Association between oral and fecal microbiome dysbiosis and treatment complications in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation.

The oral and gastrointestinal mucosae represent the main targets of the toxic effect of chemo and/or radiotherapy administered during the conditioning regimen before hematopoietic stem cell transplant (HSCT). These harmful consequences and the immunological complications that may occur after the transplant (such as Graft versus Host Disease, GvHD) are responsible for the clinical symptoms associated with mucositis during the aplasia phase, like pain, nausea, vomiting, and diarrhea. These toxicities could play a critical role in the oral and gastrointestinal microbiomes during the post-transplant phase, and the degree of microbial dysbiosis and dysregulation among different bacterial species could also be crucial in intestinal mucosa homeostasis, altering the host's innate and adaptive immune responses and favoring abnormal immune responses responsible for the occurrence of GvHD. This prospective pediatric study aims to analyze longitudinally oral and gut microbiomes in 17 pediatric patients who received allogeneic HSCT for malignant and non-malignant diseases. The oral mucositis was mainly associated with an increased relative abundance of Fusobacteria, and Prevotella species, while Streptococcus descendants showed a negative correlation. The fecal microbiome of subjects affected by cutaneous acute GvHD (aGvHD) correlated with Proteobacteria. Oral mucosal microbiota undergoes changes after HSCT, Fusobacteria, and Prevotella represent bacterial species associated with mucositis and they could be the target for future therapeutic approaches, while fecal microbiome in patients with acute GvHD (aGvHD) revealed an increase of different class of Proteobacteria (Alphaproteobacteria and Deltaproteobacteria) and a negative correlation with the class of Gammaproteobacteria.

Targeting GD2 after allogeneic SCT: effector cell composition defines the optimal use of ch14.18 and the bispecific antibody construct NG-CU (GD2-CD3).

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.

Good response with zinc acetate monotherapy in an adolescent affected by severe Wilson disease.

We describe a 17-year-old girl with haemolytic anaemia as presentation of Wilson disease. The diagnosis was based on the findings of < 20 mg/dl ceruloplasmin serum level, Kayser-Fleischer ring and Coombs-negative haemolytic anaemia. Genetic testing revealed the presence of the H1069Q heterozygous mutation. The patient was treated with Zinc acetate monotherapy, with good response, maintened after 22 months. This case emphasizes the importance of recognizing atypical clinical presentation of Wilson disease, which must always be considered in patients with Coombs-negative haemolytic anaemia. The good clinical response to treatment with zinc acetate monotherapy in our case might lend to consider the use of zinc monotherapy as initial therapy also in symptomatic patients with Wilson disease under close clinical observation. Clinical trials are needed to provide evidence for use of zinc monotherapy as first-line therapy in symptomatic patients with Wilson disease.

Viral-load and B-lymphocyte monitoring of EBV reactivation after allogeneic hemopoietic SCT in children.

EBV-associated post transplant lymphoproliferative disease (EBV-PTLD) is a life-threatening complication that may occur after hemopoietic SCT. We prospectively screened 80 children on a weekly basis using nested quantitative PCR to evaluate EBV genome copies. EBV viral load <1000 copies per 10(5) PBMC was observed in 63% of transplants, whereas it was between 1000 and 9999 copies per 10(5) PBMC in 13%, and between 10 000 and 19 999 in 10%, with no significant increase in percentage of CD20+ lymphocytes. Viral load reached > or = 20 000 copies per 10(5) PBMC in 14% of patients, and rituximab was administered to 75% of them. None of the patients except one developed a lymphoproliferative disease. Our study found that only 13% of unrelated donor HSCT recipients had a very high risk of EBV-PTLD defined as > or = 20 000 geq per 10(5) PBMC associated with an increase in CD20+ lymphocyte. We suggest that rituximab could be administered in the presence of very high levels of EBV-DNA viral load or in the presence of mid levels of EBV-DNA viral load associated with an increase in the percentage of CD20+ lymphocytes. Through this approach, we significantly reduced the number of patients treated with rituximab, and consequently the acute and chronic adverse events related to this treatment.

Daclizumab as useful treatment in refractory acute GVHD: a paediatric experience.

GVHD remains a serious complication after allogeneic SCT. We describe 13 paediatric patients treated with daclizumab for refractory acute GVHD (aGVHD). After 30 days of daclizumab administration, all patients with cutaneous aGVHD reached complete response. Among patients with gastrointestinal disease, 50 and 30% had complete and partial response, respectively, whereas 11 and 55% of patients with hepatic aGVHD achieved CR and PR, respectively. Overall, complete (46%) and partial (46%) responses were demonstrated in 92% of our patients, whereas the remaining patients (8%) were nonresponders. No life-threatening infectious episodes were recorded within 100 days from transplant in this selected group of paediatric patients. Overall 46% of patients were alive at a median of 461 days from SCT, but 50% of them developed chronic GVHD. In our experience, daclizumab proved to be a useful and safe treatment for refractory and steroid-resistant/dependent aGVHD, in particular for cutaneous and low-moderate intestinal involvement.

Strategies of the donor search for children with second CR ALL lacking a matched sibling donor.

During the last 10 years, the number of alternative Haematopoietic stem cell transplantations (HSCTs) performed on children in Europe has increased significantly and has reached 61% of the allografts. In this paper, we provide practical guidelines to help define an algorithm for the treatment of children relapsing during or after first-line chemotherapy for ALL and lacking a matched sibling donor. A simultaneous search for an unrelated donor and for a cord blood unit should be started. This study focuses mainly on the effects of some factors on survival in an effort to highlight the influence that these factors have on our choices. Matching the patient for HLA-A, -B, -C and -DRB1 alleles remains the top priority: a single HLA class I or II allele mismatch has no influence on survival, while multiple mismatching for more than one class I allele and simultaneous disparities in class I and II alleles increase mortality. The impact of additional mismatches for HLA-DQ and -DP loci on survival is still controversial. Young donor age is the most important factor that has a significant effect on better survival from among several other factors, including CMV sero-status, gender and ABO. An 18- to 30-year-old, 8/8 allele-matched donor (excluding allele matching at DQB1) or for many teams 10/10 allele-matched donor; or a 4 out of 6 (considering Ag HLA-A, -B and allelic typing of DRB1) CB unit containing more than 3.0 x 10(7) nuclear cells is considered by most institutions. The choice should be made on the basis of urgency. If a donor or a CB unit is not found within an appropriate time frame, generally less than 3 months after obtention of remission, haploidentical HSCT should be offered. Some institutions consider haploidentical HSCT the second therapeutic option when a matched donor is not available.