Adoptive Transfer of EBNA1-Specific T-Cells as a Treatment of Epstein-Barr-Virus Reactivation Following Allogeneic Stem Cell Transplantation

Abstract 2342

Reactivation of Epstein-Barr-Virus (EBV) after allogeneic stem cell transplantation (SCT) is responsible for significant morbidity and mortality. EBV is also assotiated with the development of some malingancies, such as Burkitt-Lymphoma or nasopharyngeal carcinoma (NPC). In particular, the EBV-induced lymphoproliferative disorder (PTLD) is a rare but severe condition after SCT. PTLD is often associated with insufficient immune responses against EBV in transplant recipients. There is no effective antiviral drug treatment against EBV by now. Given that T-cell immunity is crucial for protection against infection or reactivation of EBV, cellular immunotherapy is a promising therapeutic option. The Epstein-Barr-Virus Nuclear Antigen 1 (EBNA-1) has been shown to contain immunodominant T-cell epitopes with T-cell responses in the majority of the healthy population. Here we report adoptive EBNA-1-specific T-cell transfer in seven pediatric and adult patients with chemorefractory EBV-reactivation after allogenic SCT. Four patients had PTLD and one had metastatic relapse of a NPC. EBNA-1-specific T-cells were isolated from the SCT-donor by using an IFNγ-capture technique. These small T-cell populations were immediately infused to the patient without in vitro expansion steps. The adoptive T-cell transfer contained both, CD4+ T-helper cells and CD8+ cytotoxic T-cells. The patients with a mean age of 20 years were treated with antigen specific T-cells from haploidentical, matched unrelated or matched sibling donor SCT between day 72 and 410 post SCT. The T-cell dose varied from 150–7750 T-cells/ kg. No acute toxicity was observed. In vivo T-cell responses before adoptive T-cell transfer were absent and were detectable in all of the patients within the first weeks after adoptive transfer, associated with a partial clinical and/or virological response to the adoptive T-cell transfer. In three of the patients a second specific T-cell administration was needed to achieve an improvement of the EBV-related condition. PTLD or EBV-infection was not a cause of death in any of the other six patients. In conclusion we could show that adoptive T-cell-immunotherapy is safe, feasible and a promising therapeutic option in patients with EBV- infection and/or PTLD, having the advantage of not being immunosuppressive compared to chemotherapy against PTLD. Infusion of small IFNγ producing EBNA-1-specific T-cell populations resulted in an in vivo expansion of specific T-cells. Emergence of in vivo T-cell responses was closely associated with a clearance or reduction of the viral load.