Post-irradiation Hyperamylasemia Is a Prognostic Marker for Allogeneic Hematopoietic Stem Cell Transplantation Outcomes in Pediatric Population: a Retrospective Single-centre Cohort Analysis.

Background: Total body irradiation (TBI) is a mandatory step for patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). In the past, amylases have been reported to be a possible sign of TBI toxicity. We investigated the relationship between total amylases (TA) and transplant-related outcomes in pediatric recipients. Methods: We retrospectively analyzed the medical records of all the patients who underwent allogeneic HSCT between January 2000 and November 2019. Inclusion criteria were the following: recipient’s between 2 and 18, diagnosis of ALL, no previous transplantation, and use of TBI-based conditioning. Serum total amylase and pancreatic amylase were evaluated before, during and after transplantation. Cytokines and chemokines assays were retrospectively performed. Results: 78 patients fulfilled the inclusion criteria. 57 patients were treated with fractionated TBI and 21 with a single dose regimen. Overall survival (OS) was 62.8%. Elevated values of TA were detected in 71 patients (91%). TA were excellent in predicting the OS (AUC = 0.773; 95% CI = 0.66-0.86; P < 0.001). TA values below 374 U/L were correlated with a higher OS. The highest mean TA values (673 U/L) were associated with a high disease-progression mortality rate. TA showed high predictive performance for disease progression-related death (AUC = 0.865; 95% CI = 0.77 – 0.93; P < 0.0001). Elevated TA values were also connected with significantly higher levels of proinflammatory cytokines such as TNF-α, IL-6 and RANTES (P < 0.001).Conclusions: This study shows that TA is a valuable predictor of post-transplant OS and increased risk of leukemia relapse.