What is the mortality rate for haploidentical bone marrow transplants?

Mortality Rates for Haploidentical Bone Marrow Transplants

Haploidentical bone marrow transplantation carries a significant mortality risk, with historical data showing transplant-related mortality rates of approximately 40% overall, with 25% mortality within the first 100 days post-transplant. 1

Historical Mortality Data

• Myeloablative haploidentical transplants have shown high early mortality rates, with one SWOG trial reporting a 45% 6-month mortality rate, which led to early closure of the allogeneic arm of the study 1
• Long-term data from this trial showed that despite high early mortality, the overall survival at 7 years was 39%, with a plateau in the survival curve suggesting some patients achieved long-term survival 1

Mortality Based on Patient Age

• Age significantly impacts mortality rates in haploidentical transplantation:
  • For patients <16 years of age: Overall survival of approximately 95% 1
  • For patients ≥16 years of age: Overall survival of approximately 81% 1
  • Recent CIBMTR analysis showed higher mortality in patients >13 years of age following myeloablative conditioning with matched sibling donor transplants 1

Conditioning Regimen Impact on Mortality

• Non-myeloablative or reduced-intensity conditioning (RIC) regimens have been developed to decrease mortality while preserving graft-versus-tumor effects 1
• Recent studies using reduced-intensity conditioning show improved outcomes:
  • A 2018 study using RIC with ATG and post-transplant cyclophosphamide reported 6-month overall survival of 73.9% and 1-year overall survival of 48.1% 2
  • A 2017 pediatric/young adult study using non-myeloablative conditioning reported 1-year transplant-related mortality of 13% and 1-year overall survival of 56% 3

Causes of Mortality

• Infection is the most common cause of death in haploidentical transplants, accounting for approximately 18% of deaths in recent studies 2
• Other common causes include:
  • Graft failure (though rates have improved with modern protocols) 4
  • Graft-versus-host disease (GVHD) 1
  • Disease relapse 5
  • Hemorrhage 5

Recent Advances in Haploidentical Transplantation

• Modern approaches using post-transplantation cyclophosphamide have significantly improved outcomes:
  • A 2013 study reported 18% transplant-related mortality with myeloablative conditioning 5
  • A 2022 trial in severe aplastic anemia patients showed 81% 1-year overall survival with haploidentical transplantation 6

Risk Factors for Higher Mortality

• Factors associated with worse outcomes include:
  • Older age (>55 years) 1
  • Chemoresistant disease 1
  • More than one prior transplant 1
  • Active disease at time of transplant 5
  • Poor performance status 4

GVHD Impact on Mortality

• GVHD rates vary by age and conditioning regimen:
  • For patients ≤16 years: acute GVHD (grade 2-4) 12.6%; chronic GVHD 14.6% 1
  • For patients >16 years: acute GVHD (grade 2-4) 16%; chronic GVHD 23% 1
• Modern GVHD prophylaxis regimens have reduced these rates significantly, with recent studies showing grade III-IV acute GVHD rates as low as 5.2% 2

In summary, while historical mortality rates for haploidentical transplants were quite high (40% overall), modern approaches with reduced-intensity conditioning and improved GVHD prophylaxis have significantly improved outcomes, with recent studies showing 1-year survival rates between 48-81% depending on patient and disease characteristics.