Salbutamol safety in children under 2 years of age with acute wheezing: a meta-analysis of randomised controlled trials.

OBJECTIVE: To evaluate the safety of short-term use of inhaled salbutamol in children under 2 years of age with acute wheezing. DATA SOURCES: Electronic databases (PubMed, Trip, MEDLINE) and the Cochrane Library were searched for studies published up to October 2022. STUDY SELECTION: The search was restricted to randomised controlled trials published in English regarding the safety of inhaled salbutamol in wheezing children under the age of 2. DATA EXTRACTION AND SYNTHESIS: The literature search strategy yielded 3532 references. The meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. MAIN OUTCOMES AND MEASURES: The incidence of adverse reactions associated with inhaled salbutamol administration compared with placebo. RESULTS: A total of 24 records were included. In 7 studies involving 597 patients, inhaled salbutamol was compared with controls and no statistically significant difference in the incidence of adverse drug reactions was found between the two groups (OR 2.12, 95% CI 0.69 to 6.51; p=0.19). Salbutamol administration via nebulisation was associated with an increased incidence of adverse reactions (OR 6.76, 95% CI 2.01 to 22.71; p=0.002). None of the studies reported severe cardiac side effects that necessitated withdrawal from the study following salbutamol administration. Only one study reported a significant non-cardiac side effect (severe tremulousness) that necessitated withdrawal from therapy. CONCLUSIONS: Inhaled salbutamol can be safely used in children under 2 years of age with acute wheeze with the administration via a metered-dose inhaler being potentially safer than a nebulised formulation. Neither of the formulations was associated with severe adverse effects.

Transient splicing inhibition causes persistent DNA damage and chemotherapy vulnerability in triple-negative breast cancer.

Triple negative breast cancer (TNBC) is an aggressive type of breast cancer. While most TNBCs are initially sensitive to chemotherapy, a substantial fraction acquires resistance to treatments and progresses to more advanced stages. Here, we identify the spliceosome U2 small nuclear ribonucleoprotein particle (snRNP) complex as a modulator of chemotherapy efficacy in TNBC. Transient U2 snRNP inhibition induces persistent DNA damage in TNBC cells and organoids, regardless of their homologous recombination proficiency. U2 snRNP inhibition pervasively deregulates genes involved in the DNA damage response (DDR), an effect relying on their genomic structure characterized by a high number of small exons. Furthermore, a pulse of splicing inhibition elicits long-lasting repression of DDR proteins and enhances the cytotoxic effect of platinum-based drugs and poly(ADP-ribose) polymerase inhibitors (PARPis) in multiple TNBC models. These findings identify the U2 snRNP as an actionable target that can be exploited to enhance chemotherapy efficacy in TNBCs.

Epilepsy after acute central nervous system complications of pediatric hematopoietic cell transplantation: A retrospective, multicenter study.

BACKGROUND: Acute central nervous system (CNS) complications are common and well described among pediatric patients undergoing haematopoietic cell transplantation (HCT). However, their long-term outcomes are not known. The aim of this study is to describe the incidence, characteristics, and risk factors of long-term epilepsy in pediatric patients with acute CNS complications of HCT. METHODS: This retrospective study included pediatric patients who developed acute CNS complications from autologous or allogeneic HCT between 2000 and 2022. Clinical, therapeutic and prognostic data including long-term outcomes were analyzed. A diagnosis of epilepsy was provided if unprovoked seizures occurred during follow-up. RESULTS: Ninety-four patients (63 males, 31 females, median age 10 years, range 1-21 years) were included. The most common acute CNS complications were posterior reversible encephalopathy syndrome (n = 43, 46 %) and infections (n = 15, 16 %). Sixty-five patients (69 %) had acute symptomatic seizures, with 14 (16 %) having one or more episodes of status epilepticus (SE). Nine patients (9.6 %) were diagnosed with long-term focal epilepsy during the follow-up (5-year cumulative incidence from the acute complication, 13.3 %). Acute symptomatic SE during neurological complications of HCT was associated with an increased risk of long-term epilepsy (OR=14, 95 % CI 2.87-68.97). CONCLUSIONS: A higher occurrence of epilepsy has been observed in our cohort compared to the general population. Acute symptomatic SE during HCT was associated with a higher risk of long-term epilepsy. Pediatric patients with CNS complications during HCT could benefit from specific neurological follow-up. Further studies are needed to characterize mechanisms of epileptogenesis in pediatric patients undergoing HCT.

Outcomes of Radiotherapy in Oligoprogressive Breast Cancer.

INTRODUCTION: Radiotherapy (RT) shows potential for improving local control in cases of oligoprogressive metastatic breast cancer (mBC). This retrospective analysis aims to evaluate the advantages of RT in such a clinical scenario. METHODS: We conducted a retrospective analysis including patients with mBC who received radiation therapy (RT) for up to three sites of oligoprogression while continuing systemic therapy. The study took place between January 2014 and December 2021. Our endpoints were progression-free survival after radiotherapy (PFS-AR), the rate of discontinuation of systemic therapy (RDT) at three months post-RT, and overall survival (OS). We used Cox regression analysis to perform multivariate analysis for PFS-AR. RESULTS: Fifty-nine patients met the inclusion criteria. The PFS-AR was 13 months (95% CI 8.5-18.8 months). At three months, the RDT was 3% (two patients). A significant difference in median PFS-AR was observed between patients in the first + second-line group and those in the subsequent line group (p = 0.03). In the multivariate analysis conducted for PFS-AR, the biologically effective dose (BED) with α/ß = 4 > 100 Gy emerged as the sole significant variable (p = 0.0017). The median overall survival (OS) was 24.4 months (95% CI 17-24.4 months). CONCLUSIONS: This study is the first report on the outcomes of radiotherapy in a cohort of over 50 patients with oligoprogressive metastatic breast cancer (mBC). Our findings emphasize the significant relationship between PFS-AR, the number of ongoing lines of systemic therapy, and the BED of radiotherapy.

Multigenic panels in breast cancer: Clinical utility and management of patients with pathogenic variants other than BRCA1/2.

Multigene panels can analyze high and moderate/intermediate penetrance genes that predispose to breast cancer (BC), providing an opportunity to identify at-risk individuals within affected families. However, considering the complexity of different pathogenic variants and correlated clinical manifestations, a multidisciplinary team is needed to effectively manage BC. A classification of pathogenic variants included in multigene panels was presented in this narrative review to evaluate their clinical utility in BC. Clinical management was discussed for each category and focused on BC, including available evidence regarding the multidisciplinary and integrated management of patients with BC. The integration of both genetic testing and counseling is required for customized decisions in therapeutic strategies and preventative initiatives, as well as for a defined multidisciplinary approach, considering the continuous evolution of guidelines and research in the field.

Impact of Inflammatory Burden on Voriconazole Exposure in Oncohematological Pediatric Patients Receiving Antifungal Prophylaxis after Allogeneic HCT.

(1) Background: The impact of inflammation on voriconazole exposure in oncohematological pediatric patients represents a debated issue. We aimed to investigate the impact of serum C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6) levels on voriconazole exposure in oncohematological pediatric patients requiring allogeneic hematopoietic stem cell transplantation (HCT). (2) Methods: Pediatric patients undergoing allogeneic HCT and receiving therapeutic drug monitoring (TDM)-guided voriconazole as primary antifungal prophylaxis between January 2021 and December 2023 were included. The ratio between concentration and dose (C/D) of voriconazole was used as a surrogate marker of total clearance. A receiving operating characteristic curve analysis was performed by using CRP, PCT, or IL-6 values as the test variable and voriconazole C/D ratio > 0.188 or >0.375 (corresponding to a trough concentration value [Cmin] of 3 mg/L normalized to the maintenance dose of 16 mg/kg/day in patients of age < 12 years and of 8 mg/kg/day in those ≥12 years, respectively) as the state variable. Area under the curve (AUC) and 95% confidence interval (CI) were calculated. (3) Results: Overall, 39 patients were included. The median (IQR) voriconazole Cmin was 1.7 (0.7-3.0) mg/L. A CRP value > 8.49 mg/dL (AUC = 0.72; 95%CI 0.68-0.76; p < 0.0001), a PCT value > 2.6 ng/mL (AUC = 0.71; 95%CI 0.63-0.77; p < 0.0001), and an IL-6 value > 27.9 pg/mL (AUC = 0.80; 95%CI 0.71-0.88; p < 0.0001) were significantly associated with voriconazole overexposure. Consistent results were found in patients aged <12 and ≥12 years. (4) Conclusions: A single specific threshold of inflammatory biomarkers may be linked to a significantly higher risk of voriconazole exposure in oncohematological pediatric patients after HCT, irrespective of age. Adopting a TDM-guided strategy could be useful for minimizing the risk of voriconazole overexposure.

Long-Term Safety of Level II Oncoplastic Surgery after Neoadjuvant Treatment for Locally Advanced Breast Cancer: A 20-Year Experience.

Background: Oncoplastic surgery (OPS) reliability in the post-neoadjuvant chemotherapy (NACT) setting is still debated due to weak scientific evidences in such scenarios. Methods: Our analysis aims to report results obtained in a retrospective series of 111 patients consecutively treated with level II OPS after NACT at the Multidisciplinary Breast Center of the Fondazione Policlinico Universitario Agostino Gemelli IRCCS between 1998 and 2018. The surgical endpoints were the mean specimen volume, rates of positive margins (PMR), re-excision (RR), conversion to mastectomy (CMR), and complications (CR). The oncological endpoints were overall survival (OS), disease-free survival (DFS), and local recurrence (LR). To evaluate the impact of NACT on surgical and oncological outcomes at 302 months, we conducted a propensity score matching, pairing patients in post-NACT and upfront surgery groups. Results: The mean sample volume was 390,796 mm3. We registered a 3.6% of PMR, 1.8% RR, 0.9% CMR, 5% CR. The 10-year OS and 10-year DFS with a median follow-up of 88 months (6-302) were 79% and 76%, respectively, with an LR recurrence rate of 5%. The post-NACT group received significantly larger excised volumes and lower PMR. NACT did not affect surgical and oncological outcomes. Conclusions: Level II OPS can be considered a reliable alternative to mastectomy even in the post-NACT setting.

Young Women with Early-Stage Breast Cancer Treated with Upfront Surgery: Overview of Oncological Outcomes.

Background: Breast cancer in young women aged < 40 years is rare and often aggressive with less favorable survival rates. The lack of systematic screening, later stage at diagnosis, and a more aggressive disease biology may all contribute to their poor prognosis. Data on the best management remain conflicting, especially those regarding surgical management, either breast-conserving or mastectomy. To our knowledge, there are limited studies surrounding the treatment of young women with early breast cancer, and this analysis evaluated the oncological outcomes for those patients who underwent surgery upfront. Methods: We conducted a retrospective study including 130 young women with early breast cancer from a total of 373 consecutive patients treated with upfront surgery between January 2016 and December 2021 at our institution. Local recurrence-free survival (LR-FS), distant metastasis-free survival (DMFS), disease-free survival (DFS), and overall survival (OS) were evaluated. Results: The median follow-up was 61.1 months (range, 25-95). A total of 92 (70.8%) patients underwent breast-conserving surgery, while 38 (29.2%) patients underwent conservative mastectomy with immediate implant breast reconstruction. In total, 8 of 130 patients (6.2%) developed a local recurrence in the treated breast, an7 (5.4%) patients presented distant metastasis. Overall, two (1.6%) patients died due to breast cancer recurrence. Conclusions: The results of our study interestingly support breast-conserving surgery in young patients with early-stage breast cancer. While appropriate breast-conserving surgery can achieve favorable oncological outcomes and can always be considered a valid alternative to conservative mastectomy in upfront surgery, a younger age at diagnosis should never be used alone to choose the type of surgery.

Biologic and clinical analysis of childhood gamma delta T-ALL identifies LMO2/STAG2 rearrangements as extremely high-risk.

Acute lymphoblastic leukemia expressing the gamma delta T cell receptor (yo T-ALL) is a poorly understood disease. We studied 200 children with yo T-ALL from 13 clinical study groups to understand the clinical and genetic features of this disease. We found age and genetic drivers were significantly associated with outcome. yo T-ALL diagnosed in children under three years of age was extremely high-risk and enriched for genetic alterations that result in both LMO2 activation and STAG2 inactivation. Mechanistically, using patient samples and isogenic cell lines, we show that inactivation of STAG2 profoundly perturbs chromatin organization by altering enhancer-promoter looping, resulting in deregulation of gene expression associated with T-cell differentiation. High throughput drug screening identified a vulnerability in DNA repair pathways arising from STAG2 inactivation, which can be targeted by Poly(ADP-ribose) polymerase (PARP) inhibition. These data provide a diagnostic framework for classification and risk stratification of pediatric yo T-ALL.

Venetoclax: a new player in the treatment of children with high-risk myeloid malignancies?

ABSTRACT: Venetoclax selectively inhibits B-cell lymphoma 2 (BCL-2) and restores apoptotic signaling of hematologic malignant cells. Venetoclax, in combination with hypomethylating and low-dose cytotoxic agents, has revolutionized the management of older patients affected by acute myeloid leukemia (AML) and that of patients unfit to receive intensive chemotherapy. In a single phase 1 pediatric trial conducted on relapsed or refractory AML, the combination of venetoclax and intensive chemotherapy was shown to be safe and yielded promising response rates. In addition, several retrospective studies in children with AML reported that venetoclax, when combined with hypomethylating agents and cytotoxic drugs, seems to be a safe and efficacious bridge to transplant. The promising results on the use of venetoclax combinations in advanced myelodysplastic syndromes (MDS) and therapy-related MDS/AML have also been reported in small case series. This review summarizes the available current knowledge about venetoclax use in childhood high-risk myeloid neoplasms and discusses the possible integration of BCL-2 inhibition in the current treatment algorithm of these children. It also focuses on specific genetic subgroups potentially associated with response in preclinical and clinical studies.

Economic evaluation of anti-CD19 CAR T-cell pathway for large B-cell lymphomas in the real-life setting: the experience of an Italian hub center in the first three years of activity.

Poor literature report actual and detailed costs of chimeric antigen receptor (CAR) T-cell pathway in a real-life setting. We retrospectively collect data for all patients with relapsed/refractory aggressive large B-cell lymphoma who underwent leukapheresis between August 2019 and August 2022. All costs and medical resource consumption accountability were calculated on an intention-to-treat (ITT) basis, starting from leukapheresis to the time when the patient (infused or not) exited the CAR T-cell pathway for any reason. Eighty patients were addressed to leukapheresis and 59 were finally infused. After excluding CAR-T product cost, the main driver of higher costs were hospitalizations followed by the examinations/procedures and other drugs, respectively 43.9%, 26.3% and 25.4% of the total. Regarding costs of drugs and medications other than CAR T products, the most expensive items are those referred to AEs, both infective and extra-infective within 30 days from infusion, that account for 63% of the total. Density plot of cost analyses did not show any statistically significant difference with respect to the years of leukapheresis or infusion. To achieve finally 59/80 infused patients the per capita patients without CAR-T products results 74,000 euros. This analysis covers a growing concern on health systems, the burden of expenses related to CAR T-cell therapy, which appears to provide significant clinical benefit despite its high cost, thus making economic evaluations highly relevant. The relevance of this study should be also viewed in light of continuously evolving indications for this therapy.

Post-traumatic growth in oncological patients during the COVID-19 pandemic.

BACKGROUND: Post-traumatic growth (PTG) is defined as "positive psychological change experienced as a result of the struggle with highly challenging life circumstances". Diagnosis of cancer leads to many psychological challenges. The recent pandemic forced oncological patients to face other multiple stressors. Resilience is a target of interest for PTG. The aim of this study is to analyze relationships between cancer trauma, COVID-19 pandemic stress, PTG and resilience over time. PARTICIPANTS AND PROCEDURE: One hundred forty-six patients (124 females, 22 males) in active oncological treatment were enrolled from September 2020: 45.2% (n = 66) diagnosed with gynecological cancer, 23.3% (n = 34) with breast cancer, 15.1% (n = 22) with lung cancer, 16.5% (n = 24) with other cancers. We conducted a prospective longitudinal study on oncological patients evaluated at: diagnosis (T0), 6 (T1) and 12 months (T2) by means of the following self-administered tests: Distress Thermometer (DT), Hospital Anxiety and Depression Scale (HADS), Impact of Event Scale Revised (IES-R), Post-traumatic Growth Inventory (PTGI), Perceived Stress Scale (PSS), Connor-Davidson Resilience Scale (CD-RISC). RESULTS: DT decreased over time (T0 vs. T2, p < .001). HADS decreased from T0 to T2 (p < .001). The PTG subscales regarding new possibilities and appreciating life improved comparing T0 vs. T2 (p = .029; p = .013), as well as the total index of PTG (p = .027). The IES avoidance subscale score decreased over time (T0 vs. T1, p = .035). CONCLUSIONS: For some patients, the cancer experience is characterized not only by psychological distress but also by the presence and growth of positive aspects, such as the tendency to positively reconsider the value and importance of life, health and social relationships.

Managing the Risk of Foodborne Infections in Pediatric Patients with Cancer: Is the Neutropenic Diet Still an Option?

Infections pose a significant threat to morbidity and mortality during treatments for pediatric cancer patients. Efforts to minimize the risk of infection necessitate preventive measures encompassing both environmental and host-focused strategies. While a substantial number of infections in oncologic patients originate from microorganisms within their native microbiological environment, such as the oral cavity, intestines, and skin, the concrete risk of bloodstream infections linked to the consumption of contaminated food and beverages in the community cannot be overlooked. Ensuring food quality and hygiene is essential to mitigating the impact of foodborne illnesses on vulnerable patients. The neutropenic diet (ND) has been proposed to minimize the risk of sepsis during neutropenic periods. The ND aims to minimize bacterial entry into the gut and bacterial translocation. However, a standardized definition for ND and consensus guidelines for specific food exclusions are lacking. Most centers adopt ND during neutropenic phases, but challenges in achieving caloric intake are common. The ND has not demonstrated any associated benefits and does not ensure improved overall survival. Consequently, providing unified and standardized food safety instructions is imperative for pediatric patients undergoing hematopoietic cell transplantation (HCT). Despite the lack of evidence, ND is still widely administered to both pediatric and adult patients as a precautionary measure. This narrative review focuses on the impact of foodborne infections in pediatric cancer patients and the role of the ND in comparison to food safety practices in patients undergoing chemotherapy or HCT. Prioritizing education regarding proper food storage, preparation, and cooking techniques proves more advantageous than merely focusing on dietary limitations. The absence of standardized guidelines underscores the necessity for further research in this field.

Healthcare migration in Italian paediatric haematology-oncology centres belonging to AIEOP.

BACKGROUND: In Italy, there is a network of centres headed by the Italian Association of Pediatric Hematology and Oncology (AIEOP) for the diagnosis and treatment of paediatric cancers on almost the entire national territory. Nevertheless, migration of patients in a hospital located in a region different from that of residence is a widespread habit, sometimes motivated by several reasons. The aim of this paper is to assess the impact of migration of children with cancer to AIEOP centres in order to verify their optimal distribution throughout the national territory. METHODS: To this purpose, we used information on 41,205 registered cancer cases in the database of Mod.1.01 Registry from AIEOP centres, with age of less than 20 years old at diagnosis, diagnosed from 1988 to 2017. Patients' characteristics were analysed and compared using the X2 or Fisher's exact test or Mann-Whitney test, when appropriate. Survival distributions were estimated using the method of Kaplan and Meier, and the log-rank test was used to examine differences among subgroups. RESULTS: Extra-regional migration involved overall 19.5% of cases, ranging from 23.3% (1988-1997) to 16.4% (2008-2017) (p < 0.001). In leukaemias and lymphomas we observed a mean migration of 8.8% overall, lower in the North (1.2%) and Centre (7.8%) compared to the South & Isles (32.3%). In the case of solid tumours, overall migration was 25.7%, with 4.2% in the North, 17.2% in the Centre and 59.6% in the South & Isles. For regions with overall levels of migration higher than the national average, most migration cases opted for AIEOP centres of close or even neighbouring regions. Overall survival at 10 years from diagnosis results 69.9% in migrants vs 78.3% in no migrants (p < 0.001). CONCLUSIONS: There is still a certain amount of domestic migration, the causes of which can be easily identified: migration motivated by a search for high specialization, migration due to lack of local facilities, or regions in which no AIEOP centres are present, which makes migration obligatory. Better coordination between AIEOP centres could help to reduce so-called avoidable migration, but technical and political choices will have to be considered, with the active participation of sector technicians.

Ruxolitinib for the treatment of acute and chronic graft-versus-host disease in children: a systematic review and individual patient data meta-analysis.

Steroid-refractory graft-versus-host disease (SR-GvHD) represents a major complication of pediatric allogenic hematopoietic stem cell transplantation. Ruxolitinib, a selective JAK 1-2 inhibitor, showed promising results in the treatment of SR-GvHD in adult trial, including patients >12 years old. This systematic review aims to evaluate ruxolitinib use for SR-GvHD in the pediatric population. Among the 12 studies included, ruxolitinib administration presented slight differences. Overall response rate (ORR) ranged from 45% to 100% in both acute and chronic GvHD. Complete response rates (CR) varied from 9% to 67% and from 0% to 28% in aGvHD and cGvHD, respectively. Individual-patient meta-analysis from 108 children under 12 years showed an ORR and CR for aGvHD of 74% and 56%, respectively, while in cGvHD ORR was 78% but with only 11% achieving CR. Treatment-related toxicities were observed in 20% of patients, including cytopenia, liver toxicity, and infections. Age, weight, graft source, previous lines of therapy, and dose did not significantly predict response, while a higher rate of toxicities was observed in aGvHD patients. In conclusion, ruxolitinib shows promising results in the treatment of SR-GvHD in children, including those under 12 years. Specific pediatric perspective trials are currently ongoing to definitely assess its efficacy and safety.

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.

Current practices for nutritional evaluation and care during the treatment of pediatric oncology patients: a survey among AIEOP centers.

Nutritional status plays a crucial role in the mortality rates of the pediatric oncology patients. However, there is a lack of systematic approaches for nutritional assessment in this population. This study aims to assess the current practice for nutritional assessment and care of pediatric cancer patients in Italy. A 25-items web-based, nation-wide questionnaire was circulated as of January 9, 2023 among physicians within the AIEOP network, composed of 49 national centers, out of which 21 routinely perform HCT. This survey examined the practices of 21 Italian pediatric oncology centers, revealing significant heterogeneity in nutritional practices. Only half of the centers routinely assessed all patients, utilizing different clinical and biochemical parameters. The use of neutropenic diets remained prevalent after chemotherapy or stem cell transplantation. CONCLUSION: This study underscores the pressing need for unified recommendations to improve nutritional care and potentially enhance outcomes for pediatric cancer patients. WHAT IS KNOWN: • The assessment and support of nutrition are gaining interest in the overall care of children with cancer. • The assessment and management of nutritional needs in pediatric cancer patients, including those undergoing hematopoietic cell transplantation, currently lack a systematic approach. WHAT IS NEW: • There is considerable variability in the nutritional assessment and support among Italian centers treating pediatric patients with cancer. • To enhance nutritional assessment and support for pediatric cancer patients, it is essential to establish shared national and international guidelines.

Biallelic inactivation of the NF1 tumour suppressor gene in juvenile myelomonocytic leukaemia: Genetic evidence of driver function and implications for diagnostic workup.

Juvenile myelomonocytic leukaemia (JMML) is characterized by gene variants that deregulate the RAS signalling pathway. Children with neurofibromatosis type 1 (NF-1) carry a defective NF1 allele in the germline and are predisposed to JMML, which presumably requires somatic inactivation of the NF1 wild-type allele. Here we examined the two-hit concept in leukaemic cells of 25 patients with JMML and NF-1. Ten patients with JMML/NF-1 exhibited a NF1 loss-of-function variant in combination with uniparental disomy of the 17q arm. Five had NF1 microdeletions combined with a pathogenic NF1 variant and nine carried two compound-heterozygous NF1 variants. We also examined 16 patients without clinical signs of NF-1 and no variation in the JMML-associated driver genes PTPN11, KRAS, NRAS or CBL (JMML-5neg) and identified eight patients with NF1 variants. Three patients had microdeletions combined with hemizygous NF1 variants, three had compound-heterozygous NF1 variants and two had heterozygous NF1 variants. In addition, we found a high incidence of secondary ASXL1 and/or SETBP1 variants in both groups. We conclude that the clinical diagnosis of JMML/NF-1 reliably indicates a NF1-driven JMML subtype, and that careful NF1 analysis should be included in the genetic workup of JMML even in the absence of clinical evidence of NF-1.