First-in-Class Treatment Approved for Hairy Cell Leukemia
The Food and Drug Administration (FDA) has approved Lumoxiti (moxetumomab pasudotox-tdfk; AstraZeneca), a CD22-directed cytotoxin, for the treatment of adult patients with relapsed or refractory hairy cell leukemia (HCL) who received ≥2 prior systemic therapies, including treatment with a purine nucleoside analog.
The approval of Lumoxiti was based on data from a Phase 3 single-arm, open-label trial conducted in patients with histologically confirmed HCL or HCL variant with a need for therapy based on presence of cytopenias or splenomegaly and who had received prior treatment with at least 2 systemic therapies, including a purine nucleoside analog (N=80). Patients received Lumoxiti 0.04mg/kg as an intravenous infusion over 30 minutes on Days 1, 3, and 5 of each 28-day cycle for a maximum of 6 cycles or until documentation of complete response, disease progression, or unacceptable toxicity.
The primary endpoint of the study was durable complete response, defined as patients who achieved complete response with hematologic remission (hemoglobin ≥11g/dL, neutrophils ≥1500/mm3, and platelets ≥100,000/mm3 without transfusions or growth factor for at least 4 weeks) for a duration of >180 days.
Results showed that the durable complete response rate was 30% (24/80 patients; 95% CI: 20, 41); overall response rate, defined as best overall response of complete response or partial response, was 75%. Eighty percent of study patients achieved hematologic remission; median time to hematologic remission was 1.1 months.
The prescribing information for Lumoxiti includes a Boxed Warning regarding the risk of capillary leak syndrome and hemolytic uremic syndrome. The most common adverse reactions associated with treatment included infusion related reactions, edema, nausea, fatigue, headache, pyrexia, constipation, anemia, and diarrhea; increased creatinine, ALT and AST, as well as hypoalbuminemia, hypocalcemia, and hypophosphatemia were the most common laboratory abnormalities.
Lumoxiti will be supplied as 1mg lyophilized cake or powder in a single-dose vial for reconstitution and further dilution. It is expected to be available in the fourth quarter of 2018.
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