Real-World Outcomes of Adult B-Cell Acute Lymphocytic Leukemia Patients Treated With Inotuzumab Ozogamicin

Background Inotuzumab ozogamicin (InO) is an anti-CD22 monoclonal antibody–drug (calicheamicin) conjugate that has shown superior efficacy compared to conventional chemotherapy in relapsed/refractory (RR) B-cell acute lymphocytic leukemia (ALL) patients. We sought to find the safety and efficacy of InO in a real-world setting. Patients and Methods A multicenter cohort analysis on 84 RR ALL patients who received InO outside of clinical trials was conducted to evaluate response and toxicity. Results The median (range) age of patients at InO initiation was 50 (20-87) years. Forty patients (48%) had ≥ 3 therapies and 23 patients (27%) underwent allogeneic hematopoietic stem-cell transplantation (allo-HCT) before InO. The median (range) number of cycles of InO provided was 2 (1-6), and cumulative dose was 3.3 (1.8-9.3) mg/m2. Overall response rate (complete remission/complete remission with incomplete count recovery) was 63%; 44% had complete remission with minimal residual disease negativity. Twenty-three patients (27%) with response received allo-HCT. The median duration of response was 11.5 months and when censored at allo-HCT was not reached (51% in remission at 2 years). The median overall survival after InO was 11.6 months and when censored at time of allo-HCT was 13.6 months. The most common grade 3 or higher adverse events observed were transaminitis (16%), hyperbilirubinemia (5%), bleeding (4%), veno-occlusive disease (2%), and hyperglycemia (2%). In multivariate analysis, allo-HCT after InO did not retain favorable significance for duration of response (hazard ratio = 1.27; 95% confidence interval, 0.89-1.61; P = .2) or overall survival (hazard ratio = 1.10; 95% confidence interval, 0.37-3.25; P = .85). Conclusion InO was well tolerated and had significant efficacy in RR B-cell ALL patients.