ALBERT

Description: During development, mice with mutations of stem cell factor (SCF) or its receptor c-kit exhibit defects in melanogenesis, as well as hematopoiesis and gonadogenesis. Consequently, accumulating evidence suggests that the c-kit/SCF system plays a crucial role in all of these processes and in tumors which derive from them. Especially in neuroblastoma (infant tumors of neuroectoderm crest derivation such as melanocytes) it would appear that an autocrine loop exists between c-kit and SCF, and that the functional block of the c-kit receptors with monoclonal antibodies (MoAbs) results in a significant decrease in cellular proliferation. We studied the expression and role of c-kit and SCF in cell lines of soft tissue sarcoma of neuroectodermic origin, such as Ewing's sarcoma (ES) and peripheral neuro-ectodermal tumors (PNET). Using flow cytometry with MoAb CD117 PE, c-kit expression was highlighted in all six of the cell lines examined. This receptor was specifically and functionally activated by SCF, as shown by the binding experiments and the intracellular phosphotyrosine and immunoprecipitation studies that were performed. Using reverse transcriptase polymerase chain reaction analysis, five of the six cellular lines expressed the mRNA of SCF. In the medium measured by using an enzyme- linked immunosorbent assay, low concentrations of SCF were found: only the TC32 cellular line produced significantly higher levels (32 pg) than control. In serum-free culture the addition of SCF reduced the percentage of apoptotic cells from 25% to 90% in five out of the six cellular lines. This observation was confirmed by (1) the functional block of c-kit with MoAb: after 7 days of culture more than 30% of the cells were apoptotic (range 31.5% to 100%) in five out of six cell lines and there was also a decrease in the percentage of cells in phase S, and (2) c-kitantisense oligonucleotides: in the cellular lines treated with oligonucleotides (in relation to the untreated lines) there was a notable reduction (P 

Description: Introduction. Prophylaxis with factor concentrates reduces bleeding events and improves quality of life for adults and children with severe hemophilia. However, the optimal dosing and infusion frequency is not yet established. Integration of PK data into decision making is gaining support, in particular at the transition between conventional and EHL products. Here we report about 29 PK data of patients affected by hemophilia treated at our centre since childhood. Improved quality of life was our first aim, supposed that decreasing frequency of infusions or increasing the target through factor level allows a more active life without increased risk of bleeding. Patients' characteristics and methods. 18 patients (62%) were ≤ 18 years of age at PK time. 16 were affected by severe hemophilia A, 5 by moderate hemophilia A, 6 by severe hemophilia B and 2 by moderate hemophilia B. At PK time, 28 patients were on prophylaxis and 1 was on demand with recombinant factor IX. Median age at onset of prophylaxis was 9 years (range 3 months-38 years). Genetic assessment was available in 24 patients. Of these, 37.5% and 62.5% were carriers of null and not null mutations respectively. 4 patients were undergone to PK with standard products (1 Octocog alfa, 1 Simoctocog alfa, 1 Octocog alfa-Kovaltry®, 1 Turoctocog alfa) in order to define timing and dosage of successive infusions, while 25 patients switched to EHL factors (15 Efmoroctocog alfa, 2 Ionoctocog alfa, 7 Albutrepenonacog alfa, 1 Eftrenonacog alfa). In 15 patients a population-based PK (popPK) according to WAPPS-Hemo program was also performed. The annualized bleeding rate (ABR) was counted from patient's home bleeding records for one year before PK until now. Results. According to PK data, 21 patients (75%) decreased infusion frequency (100% hemophilia B and 67% hemophilia A patients). The remaining 7 hemophilia A patients maintained the same timing in order to increase the through factor level. Notably, 1 hemophilia B patient switched from on demand treatment to prophylaxis with EHL product due to the more acceptable schedule. 66% of null mutation patients and 73% of not null mutation patients decreased timing. Of 28 patients available at follow-up, 32%, 50% and 18% decreased, increased and maintained the same annual average factor consumption/kg, respectively. All patients had a good adherence after switch. In particular, the on demand patient started a regular prophylaxis with optimal compliance. ABR displayed a reduction with a median of 0 (range 0-5) after PK analysis compared to 1 (range 0-12) before the switch. Full PK vs popPK data obtained using at least two individual PK sampling points were almost similar. Conclusions. Our results remark the necessity of PK study especially in children due to the inter-individual variability independent of genetic assessment. Regarding factor IX, PK allowed us to propose timing even longer than that recommended by prescribing indications resulting in a better personalized prophylaxis. Moreover, our study demonstrates that a full PK analysis is feasible also in children. However, given similar results, popPK could be more feasible in most patients. Regarding consumption, the reduction of only 32% of patients reflects our aim to maintain a high safety profile in an active pediatric population. Nevertheless, the mean annualized consumption was just 0.6-fold increased in the remaining patients. This approach led us to further reduce ABR and in some cases to obtain a persistent no-bleeding status even with a full active life. Disclosures No relevant conflicts of interest to declare.

Description: During development, mice with mutations of stem cell factor (SCF) or its receptor c-kit exhibit defects in melanogenesis, as well as hematopoiesis and gonadogenesis. Consequently, accumulating evidence suggests that the c-kit/SCF system plays a crucial role in all of these processes and in tumors which derive from them. Especially in neuroblastoma (infant tumors of neuroectoderm crest derivation such as melanocytes) it would appear that an autocrine loop exists between c-kit and SCF, and that the functional block of the c-kit receptors with monoclonal antibodies (MoAbs) results in a significant decrease in cellular proliferation. We studied the expression and role of c-kit and SCF in cell lines of soft tissue sarcoma of neuroectodermic origin, such as Ewing's sarcoma (ES) and peripheral neuro-ectodermal tumors (PNET). Using flow cytometry with MoAb CD117 PE, c-kit expression was highlighted in all six of the cell lines examined. This receptor was specifically and functionally activated by SCF, as shown by the binding experiments and the intracellular phosphotyrosine and immunoprecipitation studies that were performed. Using reverse transcriptase polymerase chain reaction analysis, five of the six cellular lines expressed the mRNA of SCF. In the medium measured by using an enzyme- linked immunosorbent assay, low concentrations of SCF were found: only the TC32 cellular line produced significantly higher levels (32 pg) than control. In serum-free culture the addition of SCF reduced the percentage of apoptotic cells from 25% to 90% in five out of the six cellular lines. This observation was confirmed by (1) the functional block of c-kit with MoAb: after 7 days of culture more than 30% of the cells were apoptotic (range 31.5% to 100%) in five out of six cell lines and there was also a decrease in the percentage of cells in phase S, and (2) c-kitantisense oligonucleotides: in the cellular lines treated with oligonucleotides (in relation to the untreated lines) there was a notable reduction (P 

Description: Background: Identifying perioperative bleeding risk in pediatric patients undergoing major surgery is challenging because personal history is often not sufficiently informative and laboratory tests are also more susceptible to pre-analytical variables. Children with low Willebrand add further uncertainty in the treatment options. The aim of this study was to evaluate practices to assess hemorrhagic risk and manage bleeding prophylaxis in children with low von Willebrand factor levels (30 and 50 IU/dL; low VWF), known von Willebrand disease (VWD) or healthy controls undergoing ear, nose and throat (ENT) surgery. Methods: In this retrospective observational study, data from consecutive paediatric patients undergoing ENT surgery between January 1, 2010 and December 31, 2017 at the Turin Paediatric Hospital were analysed. All statistical analyses were performed using STATA (StataCorp. 2013. Been Statistical Software: Release 13. College Station, TX: StataCorp LP). Demographic and clinical characteristics of patients were assessed using the absolute frequencies and percentages for qualitative variables and percentiles for quantitative variables. The risk of bleeding was estimated from the number of patients who experienced bleeding within 21 days as a proportion of the number of patients subjected to surgery. 90% confidence intervals (90% CIs) were estimated for the evaluation of bleeding risk, using the Jeffreys method and any differences in the risk of bleeding between patient groups were tested using a proportions test. To investigate any factors associated with the therapeutic strategy used, multinomial logistic regression models were conducted. Results: Major perioperative bleeding was seen in 6.3% (5/79) of low VWF patients, 3.0% (35/1152) of healthy controls and 20.0% (5/25) of patients with VWD. In low VWF patients, perioperative bleeding prophylaxis was given to 59.5% and included subcutaneously desmopressin (n=21) and VWF-containing concentrate (n=26). Oral or intravenous tranexamic acid was administered to all low VWF patients. Of these patients, one major hemorrhagic event occurred in patients who did not receive prophylaxis and the remaining events occurred in patients treated with VWF-containing concentrate. In patients who received a VWF-containing concentrate, lower VWF ristocetin cofactor levels were observed compared with patients who received desmopressin or were untreated during surgery. No differences in clinical and laboratory features were observed between patients with low VWF treated with desmopressin and those who were untreated. Conclusions: Patients with low VWF have a higher risk of perioperative bleeding compared with healthy controls but a significantly lower risk compared with patients with VWD. The perioperative management of these patients is complex with a high risk of overtreatment. In our experience the caution of keeping the VWF-containing concentrate in the operating room available for use in case of bleeding appears to be a balanced approach. Prospective randomized studies to identify accurate methods of assessing bleeding risk and evaluate the most effective perioperative bleeding prevention are warranted. Essential bibliography: Ruchika Sharma and Veronica H. Flood. Advances in the diagnosis and treatment of Von Willebrand disease. Hematology American Society of Hematology Education Program 2017:379-384 Sadler JE. Low von Willebrand factor: sometimes a risk factor and sometimes a disease. Hematology American Society of Hematology Education Program 2009:106-112 Rodeghiero F, Tosetto A, Abshire T, et al. ISTH/SSC bleeding assessment tool: a standardized questionnaire and a proposal for a new bleeding score for inherited bleeding disorders. J Thromb Haemost. 2010;8(9):2063-2065. Casey LJ, Tuttle A, Grabell J, et al. Generation and optimization of the self-administered pediatric bleeding questionnaire and its validation as a screening tool for von Willebrand disease. Pediatr Blood Cancer. 2017;64(10) Mannuccio Mannucci P, Kyrle PA, Schulman S, Di Paola J, Schneppenheim R, Cox Gill J. Prophylactic efficacy and pharmacokinetically guided dosing of a von Willebrand factor/factor VIII concentrate in adults and children with von Willebrand's disease undergoing elective surgery: a pooled and comparative analysis of data from USA and European Union clinical trials. Blood Transfus. 2013;11(4):533-540 Disclosures No relevant conflicts of interest to declare.