Hematopoietic cell transplantation with cord blood for cure of HIV infections.

Hematopoietic cell transplantation (HCT) using CCR5-Δ32/Δ32 stem cells from an adult donor has resulted in the only known cure of human immunodeficiency virus (HIV) infection. However, it is not feasible to repeat this procedure except rarely because of the low incidence of the CCR5-Δ32 allele, the availability of only a small number of potential donors for most patients, and the need for a very close human leukocyte antigen (HLA) match between adult donors and recipients. In contrast, cord blood (CB) transplantations require significantly less stringent HLA matching. Therefore, our hypothesis is that cure of HIV infections by HCT can be accomplished much more readily using umbilical CB stem cells obtained from a modestly sized inventory of cryopreserved CCR5-Δ32/Δ32 CB units. To test this hypothesis, we developed a screening program for CB units and are developing an inventory of CCR5-Δ32/Δ32 cryopreserved units available for HCT. Three hundred such units are projected to provide for white pediatric patients a 73.6% probability of finding an adequately HLA matched unit with a cell dose of ≥2.5 × 10(7) total nucleated cells (TNCs)/kg and a 27.9% probability for white adults. With a cell dose of ≥1 × 10(7) TNCs/kg, the corresponding projected probabilities are 85.6% and 82.1%. The projected probabilities are lower for ethnic minorities. Impetus for using CB HCT was provided by a transplantation of an adult with acute myelogenous leukemia who was not HIV infected. The HCT was performed with a CCR5-Δ32/Δ32 CB unit, and posttransplantation in vitro studies indicated that the patient's peripheral blood mononuclear cells were resistant to HIV infection.

Maintenance therapy with thalidomide improves overall survival after autologous hematopoietic progenitor cell transplantation for multiple myeloma.

BACKGROUND: High-dose chemotherapy with autologous hematopoietic progenitor cell (HPC) transplantation improves survival for patients with multiple myeloma (MM); however, most patients develop recurrent disease after undergoing transplantation, and new treatment approaches are needed. The objective of this retrospective review of autologous HPC transplantation for patients with MM was to evaluate the impact of conditioning regimens and posttransplantation therapy on survival. METHODS: The authors reviewed 112 patients with MM who received autologous HPC grafts at their institution. Between June 1992 and August 2001, 54 patients received busulfan, cyclophosphamide, and etoposide (Bu/Cy/VP-16), and 58 patients received high-dose melphalan (MEL-200) followed by autologous HPC transplantation. After transplantation, 36 patients received thalidomide for maintenance or salvage therapy, and 76 patients received no posttransplantation thalidomide. RESULTS: At a median follow-up of 58 months, the median survival was 54 months. There was no statistically significant difference noted with regard to response to conditioning regimen, progression-free survival, or overall survival between the Bu/Cy/VP-16 and MEL-200 cohorts. Patients who received thalidomide after transplantation had improved median survival (65.5 months) compared with patients who did not receive thalidomide (44.5 months; P = .09). When they were separated according to reasons for thalidomide use, patients who received thalidomide as maintenance had improved overall survival compared with patients who received thalidomide as salvage (65 months vs. 54 months; P = .05). CONCLUSIONS: Combination chemotherapy provided no advantage over high-dose melphalan in patients with MM who underwent autologous HPC transplantation. The posttransplantation use of thalidomide seemed to improve the survival of patients compared with historical controls from the prethalidomide era. Further prospective trials are underway to confirm the benefit of thalidomide in the posttransplantation setting.

A randomized trial comparing the combination of granulocyte-macrophage colony-stimulating factor plus granulocyte colony-stimulating factor versus granulocyte colony-stimulating factor for mobilization of dendritic cell subsets in hematopoietic progenitor cell products.

The ability of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) administration to increase the content of blood leucocytes and hematopoietic progenitor cells (HPCs) is well established, yet the effect of these cytokines on immune function is less well described. Recent data indicate that plasmacytoid dendritic cells (DC2) may inhibit cellular immune response. We hypothesized that administration of the combination of G-CSF and GM-CSF after chemotherapy would reduce the type 2, or plasmacytoid, DC2 content of the autologous blood HPC grafts compared with treatment with G-CSF alone. To test this hypothesis, 35 patients with lymphoma and myeloma were randomized to receive either G-CSF or the combination of G-CSF plus GM-CSF after chemotherapy, and blood HPC grafts were collected by apheresis. Cytokine-related adverse events between the 2 groups were similar. More than 2 x 10(6)CD34 + cells per kilogram were collected by apheresis in 14 of 18 subjects treated with G-CSF and in 16 of 17 subjects treated with GM-CSF plus G-CSF ( p = not significant). There were minor differences between the 2 groups with respect to the content of T cells and CD34 + cells in the apheresis products. However, grafts collected from recipients of the combination of GM-CSF plus G-CSF had significantly fewer DC2 cells and similar numbers of DC1 cells compared with recipients treated with G-CSF alone. A third cohort of patients received chemotherapy followed by the sequential administration of G-CSF and the addition of GM-CSF 6 days later. Grafts from these patients had a markedly reduced DC2 content compared with those from patients treated either with G-CSF alone or with the concomitant administration of both cytokines. These data, and recent data that cross-presentation of antigen by DC2 cells may induce antigen-specific tolerance among T cells, suggest that GM-CSF during mobilization of blood HPC grafts may be a clinically applicable strategy to enhance innate and acquired immunity after autologous and allogeneic HPC transplantation.

Pharmacokinetics and pharmacodynamics of anti-thymocyte globulin in recipients of partially HLA-matched blood hematopoietic progenitor cell transplantation.

Polyclonal anti-thymocyte globulin (ATG) administered before allogeneic blood hematopoietic progenitor cell transplantation reduces the risks of graft rejection and graft-versus-host disease, but may delay posttransplant immune reconstitution caused by delayed clearance of ATG from the blood. We studied graft-versus-host disease, infections, and the kinetics of immune reconstitution in 28 patients with very poor-risk hematologic malignancies who received lymphocyte-depleted, CD34(+) cell-enriched hematopoietic progenitor cell grafts from partially HLA-matched related donors (PMRD). The incidence of these clinical events was correlated with blood ATG levels in 19 transplant recipients who received rabbit ATG (r-ATG, thymoglobulin) during conditioning. Total r-ATG and the fraction of ATG antibodies that bind human cells (active ATG) were measured for up to 45 days posttransplantation using enzyme-linked immunosorbent assay and flow cytometry assays. Three patients received equine ATG (e-ATG; total dose of 60 mg/kg/day), 3 patients received 10 mg/kg r-ATG, and 22 patients received 6 mg/kg r-ATG during conditioning. All evaluable patients engrafted. Median numbers of blood CD4(+) and CD8(+) T cells at 100 days posttransplantation were 15 and 8 cells/microL, respectively. Acute graft-versus-host disease developed in 3 of 3 recipients of e-ATG and 1 of 25 recipients of r-ATG. Rapid T-cell reconstitution was seen only in younger patients. Overall mortality was 93% (26/28 patients) with poor immune reconstitution contributing to death in 21 of 28 patients. Recipients of 6 mg/kg r-ATG had peak levels of total and active r-ATG of 64+/-20 microg/mL and 9.2+/-5.8 microg/mL, respectively, with clearance of active r-ATG (t(1/2)6 days) to sub-therapeutic levels (<1 microg/mL) by a median of 15 days posttransplantation (range, 8-38 days). Delayed immune reconstitution is likely a consequence of ex vivo and in vivo purging of donor T cells in the graft coupled with inadequate thymic function rather than persistence of active r-ATG in the blood for months posttransplantation.

Development of drug-resistant herpes simplex virus infection after haploidentical hematopoietic progenitor cell transplantation.

An unusually high incidence of acyclovir- and foscarnet-resistant herpes simplex virus (HSV) infection was noted after lymphocyte-depleted blood hematopoietic progenitor cell (HPC) transplantation from HLA-haploidentical family donors. Fourteen adults with hematologic malignancies underwent blood HPC transplantation from haploidentical family donors. Pheresis products were stringently depleted of T and B cells by immunomagnetic adsorption, and patients received no immunosuppression after transplantation. HSV reactivation occurred in all 7 evaluable HSV-1- or HSV-2-seropositive patients, at a median of 40 days after transplantation. Susceptibility testing of clinically resistant viral isolates demonstrated acyclovir resistance in all 5 cases tested. Second-line therapy produced only partial responses, and in vitro evidence of foscarnet resistance developed rapidly in all 3 patients treated with foscarnet. Healing of lesions coincided with T-cell recovery. The prolonged immunodeficiency associated with stringent lymphocyte depletion of the graft appears to strongly predispose to emergence of drug-resistant HSV. Furthermore, immune reconstitution is necessary for eradication of infection.

Facilitating T-cell immune reconstitution after haploidentical transplantation in adults.

Delayed reconstitution of cellular immunity following T-cell-depleted, CD34-enriched, allogeneic hematopoietic progenitor cell transplantation (HPCT) is the major cause of morbidity and mortality following haploidentical transplantation in adults. This is illustrated in our recent study of 28 high-risk adult patients (median age 31) who were treated with conditioning regimens containing antithymocyte globulin (ATG) before T-cell-depleted, CD34-enriched allogeneic HPCT. Overall mortality was 93% (26/28 patients) with a median survival of 4 months posttransplant. Poor cellular immune reconstitution contributed to death of 21/28 patients, with eight deaths due to opportunistic infections and seven deaths due to relapse. While recovery of normal numbers of circulating NK cells and B-cells occurred within the first 1-2 months posttransplant, recovery of normal numbers of blood T-cells was suppressed for more than 1 year. The mean half-life of active ATG levels in serum was 6 days; rapid clearance suggested that residual ATG did not contribute to the delay of posttransplant T-cell reconstitution. Rapid T-cell reconstitution was seen only in younger patients, indicating that poor thymic function and the absence of T-cells in the graft are the major causes of delayed recovery of cellular immunity. Improved cellular immunity after T-cell-depleted haploidentical HPCT will thus require novel strategies to adoptively transfer antigen specific donor T-cells without inducing lethal graft-versus-host disease (GvHD). This problem has been addressed in a preclinical murine model of MHC-mismatched bone marrow transplantation. Donor T-cells treated ex vivo with fludarabine or a UVA light-activated psoralen compound (amotosalen) have a markedly reduced ability to induce GvHD, yet the treated T-cells confer protection against murine cytomegalovirus and an infused leukemic cell line. Polyclonal donor T-cells reconstituted the blood and lymphoid compartments posttransplant and expanded in vivo. Derivatives of ex-vivo-treated donor T-cells retained the ability to produce cytokines and proliferate in response to antigen challenge. The mechanism of reduced GvHD potential of ex-vivo-treated T-cells appears to be selection of a subset of memory donor T-cells that do not initially home to secondary lymphoid organs and have reduced capacity for producing inflammation in the immediate posttransplant period. Direct selection of the memory subset by high-speed FACS confirmed the improved therapeutic index in the murine model system. Preclinical data indicate the feasibility of treating human T-cells with fludarabine, psoralen, or direct selection based upon the memory phenotype to efficiently produce a population of polyclonal donor T-cells with reduced GvHD activity. A planned clinical phase 1 trial of adoptive therapy utilizing ex vivo psoralen-treated donor T-cells in recipients of T-cell-depleted haploidentical HPCT is presented.