Th236 - The Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) Scores for HLA Class I and II Graft-versus-host Disparity Are Associated with Better Outcome in Haploidentical Transplantation of Relapsed Neuroblastoma Patients

Hee Won Cho, M.D. – Department of Pediatrics – Samsung Medical Center; In Hwa Jeong, M.D. – Department of Laboratory Medicine and Genetics – Samsung Medical Center; Won Young Heo, M.D. – Department of Laboratory Medicine and Genetics – Samsung Medical Center; Ki Woong Sung, M.D.,Ph.D. – Professor, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University, School of Medicine

Abstract Text: The clinical significance of Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) scores for HLA Class I and II Graft-versus-Host Disparity was evaluated to predict outcome in 40 patients with relapsed neuroblastoma who underwent haploidentical stem cell transplantation (haplo-SCT) from 2012 to 2022. The outcomes according to PIRCHE -I and -II scores, and significance of PIRCHE score levels according to clinical and biological characteristics before and after haplo-SCT were evaluated. The 5-year probabilities of progression-free survival (PFS) and overall survival (OS) from haplo-SCT in 40 patients were 20.5±8.9% and 30.2±8.3%, respectively. A higher PIRCHE-II score (≥39) was associated with better survival (5-yr PFS 46.4±16.3% vs. 0.0%, P< 0.001; 5-yr OS 49.1±14.4% vs. 18.2±9.0%, P=0.047) and was an independent good prognostic factor in multivariate analysis (PFS: hazard ratio 0.025, 95% confidence interval 0.09–0.72, P=0.010; OS: hazard ratio 0.038, 95% confidence interval 0.16–0.93, P=0.035). A higher PIRCHE-I score was associated with faster hematologic recovery (neutrophil p=0.046; platelet p=0.021) and shorter fever (≥38.0) duration (P=0.04). The PIRCHE-I score was also higher in patients who did not experience CMV reactivation compared to those who did (median 27 vs. 19, P=0.027). Acute and chronic GVHD were not associated with PIRCHE scores in our study. In conclusion, higher PIRCHE scores are associated with better survival, faster hematologic recovery and less infection in haplo-SCT for children with recurrent neuroblastoma.