Challenging management of severe differentiation syndrome in pediatric acute promyelocytic leukemia treated with ATRA/ATO

Abstract

The ATRA/ATO combination treatment of acute promyelocytic leukemia (APL) represents a paradigm of successful targeted and chemotherapy-free treatment in oncology. This therapeutic strategy is aimed at sparing patients from chemotherapy toxicity, while maintaining an excellent survival with a low risk of relapse. Main induction treatment-related complications are differentiation syndrome (DS) and hyperleukocytosis, which is related to DS and its severity. In the period December 2019 – December 2020, 8 children with newly diagnosed APL underwent induction therapy with ATRA/ATO in our center. In patients with WBC≥10x10⁹/L  two doses of Gemtuzumab Ozogamicin (GO) were  added. In case of severe DS or hyperleukocytosis the differentiating agents were discontinued, high dose dexamethasone (DXM) and/or hydroxyurea (HU) were recommended. Five patients presented WBC<10x10⁹/L ; all  developed hyperleukocytosis and three also had DS and were initially treated with HU and DXM; due to unsatisfactory control of the symptoms GO was added in two of them.. One of the three patients with presenting WBC≥10x10⁹/L, developed pseudotumor cerebri and another one DS. The supportive treatment was effective in all cases. Our experience shows that patients, treated with ATRA/ATO only, may develop marked hyperleukocytosis and severe DS, which may be unresponsive to discontinuation of differentiating agents and administration of HU and DXM and may benefit from the use of GO. Adequate intensive support therapy is crucial to rescue patients with severe DS.