Similar Outcomes In Adults And Children Undergoing Family HLA-Mismatched/Haploidentical Hematopoietic Cell Transplantation (HCT)

Haploidentical HCT can achieve nearly comparable therapeutic effects with HLA matched sibling HCT and may induce more potent graft-versus-tumor effects. We tested whether the outcomes for adults and children were different in haploidentical HCT and sought predictors of HCT success. Patients (pts) aged 1-65 yrs receiving myeloablative conditioning regimens with 2 to 3 antigen HLA-mismatched family member donors between 2000 and 2005 were included. 137 pts (50 children and 87 adults) were reported to CIBMTR and 181 pts (68 children and 113 adults) were from Dao-Pei Hospital in China. The CIBMTR cohort was 53% AML, 31% ALL, 9% CML, and 7% MDS, with 26% early, 24% intermediate and 50% advanced disease. More than 80% of adults and children received either ATG or in vitro T cell depletion (TCD). Median FU of survivors was 40 months for children and 38 months for adults. In the Chinese cohort there were 31% AML, 35% ALL, 28% CML, and 6% MDS with 48% early, 27% intermediate and 25% with advanced disease. All pts received ATG before HCT. Median FU of survivors was 49 months for children and 47 months for adults. In univariate analyses, 3 year survival in children and adults was 19 (95% CI [8-32])% and 24 [15-35]% in the CIBMTR cohort, p=NS and 54 [43-66]% and 53 [44-62]% in the Chinese cohort, p=NS, respectively. CIBMTR and Chinese data were analyzed separately because of differences in outcomes and pt and HCT characteristics. In the CIBMTR cohort, four subgroups were compared (Adult-No TCD; Child-No TCD; Adult-TCD, Child-TCD) due to a significant interaction between age and TCD. With TCD, adults had a higher mortality rate than children (RR 1.75, [1.08-2.84], p=0.023). However, that age effect was not observed in pts without TCD. Disease stage was also predictive of survival (p<0.001). In the Chinese cohort, Karnofsky score ≥90 was associated with better survival (RR 0.35, [0.22-0.54], p<0.001) as well as lower TRM, lower relapse and higher DFS. No significant differences were found between children and adults in TRM, relapse, DFS or survival. Our results suggest that adults and children have similar outcomes after haplo-identical HCT. In vitro TCD in adults is associated with worse outcomes in the cohort reported to CIBMTR. Other prognostic factors such as advanced disease stage in the CIBMTR cohort and Karnofsky score in the Chinese cohort are consistent with those identified in studies of HLA-matched donors.