[Central nervous system disorders secondary to histiocytoses: neurodegeneration with potential for improvement]

Histiocytoses, including Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD), are inflammatory myeloid tumors in which monocyte lineage cells aggregate in various organs, causing tissue damage. Most of these tumors harbor oncogenic mutations in mitogen-activated protein kinase (MAPK) pathway genes, typified by BRAFV600E. Some patients with LCH develop bilateral symmetrical cerebellar lesions and brain atrophy several years after diagnosis when the initial symptoms disappear, leading to cerebellar ataxia and higher cerebral dysfunction. A similar neurological disorder has also been reported in ECD. This neurological disorder can be improved with MAPK inhibitors. When patients with this neurological disorder are identified among neurodegeneration of unknown etiology or histiocytosis patients and treated early with MAPK inhibitors, the disorder can be reversible.

Cerebellar peduncle damage in Langerhans cell histiocytosis-associated neurodegenerative disease revealed by diffusion tensor imaging

PURPOSE

To confirm the hypothesis that brain white matter damage is involved in the pathogenesis and disease progression of Langerhans cell histiocytosis (LCH)-associated neurodegenerative disease (ND), we aimed to analyze pediatric patients with LCH using diffusion tensor imaging (DTI).

METHODS

We enrolled 33 patients with LCH and obtained 33 DTI datasets. Using DTI-based tractography, fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured in the cerebral and cerebellar white matter tracts. The participants were divided into three groups-non-ND, ND without clinical symptoms (r-ND), and ND with clinical symptoms (c-ND)-according to their clinical status during the examination with DTI. We compared the DTI parameters in white matter tracts were compared among the three groups.

RESULTS

In the order of non-ND, r-ND, and c-ND groups, the FA in superior cerebellar peduncle (SCP) and middle cerebellar peduncle (MCP) significantly decreased, the ADC, AD, and RD of MCP, and the RD of SCP were significantly elevated (FA-SCP; p < 0.001, FA-MCP; p = 0.026, ADC-MCP; p < 0.001, AD-MCP; p = 0.002, RD-MCP; p = 0.003, and RD-SCP; p = 0.018). Furthermore, in the simple linear regression analysis, the FA, ADC, AD, and RD values in the MCP and the FA value in the SCP were significantly influenced by the presence of neurological symptoms and ND findings on MRI (all p < 0.001).

CONCLUSION

In LCH-ND, we identified microstructural damage in the SCP and MCP. DTI parameters in these tracts may help monitor LCH-ND; therefore, future studies are required to validate these results in a large cohort.

High Plasma Presepsin Levels in Children With Hemophagocytic Lymphohistiocytosis

Presepsin is reported as a novel diagnostic and prognostic biomarker for sepsis, and its optimal cutoff value is reported to be 600 to 650 pg/mL. Three children were diagnosed with hemophagocytic lymphohistiocytosis (HLH). The cause of HLH was unknown in cases 1 and 2, while Epstein-Barr virus infection was the cause in case 3. The plasma presepsin levels at the diagnosis were 1020, 1080, and 3160 pg/mL in cases 1, 2, and 3, respectively. In case 1, the plasma level of presepsin decreased to 164 pg/mL on day 19 of her sickness, when symptoms improved. Follow-up plasma presepsin levels were missing for cases 2 and 3. No microbiological pathogens were detected in the blood cultures of any of the patients. Our cases suggest that plasma presepsin levels can be elevated in childhood HLH.

Adaptation of a Clinical Proton Pencil Beam Scanning System for FLASH Experiments

PURPOSE/OBJECTIVE(S)

To characterize a proton pencil beam scanning system for ultra-high dose rate (UHDR) irradiations and validate it with FLASH preclinical experiments.

MATERIALS/METHODS

After modifications to the beamline to maximize the beam current at isocenter in our gantry room, we characterized the UHDR beam in terms of: 1) Size and shape of the beam spot in three configurations; pristine beam, 75 mm water-equivalent-thickness (WET) range shifter (RS), and custom-built 135 mm WET RS mounted 310 mm upstream of the aperture in the snout housing. These configurations were analyzed to determine which one achieved the highest dose rate; 2) Beam transport efficiency and beam output. We compared the signal in the monitor chambers of the proton system with a Faraday cup and plane parallel ionization chamber (PPC05, IBA dosimetry) for beam current at the cyclotron from 7.5 nA to 800 nA; 3) Dose homogeneity, beam penumbra, and dose rate for the fields to be used in preclinical irradiations. All measurements were performed at isocenter, in air or at 1 cm depth in solid water, using the highest energy (about 230 MeV), which corresponded to a nominal range of 32.9 cm in water. We modeled the UHDR beam in our treatment planning system (TPS) to optimize the dose homogeneity and lateral penumbra of the irradiation fields. We performed the preclinical experiments in single fractions of 19 Gy (RBE), 21 Gy (RBE) and 23 Gy (RBE) (RBE = 1.1), targeting the pelvis of C57BL/6 mice and using survival as the endpoint. Each arm included 6-10 mice. The proton beam was used in transmission mode, positioning the center of the mouse pelvis at isocenter, and irradiating the pelvis with a 2x6 cm^2 field. Apertures were placed at 9cm from the isocenter to sharpen the lateral penumbra.

RESULTS

The range measurements with a multi-layer ionization chamber were consistent within 1 mm with the nominal range. In UHDR mode, the spot size at the isocenter varied from 4.5 mm for the pristine beam to 9.2 mm for the 135 mm RS. The spot size at isocenter remained constant when the beam intensity varied from 7.5 nA to 800 nA at the cyclotron exit. By employing the configuration with the 135 mm RS and optimizing the fields in the TPS, we achieved a dose rate of 1 Gy (RBE)/s for the conventional regime and 75(RBE) Gy/s for the UHDR regime. The monitor chambers of the proton system were affected by recombination at high dose rates: we observed about 35% higher output for the same number of monitor units delivered at 800 nA vs 7.5 nA. The delivered dose was determined with the PPC05 for each field, as this detector did not show recombination effects. When preclinical irradiations were independently monitored, the delivered dose was typically within 1% of the intended value. In three independent experiments, a dose of 21 Gy (RBE) or higher was associated with an increased survival in the UHDR arm compared to the conventional arm.

CONCLUSION

We adapted a clinical proton system for preclinical irradiations at UHDR. Our results confirm the presence of the FLASH effect.

Detection of BRAF V600E mutation in radiological Langerhans cell histiocytosis-associated neurodegenerative disease using droplet digital PCR analysis

Langerhans cell histiocytosis-associated neurodegenerative disease (LCH-ND) is the most serious late complication secondary to LCH and is gradually progressive, destructive, and irreversible. Detection of the BRAF V600E mutation in peripheral blood mononuclear cells (PBMCs), even in the absence of active LCH lesions, is considered a sign of clinical LCH-ND, presenting with both abnormal imaging findings and neurological symptoms. However, the detection of the BRAF V600E mutation in PBMCs of patients with asymptomatic radiological LCH-ND (rLCH-ND) without active LCH lesions who present only with abnormal imaging findings is unknown. In this study, we analyzed the BRAF V600E mutations in PBMCs and cell-free DNA (cfDNA) of patients with rLCH-ND without active LCH lesions (n = 5) using a droplet digital polymerase chain reaction (ddPCR) assay. The BRAF V600E mutation in PBMCs was detected in three out of five (60%) cases. The mutant allele frequencies in the three positive cases were 0.049%, 0.027%, and 0.015%, respectively. However, the cfDNA BRAF V600E mutation remained undetected in all patients. Detection of the BRAF V600E mutant allele in PBMCs may be helpful in identifying asymptomatic rLCH-ND in patients at high risk for developing LCH-ND, including those with relapses at CNS risk sites or central diabetes insipidus.

Intensification of treatment with vinca alkaloid does not improve outcomes in pediatric patients with Langerhans cell histiocytosis: results from the JPLSG LCH-12 study

Chemotherapy with cytarabine, vincristine (VCR), and prednisolone has achieved low mortality rates in pediatric patients with Langerhans cell histiocytosis (LCH). However, relapse rates remain high, making event-free survival (EFS) rates unsatisfactory. A nationwide clinical trial, LCH-12, tested a modified protocol in which the early maintenance phase was intensified with increasing dosages of VCR. Patients newly diagnosed with multifocal bone (MFB) or multisystem (MS) LCH and aged < 20 years at diagnosis were enrolled between June 2012 and November 2017. Of the 150 eligible patients, 43 with MFB were treated for 30 weeks and 107 with MS LCH were treated for 54 weeks. One patient with MS LCH died of sepsis during the induction phase. The 3-year EFS rates among patients with MFB LCH, risk organ (RO)-negative MS LCH, and RO-positive MS LCH were 66.7% (95% confidential interval [CI], 56.5-77.0%), 66.1% (95% CI 52.9-76.4%), and 51.1% (95% CI 35.8-64.5%), respectively, similar to previously observed rates. EFS rates were significantly lower in patients with disease activity scores > 6 than in those with scores ≤ 6. The strategy that included more intense treatment with VCR was not effective. Other strategies are required to improve outcomes in patients with pediatric LCH.

Relapses of multisystem/multifocal bone Langerhans cell histiocytosis in paediatric patients: Data analysis from the JLSG-96/02 study

We assessed relapse patterns in paediatric patients with relapsed Langerhans cell histiocytosis (LCH) who were initially treated with the JLSG-96/02 protocol. We analysed 187 relapse events in 101 relapsed LCH patients [31 with multifocal bone (MFB) and 70 with multisystem (MS) at LCH diagnosis] among a total 317 patients enrolled in JLSG-96/-02 studies. Relapse of LCH was defined as an exacerbation of the non-active disease (NAD) condition. Of the 317 patients, 101 (31.9%) had the first relapse at 1.5 years after initiation of therapy. The first relapse and subsequent relapses did not differ between patients with MFB and MS disease. Of the 187 relapse events, relapse occurred as a single-system disease (n = 159; 85%), in which isolated bone relapse (n = 104; 55%) was the most common. Relapse at MS disease with the risk of organ involvement is extremely rare. After relapse(s), most patients underwent chemotherapy (122/187; 65%) and 87% of them achieved NAD status again. The incidence of permanent consequences was significantly higher in patients with relapses than in those without relapses. In the JLSG cohort, bone relapse most occurred in both MFB and MS patients. Most relapses could be effectively controlled by repeated administration of the initial chemotherapy.

Pathogenic variants in SLF2 and SMC5 cause segmented chromosomes and mosaic variegated hyperploidy

Embryonic development is dictated by tight regulation of DNA replication, cell division and differentiation. Mutations in DNA repair and replication genes disrupt this equilibrium, giving rise to neurodevelopmental disease characterized by microcephaly, short stature and chromosomal breakage. Here, we identify biallelic variants in two components of the RAD18-SLF1/2-SMC5/6 genome stability pathway, SLF2 and SMC5, in 11 patients with microcephaly, short stature, cardiac abnormalities and anemia. Patient-derived cells exhibit a unique chromosomal instability phenotype consisting of segmented and dicentric chromosomes with mosaic variegated hyperploidy. To signify the importance of these segmented chromosomes, we have named this disorder Atelís (meaning - incomplete) Syndrome. Analysis of Atelís Syndrome cells reveals elevated levels of replication stress, partly due to a reduced ability to replicate through G-quadruplex DNA structures, and also loss of sister chromatid cohesion. Together, these data strengthen the functional link between SLF2 and the SMC5/6 complex, highlighting a distinct role for this pathway in maintaining genome stability.

New biomarker paves the way for a clinical trial for neurodegeneration in Langerhans cell histiocytosis

Neurodegeneration in Langerhans cell histiocytosis (ND-LCH) is a major clinical issue requiring urgent resolution. Sveijer et al. showed that plasma neurofilament light protein is a promising biomarker for screening patients with ND-LCH and determining the therapeutic effect of a mitogen-activated protein kinase inhibitor. Therefore, this can be a powerful tool for conducting clinical trials for ND-LCH. Commentary on: Sveijer M, von Bahr Greenwood T, Jädersten M, Kvedaraite E, Zetterberg H, Blennow K, et al. Screening for neurodegeneration in Langerhans cell histiocytosis with neurofilament light in plasma. Br J Haematol. 2022;00:1-8. doi: 10.1111/bjh.18247.

Reliability and Validity of the Japanese Pediatric Version of Memorial Symptom Assessment Scale

CONTEXT

Few instruments in Japanese assess health-related quality of life in pediatric cancer patients.

OBJECTIVES

To translate the Memorial Symptom Assessment Scale (MSAS) into Japanese pediatric and proxy versions (MSAS-J 7-12, MSAS-J 13-18, and MSAS-J-Proxy) and assess validity and reliability.

METHODS

Phase I comprised forward-backward translation and pilot testing in 13 children and 16 guardians. Phase II consisted of psychometric testing of the three MSAS-J versions in 162 children and 238 guardians. Internal consistency, test-retest reliability, and construct and known-group validity of the MSAS-J were assessed.

RESULTS

Cronbach's alpha coefficients for the total and subscale scores were over 0.70, excluding the psychological symptom (PSYCH) subscale score of the MSAS-J 7-12. Most MSAS-J scores significantly inversely correlated with two versions of the Pediatric Quality of Life Inventory. A strong child-guardian correlation was shown in the total and subscale scores (ICC range 0.66-0.83). Kappa estimates showed acceptable child-guardian symptom agreement. MSAS-J 7-12 and proxy differentiated patients according to clinical status.

CONCLUSION

MSAS-J is a reliable and valid instrument to assess symptoms among Japanese children with cancer.

Severe hypoglycemia in propranolol treatment for infantile hemangiomas

BACKGROUND

Infantile hemangioma (IH), formerly termed strawberry hemangioma, is a benign vascular tumor caused by capillary endothelial cell proliferation. The tumor regresses after 1 year of age, but sequelae occur in approximately half of the patients without systemic treatment. Propranolol (PPL) is currently the first-line therapeutic agent in Japan as well as in Western countries. It is not commonly known that PPL may induce severe hypoglycemia, in addition to cardiovascular and respiratory side effects.

METHODS

We retrospectively analyzed patients with severe PPL-induced hypoglycemia in the 3 years since the launch of Hemangiol®, a PPL preparation specific for IH, in Japan in 2016.

RESULTS

The incidence of severe hypoglycemia and of hypoglycemic convulsions following PPL treatment was estimated to be 0.54% and 0.35%, respectively. The incidence of hypoglycemic convulsions appeared to be higher in Japan than in Western countries. Severe hypoglycemia was common in infants aged >1 year, when PPL was used for ≥6 months. Severe hypoglycemia often develops from 05:00 a.m. to 09:00 a.m. and is frequently associated with prolonged periods of fasting, poor feeding, or poor physical conditions.

CONCLUSION

To avoid the risk of hypoglycemia, the treatment should be initiated by 6 months of age during the proliferative phase at the latest, and should not be extended indiscriminately beyond 1 year of age. Guardians should be advised not to administer PPL on an empty stomach, in the presence of poor feeding, or who are in poor physical condition, not to prolong fasting after PPL administration, and to monitor the child's condition immediately after he or she wakes up.

Low donor chimerism may be sufficient to prevent demyelination in adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a peroxisomal disorder characterized by white matter degeneration caused by adenosine triphosphate-binding cassette subfamily D member 1 (ABCD1) gene mutations, which lead to an accumulation of very-long-chain fatty acids (VLCFA). Hematopoietic stem cell transplantation (HSCT) is the most effective treatment; however, the ratio of donor-to-recipient cells required to prevent the progression of demyelination is unclear. The proband was diagnosed with the childhood cerebral form of ALD at 5 years of age based on the clinical phenotype, elevated plasma VLCFA levels, and pathogenic ABCD1 mutation c.293C>T (p.Ser98Leu). Soon after the diagnosis, he became bedridden. At 1 year of age, his younger brother was found to carry the same ABCD1 mutation; despite being asymptomatic, at 1 year and 9 months, head magnetic resonance imaging (MRI) showed high-signal-intensity lesions in the cerebral white matter. The patient underwent unrelated cord blood transplantation (UCBT) with a reduced conditioning regimen, which resulted in mixed chimerism. For 7 years after UCBT, the donor chimerism remained low (<10%) in peripheral blood and cerebrospinal fluid. However, even though a second HSCT was not performed, his neurological symptoms and brain MRI findings did not deteriorate. Our case suggests that even a small number of donor cells may prevent demyelination in ALD. This is an important case when considering the timing of a second HSCT.

Bone lesions of Langerhans cell histiocytosis triggered by trauma in children

BACKGROUND

Bone lesions of Langerhans cell histiocytosis (LCH) may be triggered by trauma.

METHODS

The characteristics of pediatric patients in the JLSG-02 study cohort who developed a bone lesion at the trauma site at diagnosis of LCH were analyzed retrospectively.

RESULTS

Of the 261 pediatric patients with LCH, 12 (4.6%), of median age 4.9 years, had trauma-triggered bone LCH lesions at diagnosis, making them significantly older than the remaining patients (P = 0.006). Trauma sites included the craniofacial regions in 10 patients and the lumbar spine and pelvis in one patient each. At the time of trauma, six patients had a bump at the site, whereas none had extradural hematomas or bone fractures. The median time from trauma to onset was 4 weeks. Of these 12 patients, three had isolated bone (IB) disease; four had multifocal bone (MFB) disease, including the bone lesion at the trauma site; and five had multisystem disease, including four with lesions in neighboring tissue and one with polyuria (posterior pituitary lesion) more than 1 year before the trauma-triggered bone lesion. Treatment responses were good in all 12 patients and none died, but relapses were observed in two patients, one each with IB and MFB disease.

CONCLUSIONS

About 5% of pediatric patients with LCH developed new trauma-triggered bone lesions at a relatively old age. These lesions can manifest as IB, or, in patients with underlying LCH diseases, as MFB or multisystem. Good clinical outcomes were observed in these patients.

[Elucidated pathogenesis and therapeutic prospects in Langerhans cell histiocytosis]

Langerhans cell histiocytosis (LCH) is characterized by immature dendritic cell proliferation, which is currently classified as an inflammatory myeloid neoplasm. Clinical features and outcomes vary from spontaneously regressing isolated bone disease to fatal liver, spleen, or hematopoietic system (risk organ) involvement-positive multisystem disease. LCH cells have the only mutation in the mitogen-activated protein kinase (MAPK) signaling pathway gene, represented by the BRAF V600E mutation, which is the driver mutation. The type of disease depends on the stage of hematopoietic cell differentiation at which the mutation occurs. LCH cells acquire anti-apoptosis and senescence-associated secretory phenotype by oncogene-induced senescence, with migration failure to lymph nodes. These cause LCH cell accumulation and various inflammatory cell recruitment in the lesion, resulting in severe inflammation. Tissue damage in LCH is due to this inflammation, not the LCH cell proliferation. Patients with a risk of organ involvement without the initial treatment response may be rescued by allogeneic hematopoietic stem cell transplantation after reducing the disease activity with MAPK inhibitors. Intravenous zoledronic acid and intrathecal cytarabine injections have been introduced into the ongoing clinical trial in Japan to reduce bone recurrence and prevent neurodegeneration as sequelae.

Virus-triggered secondary hemophagocytic lymphohistiocytosis

Primary (familial/hereditary) and secondary (non-familial/hereditary) hemophagocytic lymphohistiocytosis (HLH) are hyperinflammatory and hypercytokinemic syndromes. Secondary HLH includes infection- (eg viral/bacterial/fungal/parasitic) and non-infection- (eg collagen disease or malignancy) related diseases. Viral HLH is the major type among all age groups. Secondary viral HLH and primary HLH must be differentiated carefully because primary HLH can be associated with viral infection(s), and the outcome is dismal without a timely diagnosis and hematopoietic stem cell transplantation (HSCT). Epstein-Barr virus (EBV)-related HLH (EBV-HLH) is the most common type of viral HLH in childhood. For non-EBV-HLH, appropriate treatment of viral infection, followed by immunomodulatory agent(s) such as corticosteroids, intravenous immunoglobulin or cyclosporine A, is usually successful; however, recent SARS-CoV-2-related HLH may become life-threatening. EBV-HLH may occur heterogeneously associated with the primary infection, with chronic active EBV infection or with underlying primary HLH. Although immunomodulatory agent(s) are effective in the majority of EBV-HLH cases, management differs from that of non-EBV-HLH because severe and refractory cases may require etoposide-containing HLH-1994/2004 regimens or other experimental agents. The novel agent, emapalumab (an anti-IFN-γ monoclonal antibody) can be used to treat EBV-HLH cases to avoid the risk of secondary malignancy due to etoposide. Finally, HSCT is required for refractory EBV-HLH cases and can also be curative in some other cases.

Prognostic value of the revised International Prognostic Scoring System five-group cytogenetic abnormality classification for the outcome prediction of hematopoietic stem cell transplantation in pediatric myelodysplastic syndrome

Cytogenetic abnormalities are a major risk factor for relapse after hematopoietic stem cell transplantation (HSCT) for myelodysplastic syndrome (MDS). We aimed to evaluate the value of the five-group cytogenetic classification according to the revised International Prognostic Scoring System (R-IPSS) for predicting the outcome after HSCT in pediatric patients with MDS. We retrospectively analyzed the Japanese registration data of 242 pediatric patients with MDS. According to the R-IPSS classification, 112 (45.5%) patients had good, 55 (22.7%) had intermediate, 64 (26.4%) had poor, and 11 (4.6%) had very poor cytogenetics. The 5-year overall survival (5yOS) was 72%, 69%, 59%, and 30% in the good, intermediate, poor, and very poor cytogenetic subgroups (p = 0.026), respectively. The very good, good, and intermediate subgroups were grouped into a "standard" subgroup and reclassified into three subgroups (standard, poor, and very poor). Patients with very poor risk had worse 5yOS (hazard ratio 2.17, 95% confidence interval (CI) 1.02-4.61; p = 0.04) and a much higher 5yCIR (hazard ratio 2.52, 95% CI 1.05-6.04; p = 0.04) than those of patients in the standard group in the multivariate analysis, indicating that very poor risk cytogenetic characteristics independently predicted worse outcome after HSCT in pediatric patients with MDS.

Successful living donor liver transplantation for liver failure due to maternal T cell engraftment following cord blood transplantation in X-linked severe combined immunodeficiency disease: Case report

Maternal T cells from perinatal transplacental passage have been identified in up to 40% of patients with severe combined immunodeficiency (SCID). Although engrafted maternal T cells sometimes injure newborn tissue, liver failure due to maternal T cells has not been reported. We rescued a boy with X-linked SCID who developed liver failure due to engrafted maternal T cell invasion following living donor liver transplantation (LDLT) following unrelated umbilical cord blood transplantation (UCBT). After developing respiratory failure 3 weeks postpartum, he was diagnosed with X-linked SCID. Pathological findings showed maternal T cells engrafted in his liver and hepatic fibrosis gradually progressed. He underwent UCBT at 6 months, but hepatic function did not recover and liver failure progressed. Therefore, he underwent LDLT using an S2 monosegment graft at age 1.3 years. The patient had a leak at the Roux-en-Y anastomosis, which was repaired. Despite occasional episodes of pneumonia and otitis media, he is generally doing well 6 years after LDLT with continued immunosuppression agents. In conclusion, the combination of hematopoietic stem cell transplantation (HSCT) and liver transplantation may be efficacious, and HSCT should precede liver transplantation for children with X-linked SCID and liver failure.

Central diabetes insipidus developing in a 6-year-old patient 4 years after the remission of unifocal bone Langerhans cell histiocytosis

A six-year-old boy was referred with a one-and-a-half months history of polyuria and polydipsia. At the age of two, he had a single lytic bone lesion in his femoral head, diagnosed as Langerhans cell histiocytosis (LCH) by biopsy at another hospital. As no other affected organs were detected and the affected bone lesion was self-limited, he was not followed up afterward and was doing well. He was diagnosed with diabetes insipidus (DI) by confirming hypernatremia (Na: 148 mEq/l) with hyperosmolar serum (s-Osm 298 mOSM/kg) and inappropriately diluted urine (u-Osm 205 mOSM/kg). His polyuria and polydipsia improved dramatically using the perioral diuretic hormone, and other pituitary functions were not impaired. Magnetic resonance imaging revealed an enlarged pituitary stalk. Sensitive and specific biomarkers of germ cell tumors, including alpha-fetoprotein, placental alkaline phosphatase, and β-hCG in the cerebrospinal fluid, were not detected, indicating relapse of LCH. Genetic analysis revealed a BRAF V600E mutation in the primary bone lesion. We recommend systematic follow-up of patients with a history of LCH, even non-CNS single-system single-site disease, especially with BRAF V600E mutation.

Rapid blood cell recovery with immunosuppressive therapy combined with romiplostim in a patient with very severe hepatitis-associated aplastic anemia who underwent liver transplantation

Patients with hepatitis-associated aplastic anemia (HAA) who undergo living-donor liver transplantation (LDLT) have a poor prognosis with infections and bleeding complications. Rapid recovery of blood cells is critical for preventing these complications and improving the outcome. Immunosuppressive therapy (IST) combined with thrombopoietin receptor agonists is considered effective for aplastic anemia. However, there are no data on the benefits of adding thrombopoietin receptor agonists to IST for HAA. We present the case of a child with severe HAA who underwent LDLT, and who achieved rapid blood cell recovery with IST combined with romiplostim, a thrombopoietin receptor agonist. In addition, despite having undergone LDLT, the patient had no adverse events such as serious liver dysfunction or thrombosis. This case suggests that IST combined with thrombopoietin receptor agonists may be a promising treatment option for HAA patients undergoing LDLT.

Long-term complications in uniformly treated paediatric Langerhans histiocytosis patients disclosed by 12 years of follow-up of the JLSG-96/02 studies

Langerhans cell histiocytosis (LCH) is a rare inflammatory myeloid neoplasia derived from immature myeloid dendritic cells with the mitogen-activated protein kinase (MAPK) pathway gene mutation. LCH is rarely fatal, but patients develop various permanent consequences (PCs). We report the frequencies of LCH-related PCs in paediatric patients (n = 317) treated by the JLSG-96/02 AraC-containing regimens. One-third of LCH patients had at least one PC at a median follow-up of 12 years. Central nervous system (CNS)-related PCs (neurological and endocrinological) accounted for 21·5%, non-CNS-related 16·7%. We require novel therapeutic measures to further reduce the frequency of LCH-related PCs.

Unrelated cord blood transplantation with myeloablative conditioning for pediatric acute lymphoblastic leukemia in remission: prognostic factors

The number of individuals undergoing unrelated cord blood transplantation (UCBT) has increased in recent years; however, information on prognostic factors is limited. We retrospectively analyzed data from 475 children and adolescents receiving UCBT with myeloablative conditioning for acute lymphoblastic leukemia (ALL) in complete remission (CR), based on a nationwide registry. In the total patient cohort, 5-year leukemia-free survival (LFS) and overall survival (OS) rates after UCBT were 61.1% and 67.7%, respectively. UCBT at first CR and UCBT after 2007 were associated with good survival, while grade II-IV acute graft-versus-host disease (GVHD) was associated with low relapse rate but did not affect survival. Analysis according to human leukocyte antigen (HLA) disparity revealed that tacrolimus-based GVHD prophylaxis resulted in higher OS and lower relapse rate and nonrelapse mortality (NRM) than cyclosporine-based GVHD prophylaxis in patients transplanted with 6/6 and ≤4/6 HLA-matched umbilical cord blood. Furthermore, grade II-IV acute GVHD was associated with good LFS and low relapse rate, without high NRM, in patients receiving 5/6 HLA-matched UCBT. These data indicate that prognostic factors for ALL differ depending on HLA disparity in UCBT.

Prevalence of germline GATA2 and SAMD9/9L variants in paediatric haematological disorders with monosomy 7

Monosomy 7 (-7) occurs in various types of paediatric myeloid disorders and has a poor prognosis. Recent studies have demonstrated that patients with germline gain-of-function SAMD9/9L variants and loss-of-function GATA2 variants are prone to developing myelodysplastic syndrome (MDS) associated with -7. However, the prevalence of the genetic variants among paediatric haematologic disorders with -7 is unknown. The present study screened germline variants of GATA2 and SAMD9/9L in 25 patients with various types of paediatric haematological disorders associated with -7. The diagnoses of the 25 patients included MDS (n = 10), acute myeloid leukaemia (AML) and myeloid sarcomas (n = 9), juvenile myelomonocytic leukaemia (n = 3) and other disorders (n = 3). Seven patients with a germline pathogenic GATA2 variant were found. For SAMD9/9L screening, next-generation sequencing was used to detect low-abundance variants and found four novel germline variants. Functional analysis revealed that three out of the four variants showed growth-restricting capacity in vitro and thus, were judged to be pathogenic. Cases with GATA2 mutation tended to be older, compared to those with SAMD9/9L mutations. In conclusion, GATA2 and SAMD9/9L were sequenced in 25 patients with paediatric haematologic disorders associated with -7, and 40% of them were found to have some pathogenic germline variants in the three genes.

Impact of immunophenotypic characteristics on genetic subgrouping in childhood acute lymphoblastic leukemia: Tokyo Children's Cancer Study Group (TCCSG) study L04-16

Immunophenotyping was performed in 1044 consecutive childhood acute lymphoblastic leukemia (ALL) patients enrolled in the Tokyo Children's Cancer Study Group L04-16 trial, revealing novel findings associated with genetic abnormalities. In addition to TCF3-PBX1 and MEF2D fusions, the CD10⁽⁺⁾ subtype of KMT2A-MLLT3-positive ALL frequently exhibited the cytoplasmic-μ⁽⁺⁾ pre-B ALL immunophenotype. Although ETV6-RUNX1 was significantly correlated with myeloid antigen expression, more than half of patients expressed neither CD33 nor CD13, while the CD27⁽⁺⁾ /CD44^(-) immunophenotype was maintained. Expression of CD117 and CD56 in B-cell precursor-ALL was limited to certain subtypes including ETV6-RUNX1 and KMT2A-MLLT3. Besides BCR-ABL1, CRLF2, hyperdiploidy, and hypodiploidy, CD66c was also expressed in Ph-like kinase fusion-, PAX5 fusion-, and DUX4 fusion-positive ALL, but not in MEF2D fusion-positive ALL, indicating constant selectivity of CD66c expression. In T-ALL, SIL-TAL1-positive patients were likely to exhibit a more mature immunophenotype. Expression of CD21 and CD10 was not rare in T-ALL, while lack of CD28 was an additional feature of early T-cell precursor-ALL. Considering the immunophenotype as a prognostic maker, MEF2D fusion-positive ALL with CD5 expression may be associated with a poorer prognosis in comparison with those lacking CD5 expression. In cases with characteristic marker expression, the presence of certain fusion transcripts could be predicted accurately.