Severe RAS-Associated Lymphoproliferative Disease Case with Increasing αß Double-Negative T Cells with Atypical Features.

Autoimmune lymphoproliferative syndrome (ALPS) is a disease of lymphocyte homeostasis caused by FAS-mediated apoptotic pathway dysfunction and is characterized by non-malignant lymphoproliferation with an increased number of TCRαß+CD4-CD8- double-negative T cells (αßDNTs). Conversely, RAS-associated leukoproliferative disease (RALD), which is caused by gain-of-functional somatic variants in KRAS or NRAS, is considered a group of diseases with a similar course. Herein, we present a 7-year-old Japanese female of RALD harboring NRAS variant that aggressively progressed to juvenile myelomonocytic leukemia (JMML) with increased αßDNTs. She eventually underwent hematopoietic cell transplantation due to acute respiratory distress which was caused by pulmonary infiltration of JMML blasts. In general, αßDNTs have been remarkably increased in ALPS; however, FAS pathway gene abnormalities were not observed in this case. This case with RALD had repeated shock/pre-shock episodes as the condition progressed. This shock was thought to be caused by the presence of a high number of αßDNTs. The αßDNTs observed in this case revealed high CCR4, CCR6, and CD45RO expressions, which were similar to Th17. These increased Th17-like αßDNTs have triggered the inflammation, resulting in the pathogenesis of shock, because Th17 secretes pro-inflammatory cytokines such as interleukin (IL)-17A and granulocyte-macrophage colony-stimulating factor. The presence of IL-17A-secreting αßDNTs has been reported in systemic lupus erythematosus (SLE) and Sjögren's syndrome. The present case is complicated with SLE, suggesting the involvement of Th17-like αßDNTs in the disease pathogenesis. Examining the characteristics of αßDNTs in RALD, JMML, and ALPS may reveal the pathologies in these cases.

CHIP-associated mutant ASXL1 in blood cells promotes solid tumor progression.

Clonal hematopoiesis of indeterminate potential (CHIP) is an age-associated phenomenon characterized by clonal expansion of blood cells harboring somatic mutations in hematopoietic genes, including DNMT3A, TET2, and ASXL1. Clinical evidence suggests that CHIP is highly prevalent and associated with poor prognosis in solid-tumor patients. However, whether blood cells with CHIP mutations play a causal role in promoting the development of solid tumors remained unclear. Using conditional knock-in mice that express CHIP-associated mutant Asxl1 (Asxl1-MT), we showed that expression of Asxl1-MT in T cells, but not in myeloid cells, promoted solid-tumor progression in syngeneic transplantation models. We also demonstrated that Asxl1-MT-expressing blood cells accelerated the development of spontaneous mammary tumors induced by MMTV-PyMT. Intratumor analysis of the mammary tumors revealed the reduced T-cell infiltration at tumor sites and programmed death receptor-1 (PD-1) upregulation in CD8+ T cells in MMTV-PyMT/Asxl1-MT mice. In addition, we found that Asxl1-MT induced T-cell dysregulation, including aberrant intrathymic T-cell development, decreased CD4/CD8 ratio, and naïve-memory imbalance in peripheral T cells. These results indicate that Asxl1-MT perturbs T-cell development and function, which contributes to creating a protumor microenvironment for solid tumors. Thus, our findings raise the possibility that ASXL1-mutated blood cells exacerbate solid-tumor progression in ASXL1-CHIP carriers.

Droplet digital polymerase chain reaction assay for the detection of the minor clone of KIT D816V in paediatric acute myeloid leukaemia especially showing RUNX1-RUNX1T1 transcripts.

KIT D816V mutation within exon 17 has been particularly reported as one of the poor prognostic factors in pediatric acute myeloid leukemia (AML) with RUNX1-RUNX1T1. The exact frequency and the prognostic impact of KIT D816V minor clones at diagnosis were not examined. In this study, the minor clones were examined and the prognostic significance of KIT D816V mutation in pediatric patients was investigated. Consequently, 24 KIT D816V mutations (7.2%) in 335 pediatric patients were identified, and 12 of 24 were only detected via the digital droplet polymerase chain reaction method. All 12 patients were confined in core binding factor (CBF)-AML patients. The 5 year event-free survival of the patients with KIT D816V mutation was significantly inferior to those without KIT D816V mutation (44.1% [95% confidence interval (CI), 16.0%-69.4%] vs. 74.7% [95% CI, 63.0%-83.2%] P-value = 0.02, respectively). The 5 year overall survival was not different between the two groups (92.9% [95% CI, 59.0%-NA vs. 89.7% [95% CI, 69.6%-96.8%] P-value = 0.607, respectively). In this study, KIT D816V minor clones in patients with CBF-AML were confirmed and KIT D816V was considered as a risk factor for relapse in patients with RUNX1-RUNX1T1-positive AML.

Allogeneic Bone Marrow Transplantation versus Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies in Children: A Systematic Review and Meta-Analysis.

Peripheral blood stem cell transplantation (PBSCT) is being increasingly performed as an alternative to bone marrow transplantation (BMT); however, PBSCT has not been proven to have equivalent outcome to BMT. We conducted a meta-analysis to compare survival rates and treatment-related complications between PBSCT and BMT for pediatric hematologic malignancies. We searched Medline, Embase plus Embase classics, and the Cochrane Central Register of Controlled Trials for the terms "hematopoietic stem cell transplantation" AND "allogeneic transplantation" AND "children", including randomized controlled studies and cohort studies without language limitations. We identified 7 of 5368 studies for inclusion in our meta-analysis. The cohorts of these studies included a total of 4328 patients, 3185 who underwent BMT and 1143 who underwent PBSCT. Five-year overall survival was similar in the 2 groups (PBSCT, 56.2%; BMT, 63.5%; relative risk [RR], 1.17; 95% confidence interval [CI], .91 to 1.52), as was the 5-year event-free survival (PBSCT, 49.9%; BMT, 57.2%; RR, 1.14; 95% CI, .93 to 1.39). The incidences of nonrelapse mortality and chronic graft-versus-host disease were higher in the PBSCT group compared with the BMT group (RR, 1.73; 95% CI, 1.50 to 1.99 versus RR, 1.55; 95% CI, 1.18 to 2.03). This meta-analysis found insufficient evidence to conclude that peripheral blood stem cells are equivalent to bone marrow. The results indicate that bone marrow can still be a preferred donor source for pediatric hematologic malignancies.

Effectiveness of acyclovir prophylaxis against varicella zoster virus disease after allogeneic hematopoietic cell transplantation: A systematic review and meta-analysis.

BACKGROUND: Varicella zoster virus (VZV) disease is a common complication after hematopoietic cell transplantation (HCT). The mortality rate for disseminated VZV infection is 34%. Acyclovir has been used for the prophylaxis of VZV disease after HCT, but the effectiveness of prophylaxis is controversial. We conducted a meta-analysis of the incidence of VZV disease within the first 1 year after acyclovir prophylaxis had been discontinued and assessed the risk of VZV disease during acyclovir prophylaxis. METHODS: Medline, EMBASE plus EMBASE classics, and the Cochrane Central Register of Controlled Trials were used for a systematic search. The inclusion criteria were both randomized controlled trials and cohort studies that described the effectiveness of acyclovir as prophylaxis against VZV disease after allogeneic HCT. RESULTS: We included seven studies involving a total of 2265 patients. No mortality by VZV was identified. Acyclovir prophylaxis significantly reduced the rate of VZV infection within the first 1 year after discontinuation (risk ratio: 0.38, 95% confidence interval (CI): 0.29-0.51). The risk of VZV disease during acyclovir prophylaxis was also reduced (risk ratio: 0.17, 95% CI: 0.12-0.24). Both short-term and long-term prophylaxis reduced the incidence of VZV infection (RR: 0.51, 95% CI: 0.30-0.86 vs RR: 0.34, 95% CI: 0.22-0.54). Low-dose acyclovir (<400 mg/d) is sufficient to reduce the risk of VZV disease. CONCLUSION: This study showed that acyclovir prophylaxis reduced VZV infection after HCT with no fatal cases and acyclovir prophylaxis is beneficial. No significant adverse effects occurred and no delayed VZV disease was identified.

Intraventricular Rituximab in Pediatric CD20-positive Refractory Primary Central Nervous System Lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive type of extranodal non-Hodgkin lymphoma that carries an unsatisfactory prognosis. Treating refractory PCNSL is challenging because of resistance to conventional cytotoxic and intrathecal chemotherapies. Therefore, novel therapeutic approaches are needed. Here, we report a 12-year-old boy with CD20-positive PCNSL, which was refractory to combination chemotherapy and intravenous rituximab. However, the patient achieved complete remission after repeated intraventricular rituximab administration. The results of this case indicate that intraventricular rituximab is an effective option to treat refractory PCNSL in children.

Childhood Nephrotic Syndrome Complicated by Catastrophic Multiple Arterial Thrombosis Requiring Bilateral Above-Knee Amputation.

Background: Thromboembolic events are rare but critical complications in childhood nephrotic syndrome. The veins are more commonly affected, while arterial thrombosis is extremely rare but often life-threatening. Herein, we describe the clinical course of a 10-years-old girl with catastrophic multiple arterial thrombosis at the primary onset of nephrotic syndrome who underwent bilateral above-knee amputation. Case diagnosis/treatment: A previous healthy 10-years-old girl contracted the influenza B virus. Five days later, she suddenly developed severe ischemia in both legs. Physical examination showed eyelid and leg edema, and laboratory tests revealed hypoalbuminemia and acute kidney injury. After undergoing contrast-enhanced computed tomography, the patient was diagnosed with multiple arterial thrombosis (including the bilateral iliac arteries) due to nephrotic syndrome. Despite the performance of surgical thrombectomies, fasciotomy, and systematic heparinization, she required bilateral above-knee amputation. The patient achieved spontaneous remission of nephrotic syndrome, and her renal function fully recovered. There were no findings suggestive of secondary nephrotic syndrome and antiphospholipid syndrome. Her protein C and protein S concentrations were slightly decreased at admission. However, whole-exome sequencing revealed a thrombotic risk variant (T630I) in the PROS1 gene encoding protein S. This missense variant is often reported in patients with thrombosis or protein S deficiency, and may result in a thrombotic predisposition in some situations, such as nephrotic syndrome. Conclusions: Arterial thrombosis is a rare complication; however, it must be considered, especially in patients with new-onset nephrotic syndrome. Early recognition is important for early intervention and prevention of serious sequelae.

Association of isochromosome (7)(q10) in Shwachman-Diamond syndrome with the severity of cytopenia.

We report two male siblings with SDS. They have the same compound heterozygous mutations. Only one of the siblings acquired cytogenetic abnormality of i(7q) 2 years after diagnosis, became transfusion-dependent, and underwent allogeneic hematopoietic stem cell transplantation. These cases indicate that i(7q) is associated with significant cytopenia in SDS patients.