Radiation-sparing reduced-intensity unrelated umbilical cord blood transplantation for rare hematological disorders in children.

Graft failure is a major pitfall of unrelated umbilical cord blood transplantation (CBT) in children with rare hematological disorders other than acute leukemia, such as acquired and inherited bone marrow failure, myelodysplastic syndrome, juvenile myelomonocytic leukemia, and chronic myeloid leukemia. We developed a less-toxic conditioning regimen for CBT that achieves a higher rate of complete donor chimerism, and retrospectively compared it against two other conditioning regimens for CBT performed at our single institution. The engraftment rate with complete donor chimerism was 100% and 5-year event-free survival (5y-EFS) was 90.9% in patients using our latest regimen (n = 11) of reduced-intensity conditioning (RIC) containing fludarabine (Flu) 180 mg/m2, melphalan (MEL) 210 mg/m2, and low-dose rabbit anti-thymocyte globulin (LD-rATG) 2.5 mg/kg without irradiation (regimen C). Outcomes were better than in patients (n = 10) treated with previous regimens involving irradiation (5y-EFS 30.0%, p = 0.004): regimen A, consisting of myeloablative conditioning containing cyclophosphamide (CY) and total body irradiation (TBI) with 8-12 Gy, or regimen B, consisting of RIC with Flu, CY, horse ATG, and thoracoabdominal irradiation (TAI) with 6 Gy. In conclusion, Flu/MEL/LD-rATG (regimen C) without TBI/TAI may be preferable as RIC for unrelated CBT in children with rare hematological disorders.

Feasibility of Cancer Immunotherapy with WT1 Peptide Vaccination for Solid and Hematological Malignancies in Children.

BACKGROUND: Advances in cancer immunotherapy in the pediatric field are needed in order to improve the prognosis of children with malignancies. We conducted a prospective phase I/II study of WT1 peptide vaccination for children with relapsed or refractory malignancies. METHODS: The main eligibility criteria were affected tissues or leukemic cells expressing the WT1 gene, and patients (and donors for allogeneic hematopoietic stem cell transplantation) having HLA-A*24:02. Vaccination using the WT1 peptide (CYTWNQMNL), which was modified for higher affinity to this HLA-type molecule with the adjuvant Montanide ISA51, was performed weekly 12 times. RESULTS: Twenty-six patients were enrolled and 13 (50.0%) completed the vaccination 12 times. Evidence for the induction of WT1-specific cytotoxic T-lymphocyte (CTL) responses without severe systemic side effects was obtained. Two out of 12 patients with bulky disease exhibited a transient clinical effect (one mixed response and one stable disease), three out of six patients with minimal residual disease achieved transient molecular remission, and five out of eight patients without a detectable level of the molecular marker, but with a high risk of relapse, had the best outcome of long-term continuous complete remission. CONCLUSIONS: WT1 vaccination is a safe immunotherapy and induced WT1-specific CTL responses in children; however, as a single agent, vaccination only provided patients in remission, but with a high risk of relapse, with "long-term benefits" in the context of its use for relapse prevention. WT1 peptide-based treatments in combination with other modalities, such as anti-tumor drugs or immunomodulating agents, need to be planned.

Feasibility of HLA-haploidentical hematopoietic stem cell transplantation with post-transplantation cyclophosphamide for advanced pediatric malignancies.

BACKGROUND: Patients with advanced malignancies in non-complete remission (CR) have a dismal prognosis after HLA-matched hematopoietic stem cell transplantation (HSCT). T-cell-replete HLA-haploidentical HSCT has remarkable anti-leukemia/tumor effects on these patients, but also a high risk of severe/extensive graft-versus-host disease (GHVD). Post-transplantation cyclophosphamide (PTCY) is regarded as a GVHD-specific immunosuppressant in adults, but its feasibility is unknown in children. METHODS: We performed a prospective feasibility study of PTCY at 50 mg/kg on day 3 for children with advanced leukemias or malignant solid tumors: refractory to chemotherapy or relapsed after conventional allogeneic HSCT. Conditioning consisted of fludarabine (180 mg/m2) and melphalan (140-210 mg/m2). RESULTS: Long-term engraftments were achieved in 11 patients (73.3%) after bone marrow transplantation (BMT, n = 13) or peripheral blood (PB) stem cell transplantation (n = 2). The incidence of severe acute GHVD was 25.0% and that of extensive chronic GVHD 0.0% after evaluable BMT. CR was achieved in 6/15 and partial response in 4/15 as the best response. Finally, 11/15 experienced disease progression/relapse, 2/15 suffered treatment-related mortality without evidence of disease, and 2/15 are alive in continuous CR. CONCLUSIONS: PTCY is feasible in children; however, for a better outcome in such patients with advanced malignancies, some modifications are anticipated.

Umbilical cord blood as an alternative source of reduced-intensity hematopoietic stem cell transplantation for chronic Epstein-Barr virus-associated T or natural killer cell lymphoproliferative diseases.

Chronic Epstein-Barr virus-associated T/natural killer cell lymphoproliferative diseases represented by chronic active Epstein-Barr virus infection are lethal but are curable with several courses of chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). Recently, we reported that reduced-intensity conditioning (RIC) provided better outcomes than myeloablative conditioning because RIC was less toxic. However, it was unclear whether cord blood transplantation (CBT) works in the context of RIC. We retrospectively analyzed 17 patients who underwent RIC followed by bone marrow transplantation (RIC-BMT) and 15 patients who underwent RIC followed by CBT (RIC-CBT). The representative regimen was fludarabine and melphalan based. The overall survival rates with RIC-BMT and RIC-CBT were 92.9% ± 6.9% and 93.3% ± 6.4%, respectively (P = .87). One patient died of lung graft-versus-host disease after RIC-BMT, and 1 patient died of multiple viral infections after RIC-CBT. Although cytotoxic chemotherapy was also immunosuppressive and might contribute to better donor cell engraftment after RIC-HSCT, the rate of engraftment failure after RIC-CBT was still higher than that after RIC-BMT (not significant); however, patients who had experienced graft failure were successfully rescued with a second HSCT. Unrelated cord blood can be an alternative source for RIC-HSCT if a patient has no family donor.

Multiplex polymerase chain reaction for six herpesviruses after hematopoietic stem cell transplantation.

BACKGROUND: Herpesviruses cause life-threatening diseases after hematopoietic stem cell transplantation (HSCT). It is necessary that viral diseases are identified early and safely diagnosed. The purpose of this study was to evaluate the efficacy of multiplex polymerase chain reaction (PCR) for qualitative detection of the six herpesviruses simultaneously: herpes simplex virus type 1 and type 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus (EBV) and human herpesvirus 6B. METHODS: Multiplex PCR was applied to patients with various clinical manifestations including central nervous system, cutaneous and mucosal complications after allogeneic HSCT, and the data were retrospectively analyzed. RESULTS: Patients positive for cytomegalovirus in peripheral blood by multiplex PCR might need pre-emptive treatment, but a positive result for EBV had no specific correlation with EBV-associated post-transplant lymphoproliferative disease, and positive result for human herpesvirus 6B failed to show any clinical significance. The multiplex PCR was safe and helpful to diagnose viral diseases of local regions, for example, the central nervous system, skin and mucosa. CONCLUSIONS: It may be worthwhile to survey the six herpesviruses with multiplex PCR after HSCT.

Epstein-Barr virus latent gene sequences as geographical markers of viral origin: unique EBNA3 gene signatures identify Japanese viruses as distinct members of the Asian virus family.

Polymorphisms in Epstein-Barr virus (EBV) latent genes can identify virus strains from different human populations and individual strains within a population. An Asian EBV signature has been defined almost exclusively from Chinese viruses, with little information from other Asian countries. Here we sequenced polymorphic regions of the EBNA1, 2, 3A, 3B, 3C and LMP1 genes of 31 Japanese strains from control donors and EBV-associated T/NK-cell lymphoproliferative disease (T/NK-LPD) patients. Though identical to Chinese strains in their dominant EBNA1 and LMP1 alleles, Japanese viruses were subtly different at other loci. Thus, while Chinese viruses mainly fall into two families with strongly linked 'Wu' or 'Li' alleles at EBNA2 and EBNA3A/B/C, Japanese viruses all have the consensus Wu EBNA2 allele but fall into two families at EBNA3A/B/C. One family has variant Li-like sequences at EBNA3A and 3B and the consensus Li sequence at EBNA3C; the other family has variant Wu-like sequences at EBNA3A, variants of a low frequency Chinese allele 'Sp' at EBNA3B and a consensus Sp sequence at EBNA3C. Thus, EBNA3A/B/C allelotypes clearly distinguish Japanese from Chinese strains. Interestingly, most Japanese viruses also lack those immune-escape mutations in the HLA-A11 epitope-encoding region of EBNA3B that are so characteristic of viruses from the highly A11-positive Chinese population. Control donor-derived and T/NK-LPD-derived strains were similarly distributed across allelotypes and, by using allelic polymorphisms to track virus strains in patients pre- and post-haematopoietic stem-cell transplant, we show that a single strain can induce both T/NK-LPD and B-cell-lymphoproliferative disease in the same patient.