Survival Outcomes
The one-year OS rate for the entire cohort was 62% [95% confidence interval (CI), 0.427–0.758]. There was no significant difference between primary and relapsed cases with respect to the one-year OS rate (61% vs. 69%, p = 0.328); patients with PD at IREC initiation showed poorer one-year survival rate compared to the other patients (21% vs. 77%, p < 0.001). The cumulative incidence of relapse or PD at one year after IREC was 45% (95% CI, 0.279–0.606); patients with PD at the initiation of IREC showed a higher cumulative incidence of relapse or PD compared to the other patients (86% vs. 26%, p < 0.001).
Patients with UGT1A1 gene polymorphism (heterozygous and homozygous groups) showed a better one-year survival rate than wild-type patients (77% vs 48%, p = 0.026) (Figure 2 ); similar results were obtained in an analysis limited to primary cases (n = 36), excluding seven relapsed cases (80% vs. 44%, p = 0.012). There was no significant difference in the cumulative incidence of relapse in patients with and without UGT1A1 gene polymorphism (Figure 3 ).
After IREC, 16 patients received a total of 24 stem cell transplantations: 11 autologous peripheral blood stem cell transplantations and 13 cord blood transplantations. Treatment-related death was observed in one patient (UPN15). This patient underwent autologous peripheral blood stem cell transplantation using busulfan + melphalan regimen after three courses of IREC therapy; she died six months after transplantation due to a late-onset non-infectious pulmonary complication.