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FoxP3+regulatory T cells (Tregs) suppress GVHD while preserving graft-versus-tumor effects, making them an attractive target for GVHD therapy. The donor-derived Treg pool can potentially be derived from the expansion of preexisting natural Tregs (nTregs) or from de novo generation of inducible Tregs (iTregs) from donor Tconvs in the transplantation recipient. Using an MHC-mismatched model of acute GVHD, in the present study we found that the Treg pool was comprised equally of donor-derived nTregs and iTregs. Experiments using various combinations of T cells from wild-type and FoxP3-deficient mice suggested that both preexisting donor nTregs and the generation of iTregs in the recipient mice contribute to protection against GVHD. Surprisingly, CD8+FoxP3+T cells represented approximately 70% of the iTreg pool. These CD8+FoxP3+T cells shared phenotypic markers with their CD4+counterparts and displayed suppressive activity, suggesting that they were bona fide iTregs. Both CD4+and CD8+Tregs appeared to be protective against GVHD-induced lethality and required IL-2 and TGFβ receptor expression for their generation. These data illustrate the complex makeup of the donor-derived FoxP3+Treg pool in allogeneic recipients and their potential role in protection against GVHD.

Fifty-three patients with high-risk acute lymphoblastic leukemia (ALL) under age 50 with a histocompatible sibling donor received high-dose radiochemotherapy followed by allogeneic bone marrow transplantation (BMT). The high-risk factors used to identify the patients were: white blood cell count at initial presentation, cytogenetic abnormalities, age, extramedullary leukemic infiltration, and time from initial therapy to complete remission. Patients with one or more of the above risk factors who received BMT have a disease-free survival of 61% with a median follow-up of 66 months (range 11 months to 10.6 years), and an actuarial relapse rate of 10%. This study demonstrates that patients with high-risk ALL achieve a significant disease-free survival and cure rate with the use of allogeneic fully matched sibling BMT. However, a properly designed prospective study comparing the outcome of BMT with the best currently available chemotherapy data is required to define the ultimate role of BMT in this group of patients.

Eighty-five consecutive patients with relapsed or refractory Hodgkin's disease (HD) underwent high-dose chemotherapy or chemo/radiotherapy followed by autologous bone marrow (ABMT) and/or peripheral blood stem cell (PBSC) transplantation. Two preparative regimens were used. Twenty-two patients (26%) without prior radiation received fractionated total body irradiation (FTBI) 1,200 Gy in combination with high-dose etoposide (VP-16) 60 mg/kg and cyclophosphamide (CTX) 100 mg/kg. Sixty-three patients (74%) with prior radiotherapy received carmustine (BCNU) 450 mg/m2instead of FTBI. The median age was 32 years (range, 16 to 56). The median number of prior chemotherapy regimens was three (range, 1 to 7). Forty-three patients (51%) received transplants in first relapse or second complete remission (CR), whereas 33 (39%) received transplants after second or subsequent relapse. All relapsed patients, except one, received conventional salvage chemotherapy and/or radiotherapy in an attempt to reduce tumor bulk before transplant. At the time of analysis in April 1994, fifty-seven patients (67%) are alive, including 44 (52%) in continuous CR, with a median follow-up for the surviving patients of 28 months (range, 7 to 66). Thirty patients (35%) relapsed at a median of 9 months (range, 1 to 43). Eleven patients (13%) died of transplant-related complications including veno-occlusive disease of the liver (VOD) in five, acute and late interstitial pneumonitis in three, graft failure in one, cerebral hemorrhage in one, and therapy-induced myelodysplasia (MDS)/acute leukemia in one patient. At a median follow-up of 25 months (range, 0.6 to 66), the cumulative probability of 2-year overall and disease-free survival (DFS) of all 85 patients is 75% (95% confidence interval [CI] 64% to 84%) and 58% (95% CI 47% to 69%), respectively. Three independent prognostic variables were identified by univariate analysis: number of prior chemotherapy regimens, prior radiotherapy, and extranodal disease at ABMT. Multivariate stepwise Cox regression identified the number of prior chemotherapy regimens as the only significant prognostic factor predicting for both relapse and DFS. There were no significant differences in the outcome of the treatment between the two preparative regimens. Our results confirm that high-dose therapy and ABMT is an effective therapy for patients with relapsed or refractory HD. Earlier transplantation is recommended before the development of drug resistance and end organ damage that results from repeated attempts of salvage therapy.

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a polypeptide mediator, elaborated by certain tumors and other cell types, that exerts multiple effects on endothelium via interaction with a class of high-affinity binding sites. In this report, the interaction of VPF/VEGF with human mononuclear phagocytes (MPs) is characterized. Radioligand binding studies at 4°C showed the presence of a single class of binding sites, kd approximately 300 to 500 pmol/L (~20 times lower affinity than the high-affinity binding site on endothelial cells [ECs]), the occupancy of which correlated with VPF/VEGF-induced MP migration and expression of tissue factor. These binding results were parallelled by functional experiments which indicated that the same VPF/VEGF preparations were about an order of magnitude less effective in stimulating MP chemotaxis than in inducing EC proliferation. When MPs with surface-bound 125I-VPF/VEGF were warmed to 37°C, endocytosis and degradation occurred. Occupancy of VPF/VEGF binding site resulted in subsequent activation of intracellular signal transduction mechanisms, as shown by an increase in MP intracellular calcium concentration. Cross-linking studies with 125I-VPF/VEGF showed a new high-molecular weight band (corresponding to putative 125l-VPF/VEGF-receptor complex), the appearance of which was blocked by excess unlabeled VPF/VEGF. Consistent with these results, immunoprecipitation of 32PO4-Iabeled MPs exposed to VPF/VEGF showed a single band of similar mobility, not seen in untreated controls. These results demonstrate that the interaction of VPF/VEGF with MPs, though of lower affinity than that observed with ECs, also results from interaction of the polypeptide with a specific cell-surface protein and leads to activation of intracellular transduction mechanisms.

Twenty consecutive patients with poor-risk aggressive lymphoma who at presentation either had elevated serum lactic dehydrogenase level (LDH) and any one of the other poor-prognostic features: bulky mass ≥10 cm, advanced stage III or IV, and ≥2 extranodal sites, or normal LDH level and all other three features, underwent high-dose chemo/radiother-apy followed by unmanipulated autologous bone marrow transplantation (BMT) during their first complete remission. Eighteen had B-cell lymphoma and 2 had T-cell lymphoma. Eleven patients had high-grade (7 immunoblastic, 3 small noncleaved, non-Burkitt’s, and 1 Burkitt’s) and 9 had diffuse large cell lymphoma. All patients had achieved a complete remission following conventional chemotherapy. Four patients had also received involved field radiotherapy to areas of bulky disease. The preparative regimen consisted of high-dose etoposide 60 mg/kg and cyclophosphamide 100 mg/kg in combination with fractionated total body irradiation (FTBI) 1,200 cGy (15 patients), or single-dose TBI750 cGy (2 patients), or carmustine 450 mg/m2 (3 patients). All patients tolerated the treatment well and achieved complete hematologic recovery. Three patients have relapsed at days 79, 196, and 401 after transplantation. Seventeen patients (84%) are alive and relapse-free with a median follow-up of 34 months (range 2 to 54). We conclude that high-dose chemo /radiotherapy followed by autologous BMT can be given as consolidation therapy during first remission in these patients with minimal transplant-related toxicity.

Thalidomide has been reported to be an effective agent for treatment of chronic graft-versus-host disease (CGVHD). To determine the efficacy of this agent in patients with refractory CGVHD a total of 80 patients who failed to respond to prednisone (PSE) or PSE and cyclosporine (CSA) were treated with thalidomide. Sixteen patients (20%) had a sustained response, 9 with a complete remission and 7 with a partial response. Twenty-nine patients (36%) had thalidomide discontinued because of side effects, which included sedation, constipation, neuritis, skin rash, and neutropenia. Side effects were reversible with drug discontinuation except for mild residual neuritis in one case. Rashes and neutropenia have not previously been reported as thalidomide side effects when used for CGVHD treatment. We conclude thalidomide is immunosuppressive and active in the treatment of CGVHD. A high incidence of reversible side effects limited dose intensity and reduced the number of patients who could benefit from treatment.

Graft-versus-host disease (GVHD) is a major obstacle to successful bone marrow transplantation (BMT) from matched unrelated donor (MUD). Currently available HLA-A, -B, and -DR serologic testing may not be sensitive enough to detect clinically relevant donor/recipient (D/R) nonidentity. Better HLA matching of D/R pairs using molecular typing for class II antigens in combination with intensive GVHD prophylaxis may potentially reduce the incidence of GVHD and lead to an improved outcome of MUD transplantation. Between July 1991 and August 1993, thirty consecutive patients with hematologic malignancies underwent MUD transplantation from donors who were identical for HLA -A, -B, and -DR by serologic typing. Twenty-five D/R pairs were matched for DRB and DQB by molecular typing (restriction fragment-length polymorphism and sequence-specific oligonucleotide probe hybridization analyses), whereas five were allele mismatched at either DRB or DQB. All patients also received GVHD prophylaxis with the combination of cyclosporine (CSA), methotrexate (MTX), and prednisone (PSE). The median age was 35 years (range, 15 to 50). The diagnoses were: chronic myelogenous leukemia (CML) in chronic phase (CP) (16), CML in more than CP (3), acute leukemia in more than first complete remission (CR) (8), acute leukemia in first CR (1), and advanced high-grade lymphoma (2). The preparative regimen consisted of 1,320 cGy fractionated total body irradiation (FTBI) and 60 mg/kg cyclophosphamide (CY) daily for 2 days in 17 good-risk patients (CML/CP and acute leukemia first CR); and 1,320 cGy FTBI in combination with 60 mg/kg etoposide and 20 to 60 mg/kg CY in 13 patients with advanced leukemia and lymphoma. All patients received CSA, PSE, and MTX on days 1, 3, 6 for GVHD prophylaxis, and 10 patients also received day +11 MTX. All patients engrafted except one who died early of regimen-related toxicity. The incidence of grade III or IV acute GVHD was 24% (95% confidence interval [CI], 10% to 44%) and that of extensive chronic GVHD was 65% (95% CI, 43% to 84%). At a median follow-up of 13.6 months, 57% of the patients are alive in remission with a median Karnofsky performance status of 90%. The cumulative probability of 2-year disease-free survival for all patients was 53% (95% CI, 33% to 71%); for good-risk patients, 71% (95% CI, 46% to 87%) and for the poor-risk group, 34% (95% CI, 13% to 64%). Stepwise logistic regression analysis showed that status at BMT was the only significant prognostic variable associated with severe acute GVHD, whereas donor age greater than 30 predicted for extensive chronic GVHD. These results suggest that the utilization of both serologic and molecular typing for D/R matching with an intensive GVHD regimen may reduce the incidence of acute GVHD and may potentially improve the outcome of unrelated donor BMT. Further controlled clinical trials are warranted to confirm our results.