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.