Session: 723. Clinical Allogeneic and Autologous Transplantation - Late Complications and Approaches to Disease Recurrence: Relapse after Transplantation - Novel Strategies
Two patients with chronic lymphocytic leukemia (CLL) refractory to standard unmanipulated allogeneic donor lymphocyte infusions (DLIs) had regressions of large malignant lymph node masses after infusion of allogeneic anti-CD19-CAR T cells. One of these CLL patients obtained a complete remission that is ongoing 9 months after treatment with allogeneic anti-CD19-CAR T cells. This patient also had complete eradication of blood B cells within 9 days after her CAR-T-cell infusion. Another patient had tumor lysis syndrome requiring rasburicase treatment as his CLL dramatically regressed in lymph nodes, bone marrow, and blood within 2 weeks of his anti-CD19-CAR-T-cell infusion. A patient with mantle cell lymphoma obtained a partial remission that is ongoing 3 months after infusion of anti-CD19-CAR T cells. A fourth patient with diffuse large B-cell lymphoma has ongoing stable disease 11 months after infusion of anti-CD19-CAR T cells. The other 6 treated patients all had short periods of stable malignancy or progressive disease after their CAR-T-cell infusions. Specific eradication of blood B cells occurred after infusion of CAR T cells in 3 of 4 patients with measurable blood B cells pretreatment. None of the patients treated on this study developed GVHD after their anti-CD19-CAR-T-cell infusions, despite the fact that 6 of 10 treated patients had experienced GVHD at earlier time-points after their most recent alloHSCT. One patient, who had a history of cardiac dysfunction with prior acute illnesses, had temporary cardiac dysfunction after infusion of anti-CD19-CAR T cells. The most prominent toxicities experienced by patients were fever and hypotension; these peaked 5 to 12 days after CAR-T-cell infusions and resolved within 14 days after the T-cell infusions. Two patients had Grade 3 fever, and 2 patients had Grade 3 hypotension. No patients experienced Grade 4 toxicities that were attributable to the CAR-T-cell infusions. Elevated levels of serum interferon gamma were detected in 3 patients at the time that they were experiencing toxicities.
We detected cells containing the anti-CD19-CAR gene in the blood of 8 of 10 patients. The peak blood levels of CAR T cells varied from undetectable to 2.8% of peripheral blood mononuclear cells. The persistence of the CAR T cells in the blood of patients was limited to one month or less. When we assessed T cells from the blood of patients ex vivo, we found elevated levels of the T-cell inhibitory molecule programmed cell death protein-1 (PD-1) on CAR+ T cells compared to CAR-negative T cells. These results show for the first time that small numbers of donor-derived allogeneic anti-CD19-CAR T cells can cause regression of highly treatment-resistant B-cell malignancies after alloHSCT without causing GVHD. Malignancies that were resistant to standard DLIs regressed after anti-CD19-CAR-T-cell infusions. Future goals for improving this approach include enhancing the persistence of anti-CD19-CAR T cells and reducing toxicities. Infusion of allogeneic T cells genetically modified to recognize malignancy-associated antigens is a promising approach for treating residual malignancy after alloHSCT.
Disclosures: No relevant conflicts of interest to declare.
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