A NOVEL DRUG FOR HAIRY CELL LEUKEMIA

The US Food and Drug Administration (FDA) today approved moxetumomab pasudotox (Lumoxiti, AstraZeneca) for the treatment of adult patients with relapsed or refractory hairy cell leukemia (HCL) who have received at least two prior lines of therapy.

The agent is a CD22-directed cytotoxin or immunotoxin and is an injection for intravenous use. This is a first-in-class type of treatment for patients with HCL, which is a rare cancer.

"Lumoxiti fills an unmet need for patients with hairy cell leukemia whose disease has progressed after trying other FDA-approved therapies," said Richard Pazdur, MD, acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, in a statement. "This therapy is the result of important research conducted by the National Cancer Institute that led to the development and clinical trials of this new type of treatment for patients with this rare blood cancer."

The approval of moxetumomab pasudotox is based on efficacy and safety data from a single-arm, open-label clinical trial of 80 patients who had received prior treatment for HCL with at least two systemic therapies.

The trial's primary endpoint was durable complete response (CR), which was defined as maintenance of hematologic remission for more than 180 days after achievement of CR. A total of 30% of study patients achieved durable CR, and the overall response rate (partial or complete response) was 75%.

Common side effects of the new agent, says the FDA, include infusion-related reactions, swelling caused by excess fluid in body tissue (edema), nausea, fatigue, headache, pyrexia, constipation, anemia, and diarrhea.

Moxetumomab pasudotox's prescribing information includes a Boxed Warning about the risk of developing capillary leak syndrome. Symptoms of capillary leak syndrome include difficulty breathing, weight gain, hypotension, or swelling of arms, legs, and/or face.

The Boxed Warning also notes the risk for hemolytic uremic syndrome. Patients receiving the new drug should maintain adequate fluid intake, and blood chemistry values should be monitored frequently. Other serious warnings include decreased renal function, infusion-related reactions, and electrolyte abnormalities.

Follow Medscape senior journalist Nick Mulcahy on Twitter: @MulcahyNick

For more from Medscape Oncology, follow us on Twitter: @MedscapeOnc