Circulating cfRNA in plasma has emerged as a fascinating area of research with potential applications in disease diagnosis, monitoring, and personalized medicine. Circulating RNA sequencing technology allows for the non-invasive collection of important information about the expression of target genes, eliminating the need for biopsies. This comprehensive review aims to provide a detailed overview of the current knowledge and advancements in the study of plasma cfRNA, focusing on its diverse landscape and biological functions, detection methods, its diagnostic and prognostic potential in various diseases, challenges, and future perspectives.

Realgar-Indigo naturalis formula (RIF), an oral traditional Chinese medicine mainly containing Realgar (As₄S₄), is highly effective in treating adult acute promyelocytic leukemia (APL). However, the treatment efficacy and safety of RIF have not been verified in pediatric patients. SCCLG-APL group conducted a multicenter randomized non-inferiority trial to determine whether intravenous arsenic trioxide (ATO) can be substituted by oral RIF in treating pediatric APL. Of 176 eligible patients enrolled, 91 and 85 were randomized to ATO and RIF groups, respectively. Patients were treated with the risk-adapted protocol. Induction, consolidation, and 96-week maintenance treatment contained all-trans-retinoic acid and low-intensity chemotherapy, and either ATO or RIF. The primary endpoint was 5-year event-free survival (EFS). The secondary endpoints were adverse events and hospital days. After a median 6-year follow-up, the 5-year EFS was 97.6% in both groups. However, the RIF group had significantly shorter hospital stays and lower incidence of infection and tended to have less cardiac toxicity. All 4 relapses occurred within 1.5 years after completion of maintenance therapy. No long-term arsenic retentions were observed in either group. Substituting oral RIF for ATO maintains treatment efficacy while reducing hospitalization and adverse events in treating pediatric APL patients, which may be a future treatment strategy for APL.

Invasive fungal infection (IFI) is life-threatening in children with cancer and hematology disorders, especially when diagnosis and treatment are delayed. Conventional β-D-glucan and galactomannan tests have poor positive predictive values in the diagnosis of IFI in children with cancer. This study aims to access the diagnostic performance of C-reactive protein (CRP) and procalcitonin (PCT) in differentiating IFI from bacterial bloodstream infections in children with malignant and hematology disorders. CRP and PCT levels were measured in samples taken from patients between 12 and 24 h after fever onset, of which 24 and 102 were in the IFI and bacterial groups, respectively. We found that the CRP levels were much higher in the IFI group than the bacterial group (100.57 versus 40.04 mg/L, median, p < 0.001), while the PCT levels remained significantly lower (0.45 versus 1.29 μg/L, median, p = 0.007). Both CRP and PCT showed significant diagnostic utilities with an area under the curve (AUC) of 0.780 (95% CI, 0.664–0.896, p < 0.001) and 0.731 (95% CI, 0.634–0.828, p < 0.001) when using the cut-off values of 94.93 mg/L and 2.00 μg/L, respectively. However, the combined biomarker of CRP and PCT yielded a better diagnostic performance with an AUC of 0.934 (95% confidential interval (CI), 0.881–0.987, p < 0.001), which was significantly higher than that of CRP or PCT (both p < 0.001), with a sensitivity of 87.5% and a specificity of 87.3%. Our study demonstrates high levels of CRP combined with low PCT could differentiate IFI from bacterial bloodstream infections in immunocompromised children.

Background: Treatment outcomes for acute promyelocytic leukemia (APL) have improved with all-trans-retinoic acid and arsenic trioxide, yet relapse remains a concern, especially in pediatric patients. The prognostic value of minimal residual disease (MRD) post-induction and the impact of arsenic levels during induction on MRD are not fully understood. Objectives: To evaluate the relationship between post-induction MRD levels and relapse-free survival (RFS) in pediatric APL patients, and to investigate the correlation between blood arsenic concentration levels during induction therapy and MRD status. Design: A retrospective analysis of pediatric APL patients enrolled in a clinical trial from September 2011 to July 2020. Methods: We assessed the relationship between RFS and post-induction MRD levels using the log-rank test. The optimal MRD cut-off was determined using the “surv_cutpoint” function in the survminer R package. Arsenic concentration levels were monitored in 16 patients on days 7 and 14 of induction therapy, and Spearman correlation was used to analyze the relationship between arsenic concentrations and MRD levels. Results: Among 176 pediatric APL patients, with a median follow-up of 6 years, 4 relapsed. Patients with MRD >3.1% had significantly lower RFS compared to those with MRD ⩽3.1% (94.6% vs 100%, p = 0.023). In addition, a negative correlation was found between blood arsenic concentration levels and post-induction MRD levels. Lower arsenic concentrations were associated with higher MRD levels, with significant correlations observed for trough concentrations ( R = −0.666, p = 0.005) and peak concentrations ( R = −0.499, p = 0.049) on day 7. Conclusion: Our study highlights the prognostic significance of post-induction MRD assessment in pediatric APL. We also demonstrate a negative correlation between blood arsenic concentration levels and MRD, suggesting that lower arsenic concentrations during induction therapy may contribute to a higher MRD burden. These findings may inform strategies to optimize treatment and improve outcomes in pediatric APL. Trial registration: www.clinicaltrials.gov (NCT02200978).