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Long-term side effects of CAR T cells mostly mild



SAN DIEGO – Longer-term follow-up of patients treated with CD19-targeted chimeric antigen receptor (CAR) T cells for hematologic malignancies indicates that the altered cells are generally safe, with most late events being mild in nature and possibly related to therapies delivered before or after CAR T cells, investigators reported.

Dr. Ana Cordeiro

Among patients treated with CD19-targeted CAR T cells for relapsed or refractory chronic lymphocytic leukemia (CLL) or non-Hodgkin lymphoma (NHL), the most frequent late adverse event was hypogammaglobulinemia, which occurred in 29 of 48 patients evaluated, reported Ana Cordeiro, MD, from the Fred Hutchinson Cancer Research Center in Seattle.

“Our results suggest that CD19 CAR T cells are safe,” Dr. Cordeiro said at the annual meeting of the American Society of Hematology. “However, continuing with prospective systematic and long-term follow-up of these patients is required for better understanding of these late effects.”

Dr. Cordeiro and colleagues studied a total of 60 patients who were enrolled in a phase 1/2 trial at their center of a CD19-targeted CAR T-cell construct and survived for at least 1 year.

The goal of the study was to describe complications that occurred or persisted beyond 90 days after CAR T-cell infusion.

The cohort included 43 patients treated for NHL and 17 treated for CLL. Patients with CLL were followed for a median of 27.5 months, and patients with NHL were followed for a median of 23.8 months.

As of September 2018, 47 patients were still alive, including 15 patients with CLL (88%) and 32 patients with NHL (74%). Of the 17 patients who died, 10 died from progressive disease (2 from CLL and 8 from NHL), and 3 patients died from nonrelapse causes associated with complications from subsequent allogeneic stem cell transplantation (allo-HCT), including 1 patient from graft-versus-host disease (GVHD) and infection, 1 from infection, and 1 from cerberovascular accident/thrombotic microangiopathy.

Of 38 patients who received additional therapies, 17 had subsequent CAR T-cell infusions under the same protocol, and 16 went on to allo-HCT. Treatments for the remaining five patients were not specified.

Of the 22 patients who did not receive additional treatment for their primary malignancies, 21 were in ongoing complete remission following a single CAR T-cell infusion after a median follow-up of 28 months. However, two patients in this group did require treatment for therapy-related myelodysplastic syndrome (t-MDS). The remaining patient had a small CLL clone at last follow-up.

Late adverse events included the following:

  • Late significant cytopenias in three of 19 patients evaluated.
  • Late hypogammaglobulinemia in 29 of 48 evaluated patients.
  • A total of 138 late infections in 31 of the 60 patients.
  • Subsequent malignancies in 10 of the 60 patients, including t-MDS, nonmelanoma skin cancer, and noninvasive bladder cancer.
  • Late immune-related events in seven patients.
  • Late neurogenic/psychiatric events, including one case each of transient ischemic attack at 3.8 months, encephalopathy and myoclonic seizure in the setting of chemotherapy, and a fatal cerebrovascular accident in the setting of allo-HCT and thrombotic microangiopathy. These patients did not have acute neurotoxicity after CAR T-cell therapy, Dr. Cordeiro noted. In addition, three patients experienced exacerbation of depression or anxiety following infusion.
  • GVHD in nine patients at a median time from allo-HCT to first CAR T-cell infusion of 46.3 months (range, 6.7 months to 11 years).

Focusing on those patients who achieve complete remissions after CAR T-cell therapy could help investigators isolate late events that are most likely related to CAR T cells, Dr. Cordeiro said.

Dr. Cordeiro reported having no relevant conflicts of interest.

SOURCE: Cordeiro A et al. ASH 2018, Abstract 223.

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