ALBERT

Description: Severe congenital neutropenia (SCN) is a rare heterogeneous genetic disorder characterized by recurrent bacterial infections from early infancy due to severe chronic neutropenia. Majority of SCN patients have benefitted by the treatment with granulocyte colony-stimulating factor (G-CSF). However, patients on long-term G-CSF therapy have a relative risk of developing myelodysplastic syndrome/acute myeloid leukemia. The only curable treatment for SCN patients is hematopoietic stem cell transplantation (HSCT). Recently, HSCTs with reduced intensity conditioning regimens have been applied to the treatment for SCN patients prior to malignant transformation. However, the optimal conditioning of HSCT for SCN patients has not been established. In this study, we conducted bone marrow cell transplantations (BMT) in 16 patients with SCN using an immunomyelosuppressive conditioning regimen to minimize early and late transplant-related morbidity in Hiroshima University Hospital. A total of 17 BMT procedures were performed in 16 patients with SCN from 2008 to 2019. Five of 16 patients had experienced the engraftment failure of initial HSCT and 4 of them were referred to our hospital for re-transplantation. Fifteen of 16 patients had a heterozygous mutation in the ELANE gene. Bone marrow cells (BM) were obtained from 6 HLA-matched related, 3 HLA-matched unrelated, and 8 HLA-mismatched unrelated (7/8 antigens) donors, respectively. Conditioning regimen consisted of fludarabine, cyclophosphamide, melphalan, total body irradiation (3.6 Gy) with or without antithymocyte globulin. Short-term methotrexate and tacrolimus were administered for the prophylaxis of graft-versus-host disease (GVHD). Engraftment of neutrophils was observed within post-transplant 24 days in all patients. Two patients developed graft failure on day 40 and day 90, respectively, after the temporal engraftment. However, both patients were rescued by second BMT from different HLA-matched unrelated donors receiving the same conditioning regimen. Four patients who received BMT from HLA-matched related donors developed stable mixed chimerism without neutropenia in peripheral blood for 3 to 10 years. Although one patient who received donor lymphocyte infusion due to mixed chimerism developed grade II acute GVHD and limited chronic GVHD, the others did not develop severe GVHD. All patients are alive for 6 months to 11 years after BMT with no signs of severe infections or transplantation-related morbidity. Similar conditioning regimen has been applied to BMT for 35 patients with chronic granulomatous disease (CGD) in our hospital. In that study 4 male adulthood patients with CGD already fathered each child by their wives through spontaneous pregnancy, implying the successful preservation of patients' fertility. Collectively, our results demonstrate that BMT with a sufficient immunosuppressive conditioning regimen may be a feasible and effective treatment for SCN patients, irrespective of initial engraftment failure. The excellent results in our cohort suggest that indications for proceeding to HSCT could be extended to patients without malignant transformation.The further analyses of accumulated cases are necessary to assess the efficacy, safety, and less late adverse effects related to HSCT including fertility. Disclosures No relevant conflicts of interest to declare.

Description: Prophylactic administration of factor VIII products is necessary to prevent bleeding and preserve normal musculoskeletal function in children with severe hemophilia A (HA). Recently, extended half-life recombinant factor VIII (EHL-rFVIII) products have been utilized in HA patients. Therefore, the pharmacokinetics (PK) of EHL-rFVIII in individuals is needed to determine the appropriate administration for personalized prophylaxis according to the age, bleeding phenotype, the presence of arthropathy, and physical activity. The myPKFiTR ver 3.0 has been developed as the device to estimate the personalized dosing with a 2 sample PK based on the population PK (Bayesian) tool. In this study we report our single-center experience to study PK profiles and to individualize dose and dosing interval based on myPKFiTR. Eight patients with severe HA aged from 10 to 20 years were enrolled in this study for personalized prophylaxis. The half-life of EHL-rFVIII was approximately 15 to 18 hours in all patients studied. The clearance of FVIII was inversely correlated with the half-life of EHL-rFVIII. The EHL-rFVIII products have been basically administered twice a week. The trough levels of FVIII were more than 3% in all patients. The prophylactic regimen in adolescents was individually determined according to the personal simulation of PK study and to patients' life style and physical activities. Adolescent patients actively participated in sports, such as track and field, basketball, and football after school. The FVIII level after school was easily estimated by the use of myPKFiTR according to the dose and duration of replacement. The doses of EHL-rFVIII products were individually determined to have more than 10 to 30% of FVIII level at the time of sports activity. During personalized prophylaxis (6 to 18 months), all of patients studied have been no bleeds during sports as well as no spontaneous bleeds. Additionally, myPKFiTR has the capability of presenting the real-time FVIII level on the screen of smartphone after the replacement of EHL-rFVIII based on the individual PK. Some patients have referred their own FVIII level before the beginning of sports through their smartphone and then have decided the necessity of the replacement. These experiences suggest the enhancement of treatment concordance in the supportive relationship between patients and medical staff. Thus, the use of myPKFiTR may be essential for the optimization of prophylactic administration of EHL-rFVIII and for the medical adherence and concordance in each individual. Disclosures No relevant conflicts of interest to declare.

Description: Background: Myeloproliferative neoplasms (MPNs) are clonal hematopoietic disorders characterized by overproduction of differentiated hematopoietic cells. Among MPNs, chronic myeloid leukemia (CML) with BCR-ABL1 is the best studied subtype and is sometimes diagnosed during childhood. "Ph-negative" MPNs are typically found in older adults and are exceedingly rare during childhood. These classical Ph-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Because of this rarity, clinical features of pediatric MPNs are largely unknown, except for CML. Method: We administered questionnaires to institutions registered with the Japanese Society of Pediatric Hematology/Oncology (JSPHO). We collected clinical information of pediatric and young adult patients aged younger than 30 years who had been diagnosed with Ph-negative MPNs during 2000-2016. This study was conducted as a project of the Leukemia and Lymphoma Committee of the JSPHO. Results: We received responses from 145 institutions, which included all 107 board-certificated educational institutions of the JSPHO. A summary of the clinical features of included patients is shown in Table 1. From 2000 to 2016, 5 patients with PV, 42 with ET, and 2 with PMF were newly diagnosed with Ph-negative MPNs. Among them, 1 patient with PMF was excluded from subsequent analysis because of insufficient clinical information. The male-female ratio was almost balanced. The median age at diagnosis was 14 years for patients with PV, 9 years for patients with ET, and 1 patient with PMF was 10 months old. Only 1 patient with PV had a karyotype abnormality. The median follow-up period was 51 months since diagnosis. The JAK2V617F mutation was screened in almost all patients, and no patients with PV and 9 patients with ET had this mutation. With regard to treatment, 3 of 5 patients with PV received phlebotomy. Among patients with ET, aspirin was used most frequently (21 patients), followed by anagrelide (11 patients). However, 2 patients with PV and 8 patients with ET received no therapeutic approach. With regard to adverse events, hemorrhage and thrombosis were observed in 4 and 3 patients with ET, respectively, but these events were not found in patients with PV or PMF. Transformation to leukemia or myelofibrosis was found in 1 and 1 patient with PV, and 1 and 3 patients with ET, respectively. Among the patients who received no therapeutic approach, only 1 patient with PV experienced a hemorrhagic event and no other patients experienced any adverse events. Only 1 child with PV died owing to subsequent development of myelofibrosis and acute myeloid leukemia approximately 11 years after the initial diagnosis of PV. Conclusion: To the best of our knowledge, this is the first nationally-representative survey to clarify the clinical aspects of pediatric patients with Ph-negative MPNs. Although the methodology was not standardized, the frequency of the JAK2V617F mutation appears to be lower than that previously reported for adult patients. Moreover, the incidence of adverse events, such as thrombosis, hemorrhage, leukemia development, and transformation to myelofibrosis, was much lower than that of adult patients. As a result, although at relatively short durations of follow-up, the prognosis of pediatric patients with Ph-negative MPNs appears to be comparatively good. Further study with genetic analysis is warranted to determine the clinical and genetic features of pediatric patients with Ph-negative MPNs. Disclosures Mitsui: Astellas pharmaceutica: Research Funding; Daiichi Sankyo pharmaceutical: Research Funding; Chugai pharmaceutical: Research Funding; Teijin pharmaceutical: Research Funding; JCR pharmaceutical: Research Funding; Maruho pharmaceutical: Research Funding; MSD pharmaceutical: Research Funding; Shionogi pharmaceutical: Research Funding.

Description: Photolyases are flavoenzymes responsible for the repair of carcinogenic DNA damage caused by ultraviolet radiation. They harbor the catalytic cofactor flavin adenine dinucleotide (FAD). The light-driven electron transfer from the excited state of the fully-reduced form of FAD to the DNA lesions causes rearrangement of the covalent bonds, leading to the restoration of intact nucleobases. In addition to the catalytic chromophore, some photolyases bear a secondary chromophore with better light absorption capability than FAD, acting as a light-harvesting chromophore that harvests photons in sunlight efficiently and transfers light energy to the catalytic center, as observed in natural photoreceptor proteins. Inspired by nature, we covalently and site-specifically attached a synthetic chromophore to the surface of photolyase using oligonucleotides containing a modified nucleoside and a cyclobutane-type DNA lesion, and successfully enhanced its enzymatic activity in the light-driven DNA repair. Peptide mapping in combination with theoretical calculations identified the amino acid residue that binds to the chromophore, working as an artificial light-harvesting chromophore. Our results broaden the strategies for protein engineering and provide a guideline for tuning of the light perception abilities and enzymatic activity of the photoreceptor proteins.

Description: Porosity reduction in rocks from a fault core can cause elevated pore fluid pressures and consequently influence the recurrence time of earthquakes. We investigated the porosity distribution in the New Zealand's Alpine Fault core in samples recovered during the first phase of the Deep Fault Drilling Project (DFDP-1B) by using two-dimensional nanoscale and three-dimensional microscale imaging. Synchrotron X-ray microtomography-derived analyses of open pore spaces show total microscale porosities in the range of 0.1 %–0.24 %. These pores have mainly non-spherical, elongated, flat shapes and show subtle bipolar orientation. Scanning and transmission electron microscopy reveal the samples' microstructural organization, where nanoscale pores ornament grain boundaries of the gouge material, especially clay minerals. Our data imply that (i) the porosity of the fault core is very small and not connected; (ii) the distribution of clay minerals controls the shape and orientation of the associated pores; (iii) porosity was reduced due to pressure solution processes; and (iv) mineral precipitation in fluid-filled pores can affect the mechanical behavior of the Alpine Fault by decreasing the already critically low total porosity of the fault core, causing elevated pore fluid pressures and/or introducing weak mineral phases, and thus lowering the overall fault frictional strength. We conclude that the current state of very low porosity in the Alpine Fault core is likely to play a key role in the initiation of the next fault rupture.