Key Points• Infusion of CMV-specific T cells early posttransplant does not increase acute or chronic graft-versus-host disease.• CMV-specific T cells early posttransplant reduce the need for pharmacotherapy without increased rates of CMV-related organ damage.We investigated the use of adoptively transferred donor-derived cytomegalovirus (CMV) specific cytotoxic T lymphocytes (CTL) as immune reconstitution postallogeneic transplant in a phase 2 study. Fifty patients were infused with a single dose of 2 3 10 7 cells/m 2 after day 28 post-transplant. Twenty-six patients reactivated CMV posttransplant (only 5 post-CTL infusion) and 9 required therapy with ganciclovir or foscarnet (only 1 post-CTL infusion).There was 1 case of fatal CMV disease, attributable to high levels of antithymocyte globulin at the time of T cell infusion. We compared the patients in the phase 2 study with a group of contemporaneous controls also treated at the trial centers. There was no increase in acute or chronic graft-versus-host disease attributable to CTL infusion; overall and progressionfree survival were similar in both groups. There was a reduction in the percentage of patients who required CMV directed antiviral therapy (17% vs 36%, P 5 .01) and in the total number of treatment days in the cohort receiving CTL (3.4 days vs 8.9 days, P 5 .03) without a reduction in CMV reactivation rates. We postulate that adoptively transferred cells are able to expand in response to viral antigen, limit viral replication, and prevent progression to tissue infection. This study was registered on the Australian Clinical

Key Points Partially HLA-matched third-party CMV-specific T cells provide long-term viral control in HSCT patients with resistant CMV infection. Viral control occurs in the setting of recovery of CD8+ terminally differentiated effector T cells.

CD19-specific chimeric antigen receptor (CAR19) T-cells effectively induce remission of B-cell malignancy, but the cost and complexity of production using viral vectors is a factor limiting widespread application. Furthermore, the small cargo capacity of viral vectors may hamper future development of more heavily engineered CAR T-cells. We demonstrated the feasibility of generating CAR19 T-cells from HLA-matched donors of sibling allogeneic hematopoietic stem cell transplant (HSCT) patients via a simple and inexpensive method using the high-capacity piggyBac transposon. A cohort of 10 patients with relapsed or refractory B-cell acute lymphoblastic leukemia or aggressive lymphoma following HSCT were the first human subjects to receive piggyBac-generated CAR19 T-cells. Treatment with intra-patient escalating doses of CAR19 T-cells was effective, with all 9 evaluable patients achieving complete remission. At a median follow-up of 18.0 months, 5 patients remained in complete remission of B-cell malignancy. One patient died of viral sepsis. Four patients developed cytokine release syndrome of maximum grade 2, and no neurotoxicity or new graft-versus-host disease occurred. However, two patients developed malignant CAR19 T-cell tumors, one of whom was successfully treated; one patient died of the secondary tumor. The piggyBac system represents a feasible alternative to viral vectors for the generation of effective CAR19 T-cells, but its oncogenic potential in the context of the described production process will need to be addressed before any further clinical use is possible. This trial was registered at www.anzctr.org.au as ACTRN12617001579381.

Hematopoietic stem cell transplantation (HSCT) donor-generated virus-specific T cells (VSTs) can provide effective treatment for viral infection post-HSCT but are not readily accessible to all patients. Off-the-shelf cryopreserved VSTs suitable for treatment of multiple patients are an attractive alternative. We generated a bank of 17 cytomegalovirus (CMV)-, 14 Epstein-Barr virus (EBV)-, and 15 adenovirus (AdV)-specific T cell products from 30 third-party donors. Donors were selected for expression of 6 core HLA antigens expressed at high frequency in the local transplant population. T cells were generated by co-culturing venous blood or mobilized hematopoietic stem cell (HSC)-derived mononuclear cells with monocyte-derived dendritic cells pulsed with overlapping peptides covering CMV pp65, AdV5 hexon, or EBV BZLF1/LMP2A/EBNA1 proteins. Addition of a CD14 selection step instead of plate adherence to isolate monocytes before culture initiation significantly improved expansion in cultures from HSC material. Phenotyping showed the CD8 subset to have significantly higher numbers of terminal effector T cells (CD45RA62L) and lower numbers of effector memory T cells (CD45RA62L) when compared with the CD4 subset. Increased expression of the immunoinhibitory markers PD-1 and TIM-3 was noted on CD4 but not CD8 cells when compared with the control group. VST showed antiviral activity restricted through a variety of common HLAs, and modelling suggested a suitably HLA-matched product would be available for >90% of HSCT patients. Only a small number of carefully selected third-party donors are required to generate a VST bank of broad coverage, indicating the feasibility of local banking integrated into existing allogeneic HSCT programs.

Uncontrolled cytomegalovirus (CMV) reactivation after allogeneic hematopoietic stem cell transplantation causes significant morbidity and mortality. Adoptive transfer of CMV-specific cytotoxic T lymphocytes (CTLs) is a promising therapy to treat reactivation and prevent viral disease. In this article, we describe the generation of clinical-grade CMV-specific CTLs directly from granulocyte colony-stimulating factor-mobilized hemopoietic progenitor cell (G-HPC) products collected for transplantation. This method requires less than 2.5% of a typical G-HPC product to reproducibly expand CMV-specific CTLs ex vivo. Comparison of 11 CMV CTL lines generated from G-HPC products with 52 CMV CTL lines generated from nonmobilized peripheral blood revealed similar expansion kinetics and phenotype. G-HPC-derived CTLs produced IFN-γ after reexposure to CMVpp65 antigen and exhibited CMV-directed cytotoxicity but no alloreactivity against transplantation recipient-derived cells. Seven patients received CMV-specific CTL lines expanded from G-HPC products in a prophylactic adoptive immunotherapy phase I/II clinical trial. Use of G-HPC products will facilitate integration of CTL generation into established quality systems of transplantation centers and more rapid inclusion of T cell therapies into routine clinical care.

Possible clinical uses for BKV-specific T cells generated using this method include immune reconstitution posthemopoietic stem-cell transplantation or prophylaxis and treatment of immune deficiency in renal transplant recipients, fulfilling the need for effective therapy for BKV-related hemorrhagic cystitis and renal dysfunction.

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Virus-specific T-cells (VST) from third-party donors mediate short- and long-term antiviral effects in allogeneic stem cell transplant (HSCT) recipients with relapsed or refractory viral infections. We investigated early administration of third-party VST together with antiviral therapy in patients requiring treatment for their first CMV or EBV infection. Thirty HSCT patients were treated with 1-4 VST infusions (2x107cells/m2; CMV=27, EBV=3) at a median of 4 days after initiation of antiviral treatment. The overall viral response rate was 100% with a complete response rate of 94%. Of the 28 patients who achieved a CR, 23 remained virus PCR negative (n=9) or below quantitation limit (n=14) for the duration of follow up. 4 patients had brief episodes of quantifiable reactivation not requiring additional therapy and one patient required a second infusion following initial CR, and remained PCR negative thereafter. All 3 patients treated for EBV PTLD achieved sustained CR. Rates of acute and chronic GVHD post-infusion were 13% (4/30) and 23% (7/30) respectively. There were no serious adverse events related to infusion. VST infusion was associated with rapid recovery of CD8+CD45RA-CD62L- and a slower recovery of CD4+CD45RA-CD62L- effector memory T-cells; CMV-specific T-cells comprised up to 13% of CD8+ cells. At 1 year post-transplant, non relapse mortality was 10%, cumulative incidence of relapse was 7%, overall survival was 88% and 25/27 patients had ECOG 0 or 1. Early administration of third-party VST in conjunction with antiviral treatment appears safe and leads to excellent viral control and clinical outcomes. Study ID ACTRN12618000343202.