US FDA approves AstraZeneca’s Lumoxiti (moxetumomab pasudotox) for the treatment of patients with hairy cell leukemia (HCL) who have undergone at least two prior therapies.

Hairy cell leukemia (HCL) is a rare, slow-progressing form of blood cancer. In patients with HCL, the bone marrow produces too many abnormal (“hairy”) lymphocytes (B cells). These abnormal cells eventually outnumber normal white and red blood cells and platelets. If untreated, HCL can lead to infections, bleeding, and anemia. While many patients respond favorably to existing treatments, 30 to 40% experience relapses after five to 10 years as the cancer develops resistance to chemotherapy drugs. 

MedImmune, the R&D arm of AstraZeneca, has developed a new treatment for patients that suffer relapses of HCL. Lumoxiti (moxetumomab pasudotox) is an antibody-drug conjugate (ADC) and a CD22-directed cytotoxin comprising a CD22-targeting antibody fused with a bacterial toxin. The antibody binds to the cancerous B lymphocytes and then releases the bacterial toxin, which inhibits protein synthesis and triggers apoptotic cell death. 

The US Food and Drug Administration recently approved Lumoxiti for the treatment of patients with HCL that have undergone at least two prior therapies. It is the first new treatment for HCL approved by the agency in over 20 years.

AstraZeneca has also filed a new drug application for moxetumomab pasudotox with the European Medicines Agency, which granted Lumoxiti an orphan drug designation in 2013. The company expects to launch the drug in the US before the end of 2018. Analysts estimate peak sales for Lumoxiti of $500 million.

This approval comes approximately one year after AstraZeneca received FDA approval for Calquence (acalabrutinib), a kinase inhibitor indicated for the treatment of adult patients with mantle cell lymphoma (MCL) who have received at least one prior therapy.