Gemtuzumab Ozogamicin After Allogeneic Stem Cell Transplantation for Acute Leukemia

Controversy abounds that anti-CD33 immunoconjugate, genutuzumab ozogamicin (GO) is really effective or not as a treatment for relapsed acute myeloid leukemia (AML). Consequently, GO is now commercially available in Japan, but not in USA or Europe. In this study, we have retrospectively analyzed the clinical impact of GO therapy as salvage or maintenance setting after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

During last 5 years, GO was given to 19 patients with AML as salvage therapy for disease recurrence (n = 15 patients) or maintenance therapy (n = 4 patients) after allo-HSCT in our institution. Clinical characteristics of these 19 patients are summarized (see Table): Median age was 44 years (range, 21–70 years). GO was basically administered at a dose of 3 mg/m². The median cycle of GO therapy was 3 cycles (range, 1–12 cycles) and 3 cycles (range, 1–4 cycles) as salvage and maintenance therapy, respectively. GO was administered at a median of 205 days after allo-HSCT (range, 38–3,111 days) in the setting of salvage therapy, while as maintenance therapy, patients with high risk AML received GO as early as 29 days after allo-HSCT (range, 24–71 days).

Two of 15 patients with recurrent disease achieved complete remission and 4 patients showed partial response (>50% decrease of bone marrow blast percentage). Thus, a total of 6 patients (40%) exhibited initial response to GO. However, 5 patients of them developed irreversible hepatic veno-occulusive disease (VOD) and eventually died at median of 146 days after GO therapy (range, 9–206 days). In view of 4 patients with maintenance therapy, 1 patient have faced to the subsequent disease relapse but no patients developed severe adverse effects including hepatic VOD and all patients are currently alive, albeit short follow-up. This small study demonstrates that GO offers an alternative tool for rescuing relapsed AML after allo-HSCT, but increases the risk of developing life-threatening hepatic VOD. Thus, further clarification is needed regarding which patients to treat with GO and at what dose of GO.

No relevant conflicts of interest to declare.