Acute promyelocytic leukemia: A single institution's experience

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Background: Acute Promyelocytic Leukemia (APL) is highly curable but carries high risk of early morbidity and mortality, including hemostatic abnormalities, differentiation syndrome and infection. Induction regimens include all-trans-retinoic acid (ATRA) to promote promyelocyte differentiation and arsenic trioxide (ATO), with chemotherapy added for high-risk patients. Our objective was to characterize clinical characteristics and complications during APL induction. Methods: Electronic medical records were screened for ATRA, ATO, or idarubicin from 2011-2021. APL induction hospitalization records were reviewed for: demographics, white blood cell (WBC) and platelet count at presentation, fibrinogen at presentation, time to ATRA administration, time to complete remission (CR), infection, thrombohemorrhagic complications, ATO related QT interval prolongation, incidence of and time to differentiation syndrome. Results: 56 patients (pts) (median age 50) were analyzed. Mean time from initial presentation at our institution to ATRA administration was 1.5 days (range 0-6 days). Findings upon arrival: median WBC 1.7 K/UL (range 0.3-134.9), median platelets 32 K/UL (range 7-373), hypofibrinogenemia in 39.2% (N = 22) (median 161 MG/DL, range 35-473). 80.3% had documented thrombohemorrhagic complications during induction hospitalization: DIC (N = 24), venous thromboembolism (N = 12), gastrointestinal bleed (N = 6), oral mucosal bleeding (N = 5), vaginal bleeding (N = 3), gross hematuria (N = 3), intracranial hemorrhage (N = 3), epistaxis (N = 2), intraocular hemorrhage (N = 1), cerebral vascular accident (CVA) (N = 1). 21% (N = 12) developed differentiation syndrome with mean time of onset of 8.8 days (range 1-23 days). 55% (N = 31) had clinically significant infections most commonly neutropenic fever (N = 13), bacterial pneumonia (N = 10), skin (N = 5) and bacteremia (N = 5). 48 pts were given ATO during induction and 31% (N = 15) developed QT interval prolongation with no arrhythmias in the cohort. Among 8 pts who did not receive ATO, one died prior to therapy initiation and 7 were treated prior to ATO as standard of care. Among evaluable patients (N = 51): 98% (N = 50) achieved complete remission (CR) or complete remission with incomplete count recovery (CRi). Median time to CR was 35 days (range 27-50). 6 pts did not achieve CR or had unknown status: 1 patient died during induction (CVA) and 5 had post-induction bone marrow evaluations at outside facilities. Conclusions: Thrombohemorrhagic complications, infection and differentiation syndrome are critical to be mindful of during the early phase of treatment in APL. Our data adds to the landscape of knowledge regarding the incidence and timeline of complications. Although we observed prolonged QTc in pts on ATO, there were no arrhythmias detected and all pts were able to quickly resume therapy.

Blastic plasmacytoid dendritic cell neoplasm should be treated with acute leukemia type induction chemotherapy and allogeneic stem cell transplantation in first remission

Blastic plasmacytoid dendritic cell (BPDC) neoplasm is a rare but clinically aggressive tumor known to be derived from the precursors of plasmacytoid dendritic cells (CD123+) with a high frequency of cutaneous and bone marrow involvement. Though majority of the patients initially respond to multi-agent chemotherapy, most would relapse within a year. We hereby report a patient with disseminated cutaneous BPDC with marrow involvement diagnosed by typical histo-pathological and flow-cytometric findings. He was subsequently treated with leukemia type induction regimen followed by allogeneic stem cell transplantation in first complete remission. He is now 18 months posttransplantation with continued remission with full donor chimerism. We recognize that BPDC with marrow involvement behaves like acute myeloid leukemia and aggressive treatment followed by stem cell transplantation may lead to long-term remission in selected cases.