Improved post-transplant outcomes following inotuzumab ozogamicin-based salvage therapy in relapsed/refractory B-ALL: a real-world retrospective study.

Relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL) remains challenging, and allogeneic hematopoietic cell transplantation (allo-HCT) is often the only curative option. Inotuzumab ozogamicin (InO) has demonstrated high remission rates in salvage settings, but concerns regarding sinusoidal obstruction syndrome (SOS) have limited its use as a bridge to transplantation. We retrospectively evaluated post-transplant outcomes following an InO-based salvage strategy in adults with r/r B-ALL who underwent allo-HCT at a single center in Japan. Eighty-one patients were included (median age, 50 years). Twenty patients received InO before transplantation, while 61 patients previously treated with conventional chemotherapy served as a historical reference. Sequential immunotherapy was common in the InO group, with most receiving blinatumomab. The CR/CRi rate before HCT was higher in the InO group. With a median follow-up of 48 months, the estimated 3-year overall survival and disease-free survival in the InO group were 55.3% and 56.3%, respectively. The favorable outcomes associated with InO-based therapy were more evident in Philadelphia chromosome-negative disease. SOS occurred more frequently in the InO group but was generally mild. These findings provide real-world evidence supporting the feasibility of an InO-based sequential salvage strategy as a bridge to allo-HCT in patients with r/r B-ALL.