Serum 5-S-cysteinyldopa as a predictive biomarker for stem cell transplantation-related complications in children and young adults.

Diffuse hyperpigmentation is common in patients who undergo chemotherapy or stem cell transplantation (SCT). However, only a few studies have reported the relation between skin reactions and SCT-related complications. Serum 5-S-cysteinyldopa (5SCD), a pheomelanin precursor, is elevated in individuals with hyperpigmentation. Here, we serially examined 5SCD levels during SCT to determine their association with SCT-related complications. We prospectively analyzed serum 5SCD levels in 41 patients (median age: 7.9 years; range: 0-22 years) who underwent SCT (allogeneic in 34 patients and autologous in 7 patients). The serum level of 5SCD increased on day 0, remained high on day 5, and gradually decreased to baseline levels on day 40 after SCT. An increase in 5SCD levels on day 0 was associated with the presence of viral reactivation (odds ratio [OR]: 3.32; 95% confidence interval [CI] 1.07-10.21, p = 0.002) while an increase in 5SCD levels on day 5 was associated with pre-engraftment syndrome (OR: 2.18; 95% CI 1.11-4.26, p = 0.007). In patients who underwent allogeneic SCT, the difference between the baseline level of 5SCD before SCT and the highest level after SCT was associated with acute graft-versus-host disease (GVHD) (OR for a 10 nmol/L increase in biomarker levels: 1.90; 95% CI 1.04-3.45, p = 0.015) and acute cutaneous GVHD (OR for a 10 nmol/L increase in biomarker levels: 2.34; 95%CI 1.11-4.52, p = 0.005). The conditioning regimen was not associated with serum 5SCD levels. Therefore, this study demonstrated the potential of 5SCD as a predictive biomarker for SCT-related complications, such as viral reactivation, pre-engraftment syndrome, and acute GVHD.