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Hematopoietic stem and progenitor cell (HSPC)-based gene therapy (GT) requires the collection of a large number of cells. While bone marrow (BM) is the most common source of HSPCs in pediatric donors, the collection of autologous peripheral blood stem and progenitor cells (PBSCs) is an attractive alternative for GT. We present safety and efficacy data of a 10-year cohort of 45 pediatric patients that underwent PBSC collection for backup and/or purification of CD34+ cells for ex vivo gene transfer. Median age was 3.7 years and median weight 15.8 kg. After mobilization with lenograstim/plerixafor (n=41) or lenograstim alone (n=4), and 1-3 cycles of leukapheresis, median collection was 37 x106 CD34+ cells/kg. The procedures were well tolerated. Patients that collected ≥7 and ≥13 x106 CD34+ cells/kg in the first cycle had pre-apheresis circulating counts of at ≥42 and ≥86 CD34+ cells/μL respectively. Weight-adjusted CD34+ cell yield was positively correlated with peripheral CD34+ cell counts, and influenced by female gender, disease and drug dosage. All patients received a GT product above the minimum target, ranging from 4 to 30.9 x106 CD34+ cells/kg. Pediatric PBSC collection compares well to BM harvest in terms of CD34+ cell yields for the purpose of GT, with a favorable safety profile.

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to an extensive reorganization of the healthcare system in Italy, with significant deferment of the treatment of urology patients. We aimed to assess the impact of deferred treatment during the SARS-CoV-2 pandemic on the need for blood transfusions in 3 Italian urology departments. Methods: We reviewed hospital chart data on blood transfusions at the urology units of 3 academic centers in the north of Italy from March to April 2020. Data were compared with values from the same time frame in 2019 (March to April 2019). Results: We observed significant reductions of the number of patients admitted to the urology units from March to April 2020 (373 vs. 119) and the number of performed surgeries (242 vs. 938) compared to 2019. Though, the number of transfused blood units was comparable between the 2 years (182 vs. 252), we found a greater mean number of blood units transfused per admission in 2020 (0.49 vs. 0.22; p < 0.0001). As a whole, the transfusion rate for hematuria was higher in 2020 than in 2019 (36 vs. 7.9%; p < 0.0001). Discussion/Conclusion: The observed increased number of blood transfusions needed throughout the SARS-CoV-2 era could have had a negative impact on both patients and the healthcare system. It is possible to speculate that this is the consequence of a delayed diagnosis and deferred treatment of acute conditions.

Collection of an adequate amount of autologous haematopoietic stem progenitor cells (HSPC) is required for ex vivo manipulation and successful engraftment for certain inherited disorders. Fifty-seven paediatric patients (age 0.5–11.4 years) underwent a bone marrow harvest for the purpose of HSPC gene therapy (GT), including adenosine deaminase-severe combined immunodeficiency (ADA-SCID), Wiskott–Aldrich syndrome (WAS) and metachromatic leukodystrophy (MLD) patients. Total nucleated cells and the percentage and absolute counts of CD34+ cells were calculated at defined steps of the procedure (harvest, CD34+ cell purification, transduction with the gene transfer vector and infusion of the medicinal product). A minimum CD34+ cell dose for infusion was 2 × 106/kg, with an optimal target at 5–10 × 106/kg. Median volume of bone marrow harvested was 34.2 ml/kg (range 14.2–56.6). The number of CD34+ cells collected correlated inversely with weight and age in all patients and particularly in the MLD children group. All patients reached the minimum target dose for infusion: median dose of CD34+ cells/kg infused was 10.3 × 106/kg (3.7–25.9), with no difference among the three groups. Bone marrow harvest of volumes > 30 ml/kg in infants and children with ADA-SCID, WAS and MLD is well tolerated and allows obtaining an adequate dose of a medicinal product for HSPC-GT.

We studied circulating (C)CD34 + cells by flow cytometry in 96 patients with myelodisplastic syndromes (MDS) at diagnosis, and in a subset of 35 cases during follow-up. CCD34 + counts were stratified within both International Prognostic Scoring System (IPSS) and World Health Organization (WHO) categories. Counts >10/μl were associated with poorer leukemia-free survival, a prognostic value for evolution independent from that of WHO, and a higher progression probability within intermediate-risk IPSS and WHO classes. When serial measurements were performed, counts >10/μl more frequently correlated to evolution. Separating newly diagnosed patients on the basis of 10/μl cut-off of circulating CD34 + cells retains prognostic utility, especially in intermediate-risk MDS.

Systematic data on the ability of pegfilgrastim to mobilize stem cells after chemotherapy are scarce. We evaluated the efficacy of a single 6 mg dose of pegfilgrastim for mobilizing peripheral blood stem cells (PBSC) in aggressive lymphoma patients. Between July 2004 and October 2005, 17 aggressive non-Hodgkin's lymphoma and 11 poor-risk Hodgkin's lymphoma were treated with cycles containing cisplatin-aracytin. At the end of chemotherapy, the patients received 6 mg of pegfilgrastim. Duration of grade 4 neutropenia, adverse events, time to neutrophil recovery, peak and harvest of CD34+ cells were recorded. Twenty-seven out of 28 patients harvested a median of 17.3 x 10(6)/CD34+ cells (range 2.5-28.9) after a median of 9 days (range 8-12 days), with a single apheresis procedure in 25 cases. All patients had grade 3-4 neutropenia, median duration 3 days. The only adverse event was mild bone pain. To date, 13 patients have been autografted with a median of 15.4 x 10(6) CD34+ pegfilgrastim-mobilized cells per kg (range 2.5-28.9) with rapid and sustained engraftment. Mobilization, harvesting and autografting of pegfilgrastim-mobilized PBC can be successfully achieved in pretreated patients with aggressive lymphoma.