(429) ST2 Measured as Part of Clinical Care Identifies Children Post-HCT at Risk for Respiratory Failure

Introduction: Early identification of respiratory failure in children post-hematopoietic cell transplant (HCT) is an imperative next step to improve outcomes. Soluble Stimulation-2 (ST2) is a plasma biomarker shown in clinical research settings to be associated with the development of respiratory failure and other post-HCT complications. However, it is unclear if this marker is applicable in clinical practice to determine patients at risk for critical care interventions.

Methods: Between 2019-2022, a pediatric cohort (n=75) undergoing allogenic HCT had ST2 levels measures by Viracor laboratory as part of standard clinical care. All ST2 levels were obtained prior to respiratory failure with the majority (92%) having levels measured at day 7±2 post-HCT. Wilcoxon rank sum test, logistic regression and receiver operating characteristic curves were conducted for this analysis. A sub-analysis of patients receiving nasal canula (n=24) was conducted to determine patients at high risk of respiratory failure requiring intubation.

Results: Eleven (15%) required noninvasive respiratory support [high flow nasal cannula / noninvasive ventilation] (n=3) or intubation (n=8). The median ST2 for the entire cohort was 19.0 ng/mL. Those with respiratory failure had a higher median ST2, 57.5 ng/mL (IQR: 39.6, 160.0) compared to those without respiratory failure, 15.5 ng/mL (IQR: 9.1, 33.1), p< 0.0001. ST2 levels were dichotomized into high/low based on our previous publication where a high ST2 level was ≥ 54.5 ng/mL. Those with high ST2 (≥54.5 ng/mL), had a significantly higher odds of developing respiratory failure, OR=9.8 (95%:CI 3.4, 40.5, p=0.002). ST2 also had a high discriminative ability to determine which patients will develop respiratory failure with an AUC=0.88. In the subanalysis of patients receiving nasal cannula, 8 (33%) required intubation and had a higher median ST2 54.2 (IQR: 36.9, 110.8) compared to 20.5 (IQR: 13.0, 40.0) in those who never needed intubation, p= < 0.001. Those with a high ST2 level also had a higher risk of PICU mortality (HR=15.8 [95% CI: 1.6, 152.2] p=0.017).

Conclusions: In this cohort of children post-HCT, ST2 measured by a clinically available lab test, as early as day 7, can accurately identify those at highest risk of developing respiratory and PICU mortality.