Adelmo Terenzi

Tregs prevent GVHD and promote immune reconstitution in HLA-haploidentical transplantation

Hastening posttransplantation immune reconstitution is a key challenge in human leukocyte antigen (HLA)-haploidentical hematopoietic stem-cell transplantation (HSCT). In experimental models of mismatched HSCT, T-regulatory cells (Tregs) when co-infused with conventional T cells (Tcons) favored posttransplantation immune reconstitution and prevented lethal graft-versus-host disease (GVHD). In the present study, we evaluated the impact of early infusion of Tregs, followed by Tcons, on GVHD prevention and immunologic reconstitution in 28 patients with high-risk hematologic malignancies who underwent HLA-haploidentical HSCT. We show for the first time in humans that adoptive transfer of Tregs prevented GVHD in the absence of any posttransplantation immunosuppression, promoted lymphoid reconstitution, improved immunity to opportunistic pathogens, and did not weaken the graft-versus-leukemia effect. This study provides evidence that Tregs are a conserved mechanism in humans.

Full Haplotype-Mismatched Hematopoietic Stem-Cell Transplantation: A Phase II Study in Patients With Acute Leukemia at High Risk of Relapse

PURPOSE Establishment of hematopoietic stem-cell (HSC) transplantation from mismatched relatives is feasible for patients with acute leukemia. As our original method of graft processing was unsuitable for large-scale clinical studies, we use automated devices for CD34+ cell purification. PATIENTS AND METHODS Sixty-seven patients with acute myeloid leukemia (AML; 19 complete remission [CR] 1, 14 CR 2, nine CR > 2, 25 in relapse) and 37 with acute lymphoid leukemia (ALL; 14 CR 1, eight CR 2, two CR > 2, 13 in relapse) were conditioned with total-body irradiation, thiotepa, fludarabine, and antithymocyte globulin. Peripheral-blood progenitor cells were mobilized with recombinant human granulocyte colony-stimulating factor and depleted of T-cells using CD34+ cell immunoselection. No post-transplantation graft-versus-host disease (GvHD) prophylaxis was administered. RESULTS Primary engraftment was achieved in 94 of 101 assessable patients. Six of the seven patients who rejected the primary graft, engrafted after a second transplantation. Overall, 100 of 101 patients engrafted. Acute GvHD developed in eight of 100 patients, and chronic GvHD, in five of 70 assessable patients. Thirty-eight patients died of nonleukemic causes. Relapse occurred in nine of 66 patients receiving transplantation in remission and in 17 of 38 receiving transplantation in relapse. Median follow-up of the 40 patients who survived event-free was 22 months (range, 1 to 65 months). Event-free survival (+/- standard deviation) rate was 48% +/- 8% and 46% +/- 10%, respectively, for the 42 AML and 24 ALL patients receiving transplantation in remission. CONCLUSION Our transplantation procedure provides reliable, reproducible CD34+ cell purification, high engraftment rates, and prevention of GvHD. The mismatched-related transplant emerges as a viable, alternative source of stem cells for acute leukemia patients without matched donors and/or those who urgently need transplantation.

HLA-haploidentical transplantation with regulatory and conventional T-cell adoptive immunotherapy prevents acute leukemia relapse

Posttransplant relapse is still the major cause of treatment failure in high-risk acute leukemia. Attempts to manipulate alloreactive T cells to spare normal cells while killing leukemic cells have been unsuccessful. In HLA-haploidentical transplantation, we reported that donor-derived T regulatory cells (Tregs), coinfused with conventional T cells (Tcons), protected recipients against graft-versus-host disease (GVHD). The present phase 2 study investigated whether Treg-Tcon adoptive immunotherapy prevents posttransplant leukemia relapse. Forty-three adults with high-risk acute leukemia (acute myeloid leukemia 33; acute lymphoblastic leukemia 10) were conditioned with a total body irradiation-based regimen. Grafts included CD34(+) cells (mean 9.7 × 10(6)/kg), Tregs (mean 2.5 × 10(6)/kg), and Tcons (mean 1.1 × 10(6)/kg). No posttransplant immunosuppression was given. Ninety-five percent of patients achieved full-donor type engraftment and 15% developed ≥grade 2 acute GVHD. The probability of disease-free survival was 0.56 at a median follow-up of 46 months. The very low cumulative incidence of relapse (0.05) was significantly better than in historical controls. These results demonstrate the immunosuppressive potential of Tregs can be used to suppress GVHD without loss of the benefits of graft-versus-leukemia (GVL) activity. Humanized murine models provided insights into the mechanisms underlying separation of GVL from GVHD, suggesting the GVL effect is due to largely unopposed Tcon alloantigen recognition in bone marrow.

Improved Outcome With T-Cell–Depleted Bone Marrow Transplantation for Acute Leukemia

PURPOSE To eliminate the risk of rejection and lower the risk of relapse after T-cell-depleted bone marrow transplants in acute leukemia patients, we enhanced pretransplant immunosuppression and myeloablation. PATIENTS AND METHODS Antithymocyte globulin and thiotepa were added to standard total-body irradiation/cyclophosphamide conditioning. Donor bone marrows were depleted ex vivo of T lymphocytes by soybean agglutination and E-rosetting. This approach was tested in 54 consecutive patients with acute leukemia who received transplants from HLA-identical sibling donors or, in two cases, from family donors mismatched at D-DR. No posttransplant immunosuppressive treatment was given as graft-versus-host disease (GVHD) prophylaxis. RESULTS Neither graft rejection nor GVHD occurred. Transplant-related deaths occurred in six (16.6%) of 36 patients in remission and in seven (38.8%) of 18 patients in relapse at the time of transplantation. The probability of relapse was .12 (95% confidence interval [CI], 0 to .19) for patients with acute myeloid leukemia and .28 (95% CI, .05 to .51) for patients with acute lymphoblastic leukemia who received transplants at the first or second remission. At a median follow-up of 6.9 years (minimum follow-up, 4.9 years), event-free survival for patients who received transplants while in remission was .74 (95% CI, .54 to .93) for acute myeloid leukemia patients and .59 (95% CI, .35 to .82) for acute lymphoblastic leukemia patients. All surviving patients have 100% performance status. CONCLUSION Adding antithymocyte globulin and thiotepa to the conditioning regimen prevents rejection of extensively T-cell-depleted bone marrow. Even in the complete absence of GVHD, the leukemia relapse rate is not higher than in unmanipulated transplants.

Haploidentical hematopoietic transplantation from KIR ligand–mismatched donors with activating KIRs reduces nonrelapse mortality

Because activating killer cell immunoglobulinlike receptors (KIRs) are heterogeneously expressed in the population, we investigated the role of donor activating KIRs in haploidentical hematopoietic transplants for acute leukemia. Transplants were grouped according to presence vs absence of KIR-ligand mismatches in the graft-vs-host direction (ie, of donor-vs-recipient natural killer [NK]-cell alloreactivity). In the absence of donor-vs-recipient NK-cell alloreactivity, donor activating KIRs had no effects on outcomes. In the 69 transplant pairs with donor-vs-recipient NK-cell alloreactivity, transplantation from donors with KIR2DS1 and/or KIR3DS1 was associated with reduced risk of nonrelapse mortality, largely infection related (KIR2DS1 present vs absent: hazard ratio [HR], 0.25; P = .01; KIR3DS1 present vs absent: HR, 0.18; P = .006), and better event-free survival (KIR2DS1 present vs absent: HR, 0.31; P = .011; KIR3DS1 present vs absent: HR, 0.30; P = .008). Transplantation from donors with KIR2DS1 and/or KIR3DS1 was also associated with a 50% reduction in infection rate (P = .003). In vitro analyses showed that KIR2DS1 binding to its HLA-C2 ligand upregulated inflammatory cytokine production by alloreactive NK cells in response to infectious challenges. Because ∼40% of donors able to exert donor-vs-recipient NK-cell alloreactivity carry KIR2DS1 and/or KIR3DS1, searching for them may become a feasible, additional criterion in donor selection.

Anti-CD30 (BER=H2) immunotoxins containing the type-1 ribosome-inactivating proteins momordin and PAP-S (pokeweed antiviral protein from seeds) display powerful antitumour activity against CD30+ tumour cells in vitro and in SCID mice.

The anti‐CD30 immunotoxin (IT) Ber‐H2/saporin is effective in patients with refractory Hodgkin’s disease. However, responses are short and partial, one of the main reasons being the inability to repeat IT doses because of formation of human antibodies against the murine antibody and/or the toxin. To overcome this problem, we constructed two new anti‐CD30 ITs by covalently linking the mouse monoclonal antibody Ber‐H2 to the type 1 ribosome‐inactivating proteins (RIPs) momordin (MOM) and pokeweed antiviral protein from seeds (PAP‐S), which do not cross‐react with each other or with saporin. Both ITs inhibited protein synthesis by Hodgkin’s disease and anaplastic large‐cell lymphoma (ALCL)‐derived CD30+ target cell lines with a very high efficiency (IC50 ranging from < 5 × 10−13 m to 2.75 × 10−11m, as RIP). In a SCID mouse model of xenografted CD30+ human ALCL, a 3 d treatment with non‐toxic doses of Ber‐H2/MOM (50% LD50), started 24 h after transplantation, prevented tumour development in about 40% of the animals and significantly delayed tumour growth rate in the others. Main toxicity signs in mice and rabbits were a dose‐related increase of serum transaminases (AST and ALT) and creatine phosphokinase (CPK). LD50 (as RIP) in Swiss mice was 7 mg/kg for Ber‐H2/MOM and 0.45 mg/kg for Ber‐H2/PAP‐S. Sequential administration of two anti‐CD30 ITs (Ber‐H2/MOM and Ber‐H2/saporin) was well tolerated and did not result in formation of antibodies cross‐reacting with the two plant toxins. The results presented in this paper suggest that, in the future, sequential administration of anti‐CD30 humanized antibodies linked to antigenically distinct type 1 RIPs (saporin, MOM, PAP‐S) should be feasible.

Prospective randomized clinical trial of teicoplanin for empiric combined antibiotic therapy in febrile, granulocytopenic acute leukemia patients.

The increasing prevalence of bacteremia caused by gram-positive bacteria in granulocytopenic acute leukemia patients prompted us to evaluate, in a prospective randomized trial, the role of teicoplanin, a new glycopeptide antibiotic, when it was added to amikacin plus ceftazidime, as an empiric therapy of fever in these patients. Of 47 evaluable episodes, 22 were treated with the teicoplanin regimen and 25 were treated with the combination of amikacin and ceftazidime. The overall response to therapy of patients treated with teicoplanin was slightly better (82% improvement) than that obtained with amikacin plus ceftazidime (52%). The response rate of patients with gram-positive bacteremias was 80% (4 of 5) to the regimen that included teicoplanin; 25% (1 of 4) of the patients treated with amikacin plus ceftazidime responded to treatment; and for patients with gram-negative bacteremias, the response rates were, respectively, 100% (4 of 4) and 70% (7 of 10). The better results obtained with amikacin-ceftazidime-teicoplanin treatment were most evident in patients with profound (less than 100/mm3) and persistent neutropenia (83 versus 30% improvement). Furthermore, a good response rate of patients with gram-positive bacteremias (seven of eight; 87% improvement) was achieved in a small group of bone marrow transplant patients who were all treated with amikacin-ceftazidime-teicoplanin. No severe side effects were documented in any patient. Teicoplanin, as a drug administered as a single daily dose, seems to be a safe and useful anti-gram-positive agent when used in combination with amikacin-ceftazidime as an empiric therapy of febrile episodes in granulocytopenic acute leukemia patients.

Haploidentical stem cell transplantation for acute leukemia

Premise: Since March 1993, 133 patients with high-risk acute leukemia (66 AML, 67 ALL) have received a megadose of T-cell depleted hematopoietic stem cells. The 1993–95 conditioning protocol included TBI, thiotepa, ATG and CY for 36 patients who received an inoculum made up of lectin-separated bone marrow and PBPCs. After 1995, to minimise the extra-hematological toxicity of the conditioning and eliminate GvHD, we substituted fludarabine for CY in the conditioning and PBPCs were depleted of T-cells by a positive selection of the CD34+ cells using CellPro (n=44 patients) or, since January 1999, CliniMacs (n=53 patients). A later modification to the protocol in January 1999 was the suspension of post transplant G-CSF.Work in Progress: We report here the results in the last 53 acute leukemia patients all of whom were transplanted under our modified protocol. Ages ranged from 9 to 62 years with a median of 38 years for the 33 patients with AML and 23 for the 20 with ALL. All were at high risk because 25 were actually in relapse at transplant, 16 were in second or later CR and even the 12 patients in CR1 were at high risk because of the unfavourable prognostic features. Overall 52/53 patients (98%) engrafted. The TBI-Fludarabine-based conditioning was well tolerated even in the 14 patients between 45 and 62 years of age. There was no veno-occlusive disease of the liver and the incidence of severe mucositis was low. Even though no post-transplant immunosuppressive therapy was given, acute GvHD grade≥II occurred in only 4 cases and only one progressed to chronic GvHD. Overall, 16 patients (30%) have died of non-leukemic causes. Relapses occurred mainly in patients who were already in relapse at transplant (12/25). Only 3 of the 28 who were in any CR at transplant have so far relapsed. As our group has already shown, donor-vs-recipient NK cell alloreactivity exerts a specific graft-vs-AML effect in the absence of GvHD. In fact, leukemia relapse was largely controlled in AML recipients whose donor was NK alloreactive, with only 2 out of 16 relapsing. To date, 13 of 18 AML (72%) and 5 of 10 ALL (50%) who were in any CR at transplant, survival for patients transplanted in CR is 60% in the 18 AML patients and 38% in the 10 ALL. The probability of EFS was significantly better in the 16 AML patients whose transplant included donor vs recipient NK cell alloreactivity than in those whose transplant did not (70% vs 7%). In conclusion, given our current results, the most suitable candidate for the full haplotype mismatched transplant should be in early stage disease and selection of an NK alloreactive donor is recommended.

Evaluation of immunotoxins containing single‐chain ribosome‐inactivating proteins and an anti‐CD22 monoclonal antibody (OM124): in vitro and in vivo studies

Immunotoxins were prepared with three ribosome‐inactivating proteins (RIP), momordin, pokeweed antiviral protein from seeds (PAP‐S) and saporin‐S6, linked to the anti‐CD22 monoclonal antibody OM124. These immunotoxins inhibited protein synthesis by CD22‐expressing cell lines Daudi, EHM, BJAB, Raji and BM21 with IC50 (concentration causing 50% inhibition) ranging from < 5 × 10−15 to 7.6 × 10−11 M as RIP, and IC90 (concentration causing 90% inhibition) ranging from 5 × 10−14 to 5 × 10−8 M, with no effect on a CD22‐negative HL60 cell line at the highest concentration tested (5 × 10−8 M). Apoptosis was induced in sensitive cells. The formation of bone marrow colonies was inhibited by no more than 40% by the immunotoxins at concentrations up to 10−9 M. Treatment with the immunotoxins, alone or in combination, significantly extended the survival time of mice bearing transplanted Daudi cells. A treatment with cyclophosphamide and OM124/saporin immunotoxin was particularly effective in SCID mice transplanted with a low number of cells (3 × 10−6), when 60% of the animals remained tumour‐free.

5-Azacytidine prevents transgene methylation in vivo

Retroviral sequence can silence transgene expression in vitro and in vivo. We report that this effect can be efficiently prevented by in vivo administration of the demethylating agent 5-azacytidine (aza-C). We engineered the U937 human cell line with a retroviral vector consisting of the thymidine kinase suicide gene (tk), which induces sensitivity to ganciclovir (gcv) and through an IRES sequence, the bacterial beta-galactosidase gene (lacZ) as a marker gene. About 90% of the U937 cells expressed the transgene. By injecting the transduced U937 cells in severe combined immunodeficient disease (SCID) mice, we generated a tumour which, during in vivo treatment with aza- C, maintained the high expression of lacZ and tk genes at the baseline values. LacZ-positive cells in the tumour masses after death was weak (1–2%) in the control group, while in mice treated with aza-C it was maintained at 90%. The delay in tumour onset was significanly longer when animals were treated with both aza-C and gcv (P < 0.0001) compared with animals treated with gcv or with aza-c alone. the prevention of silencing phenomena has important implications for gene therapy, because an efficient transduction associated with appropriate drug therapy, might be a powerful strategy for successful application of gene therapy protocols.