Ruxolitinib-based regimen in children with primary hemophagocytic lymphohistiocytosis

Abstract

Primary hemophagocytic lymphohistiocytosis (pHLH) is a rare immune disorder and hematopoietic stem-cell transplantation (HSCT) is the only potentially curative treatment. Given the high pre-HSCT mortality of pHLH patients reported in the HLH-2004 study (17%), more regimens to effectively control the disease and form a bridge with HSCT are needed. We conducted a retrospective study of pHLH children treated by Ruxolitinib (RUX) based regimen. Generally, patients received RUX until HSCT or unacceptable toxic side-effect. Methylprednisolone and etoposide were added sequentially when the disease was suboptimally controlled. The primary end point was 1-year overall survival. 21 pHLH patients (12 previously treated and 9 previously untreated) were included with a median follow-up of 1.4 years. At last follow-up, 17 (81.0) patients were alive with a 1- year overall survival of 90.5% (95% CI, 84.1 to 96.9). Within the first 8 weeks, all patients had an objective response, of which 19 (90.5) achieved complete response (CR) and 2 (9.5) achieved partial response (PR) as a best response. 17 (81.0) patients received HSCT, of which 13 (76.5) had CR, 3 (17.6) had PR and 1 (5.9) had disease reactivation at the time of HSCT. 15 (88.2) patients were alive post-HSCT. Notably, 8 (38.1) patients received 0 doses of etoposide, suggesting the potential of RUX-based regimen to reduce chemotherapy intensity. Patients tolerated RUX-based regimen well and the most frequently observed adverse events (AEs) were hematologic AEs. Overall, RUX-based regimen was effective and safe and could be used as a bridge to HSCT for pHLH children.