HPC collection in children is an efficient and well tolerated technique, performed as an outpatient procedure. With the new mobilization schemes and leukapheresis technology, we can collect a high number of HPC allowing pediatric oncologist to establish more aggressive chemotherapy protocols hoping to improve patient outcome.

<b>Introduction:</b> Leukostasis refers to clinical symptoms caused by hyperleukocytosis seen in some haematological diseases such as leukaemia. Cytoreduction can be achieved by therapeutic leukapheresis. The aim of this study was to retrospectively analyse the procedures performed in our Centre and to evaluate their efficacy and safety. <b>Methods:</b> This was a retrospective study of all the therapeutic leukapheresis procedures carried out in our Centre between January 1998 and December 2020. The sample collection was obtained through the review of the clinical files of the respective patients. Statistical analysis was performed using the software R v.4.0.1. A total of 54 therapeutic leukapheresis procedures were performed in 31 patients in our Centre. <b>Results:</b> After these procedures clinical improvement was observed in 16 patients and we verify that there was a significant difference in survival between the group that improved and the group that maintained the same clinical condition or worsened. The lack of immediate clinical improvement was a sign of a poor prognosis. Laboratory efficacy occurred in 16 patients who had a reduction in white blood cell count, with a 39.1% reduction after 24 h, and did not succeed in 15 patients, who had no reduction. However, in this case there is no significant difference in survival between the two groups. There was some complication in 53.9% of the procedures, with hypocalcaemia being the most frequent, which was observed in 22 procedures. Only 4 patients experienced serious side effects but these adverse reactions cannot be attributed to the procedures carried out. The overall survival rate 6 months after this treatment was 51.6%. <b>Conclusion:</b> Despite the reduced number of patients, we conclude that therapeutic leukapheresis is a safe and effective option that may still have a therapeutic role in some cases.

Background: Chronic graft-versus-host disease (cGvHD) is a major complication after allogeneic hematopoietic cell transplantation. Extracorporeal photopheresis (ECP) is an immunotherapy treatment for cGvHD, although suitable response biomarkers are lacking. Materials & methods: We analyzed data from six cGvHD patients undergoing ECP at a reference center from 826 to 2866 days. Circulating Tregs were enumerated, patient’s clinical evolution, immunosuppression dose and adverse events (AEs) registered. Results: We observed an increase in Tregs, a decrease in immunosuppression dosage and symptoms improvement. Mild AEs occurred at a very low rate. Conclusion: In these patients, the improvement of cGvHD, with low AEs, confirms a place for ECP as treatment. Improvements were accompanied by an increase in circulating Tregs, suggesting their role as a biomarker.

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