The study published in the Journal of Investigative Medicine High Impact Case Reports found that treatment resulted in complete bone marrow response in refractory BPDCN.
Prashanth Ashok Kumar, MBBS, of the division of hematology/oncology at the State University of New York’s Upstate Medical University in Syracuse, and colleagues conducted the case study. According to the authors, the patient was a 62-year-old man who had symptoms of generalized lymphadenopathy, diffuse skin lesions on his scalp and back, anemia, and worsening severe fatigue.
Peripheral blood showed 25% blast presence; imaging revealed splenomegaly and axillary, mediastinal, and inguinal lymphadenopathy.1 “Flow cytometry of the peripheral blood showed monocytic precursors expressing CD56 and CD123 consistent with BPDCN. Initial bone marrow biopsy and aspiration revealed 37% blasts. The cells expressed CD7, CD33, CD38, CD56, CD71, CD117, CD123, and HLA-DR,” researchers reported.1
BPDCN has been mostly treated with intense chemotherapy regimens that have been used for acute lymphoblastic leukemia (ALL), lymphoblastic lymphoma (LBL), non-Hodgkin’s lymphoma (NHL), or acute myeloid leukemia (AML), the authors reported. “ALL/LBL-like regimens were noted to have a better outcome compared with AML-type regimens,” researchers noted. They said CD123 is a marker of BPDCN, and that FDA approved first-line treatment consists of tagraxofusp (SL-401) that specifically targets this antigen.
Tagraxofusp (SL-401) has a 90% response rate as a first treatment, however, there are risks such as capillary leak syndrome, which can be fatal. BPDCN can recur, and researchers said therapies for relapses are not yet well documented. “Besides treatment in a clinical trial setting, tagraxofusp or induction chemotherapeutic regimens would have to be used based on what was used in the first-line setting, followed by allogenic transplant,” researchers wrote.1
Following the patient’s initial diagnosis, he was treated with tagraxofusp for 6 months with 8 cycles of therapy.1 Researchers said a biopsy of a scalp lesion revealed recurrence of BPDCN so he was given Hyper-CVAD. The patient then required hospitalization in the ICU for progressive hypoxia and neutropenic fever, which was treated with broad spectrum antibiotics and steroids for pneumonitis caused by cyclophosphamide treatment.1 “Cerebrospinal fluid (CSF) analysis revealed 76% blasts for which intrathecal (IT) methotrexate therapy was started,” researchers reported.1
After the patient recovered, he had a CD 34+ allogenic stem cell transplant with fludarabine and melphalan conditioning, according to researchers. After the transplant he experiences complications due to engraftment syndrome, and infections consisting of Staphylococcal epidermidis bacteremia and Clostridium difficile.1 Researchers said he also experienced angioedema and generalized exanthematous pustulosis and had to return to the ICU.
A follow up bone marrow test showed a recurrence of BPDCN with blasts increasing to 47.5% and a positive result for the disease in his cerebral spinal fluid. The authors said the patient was then readmitted to the hospital for the recurrence, and had another bone marrow test. “The aspirate appeared crowded with cells and contained numerous blasts,” researchers said. The patient tested positive for antigens CD123, CD117, CD3, CD34, CD13, HLADR Per-CP, and CD33.1
Since the patient’s disease was resistant to treatment and rapidly getting worse, researchers tried a fixed-dose combination of cytarabine (vyxeos) and liposomal daunorubicin based on another study that showed effectiveness in other aggressive leukemia cancers like acute myeloid leukemia.2 In addition to vyxeos, IT methotrexate was given once again.
After 1 month of vyxeos treatment, there was no evidence of BPDCN in the patient’s bone marrow when retested. However, researchers said the patient’s condition worsened and he was hospitalized for neutropenic fever, pseudomonas infection, and sepsis and died. In spite of this outcome, bone marrow response after vyxeos treatment shows possibilities in BPDCN recurrence, the authors said.
“To the best of our knowledge, we report one of the first cases of BPDCN that showed a complete bone marrow response to vyxeos. This is promising for the future and prompts the need for clinical trials evaluating its use in this rare malignancy,” researchers concluded.1 They noted that further trials may be challenging due to the rarity of BPDCN making it difficult to recruit enough study participants. However, they noted several trials are in progress and that further study of vyxeos is warranted.