Background: Realgar-Indigo naturalis formula (RIF) containing A 4S 4 as a major ingredient is an oral arsenic available in China. The efficacy of RIF on pediatric acute promyelocytic leukemia (APL) is comparable to arsenic trioxide (ATO). However, it remains to be explored that the effects of these two arsenicals on differentiation syndrome (DS) and coagulation disorder which are the two main life-threatening events in children with APL. Procedure: We analyzed 68 consecutive children with newly diagnosed APL involved in SCCLG-APL study (NCT02200978). Patients received all-trans retinoic acid (ATRA) on day 1 of induction therapy. ATO (0.16 mg/kg·d) or RIF (135 mg/kg·d) was administrated on day 5 after mitoxantrone on day 3 (non-high-risk group, NHR) or day 2-4 (high-risk group, HR). Results: The incidences of DS were 3.0% and 5.7% in ATO (n = 33) and RIF (n = 35) groups ( p = 0.590), and 10.3% and 0% in patients with and without differentiation-related hyperleukocytosis, respectively ( p = 0.04). The dynamic changes of WBC between the ATO and RIF groups were not statistically different. However, patients with high WBC counts or percentage of promyelocytes in peripheral blood tended to develop differentiation-related hyperleukocytosis. The improvement of coagulation indexes in the ATO and RIF groups had no statistical difference. Fibrinogen and prothrombin time had the quickest recovery rate. Conclusions: This study provides evidences that the incidence of DS and recovery of coagulopathy are similar whenever treating with RIF or ATO in children with APL.

Objective: Cytokine storms are central to the development of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH). Previous studies showed that single nucleotide polymorphisms (SNPs) of cytokine genes may be associated with the development of EBV-HLH in children. We investigated the associations between SNPs and haplotypes of interleukin-2 receptor subunit alpha (IL2RA), interleukin-10 (IL-10), interferon gamma (IFN-γ), IFN regulatory factor 5 (IRF5), and C-C chemokine receptor 2 (CCR2) and susceptibility to EBV-HLH in children. Methods: 66 children with EBV-HLH and 58 healthy EBV-seropositive controls were enrolled in the study. SNPs of IL2RA rs2104286, rs12722489, and rs11594656, IL-10 rs1800896, rs1800871, and rs1800872, IFN-γ rs2430561, IRF5 rs2004640, and CCR2 rs1799864 were assayed and genotyped using the SNaPshot technique. Results: The frequencies of the AA genotype and A allele of IL2RA rs2104286 and IL-10 rs1800896, and the CC genotype and C allele of IL-10 rs1800872 were significantly higher in the EBV-HLH group compared with those in the control group, respectively. The frequencies of genotypes and alleles of IL2RA rs2104286, IL-10 rs1800871, IFN-γ rs2430561, IRF5 rs2004640, and CCR2 rs1799864 were similar in both groups. In addition, the IL2RA AGT (rs2104286-rs12722489-rs11594656) and IL-10 ACC (rs1800896-rs1800871-rs1800872) haplotypes were also significantly more frequent in the EBV-HLH group. Conclusions: The SNPs of IL2RA rs2104286, IL-10 rs1800896 and rs1800872 and the haplotypes of IL2RA AGT and IL-10 ACC are highly associated with susceptibility to EBV-HLH in children.