Inotuzumab ozogamicin safe, effective in relapsed, refractory paediatric ALL
05 Jul 2022
Inotuzumab ozogamicin is well tolerated and demonstrates clinical activity in children with relapsed or refractory acute lymphoblastic leukaemia (ALL), according to the results of a phase II trial.
The trial included 32 patients aged 1–18 years with relapsed or refractory CD22-positive B cell ALL (BCP-ALL). Of these, 28 children received inotuzumab ozogamicin at 1.8 mg/m2 and 27 were evaluable for response.
The primary study endpoint was the objective response rate (ORR), defined as the combined complete remission (CR), CR with insufficient platelet recovery and without recovery of counts rate, and measured as best response during the entire treatment. Secondary endpoints included ORR after cycle one, event-free survival, overall survival, duration of response, minimal residual disease (MRD) negativity rate, and safety.
The study met the primary endpoint, with the estimated ORR being 81.5 percent (95 percent confidence interval [CI], 61.9–93.7). Eighteen out of the 22 responders (81.8 percent) had a negative MRD result.
Survivors were followed for a median of 16 months (interquartile range, 14.49–20.07 months). Event-free survival at 1 year was 36.7 percent (95 percent CI, 22.2–60.4), while overall survival was 55.1 percent (95 percent CI, 39.1−77.7). A total of 18 patients received consolidation with haematopoietic stem cell transplantation and/or chimeric antigen receptor T-cells therapy.
In terms of safety, seven patients developed sinusoidal obstructive syndrome.
Finally, MRD negativity correlated with calicheamicin sensitivity in vitro but not with CD22 surface expression, saturation, or internalization.