Daratumumab for post-HSCT refractory IMCs Effective treatment with daratumumab in post-HSCT refractory immune-mediated cytopenias: a case report and literature review

XiaoYu Jing^1,2,3Dong-Jun Li^1,2Sheng-Nan Li^1,4Qing-Kai Dai⁵Shu-Wen Sun^2,3Liang Huang⁶Yuan Ai^2,3Ju Gao^2,3Yi-Ping Zhu^2,3Jiaqi Ni^6,7,8*Xiao-Xi Lu^3,9*

• ¹West China Second University Hospital, Sichuan University, Chengdu, China
• ²Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects, Sichuan University, Ministry of Education, Chengdu, China
• ³Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
• ⁴West China School of Clinical Medicine, Sichuan University, Chengdu, China
• ⁵Department of Laboratory Medicine, West China Second University Hospital, Chengdu, China
• ⁶Department of Pharmacy/Evidence-Based Pharmacy Center, West China Second University Hospital, Sichuan University, Chengdu, China
• ⁷Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
• ⁸West China School of Pharmacy, Sichuan University, Chengdu, China
• ⁹NHC(National Health Commission) Key Laboratory of Chronobiology, Sichuan University, Chengdu, China

Immune-mediated cytopenias (IMCs) following allogeneic hematopoietic stem cell transplantation (HSCT) can lead to substantial morbidity and mortality, presenting a major therapeutic obstacle. Here, we report a case of a pediatric patient with acquired aplastic anemia. Nine months after HSCT, this patient developed severe, refractory hemolytic anemia and immune-mediated thrombocytopenia (IMT). Despite treatment with corticosteroids, intravenous immunoglobulin (IVIG), rituximab, along with avatrombopag, romiplostim, acetylcysteine, and decitabine, the patient's platelet count showed no signs of improvement. Subsequently, daratumumab, a monoclonal antibody targeting CD38, was administered. This treatment induced a rapid and sustained response. Four months after initial daratumumab administration, the percentage of CD38-positive immune cells in the patient's peripheral blood increased, which was concurrent with another decline in platelet levels. After re-initiating daratumumab therapy, the patient's platelet count returned to normal levels. The only significant adverse effect noted was a delayed recovery of humoral immunity. Daratumumab, by targeting antibody-producing plasma cells, shows promise as a therapeutic alternative for refractory IMCs in post-HSCT patients.