Prognostic factors for outcome in patients with refractory and relapsed acute lymphocytic leukemia treated with inotuzumab ozogamicin, a CD22 monoclonal antibody

Inotuzumab ozogamicin was found to be highly active in patients with refractory-relapsed acute lymphocytic leukemia (ALL), with an overall response rate of 58% and a median survival of 6.3 months. Identifying factors associated with different outcomes on inotuzumab therapy may help select patients for this treatment and advice of prognosis. A total of 89 patients treated with inotuzumab on previous studies were analyzed. Inotuzumab was given at 1.3-1.8 mg/m² intravenously (IV) × 1 every 3-4 weeks or weekly (0.8 mg/m² day 1, 0.5 mg/m² days 8 and 15) every 3-4 weeks. Pretreatment factors associated with achieving marrow complete response (CR) and with survival were analyzed using standard statistical methods. The median survival of patients with at least marrow CR was 9.2 months versus 3.4 months for those without marrow CR (P<0.001). By multivariate analysis, a high peripheral blood absolute blast count and low platelet count were independently associated with a lower likelihood of achieving at least marrow CR. Baseline characteristics independently associated with worse survival included adverse cytogenetics [complex karyotype, translocation (4;11), translocation (9;22), abnormal chromosome 17], disease beyond first salvage, and high peripheral blood absolute count. Patients with 0, 1-2, or 3 adverse factors had a median survival of 39+, 7.5, and 2.4 months, respectively. Our current analyses identified a subset of adult patients with ALL in whom outcome of therapy with inotuzumab ozogamicin can be differentially predicted.