Treatment of pediatric primary hemophagocytic lymphohistiocytosis with the HLH-94/2004 regimens and hematopoietic stem cell transplantation in China

We aimed to clarify the clinical characteristics, prognostic factors, and effectiveness of the HLH-94/2004 regimens and hematopoietic stem cell transplantation (HSCT) in pediatric patients with primary hemophagocytic lymphohistiocytosis (pHLH) in China. A retrospective analysis was performed on 38 patients with pHLH at Beijing Children’s Hospital. PRF1 (34.2%) and UNC13D (31.6%) were the most common mutations in the pHLH. Thirty-eight patients were treated with the HLH-94/2004 regimens after diagnosis. Twenty-six patients (72.2%) responded to first-line treatment (complete response: 55.5%, partial response: 16.7%). The median survival time was 23 months. The overall survival (OS) rate at 3 years was 74.7%. There was no significant difference in the response rate (72% vs. 63.6%, P = 0.703) or 3-year OS (83.6% vs. 66.7%, P = 0.443) between the patients treated with the HLH-94 regimen and those treated with the HLH-2004 regimen. The incidences of all side effects in patients treated with the HLH-94 or HLH-2004 regimen were 32.0% and 18.2%, respectively ( P = 0.394). Among 15 patients treated with HSCT, neither the preconditioning regimen nor the donor type affected patient prognosis ( P = 0.205 and P = 0.161, respectively). The disease status (remission or nonremission) before preconditioning did not affect prognosis or the incidence of GVHD. Furthermore, a higher bilirubin level (≥ 30 μmol/L) was correlated with a poorer prognosis in pHLH patients ( P = 0.026). The effectiveness rates of the HLH-94 and HLH-2004 regimens, chemotherapy, and HSCT were similar in pHLH patients. A bilirubin level ≥ 30 μmol/L might be an adverse prognostic factor in pHLH.