Emily Blyth

Donor-derived CMV specific T-cells reduce the requirement for CMV-directed pharmacotherapy after allogeneic stem cell transplantation

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 × 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 progression-free 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 = .01) and in the total number of treatment days in the cohort receiving CTL (3.4 days vs 8.9 days, P = .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 Trial Registry as #ACTRN12605000213640 and #ACTRN12607000224426.

Prophylactic infusion of cytomegalovirus-specific cytotoxic T lymphocytes stimulated with Ad5f35pp65 gene-modified dendritic cells after allogeneic hemopoietic stem cell transplantation

Cytomegalovirus (CMV) and its therapy continue to contribute to morbidity and mortality in hemopoietic stem cell transplantation (HSCT). Many studies have demonstrated the feasibility of in vitro generation of CMV-specific T cells for adoptive immunotherapy of CMV. Few clinical trials have been performed showing the safety and efficacy of this approach in vivo. In this study, donor-derived, CMV-specific T cells were generated for 12 adult HSCT patients by stimulation with dendritic cells transduced with an adenoviral vector encoding the CMV-pp65 protein. Patients received a prophylactic infusion of T cells after day 28 after HSCT. There were no infusion related adverse events. CMV DNAemia was detected in 4 patients after infusion but was of low level. No patient required CMV-specific pharmacotherapy. Immune reconstitution to CMV was demonstrated by enzyme linked immunospot assay in all recipients with rapid increases in predominantly CMV-pp65 directed immunity in 5. Rates of graft-versus-host disease, infection, and death were not increased compared with expected. These results add to the growing evidence of the safety and efficacy of immunotherapy of CMV in HSCT, supporting its more widespread use. This study was registered at www.anzctr.org.au as #ACTRN12605000213640.

BK virus-specific T cells for use in cellular therapy show specificity to multiple antigens and polyfunctional cytokine responses.

Background. BK virus (BKV) infection causes hemorrhagic cystitis posthemopoietic stem-cell transplant and graft loss in renal transplant recipients. Reactivation occurs in up to 60% of patients in both groups. Treatment-related cellular immunosuppression is a major contributor to the development of BKV-related disease, but the targets of the immune response are not well characterized. Immunotherapy by adoptive transfer of cellular effectors has been shown to be effective in controlling and preventing some virus-related diseases in transplant recipients, particularly Epstein-Barr virus and cytomegalovirus. Infusion of BKV-specific T cells may potentially reconstitute functional BKV immunity and reduce clinical complications of BKV infection. Methods. BKV-specific T cells for clinical use in adoptive immunotherapy were generated using monocyte-derived dendritic cells pulsed with overlapping peptide mixes spanning the five BKV proteins VP1, VP2, VP3, large T antigen, and small T antigen. Phenotypic and functional characteristics of the cells were investigated as well as their antigen specificity. Results. Expanded CD4+ and CD8+ cells responded to restimulation with BKV peptides principally from VP1, large T, or small T antigens; produced multiple cytokines; and showed cytotoxic activity against antigen-coated targets. Conclusions. 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.

Influence of Stem Cell Source on Outcomes of Allogeneic Reduced-Intensity Conditioning Therapy Transplants Using Haploidentical Related Donors

We compared outcomes for 2 retrospective cohorts of patients undergoing reduced-intensity conditioning (RIC) therapy transplants using haploidentical related donors and post-transplant prophylaxis against graft-versus-host disease (GVHD) with high-dose cyclophosphamide, tacrolimus, and mycophenolate. The first cohort of 13 was transplanted with bone marrow (BM) as the stem cell source, whereas the second cohort of 23 used peripheral blood stem cells (PBSCs) mobilized with granulocyte colony-stimulating factor. The BM cohort received a single 60-mg/kg dose of cyclophosphamide on day +3, whereas the PBSC cohort received 2 doses on days +3 and +4. Patients in the first cohort were slightly older and had a higher proportion of acute myeloid leukemia, but there were no differences in the distribution of Disease Risk Index scores between the 2 groups. Patients in the PBSC group received double the number of CD34(+) cells in the stem cell graft. Times to neutrophil and platelet recovery were not different between the 2 groups. Three patients, all in the PBSC group, failed to engraft but recovered with autologous hemopoiesis and survived. The 6-month cumulative incidences of acute GVHD were 55.1% for BM and 48.5% for PBSCs (P = .651), whereas 24-month cumulative rates for chronic GHVD were 28.6% for BM and 32.3% for PBSCs (P = .685). Only 2 patients, both in the BM group, died of nonrelapse causes, both of second cancers. The 2-year cumulative incidences of relapse were 43.9% for BM and 23.5% for PBSCs (P = .286). Overall survival at 2 years was significantly better for PBSC patients (P = .028), at 83.4% versus 52.7% for BM. Relapse-free and event-free survival did not differ significantly between BM and PBSC groups. In this retrospective analysis, we conclude that the use of PBSCs for haploidentical RIC transplants is a feasible strategy, with equivalent rates of acute and chronic GVHD and risk of relapse and low nonrelapse mortality compared with BM.

Low-cost generation of Good Manufacturing Practice–grade CD19-specific chimeric antigen receptor–expressing T cells using piggyBac gene transfer and patient-derived materials

BACKGROUND AIMS Protocols for the production of CD19-specific chimeric antigen receptor (CAR19) T cells are often complex and expensive because of the use of retroviral and lentiviral vectors or the need for CAR19 T-cell enrichment. We aimed to simplify the generation of CAR19 T cells from the peripheral blood of normal donors and patients using the piggyBac transposon system of gene modification. METHODS We varied electroporation voltage, cytokines and stimulation conditions for the generation and expansion of CAR19 T cells over a 3-week culture period. RESULTS Using optimized electroporation voltage, interleukin-15 alone and co-culturing CAR T cells with peripheral blood mononuclear cells, we were able to expand CAR19 T-cell cultures by up to 765-fold over 3 weeks in normal donors and 180-fold in patients with B-cell malignancies. Final median CAR19 expression of 72% was seen in normal donors, and 81% was seen in patients with acute lymphoblastic leukaemia, chronic lymphocytic leukemia or non-Hodgkin lymphoma. CAR19 T cells produced interferon gamma on stimulation with CD19(+) cell lines and efficiently lysed both CD19(+) cell lines and primary leukemia cells. In addition, combining CAR expression with an inducible caspase safety switch allowed elimination of CAR19 T cells by the application of a small molecule dimerizer. DISCUSSION We have produced a simple, inexpensive and easily adoptable protocol for the generation of CAR19 T cells suitable for use in clinical trials using the piggyBac transposon system. This provides a robust platform for further enhancing the T-cell product and testing new CAR technologies.

Robust polyfunctional T-helper 1 responses to multiple fungal antigens from a cell population generated using an environmental strain of Aspergillus fumigatus

BACKGROUND AND AIMS Aspergillus fumigatus infections are the leading cause of invasive fungal infection-related deaths in stem cell transplant patients, and may be amenable to correction with adoptive immunotherapy providing T lymphocytes specific for A. fumigatus. However, a clinically usable source of antigen and a reliable procedure for the generation of large numbers of Aspergillus-specific T lymphocytes to clinical-grade standards is not available. METHODS An environmental strain of A. fumigatus (WMAfES) was isolated and cultured using materials and reagents suitable for clinical manufacture. Water-soluble lysate from germinated conidia of WMAfES was used as the antigen source. Peripheral blood mononuclear cells were stimulated with antigen-pulsed autologous dendritic cells on days 0 and 7. Cells were expanded with a cocktail of interleukin (IL)-2, IL-7 and IL-15 from days 7 to 21. RESULTS We obtained a mean 32.8-fold increase in cell numbers over 21 days of culture (n = 8). Resultant cultures were predominantly effector and central memory CD4(+) T cells, which produced T-helper (h)1 and Th17 cytokines when restimulated with A. fumigatus antigen derived from environmental or clinically isolated A. fumigatus. Cultured cells exhibited a high level of specific expansion and chemokine production when restimulated. Moreover, cultured cells cross-reacted with antigens from other fungi, including Penicillium, Candida albicans and other non-fumigatus Aspergillus species. CONCLUSIONS We describe a simple, robust, reproducible and clinically applicable procedure using a clinically appropriate antigen preparation for the expansion of polyfunctional A. fumigatus-specific T cells from normal donors of varying HLA types.

Adoptive T Cell Immunotherapy for Treatment of Ganciclovir-Resistant Cytomegalovirus Disease in a Renal Transplant Recipient

Cytomegalovirus (CMV) is a significant cause of morbidity, mortality and graft loss in solid organ transplantation (SOT). Treatment options for ganciclovir‐resistant CMV are limited. We describe a case of ganciclovir‐resistant CMV disease in a renal transplant recipient manifested by thrombotic microangiopathy‐associated glomerulopathy. Adoptive T cell immunotherapy using CMV‐specific T cells from a donor bank was used as salvage therapy. This report is a proof‐of‐concept of the clinical and logistical feasibility of this therapy in SOT recipients.

Clinical-grade varicella zoster virus-specific T cells produced for adoptive immunotherapy in hemopoietic stem cell transplant recipients

BACKGROUND AIMS Varicella zoster virus (VZV) causes life-long latent infection in healthy individuals, which reactivates in 10-68% of stem cell transplant patients. Reconstituting immunity through adoptive transfer of T cells specific for VZV may aid in the prophylaxis and treatment of VZV infections. The potential for generating T cells specific for VZV using a clinically approved VZV vaccine strain was investigated. METHODS The Varivax® vaccine was used to stimulate peripheral blood mononuclear cells from healthy donors. Only reagents approved for clinical manufacture were used. Monocyte-derived dendritic cells pulsed with Varivax (R) were used to stimulate autologous mononuclear cells at a responder to stimulator ratio of 10:1. On day 7, a second stimulation was performed; 20 U/mL interleukin (IL)-2 were added from day 7 and 50 U/mL IL-2 from day 14 onwards. Cell phenotype and functionality were assessed after 21 days of culture. RESULTS A mean increase of 11-fold in cell number was observed (n= 18). Cultures were mainly T cells (mean CD3 (+) 89.7%, CD4 (+) 54.2%, CD8 (+) 28.7%) with effector and central memory phenotypes. Cells produced one or more T helper (Th)1 cytokine (interferon-γ, tumor necrosis factor-α and IL-2), and CD4 (+) (but not CD8 (+) ) cells expressed the cytoxicity marker CD107 when restimulated with VZV antigens. CONCLUSIONS We have demonstrated a clinically applicable method that yields high numbers of highly reactive T cells specific for VZV. We propose that reconstructing host immunity through adoptive transfer of VZV-specific T cells will reduce the frequency of clinical VZV infection in the period of severe immune suppression that follows allogeneic stem cell transplantation.

Single-Agent High-Dose Cyclophosphamide for Graft-versus-Host Disease Prophylaxis in Human Leukocyte Antigen–Matched Reduced-Intensity Peripheral Blood Stem Cell Transplantation Results in an Unacceptably High Rate of Severe Acute Graft-versus-Host Disease

High-dose cyclophosphamide given early after allogeneic hemopoietic cell transplantation has been shown to be effective prophylaxis against graft-versus-host disease (GVHD) in the setting of HLA-matched myeloablative bone marrow grafts, allowing avoidance of long-term immunosuppression with calcineurin inhibitors in some patients. Whether this approach is feasible using granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell grafts is unknown. We conducted an exploratory phase 2 trial of cyclophosphamide given at 50 mg/kg i.v. on days 3 and 4 after transplantation as sole GVHD prophylaxis in recipients of G-CSF-mobilized peripheral blood stem cell grafts from HLA-matched related or unrelated donors after reduced-intensity conditioning therapy with fludarabine, carmustine, and melphalan. Five patients, ages 52 to 67 years, with high-risk hematologic malignancies were enrolled. Four of the 5 developed severe acute GVHD of grades 3 to 4, requiring treatment with methylprednisolone and cyclosporine; 3 were steroid refractory and were given salvage therapy. One of these 4 patients died of hepatic GVHD, one died of sepsis, and 2 survived. We conclude that post-transplantation cyclophosphamide is inadequate as sole GVHD prophylaxis in the context of peripheral blood reduced-intensity conditioning transplantations from HLA-matched donors. This trial is registered at ACTRN12613001154796.

In vitro generation of influenza-specific polyfunctional CD4+ T cells suitable for adoptive immunotherapy.

BACKGROUND AIMS Influenza viruses cause potentially fatal respiratory infections in stem cell transplant patients. Specific T cells provide long-lived host adaptive immunity to influenza viruses, and the potential for generating such cells for clinical use was investigated. METHODS The inactivated influenza vaccine (Fluvax) approved for human use was used as the antigen source. Monocyte-derived dendritic cells pulsed with Fluvax were used to stimulate autologous peripheral blood mononuclear cells (PBMC) on days 0 and 7. Cells were expanded with interleukin (IL)-2 from day 7 onwards. Cell numbers and phenotype were assessed on day 21. The presence of influenza virus-specific cells was assessed by cytokine production and proliferative responses following restimulation with influenza antigens. RESULTS Over 21 days of culture, a mean fold increase of 26.3 in cell number was observed (n = 7). Cultures were predominantly effector and central memory CD4+ cells, and expressed a phenotype characteristic of activated antigen-specific cells capable of B-cell helper function. Cytotoxic CD4+ and CD8+ cells specific for influenza and a high percentage of CD4+ cells specific for each of three influenza viruses targeted by Fluvax (H1N1, H3N2 and Brisbane viruses) were generated. In addition, T cells expanded when restimulated with antigens derived from influenza viruses. CONCLUSIONS We have demonstrated a clinically usable method for producing influenza virus-specific T cells that yield high numbers of highly reactive CD4+ cells suitable for adoptive immunotherapy. We propose that reconstructing host immunity through adoptive transfer of influenza virus-specific T cells will reduce the frequency of influenza-related deaths in the period of severe immune suppression that follows stem cell transplantation.