DISCUSSION:
Pediatric cases of BPDCN has been defined increasingly since 2008 with the report of World Health Organization as a part of AML(4). But lack of experience effects proper diagnosis and optimal treatment.
In 2010, Jegalian et al defined diagnostic features and clinical implications for children and they concluded that BPDCN is less aggressive for pediatric age group and high risk ALL chemotherapy is effective for treatment. Furthermore stem cell transplantation can be a choice in second complete remission(5). In adults; stem cell transplantation is being used as a consolidation therapy due to aggressiveness of the disease(6). Later than, skin involvement was defined as an indicative finding for aggressiveness of the disease in children(7). There is still no consensus about the curative treatment of BPDCN in children.
Tagraxofusp-erz is a recombinant cytotoxin consisting human IL-3 fused to a truncated diphteria toxin and approved for BPDCN (for patients age above 2 years and older) since December 2019. (1,8). There are a handful of pediatric patients who were treated with tagraxofusp-erzs in literature and our patient had treatment for two cycles and reached a remission and a bridge to stem cell transplantation. To obtain remission, we also preferred to add a bcl-2 inhibitor; venetoclax with potential benefit for remission which was successfully applied in literature to a 77 years old patient with comorbidities without significant adverse effect(9). The literature emphasize the risk of transient remission for both adults and children yet for patients in second remission, tagraxofusp is advised as an optimal therapy to decrease residual disease and bridge to stem cell transplantation(6).
Our patient had relapsed six months after stem cell transplantation. Considering previous toxicities, therapy changed to a venetoclax and azacytidine combination treatment notified with efficacy and a very favorable toxicity profile in literature(10). Despite encouraging results no benefit was obtained.