What are the recommendations for managing HTLV-1 (Human T-lymphotropic virus 1) in patients undergoing Hematopoietic Stem Cell Transplantation (HSCT)?

Management of HTLV-1 in HSCT Patients

HTLV-1 screening should be performed for all HSCT donors and recipients, with HTLV-1 seronegative donors preferred to reduce the risk of donor-derived infection and associated complications. 1

Screening Recommendations

Pre-Transplant Screening

• All HSCT candidates and all designated allogeneic HSCT donors should be screened for HTLV-1 1, 2
• HTLV-1 seronegative donors are strongly preferred to avoid the risk of donor-derived HTLV-1 associated diseases 1
• When only HTLV-1 seropositive related donors are available:
  • Exclude the presence of abnormally abundant HTLV-1–infected clones using Southern blotting or PCR-based clonality methods 1
  • Inform recipients about the potential risks of HTLV-1 transmission and associated diseases 2

Testing Methods

• Currently approved screening assays do not distinguish between HTLV-1 and HTLV-2, requiring confirmatory testing 2
• Confirmatory tests should be performed, especially for living donors where time permits 2

Risk Assessment and Management

Risk Stratification

• HTLV-1 seropositive recipients should be considered at higher risk for developing HTLV-1-associated diseases post-transplant due to immunosuppression 2
• The risk of developing HTLV-1-associated diseases (primarily adult T-cell leukemia/lymphoma or HTLV-1-associated myelopathy) is <5% in the general population but may be higher in immunosuppressed HSCT recipients 2

Post-Transplant Monitoring

• HTLV-1-infected recipients should be closely monitored for:
  • Development of neurological symptoms (myelopathy)
  • Signs of adult T-cell leukemia/lymphoma
  • Changes in HTLV-1 proviral load 1
• Consider regular HTLV-1 proviral load monitoring in infected recipients or recipients who received organs from infected donors 3

Management of HTLV-1 Positive Recipients

Immunosuppression Considerations

• There is no proven antiviral treatment for established HTLV-1 infection 2
• Consider minimizing immunosuppression when clinically feasible in HTLV-1 positive recipients 2, 3
• Early recognition of HTLV-1-associated diseases is crucial for prompt intervention 4

Therapeutic Options

• For recipients who develop HTLV-1-associated complications:
  • Consider antiretroviral therapy with zidovudine and raltegravir, which may provide benefit if initiated early 3
  • For HTLV-1-associated adult T-cell leukemia/lymphoma, follow treatment protocols for ATL, potentially including up-front allogeneic HSCT after response to first-line therapy 1

Special Considerations

Inadvertent Transmission

• In cases of inadvertent HTLV-1 transmission:
  • Monitor recipients closely for seroconversion and symptoms
  • Consider early intervention with antiretroviral therapy 3
  • Be vigilant for rapid development of HTLV-1-associated myelopathy, which has been reported within one year post-transplant 5

Geographical Considerations

• Higher vigilance is warranted for donors from HTLV-1 endemic regions (Caribbean, parts of Africa, South America, Japan, and other parts of Asia) 2, 6

Common Pitfalls and Caveats

• False-positive HTLV screening results are common in low-prevalence areas and can lead to unnecessary organ wastage 3
• The natural history of HTLV-1 transmission in HSCT is not fully understood due to suboptimal screening platforms and lack of long-term follow-up 3
• Currently, there is no definitive evidence on the optimal management of immunosuppression in HTLV-1 positive recipients 2
• The risk of developing HTLV-1-associated diseases post-transplant is not well characterized, but immunosuppression likely increases this risk 2

By implementing these recommendations, transplant centers can minimize the risk of HTLV-1 transmission and associated complications in HSCT recipients while maintaining access to life-saving transplantation procedures.