailed analysis involved a patient who remained in complete remission for 10.1 years. At 9.3 years after infusion, most persisting CAR T cells were double-negative for CD4 and CD8 and showed an effector-memory-like phenotype.
The cells retained transcriptional features associated with activation and proliferation and showed enrichment of programs related to interferon signaling, immune activation and aerobic metabolism. They also expressed cytotoxicity-associated genes, while showing increased expression of several immune checkpoint markers compared with CAR-negative T cells.
The CAR T-cell population also changed substantially over time. Cells were predominantly CD8-positive during the early expansion phase, whereas double-negative cells became increasingly prominent during long-term follow-up.
A Rare CAR T-Cell Clone Became Dominant
T-cell receptor sequencing showed marked clonal selection during long-term persistence. At peak expansion, 1,593 CAR-positive clonotypes were identified, compared with 68 at year 9.3.
One clonotype accounted for nearly 70% of CAR-positive T cells at 9.3 years, despite representing less than 0.1% of the CAR T-cell population at the peak of expansion on day 14. This suggests that a rare population present early after treatment can selectively persist and become dominant years later.
Integration-site analysis identified 111 unique insertion sites but did not identify dominant integration into genes previously associated with enhanced CAR T-cell persistence, providing no evidence that insertional mutagenesis explained the expansion of the dominant clone.
Persistence May Have Both Benefits and Risks
The findings support the possibility that long-lived CAR T cells may contribute to prolonged immune surveillance. However, the study does not establish that persistent CAR T cells are required for durable remission. Some patients maintained long-term disease control without detectable persistent CAR T cells.
Prolonged CAR T-cell activity may also have clinical consequences. The patient with the longest documented persistence had sustained B-cell aplasia, profound hypogammaglobulinemia, required monthly intravenous immunoglobulin replacement and experienced recurrent infections.
What the Study Adds
The study provides a deeper biological explanation for the long-term clinical outcomes reported by the Penn Medicine team in the June NEJM study. Rather than simply disappearing after their initial expansion, a subset of CD19 CAR T cells can persist for years and undergo substantial changes in phenotype, transcriptional state and clonal composition.
The researchers note that the detailed biological findings were largely driven by a small number of long-term responders, including one patient with exceptionally prolonged persistence. Larger studies will be needed to determine which CAR T-cell characteristics are associated with durable disease control and which may contribute to long-term complications.
Reference
Decade-long persistence of CD19 CAR T cells in B cell lymphomas | Nature Medicine
About the Writer
Mayuresh Sunil Salvi (Linkedin) is a PharmD professional and healthcare writer with a strong interest in pharmacovigilance, drug safety, and emerging medical research. He is passionate about exploring new drug discoveries, clinical research, and advances in evidence-based medicine. His interests also include ward rounds, prescription audits, and treatment analysis to support rational pharmacotherapy and improved patient care.