Last reviewed: 30 Sep 2020
Last updated: 14 Nov 2018
14 Nov 2018

First-in-class treatment approved in the US for relapsed or refractory hairy cell leukemia

The US Food and Drug Administration has approved moxetumomab pasudotox for the treatment of adults with relapsed or refractory hairy cell leukemia (HCL) who have received at least two prior systemic therapies, including treatment with a purine nucleoside analog.

Moxetumomab pasudotox is a CD22-directed cytotoxin, and is a first-in-class treatment for HCL. Approval was based on a single-arm phase III clinical trial involving 80 patients with relapsed or refractory HCL who had received at least two prior systemic therapies (including at least one purine nucleoside analog). The trial showed a durable complete response rate of 30% (the proportion of patients maintaining hematologic remission for more than 180 days after achieving a complete response), and an overall response rate of 75% (the proportion of patients with a partial or complete response).[34]

Approval comes with a black box warning for capillary leak syndrome and hemolytic uremic syndrome, which are potentially life-threatening adverse effects of treatment.

HCL is a rare indolent leukemia that affects B cells, and it can be life-threatening. Around 30% to 40% of patients with HCL relapse after initial treatment.[35][36] Few treatments are available for relapsed or refractory HCL, and there is currently no agreed standard of care.

See Management: approach

See Management: treatment algorithm

Original source of updateexternal link opens in a new window



History and exam

Key diagnostic factors

  • abdominal fullness or discomfort
  • splenomegaly

Other diagnostic factors

  • weakness and fatigue
  • pallor and petechiae
  • fever
  • recurrent infections
  • hepatomegaly
  • superficial and deep lymphadenopathy
  • neurologic findings
  • associated systemic immunologic disorders

Risk factors

  • middle age
  • male sex
  • white ancestry
  • western hemisphere location
  • environmental exposures
  • genetic predisposition
  • Epstein-Barr virus
  • infectious mononucleosis

Diagnostic investigations

Investigations to consider

  • bone marrow aspiration or biopsy
  • immunophenotyping
  • flow cytometry
  • tartrate-resistant acid phosphatase (TRAP)
  • CT of abdomen
More investigations to consider

Emerging tests

  • genetics/molecular testing
More emerging tests

Treatment algorithm


Associate Professor

USF Center for Comparative Effectiveness Research and Evidence Based Medicine

Department of Internal Medicine, College of Medicine

Moffitt Cancer Center & Research Institute, Department of Health Outcomes & Behavior

University of South Florida




AK declares that he has no competing interests.


Division of Hematology-Oncology

Blood and Marrow Transplantation Program

Mayo Clinic




MKD declares that he has no competing interests.

Dr Ambuj Kumar and Dr Mohamed Kharfan-Dabaja would like to gratefully acknowledge Dr Benjamin Djulbegovic, a previous contributor to this topic. BD declares that he has no competing interests.

Peer reviewersVIEW ALL

Consultant Haemato-Oncologist

Section of Haemato-Oncology

Brookes Lawley Institute of Cancer




DC declares that he has no competing interests.

Clinical Professor of Medicine

University of Texas Health Science Center San Antonio

San Antonio



RL declares that he has no competing interests.

Chief Fellow

Section of Hematology and Oncology

Department of Internal Medicine

Wake Forest University Baptist Medical Center




RC declares that she has no competing interests.

Consultant Hematologist

The Royal Marsden Hospital





CD declares that she has no competing interests.

Use of this content is subject to our disclaimer