Micrograph showing ALL
Health Canada has approved inotuzumab ozogamicin (Besponsa™) as monotherapy for adults with relapsed or refractory, CD22-positive, B-cell precursor acute lymphoblastic leukemia (ALL).
Inotuzumab ozogamicin is the first and only CD22-directed antibody-drug conjugate approved for this indication.
The product consists of a monoclonal antibody targeting CD22 and a cytotoxic agent known as calicheamicin.
Health Canada’s approval of inotuzumab ozogamicin is based on results from the phase 3 INO-VATE trial, which were published in NEJM in June 2016.
The trial enrolled 326 adults with relapsed or refractory B-cell precursor ALL.
Patients received inotuzumab ozogamicin or 1 of 3 chemotherapy regimens—high-dose cytarabine; cytarabine plus mitoxantrone; or fludarabine, cytarabine, and granulocyte colony-stimulating factor.
The rate of complete remission, including incomplete hematologic recovery, was 80.7% in the inotuzumab arm and 29.4% in the chemotherapy arm (P<0.001). The median duration of remission was 4.6 months and 3.1 months, respectively (P=0.03).
Forty-one percent of patients treated with inotuzumab and 11% of those who received chemotherapy proceeded to stem cell transplant directly after treatment (P<0.001).
The median progression-free survival was 5.0 months in the inotuzumab arm and 1.8 months in the chemotherapy arm (P<0.001).
The median overall survival was 7.7 months and 6.7 months, respectively (P=0.04). This did not meet the prespecified boundary of significance (P=0.0208).
Liver-related adverse events were more common in the inotuzumab arm than the chemotherapy arm. The most frequent of these were increased aspartate aminotransferase level (20% vs 10%), hyperbilirubinemia (15% vs 10%), and increased alanine aminotransferase level (14% vs 11%).
Veno-occlusive liver disease occurred in 11% of patients in the inotuzumab arm and 1% in the chemotherapy arm.
There were 17 deaths during treatment in the inotuzumab arm and 11 in the chemotherapy arm. Four deaths were considered related to inotuzumab, and 2 were deemed related to chemotherapy.