FDA has approved AstraZeneca’s moxetumomab pasudotox-tdfk, a CD22-directed cytotoxin indicated for adult patients with relapsed or refractory hairy cell leukemia who received at least two prior systemic therapies, including treatment with a purine nucleoside analog.
The approval was based on Study 1053 (NCT01829711) in patients with histologically confirmed HCL or HCL variant requiring treatment based on presence of cytopenias or splenomegaly and who had received prior treatment with at least two systemic therapies, including one PNA. Eligible patients had serum creatinine ≤1.5 mg/dL or creatinine clearance ≥60 mL/min as estimated by the Cockcroft Gault equation. A total of 80 patients were enrolled; 77 with classic HCL and 3 with HCL variant. Patients received moxetumomab pasudotox-tdfk, 0.04 mg/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 (CR), disease progression, or unacceptable toxicity.
Efficacy in HCL was evaluated by the blinded independent review committee-assessed rate of durable CR confirmed by maintenance of hematologic remission (hemoglobin ≥11 g/dL, neutrophils ≥1500/mm3, and platelets ≥100,000/mm3 without transfusions or growth factor for at least 4 weeks) more than 180 days after IRC-assessed CR. The IRC-assessed durable CR rate was 30 percent (24/80 patients; 95% CI: 20, 41). The IRC-assessed CR rate was 41 percent (33/80 patients; 95% CI 30,53).
The most common non-laboratory adverse reactions (≥20%) of any grade were infusion related reactions, edema, nausea, fatigue, headache, pyrexia, constipation, anemia, and diarrhea. The most common grade 3 or 4 adverse reactions (reported in at least ≥5% of patients) were hypertension, febrile neutropenia, and hemolytic uremic syndrome. Adverse reactions resulting in permanent discontinuation of moxetumomab pasudotox-tdfk occurred in 15 percent (12/80) of patients. The most common adverse reaction leading to discontinuation was HUS (5%). The most common adverse reactions resulting in dose delays, omissions, or interruptions was pyrexia (3.8%).
The recommended dose of moxetumomab pasudotox-tdfk is 0.04 mg/kg administered as a 30-minute intravenous infusion on days 1, 3, and 5 of each 28-day cycle for a maximum of 6 cycles or until occurrence of disease progression or unacceptable toxicity.