What question did this study set out to answer?

To evaluate the real-world use and outcomes of inotuzumab ozogamicin in high-risk patients with relapsed/refractory B-ALL.

May 30, 2026

Real-world experience with inotuzumab ozogamicin in high-risk and R/R B-cell acute lymphoblastic leukemia.

Key Points

To evaluate the real-world use and outcomes of inotuzumab ozogamicin in high-risk patients with relapsed/refractory B-ALL.
Retrospective analysis of 15 consecutive B-ALL patients treated with inotuzumab at our center from October 2022 to January 2026.
Assessment of demographics, disease biology, indication for treatment, InO dosing, response rates, transplant outcomes, and toxicities.
Combination therapy with mini-HCVD was administered to 53% of patients.
80% achieved complete response (CR) or CR with incomplete recovery (CRi).
60% of patients had minimal residual disease (MRD)-negative complete response (CR).
27% developed transplant-associated thrombotic microangiopathy (TA-TMA), with severe sinusoidal obstruction syndrome (SOS)/veno-occlusive disease (VOD) in 6.6% of patients.

Abstract

e18507 Background: Inotuzumab ozogamicin (InO) is an effective CD22-directed antibody–drug conjugate for relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). However, real-world data describing dose-modified InO use in combination or as monotherapy, particularly in post-transplant settings and regions with a high prevalence of metabolic liver disease, is limited. Methods: We retrospectively analyzed consecutive patients with B-ALL treated with InO at our center from October 22,2022 to January 1, 2026. Data collected included demographics, disease biology, indication for InO use, combination with chemotherapy (mini-HCVD), InO dosing and cumulative exposure, response (CR/CRi and MRD), transplant outcomes, and toxicities including SOS/VOD and transplant-associated thrombotic microangiopathy (TA-TMA). Results: 15 patients with B-ALL were included (median age ~17 years; range 6–65); 53% had high-risk biology (TP53, IKZF+, or Ph+). InO was used as bridge to allo-HSCT (47%), post-allo relapse therapy (27%), post-allo maintenance (27%), sequentially with blinatumomab (20%), or as pre-phase stabilization (7%). Inotuzumab was administered in combination with mini-HCVD in 8 of 15 patients (53%), while the remainder received single-agent InO or other combinations based on disease burden and clinical context. All patients received 0.3 mg/m² per dose. The median number of doses was 4 (range 1–12), with a median cumulative dose of ~1.2 mg/m² (range 0.3–3.6 mg/m²), substantially lower than label-based cumulative exposure, reflecting combination therapy, frequent post-transplant use, and regional concern for baseline hepatic vulnerability including underlying fatty liver disease. Overall, CR/CRi was achieved in 80%, with MRD-negative CR in 60%, including patients with TP53-mutated and Ph+ disease. Among transplant-eligible patients, 70% were successfully bridged to allo-HSCT, and durable CR ≥12 months was observed in 40%. Severe SOS/VOD occurred in 1 patient (6.6%), in the post-allo relapse setting, and was fatal. TA-TMA was observed in 27%, clustering in post-allo settings. Conclusions: In this real-world cohort, dose-modified inotuzumab ozogamicin, frequently combined with mini-HCVD, produced high response and MRD-negativity across high-risk B-ALL. Toxicity appeared context-dependent even at lower doses, with rare but severe SOS/VOD and a notable endothelial toxicity signal in post-allo settings. These findings support cautious dosing and timing-based integration of inotuzumab ozogamicin, particularly in transplant-exposed populations and regions with prevalent metabolic liver disease. Parameter Result Patients (B-ALL) 15 Median age (range) ~17 years (6–65) High-risk biology 53% Inotuzumab + mini-HCVD 8 patients (53%) Median InO doses 4 (range 1–12) Median cumulative dose ~1.2 mg/m² CR/CRi 80% MRD-negative CR 60% SOS/VOD 6.6% TA-TMA 27%

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