INO-CD22: A multicenter, real-world study of inotuzumab ozogamicin safety and effectiveness in adult patients with relapsed/refractory acute lymphoblastic leukemia

Background: Inotuzumab ozogamicin (IO) has helped to change the treatment paradigm in B-cell acute lymphoblastic leukemia (B-ALL) but real-world data are limited. Methods: The INO-CD22 study is a multicenter retrospective cohort study of adult patients with relapsed/refractory B-ALL treated with IO in 24 Italian centers from 2014 to 2019, with the aim of assessing the response, survival, and toxicity of IO. Results: Data for 73 eligible patients were obtained: the median age at the start of IO treatment was 52.7 years (I-III quartiles, 51.9-53.5 years), the median number of previous lines was three (I-III quartiles, two to four), and prior exposure to induction standard chemotherapy and blinatumomab occurred in 85% and 57.5% of cases, respectively. IO was administered following the label schedule. A 74.0% overall response rate was achieved, with a 69.8% complete remission rate and a 4.1% complete remission with incomplete hematologic reconstitution rate. The median duration of response was 4.4 months (I-III quartiles, 2.3-11.2 months). With a median follow-up of 37.2 months, the median overall survival (OS) was 7.9 months (95% CI, 6.08-12.42 months) with a 3- and 5-year OS of 21.2% (95% CI, 11.9%-32.3%) and 5.3% (95% CI, 9.6%-29.8%), respectively. Overall, 37% of patients were able to proceed to allogeneic hematopoietic stem cell transplantation. Eight patients (11.0%) experienced veno-occlusive disease/sinusoidal obstruction syndrome; the most frequent grade ≥3 nonhematologic adverse events were liver toxicities and pneumonia (two grade 4 and one grade 5, respectively). Conclusions: Despite the limitations of retrospective studies, the INO-CD22 study highlights the favorable safety profile and clinical activity of IO within a real-world context.