Letermovir for Cytomegalovirus infection in pediatric patients undergoing allogenic hematopoietic stem cell transplantation: a real-life study by the Infectious Diseases Working Group of Italian Association of Pediatric Hematology-Oncology (AIEOP).

Letermovir prophylaxis revolutionized the approach to Cytomegalovirus infection in adult hematopoietic stem cell transplant (HCT), while data in pediatric setting are still lacking. We retrospectively analyzed 87 HCT children transplanted in 11 AIEOP centers receiving letermovir as off-label indication between January 2020 and November 2022. Letermovir was used as primary, secondary prophylaxis or CMV treatment in 39, 26 and 22 cases, respectively; no discontinuation due to toxicity was reported. Median duration was 100 days (14-256) for primary and 96 days (8-271) for secondary prophylaxis, respectively. None of the patients experienced CMV-clinically significant reactivation during Letermovir primary prophylaxis; one patient developed breakthrough infection during secondary prophylaxis, and 10 and 1 patient experienced asymptomatic CMV-reactivation and CMV-primary infection after drug discontinuation, respectively. Median duration of letermovir in CMV treatment was 40 days (7-134), with 4/22 patients suffering CMV-pneumonia, with an overall response rate of 86.4%. With a median follow-up of 10.7 months (8.2-11.8), estimated 1-year overall survival was 86%; no CMV-related deaths were reported in prophylaxis groups. This is the largest report on Letermovir use in pediatric HCT; real-life data confirm an excellent toxicity profile, with high efficacy as CMV prophylaxis; results in CMV-infection treatment should be investigated in larger, prospective trials.

Early gut microbiota signature of aGvHD in children given allogeneic hematopoietic cell transplantation for hematological disorders.

BACKGROUND: The onset of acute Graft-versus-Host Disease (aGvHD) has been correlated with the gut microbiota (GM) composition, but experimental observations are still few, mainly involving cohorts of adult patients. In the current scenario where fecal microbiota transplantation has been used as a pioneer therapeutic approach to treat steroid-refractory aGvHD, there is an urgent need to expand existing observational studies of the GM dynamics in Hematopoietic Stem Cell Transplantation (HSCT). Aim of the present study is to explore the GM trajectory in 36 pediatric HSCT recipients in relation to aGvHD onset. METHODS: Thirty-six pediatric patients, from four transplantation centers, undergoing HSCT were enrolled in the study. Stools were collected at three time points: before HSCT, at time of engraftment and > 30 days following HSCT. Changes in the GM phylogenetic structure were studied by 16S rRNA gene Illumina sequencing and phylogenetic assignation. RESULTS: Children developing gut aGvHD had a dysbiotic GM layout before HSCT occurred. This putative aGvHD-predisposing ecosystem state was characterized by (i) reduced diversity, (ii) lower Blautia content, (iii) increase in Fusobacterium abundance. At time of engraftment, the GM structure underwent a deep rearrangement in all patients but, regardless of the occurrence of aGvHD and its treatment, it reacquired a eubiotic configuration from day 30. CONCLUSIONS: We found a specific GM signature before HSCT predictive of subsequent gut aGvHD occurrence. Our data may open the way to a GM-based stratification of the risk of developing aGvHD in children undergoing HSCT, potentially useful also to identify patients benefiting from prophylactic fecal transplantation.

A survey on hematology-oncology pediatric AIEOP centres: The challenge of posterior reversible encephalopathy syndrome.

OBJECTIVES: Posterior reversible encephalopathy syndrome (PRES) is one of the most common neurological complications in hematology-oncology pediatric patients. Despite an increasingly recognized occurrence, no clear consensus exists regarding how best to manage the syndrome, because most cases of PRES have reported in single-case reports or small series. Aim of this paper is to identify incidence, clinical features, management, and outcome of PRES in a large series of hematology-oncology pediatric patients. METHODS: The cases of PRES occurred in twelve centers of the Italian Association of Pediatric Hematology and Oncology were reported. RESULTS: One hundred and twenty-four cases of PRES in 112 pediatric patients were recorded with an incidence of 2.1% and 4.7%, respectively, in acute lymphoblastic leukemia in first complete remission and hematopoietic stem cell transplantation (HSCT). The majority of cases occurred after a cycle of chemotherapy rather than after stem cell transplant. PRES after chemotherapy significantly differs from that after HSCT for diagnosis, time of presentation, risk factors, management, and outcome. CONCLUSIONS: This study demonstrates that PRES is a common neurological complication and occurring preferentially in course of induction treatment of some hematologic malignancies, as ALL and after HSCT. It also highlights great clinical differences in the management and outcome in patients with PRES occurring after chemotherapy or after HSCT.

Focal nodular hyperplasia of the liver in children after hematopoietic stem cell transplantation.

FNH is a non-malignant neoplasia of the liver rarely described in children. A significant percentage of the pediatric cases have been reported in patients with a history of malignant disease treated with chemo-radiation therapy and in children who were given HSCT. Little is known about the pathogenesis of FNH in transplanted children, but many risk factors linked to the HSCT procedure have been hypothesized. The detection of hepatic nodules, particularly in children who underwent HSCT for a previous malignancy, always raises a diagnostic dilemma. To help the physicians in the diagnostic management of this rare entity, we have retrospectively evaluated a series of transplanted children diagnosed with FNH in our Center over the last 15 yr. In this period, we found 10 new diagnoses of FNH. The diagnostic work-up included CEUS, abdominal CT, and MRI. A liver biopsy was performed in two patients. The median FUP time after diagnosing FNH was 3.8 yr, with an abdominal US and no malignant transformation were observed. Possible risk factors and indications for the management of FNH in transplanted children are reported and discussed in a comprehensive review of the literature.

All-trans retinoic acid in the treatment of pediatric acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is a rare form of acute myeloid leukemia with specific epidemiological, pathogenetic and clinical features. Its frequency varies widely among nations, with a decreased incidence among 'Nordic' origin populations. The molecular hallmark of the disease is the presence of a balanced reciprocal translocation resulting in the PML/RAR-α gene fusion, which represents the target of the all-trans retinoic acid (ATRA) therapy. The introduction of ATRA in conjunction with anthracyclines marked a turning point in the treatment of APL, previously associated with a significant morbidity and mortality. Nowadays the standard front-line therapy for pediatric APL includes ATRA in every phase of the treatment, resulting in a complete remission rate of 90-95%. Here we provide an overview of the role of ATRA in the treatment of pediatric APL, summarizing the most relevant clinical results of recent decades and investigating future therapeutic perspectives for children with APL.

Retinoids in pediatric onco-hematology: the model of acute promyelocytic leukemia and neuroblastoma.

Retinoids are lipophilic compounds derived from vitamin A, which have been extensively studied in cancer prevention and therapy. In pediatric oncology, they are successfully used for the treatment of acute promyelocytic leukemia (APL) and high-risk neuroblastoma (HR-NBL). APL is a subtype of acute myeloid leukemia (AML) clinically characterized by a severe bleeding tendency with a highrisk of fatal hemorrhage. The molecular hallmark of this disease is the presence of the promyelocytic leukemia (PML)-retinoic acid receptor-α (RAR α) gene fusion that plays a critical role in promyelocytic leukemogenesis and represents the target of retinoid therapy. The introduction in the late 1980s of all-trans retinoic acid (ATRA) into the therapy of APL radically changed the management and the outcome of this disease. Presently, the standard front-line therapeutic approach for pediatric APL includes anthracycline-based chemotherapy and ATRA, leading to a complete remission in almost 90% of the patients. Neuroblastoma (NBL) is an aggressive childhood tumor derived from the peripheral neural crest. More than half of patients have a high-risk disease, with a poor outcome despite intensive multimodal treatment. Although the exact mechanism of action remains unclear, the introduction of 13-cis-retinoic acid (13-cis-RA) in the therapy of NBL has improved the prognosis of this disease. Currently, the standard treatment for HR-NBL consists of myeloablative therapy followed by autologous hematopoietic stem cell transplantation (HSCT) and maintenance with 13-cis-RA for the treatment of minimal residual disease, leading to a 3-year disease-free survival rate (DFS) of about 50%. In this paper the authors provide a review of the peer-reviewed literature on the role of retinoids in the treatment of pediatric APL and HR-NBL, summarizing the most relevant clinical trial results of the last decades, analyzing the ongoing trials, and investigating future therapeutic perspectives of children affected by these diseases.

Hematopoietic stem cell transplantation for curing children with severe autoimmune diseases: is this a valid option?

The cure of children with severe AD, especially patients with severe, progressive, and therapy-resistant autoimmunity, represents a challenge for current medical practice. The idea of HSCT as a promising therapeutic opportunity was borne accidentally from finding patients who, after undergoing HSCT for a hematological indication, were cured of a concomitant AD. Thus, over the last two decades, HSCT has been extensively investigated, and it has become an appealing therapy for rheumatological (juvenile rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis) and hematological diseases (immune cytopenias). Recently, interesting results have been also described in type 1 diabetes mellitus and Crohn's disease. Although the use of HSCT has been steadily rising in the last few years, many questions are still open, especially after the discoveries of many new biological agents. Given the low incidence of ADs in children, most of the data about the use of the HSCT for these diseases are taken from a mixed cohort of adults and children. The aim of this review is to summarize the published studies and to try to answer the question as to whether this procedure can be considered a promising approach.

Granulocytic sarcoma of the knee and the spine as aleukemic relapse of acute myeloid leukemia in a child.

Granulocytic sarcoma is a very rare disease in childhood, which may precede the clinical manifestations of acute myeloid leukemia or may occur as a relapse of a nonleukemic acute myeloid leukemia. It is a malignant, solid tumor consisting of myeloblasts or immature myeloid cells occurring in extramedullary sites. We report interesting magnetic resonance images of a nonleukemic relapse of acute myeloid leukemia in a child presenting as a granulocytic sarcoma unusually localized to the knee and spine.