Updates in Novel Therapies for Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN)

Allogeneic hematopoietic stem cell transplantation with myeloablative conditioning regimen for blastic plasmacytoid dendritic cell neoplasm patients in complete remission: a single center study

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematopoietic malignancy characterized by poor prognosis even following an allogeneic hematopoietic stem cell transplantation (allo-HSCT). We retrospectively analyzed 15 patients diagnosed with BPDCN who underwent an allo-HSCT with myeloablative conditioning (MAC) at our center. The male to female ratio was 11:4. The median age of 36 (range: 6-70) years, all patients initially presented with extramedullary lesions (13 with cutaneous lesions, 1 in the breast and 1 in the lymph nodes) and involved the bone marrow, two cases were diagnosed as central nervous system leukemia (CNSL). Nine patients were in CR1 and six patients were in CR2 status prior to HSCT. All patients received the MAC regimen and an unmanipulated graft. All patients successfully engraftment and achieved full donor chimerism. One patient developed poor graft function, three patients developed aGVHD (Grade I, II, and IV), and seven patients developed cGVHD (mild in 6; moderate in 1). The median follow-up time for survival was 34 (range: 6-64) months. The primary endpoint, overall leukemia-free survival (LFS) rate and overall survival rate was 73.3 ± 10.5%. Allo-HSCT with MAC is a valid option for BPDCN patients in complete remission.

Allogeneic TCRαβ deficient CAR T-cells targeting CD123 in acute myeloid leukemia

Acute myeloid leukemia (AML) is a disease with high incidence of relapse that is originated and maintained from leukemia stem cells (LSCs). Hematopoietic stem cells can be distinguished from LSCs by an array of cell surface antigens such as CD123, thus a candidate to eliminate LSCs using a variety of approaches, including CAR T cells. Here, we evaluate the potential of allogeneic gene-edited CAR T cells targeting CD123 to eliminate LSCs (UCART123). UCART123 cells are TCRαβneg T cells generated from healthy donors using TALEN® gene-editing technology, decreasing the likelihood of graft vs host disease. As safety feature, cells express RQR8 to allow elimination with Rituximab. UCART123 effectively eliminates AML cells in vitro and in vivo with significant benefits in overall survival of AML-patient derived xenograft mice. Furthermore, UCART123 preferentially target AML over normal cells with modest toxicity to normal hematopoietic stem/progenitor cells. Together these results suggest that UCART123 represents an off-the shelf therapeutic approach for AML.

CD123, the interleukin-3 receptor alpha chain, is aberrantly expressed in acute myeloid leukemia blasts and leukemia stem cells. Here the authors report the design and characterize the anti-tumor activity of allogeneic CD123-targeted CAR-T cells as a therapeutic approach for acute myeloid leukemia.

Targeting CD123 in BPDCN: an emerging field

INTRODUCTION

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy with historically poor outcomes for patients, often refractory to traditional chemotherapy. Recent research has focused on targeted therapy to improve responses and limit potential toxicity.

AREAS COVERED

CD123 (also known as IL-3 Rα) is a cell surface marker and attractive therapeutic target for many myeloid malignancies, particularly BPDCN, whose cells ubiquitously overexpress CD123. We review the history of CD123 research regarding BPDCN, recent advances including FDA approval of tagraxofusp (formerly SL-401) for BPDCN, and ongoing clinical studies utilizing novel therapeutic strategies to target CD123.

EXPERT OPINION

The approval of tagraxofusp for the treatment of BPDCN in December 2018 drastically changed the treatment landscape for patients with this rare neoplasm. While tagraxofusp is better tolerated than traditional multi-agent chemotherapy regimens, it requires close monitoring and sound clinical judgment by providers to prevent and mitigate severe treatment-related complications with special attention to the recognition and management of capillary leak syndrome (CLS). Several other promising strategies for targeting CD123 in BPDCN are currently under investigation, including antibody-drug conjugates, T-cell engagers, and CAR-T cellular therapeutics. These CD123 targeted approaches may soon become standard of care for patients with this difficult to treat malignancy.

Rapidly progressing blastic plasmacytoid dendritic cell neoplasm causing diffuse skin thickening: A case report with sequential computed tomography examinations

Blastic plasmacytoid dendritic cell neoplasm is a rare aggressive myeloid malignancy thought to be derived from precursor plasmacytoid dendritic cells. Rapid progression and poor prognosis have been known. We herein present a case of BPDCN in a previously healthy man who presented with suddenly developed multiple deep purple skin rashes, with sequential computed tomography examinations. The follow-up computed tomography demonstrated that multiple skin nodules observed in the initial MRI fused, resulting in a thickening of the entire skin, with some surface erosions and crusting. Blastic plasmacytoid dendritic cell neoplasm should be considered in the differentials in patients with a sudden onset and rapidly progressing skin rash or thickening.

Blastic plasmacytoid dendritic cell neoplasm with cutaneous presentation: A case series in children

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematologic malignancy that can present with multiorgan involvement including the skin. While this entity accounts for 0.1% of all cutaneous lymphomas in adults, fewer than 90 pediatric cases have been described in the literature. We present three cases of pediatric BPDCN, highlighting the variable cutaneous and clinical presentation.