Real-world outcomes of inotuzumab ozogamicin treatment for adult relapsed or refractory acute lymphoblastic leukemia: a result from Korea post-marketing surveillance

Inotuzumab ozogamicin (InO), a CD22-targeted antibody-drug conjugate, delivers the cytotoxic agent, calicheamicin, to B-cell precursor of relapsed or refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL) cells. It has demonstrated efficacy in phase 3 trials, leading to approval in multiple countries, including the U.S., Japan, and South Korea. In our post-marketing surveillance (PMS) study, we evaluated the safety and effectiveness of InO in adults with R/R B-ALL based on approximately 5 years of PMS data. A prospective, observational, multicenter PMS study was conducted in Korea to evaluate the real-world safety and effectiveness of InO in adult patients with R/R B-ALL (NCT04307134). A total of 107 patients were included in the safety analysis, with a median treatment duration of 43.0 days and a median of 2.0 InO cycles. Common adverse events (AEs) were hematologic (58.9%), infectious (50.5%), and gastrointestinal (45.8%), with neutropenia (27.1%) and febrile neutropenia (26.2%) among the most frequent. Serious AEs occurred in 31.8% of patients, most commonly infections such as septic shock (6.5%) and pneumonia (4.7%). Veno-occlusive disease was observed in 2.8% of patients. In the effectiveness analysis set (N = 94), median progression-free survival was 3.6 months (95% CI: 3.0–4.7 months), overall survival was 10.2 months (95% CI: 6.0–NA months), and duration of remission was 3.8 months. (95% CI: 3.0–5.4 months). These findings support the clinical utility and safety profile of InO in Korean patients with R/R B-ALL, reflecting real-world outcomes.