Real-world treatment outcome and toxicity analysis of inotuzumab ozogamicin in adult patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia: multicenter prospective observational study.

BACKGROUND

Adults with relapsed or refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) have dismal prognoses, underscoring the need for effective salvage therapies. Inotuzumab ozogamicin (INO) and blinatumomab (BLIN) have demonstrated efficacy in achieving complete remission (CR) and measurable residual disease (MRD) response.

OBJECTIVES

We tried to evaluate the clinical outcomes and toxicities of INO in adults with R/R BCP-ALL.

DESIGN

Prospective observational multicenter study.

METHODS

A total of 100 patients (25 Ph-positive, 75 Ph-negative) received INO (0.8 mg/m2 on week 1; 0.5 mg/m2 on weeks 2-3) for the initial cycle, followed by 0.5 mg/m2 dosing in subsequent cycles. Allogeneic hematopoietic cell transplantation (allo-HCT) was planned after remission.

RESULTS

Among the cohort, 7 patients were primary refractory (4 post-BLIN), 36 relapsed after chemotherapy (23 post-BLIN), and 57 relapsed after allo-HCT (23 post-BLIN). Extramedullary relapse occurred in 39% of patients. After the first cycle, 60% achieved CR or CR with incomplete hematologic recovery; the overall best response rate after two cycles was 67%, with MRD negativity achieved in 63.1%. Thirty-nine patients (58.2%) underwent allo-HCT. Early mortality occurred in 12%, and hepatic veno-occlusive disease/sinusoidal obstruction syndrome was observed in 10%. With a median follow-up of 31.5 months, the 3-year overall survival was 21.3% in the entire cohort and 37.6% among transplanted patients.

CONCLUSION

INO represents a potent salvage option for R/R BCP-ALL. However, substantial toxicities highlight the critical need for careful patient selection and dose optimization strategies to maximize its therapeutic benefit.

TRIAL REGISTRATION: This study was registered in Clinical Research Information Service (CRIS #KCT0010009) which is connected to WHO ICTRP (Operated by Korea Centers for Disease Control and Prevention, Ministry of Health and Welfare, Republic of Korea).