Immune recovery was retrospectively analyzed in a cohort of 41 patients with acute leukemia, myelodysplastic syndrome and nonmalignant diseases, who received αβ T- and B-cell-depleted allografts from ...haploidentical family donors. Conditioning regimens consisted of fludarabine or clofarabine, thiotepa, melphalan and serotherapy with OKT3 or ATG-Fresenius. Graft manipulation was carried out with anti-TCRαβ and anti-CD19 Abs and immunomagnetic microbeads. The γδ T cells and natural killer cells remained in the grafts. Primary engraftment occurred in 88%, acute GvHD (aGvHD) grades II and III-IV occurred in 10% and 15%, respectively. Immune recovery data were available in 26 patients and comparable after OKT3 (n=7) or ATG-F (n=19). Median time to reach >100 CD3+ cells/μL, >200 CD19+ cells/μL and >200 CD56+ cells/μL for the whole group was 13, 127 and 12.5 days, respectively. Compared with a historical control group of patients with CD34+ selected grafts, significantly higher cell numbers were found for CD3+ at days +30 and +90 (267 vs 27 and 397 vs 163 cells/μL), for CD3+4+ at day +30 (58 vs 11 cells/μL) and for CD56+ at day +14 (622 vs 27 cells/μL). The clinical impact of this accelerated immune recovery will be evaluated in an ongoing prospective multicenter trial.
Summary
Neonates show an impaired anti‐microbial host defence, but the underlying immune mechanisms are not understood fully. Myeloid‐derived suppressor cells (MDSCs) represent an innate immune cell ...subset characterized by their capacity to suppress T cell immunity. In this study we demonstrate that a distinct MDSC subset with a neutrophilic/granulocytic phenotype (Gr‐MDSCs) is highly increased in cord blood compared to peripheral blood of children and adults. Functionally, cord blood isolated Gr‐MDSCs suppressed T cell proliferation efficiently as well as T helper type 1 (Th1), Th2 and Th17 cytokine secretion. Beyond T cells, cord blood Gr‐MDSCs controlled natural killer (NK) cell cytotoxicity in a cell contact‐dependent manner. These studies establish neutrophilic Gr‐MDSCs as a novel immunosuppressive cell subset that controls innate (NK) and adaptive (T cell) immune responses in neonates. Increased MDSC activity in cord blood might serve as key fetomaternal immunosuppressive mechanism impairing neonatal host defence. Gr‐MDSCs in cord blood might therefore represent a therapeutic target in neonatal infections.
Immune recovery was retrospectively analyzed in a cohort of 41 patients with acute leukemia, myelodysplastic syndrome and nonmalignant diseases, who received alpha beta T- and B-cell-depleted ...allografts from haploidentical family donors. Conditioning regimens consisted of fludarabine or clofarabine, thiotepa, melphalan and serotherapy with OKT3 or ATG-Fresenius. Graft manipulation was carried out with anti-TCR alpha beta and anti-CD19 Abs and immunomagnetic microbeads. The gamma delta T cells and natural killer cells remained in the grafts. Primary engraftment occurred in 88%, acute GvHD (aGvHD) grades II and III-IV occurred in 10% and 15%, respectively. Immune recovery data were available in 26 patients and comparable after OKT3 (n=7) or ATG-F (n=19). Median time to reach >100 CD3+ cells/ mu L, >200 CD19+ cells/ mu L and >200 CD56+ cells/ mu L for the whole group was 13, 127 and 12.5 days, respectively. Compared with a historical control group of patients with CD34+ selected grafts, significantly higher cell numbers were found for CD3+ at days +30 and +90 (267 vs 27 and 397 vs 163 cells/ mu L), for CD3+4+ at day +30 (58 vs 11 cells/ mu L) and for CD56+ at day +14 (622 vs 27 cells/ mu L). The clinical impact of this accelerated immune recovery will be evaluated in an ongoing prospective multicenter trial.
Langerhans cell histiocytosis (LCH) is a clonal histiocytic disorder with recurrent mutations of
BRAF
and
MAP2K1
, but data on the impact of genetic features on progression and long-term sequelae are ...sparse. Cases of pediatric LCH with long-term follow-up from our institution were analyzed for mutations in
BRAF
V600
and
MAP2K1
exons 2 and 3 by immunostaining with mutation-specific VE1 antibody, as well as allele-specific PCR and sequencing, respectively. Clinical and follow-up data were obtained from our files and a questionnaire sent to all former patients. Sixteen of 37 (43%) evaluable cases showed
BRAF
V600E
, one case a
BRAF
V600D
and eleven (30%) a
MAP2K1
mutation. Nine cases were unmutated for both genes. All cases with risk organ involvement showed either
BRAF
V600
or
MAP2K1
mutation. Patients with
BRAF
V600
mutation excluding Hashimoto-Pritzker cases had a significantly higher risk for relapses (
p
= 0.02). Long-term sequelae were present in 19/46 (41%) patients (median follow-up 12.5 years, range 1.0 to 30.8) with a trend for higher rates in mutated cases (mutated = 9/17, 53% versus non-
BRAF
V600
/
MAP2K1
mutated = 2/7, 29%). In addition, 8/9 cases with skin involvement including all Hashimoto-Pritzker cases (
n
= 3) were positive for
BRAF
V600E
. Infants below 2 years more frequently had
BRAF
V600
mutations (
p
= 0.013). Despite favorable prognosis, pediatric LCH shows a high frequency of relapses and long-term medical sequelae.
We investigated whether T cell-recruiting bispecific anti-CD3/GD2 antibody NG-CU might be an alternative to therapeutic anti-GD2 monoclonal antibody (mAb) ch14.18, mediating complement-dependent ...cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) through natural killer (NK) cells for immunotherapy in high-risk/relapsed neuroblastoma after autologous/allogeneic stem cell transplantation (auto/alloSCT). Different antibody concentrations and effector-to-target ratios (
E:T
) were evaluated using xCELLigence RTCA system, peripheral blood mononuclear cells (PBMCs) (healthy donors and patients after alloSCT), and neuroblastoma cell lines (LS/LAN-1). Mean specific lysis of LS cells utilizing PBMCs from healthy donors and ch14.18 (1 µg/ml) was 40/66/75% after 12/24/48 h compared to 66/93/100% in the presence of NG-CU (100 ng/ml). NG-CU showed enhanced cytotoxicity compared to ch14.18, even at lower concentrations and
E
:
T
ratios, and completely eradicated LS cells after 72 h. To decipher the influence of effector cell subsets on lysis, different ratios of T and NK cells were tested. At a ratio of 1:1, ch14.18 was more effective than NG-CU. Using patient PBMCs taken at different time points posttransplant, significant lysis with both constructs was detectable depending on percentages and total numbers of T and NK cells; in the early posttransplant phase, NK cells were predominant and ch14.18 was superior, whereas later on, T cells represented the majority of immune cells and NG-CU was more effective. Our study highlights the importance of analyzing effector cell subsets in patients before initiating antibody-based therapy. Consequently, we propose an adjusted administration of both antibody constructs, considering the state of posttransplant immune recovery, to optimize anti-tumor activity.
We report a prospective multicenter phase II study of haploidentical hematopoietic stem cell transplantation using CD3/CD19-depleted grafts after reduced intensity conditioning with fludarabine, ...thiotepa, melphalan and OKT-3.
Sixty-one adults with a median age of 46 years (range 19-65 years) have been enrolled. Diagnoses were acute myeloid leukemia (n=38), acute lymphoblastic leukemia (n=8), non-Hodgkin's lymphoma (n=6), myeloma (n=4), chronic myeloid leukemia (n=3), chronic lymphatic leukemia (n=1) and myelodysplastic syndrome (n=1). Patients were considered high risk because of refractory disease (n=18), cytogenetics (n=6), complete remission (≥ 2) (n=9), chemosensitive relapse in partial remission (n=4) or relapse after prior hematopoietic stem cell transplantation (n=15 allogeneic, n=8 autologous, n=1 both). At haploidentical hematopoietic stem cell transplantation, 30 patients were in complete remission and 31 in partial remission. Grafts contained a median of 7.0 × 10(6) (range 3.2-22) CD34(+) cells/kg, 4.2 × 10(4) (range 0.6-44) CD3(+) T cells/kg and 2.7 × 10(7) (range 0.00-37.3) CD56(+) cells/kg.
Engraftment was rapid with a median of 12 days to granulocytes more than 0.5 × 10(9)/L (range 9-50 days) and 11 days to platelets more than 20 × 10(9) (range 7-38 days). Incidence of grade IIIV acute graft-versus-host-disease and chronic graft-versus-host-disease was 46% and 18%, respectively. Non-relapse mortality on Day 100 was 23% and 42% at two years. Cumulative incidence of relapse/progression at two years was 31%. Kaplan-Meier estimated 1-year and 2-year overall survival with median follow up of 869 days (range 181-1932) is 41% and 28%, respectively.
This regimen allows successful haploidentical hematopoietic stem cell transplantation with reduced intensity conditioning in high-risk patients lacking a suitable donor. (clinicaltrials.gov identifier:NCT00202917).
Transplantation of haploidentical stem cells has become a well-established approach, which makes a potential donor available for almost all patients. This review focuses on current results and new ...strategies, especially in pediatric patients with malignant diseases. CD34(+) positive selection was the most common procedure for graft manipulation in the past years, whereas T and B cell depletion is a promising new method. GVHD could herewith be effectively reduced and primary engraftment was reported in 83-100% of patients after transplantation of high stem cell doses. For patients with ALL in remission, disease-free survival at 3 years ranged between 22 and 48%. TRM, mainly because of viral infections, was improved by the use of reduced-intensity conditioning (which helped to speed up T cell recovery) and by close monitoring of viral loads and prophylactic/preemptive therapy. The role of donor-derived Ag-specific T cells against viral and fungal antigens is currently under investigation. Patients with active disease at the time of transplantation had a poor outcome and several attempts to improve these results are currently evaluated, such as co-infusion of natural killer cells, co-transplantation of MSC, use of new antileukemic drugs and post-transplant immunotherapy.
Oral antifungal prophylaxis with extended-spectra azoles is widely used in pediatric patients after allogeneic hematopoietic stem cell transplantation (HSCT), while controlled studies for oral ...antifungal prophylaxis after bone marrow transplantation in children are not available. This survey analyzed patients who had received either itraconazole, voriconazole, or posaconazole. We focused on the safety, feasibility, and initial data of efficacy in a cohort of pediatric patients and adolescents after high-dose chemotherapy and HSCT. Fifty consecutive pediatric patients received itraconazole, 50 received voriconazole, and 50 pediatric patients received posaconazole after HSCT as oral antifungal prophylaxis. The observation period lasted from the start of oral prophylactic treatment with itraconazole, voriconazole, or posaconazole until two weeks after terminating the oral antifungal prophylaxis. No incidences of proven or probable invasive mycosis were observed during itraconazole, voriconazole, or posaconazole treatment. A total of five possible invasive fungal infections occurred, two in the itraconazole group (4 %) and three in the voriconazole group (6 %). The percentage of patients with adverse events potentially related to clinical drugs were 14 % in the voriconazole group, 12 % in the itraconazole group, and 8 % in the posaconazole group. Itraconazole, voriconazole, and posaconazole showed comparable efficacy as antifungal prophylaxis in pediatric patients after allogeneic HSCT.
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