FDA Approves Inotuzumab Ozogamicin in Pediatric B-Cell Precursor ALL

The US Food and Drug Administration (FDA) has approved inotuzumab ozogamicin (Besponsa) for pediatric patients one year and older with relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukemia (ALL).

The efficacy of inotuzumab ozogamicin was assessed in a multicenter, single-arm, open-label study involving 53 pediatric patients aged one year and older with relapsed or refractory CD22-positive B-cell precursor ALL. Two dose levels were evaluated: an initial dose of 1.4 mg/m²/cycle in 12 patients and 1.8 mg/m²/cycle in 41 patients, according to the FDA press release announcing the approval.

The efficacy endpoints were complete remission (CR), duration of CR, and the proportion of patients achieving CR with measurable residual disease (MRD) negativity. CR was defined as <5% blasts in the bone marrow, absence of peripheral blood leukemia blasts, full recovery of peripheral blood counts (platelets ≥100×10⁹ and ANC ≥1×10⁹/L), and resolution of any extramedullary disease. MRD negativity was defined as leukemic cells comprising <1×10^-4 (<0.01%) of bone marrow nucleated cells by flow cytometry or polymerase chain reaction (PCR).

Among all patients, 22 out of 53 (42%; 95% CI, 28.1-55.9) patients achieved CR, with a median duration of CR of 8.2 months (95% CI, 2.6-not evaluable). The MRD negativity rate in patients with CR was 95.5% (95% CI, 77.2-99.9) based on flow cytometry and 86.4% (95% CI, 65.1-97.1) based on real-time quantitative PCR.

The most common adverse reactions were thrombocytopenia, pyrexia, anemia, vomiting, infection, hemorrhage, neutropenia, nausea, leukopenia, febrile neutropenia, increased transaminases, abdominal pain, and headache, according to the FDA.