Discussion
Our study showed that ruxolitinib therapy in children with TM accompanied by prominent features of IE leads to considerable reduction of the spleen volume and the RBC transfusion requirement. This correlates with significant decrease in sTfR concentration and tendency to declining of erythrocyte progenitor in the bone marrow. The maximum effect of IE suppression was achieved mostly after the first 3 months of ruxolitinib therapy. It appears that therapeutic effect of ruxolitinib was dose-dependent as clinical and laboratory features of IE rapidly returned to initial after ruxolitinib dose reduction.
The outcomes of HSCT were favorable in 7 out of the 8 “difficult-to-transplant” patients with TM. We suggest that IE which is one of the main risk factors potentially leading to primary and secondary severe graft failure and immune suppression may both impact on the favorable engraftment rate. There are two important limitation factors of ruxolitinib therapy, one is rapid loss of response after drug interruption and another is potentially severe AE with long-term use. Thus, short-term application of ruxolitinib in patients with TM and pronounced IE can be used safely and seems to be a promising approach for preparing pediatric patients with TM and pronounced IE for HSCT.