North American Blastic Plasmacytoid Dendritic Cell Neoplasm Consortium: Position on Standards of Care and Areas of Need.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with historically poor outcomes and no worldwide consensus treatment approach. Unique among most hematologic malignancies for its frequent cutaneous involvement, BPDCN also can invade other extramedullary compartments including the central nervous system. Generally affecting older adults, many patients are unfit to receive intensive chemotherapy, and while hematopoietic stem cell transplantation is preferred for younger, fit individuals, not all are eligible. One recent therapeutic breakthrough is that all BPDCNs express CD123 (IL3Rα), and that this accessible surface marker can be pharmacologically targeted. The first-in-class agent for BPDCN, tagraxofusp, which targets CD123, was approved in December 2018 in the United States for patients with BPDCN ages 2 and older. Despite favorable response rates in the frontline setting, many patients still relapse in the setting of monotherapy, and relapsed/refractory BPDCN patient outcomes remain dismal. Therefore, novel approaches targeting both CD123 and other targets are actively being investigated. In order to begin to formally address the state of the field, we formed a new collaborative initiative, the North American BPDCN Consortium (NABC). This group of experts includes a multi-disciplinary panel of hematologists/oncologists, hematopoietic stem cell transplant physicians, pathologists, dermatologists, and pediatric oncologists, and was tasked with defining the current standard of care in the field and identifying the most important research questions and future directions in BPDCN. The position findings of the NABC's inaugural meetings are presented herein.