Hairy Cell Leukemia Foundation
Building Leadership
Hairy cell leukemia is a chronic and rare form of adult leukemia. It is estimated that approximately 2% of adult patients with leukemia have this form of disease. While the cause of this malignancy is not known, the origin of the malignant cell is thought to develop from the memory B cell compartment. These malignant cells infiltrate the bone marrow, the spleen, and the liver from the time of diagnosis. While lymph nodes in the abdomen may be involved, lymph nodes are rarely enlarged on physical examination. Hairy cell leukemia is treatable, but not curable. While the cause is not known, the treatment is usually very effective in helping patients lead a normal life.
Last updated 04/30/2026
Clinical
Disease Class
Cancer
Hematological diseases
Body Systems
Hematopoietic / Lymphatic / Immune
Organs
Blood
Bone marrow
Bones
Spleen
Known Genetic Link
Yes, genetic factors contribute to the risk or severity of the condition
Causative Genes
BRAF
Contributory Genes
BRAF
Type of Inheritance
Not specified / unknown
Newborn Screening
Not applicable
Disease Mechanism(s)
Abnormal cell proliferation
Age of Onset
Adulthood (age 18-64)
Elderly (age 65+)
Average Age at Diagnosis
Adulthood (age 18-64)
Life Expectancy
Adulthood (age 18-64)
Elderly (age 65+)
Affected Sex(es)
Female
Male
National Prevalence
Unknown
Global Prevalence
Unknown
National Incidence
Less than 10
Global Incidence
Unknown
Populations and/or ancestry with higher prevalence
The incidence of HCL is approximately three times higher in White than in Black populations.
Symptoms / Phenotypes
anemia
bruising susceptibility
fatigue
hemorrhage/bleeding
night sweats
pancytopenia
splenomegaly
Biomarkers
Diagnostic
· CD19, CD20, CD22, CD11c, CD25, CD103, and CD123; BRAF V600E mutation
Therapeutic
· CD19, CD20, CD22; BRAF V600E mutation
Existing Therapies
Off-Label Drug Use
Regulatory Agency-Approved to Cure or Modify the Disease
· cladribine, pentostatin, moxetumomab pasudotox (no longer commercially available)
Therapies in Development
Antibody-based therapy (monoclonal antibodies, biologics)
· rituximab and obinutuzumab are being used in combination with vemurafenib (non-chemotherapy BRAF inhibitor) in clinical trials
Cellular therapies (stem cell transplants, CAR-T therapies, etc.)
· One CAR-T clinical trial in HCL is underway; BAFF CAR-T has also been studied in HCL variant, but has not progressed to clinical trial
Immunotherapy
Repurposed drug
· vemurafenib is a BRAF inhibitor approved by the FDA for use in melanoma; it is being studied in HCL in clinical trials
Therapeutic Development Stages
In clinical trials (Phase I, II, III, or IV)
In research/exploratory phase
Therapeutic Development Role
Funding
Recruitment and outreach to patients
Results dissemination (including publications)
Organizational & Research
Cell Lines
None
Cell Lines, share
N/A
Disease Model
Mouse
Disease Model, Involvement
Funded
Disease Model, share
Unsure
Organizational Challenges
Yes. Access to drugs and industry funding for clinical trials remains a challenge.
Clinical Trial Role
Funding
Recruitment and outreach, patients
Results dissemination, publication
Clinical Trial Types
Phase 1
Phase 2
Biobank, Institution
None
Center of Excellence, Institution
Autonomous University of Barcelona
Bnai-Zion Medical Center
CHU Caen
CREO - Research Centre of Haematology and Oncology
CancerCare Manitoba
Charite-Universitatsmedizin
Lund University
Mayo Clinic
Medical University of Lodz
NIH
Peter MacCallum Cancer Centre
Scripps Clinic
Semmelweis University Medical School
The Ohio State University (OSU)
The Royal Marsden Hospital NHS Foundation Trust
The University of Texas MD Anderson Cancer Center
University of Alberta
University of Barcelona
University of Bologna
University of New Mexico
University of Rochester
University of Siena
University of Southampton
Zucker School of Medicine at Hofstra University/Northwell Health
Center of Excellence, Involvement
Consulted
Designed
Endorsed/Certified/Accredited
Funded
Registry
Yes, we have a registry that we created
Data Collected, Registry
Clinical data
Electronic health records/electronic medical records
Genetic data
Medication usage
Other
Data Entered by, Registry
Clinicians
Platform, Registry
REDCap
Natural History Study
No, we do not have a natural history study and have no plans to create or collaborate on one
FDA Patient Listening Session
No
FDA Patient-Focused Drug Development (PFDD) Program
No
ICD Codes
Yes, we have an ICD-10 code specific to our exact disease
Diagnostic Guidelines
Yes, we have guidance available on our website
Yes, we have published formal guidelines in a peer-reviewed journal
Science Advisory Board Policies
Yes, not willing to share SAB policies
Research Network Policies
Has CRN but no policies
Patient Priority Survey
Yes
Patient Priority Survey, share
No
Research Roadmap
Yes we have a Research Roadmap, and will share policies
International Chapters
None
International Partners
Europe
North America
South America
Other International Research Initiatives
None