FDA Accepts BLA for Hairy Cell Leukemia Treatment

AstraZeneca and MedImmune have announced the US Food and Drug Administration (FDA) has accepted the Biologics License Application (BLA) for moxetumomab pasudotox for the treatment of hairy cell leukemia (HCL). The FDA has granted moxetumomab pasudotox BLA Priority Review status with a Prescription Drug User Fee Act (PDUFA) date set for the third quarter of 2018. Since there is no established standard of care and few treatments available for patients with HCL to date, this news is significant, according to a joint company statement.¹

Moxetumomab pasudotox (formerly known as CAT-8015 or HA22) is an investigational anti-CD22 recombinant immunotoxin. The drug is targeted towards HCL patients who have experienced relapsed or refractory HCL and who have received a minimum of 2 prior lines of therapy. Immunotoxins are a class of anticancer agents that combine the selectivity of antibodies to target drug delivery and the potency of toxins to kill target cancer cells.

The makeup of moxetumomab pasudotox consists of a binding portion of an anti-CD22 antibody fused to a toxin. CD22 is a B-lymphocyte restricted transmembrane protein with a higher receptor density in HCL cells relative to normal B cells. This property makes it an attractive therapeutic target for the treatment of this cancer. Once the molecule binds to CD22, it becomes internalized and processed before releasing its modified protein toxin that inhibits protein translation. This process leads to apoptotic cell death.¹

Optimism surrounds the drug due to its phase 3 (‘1053’) clinical trial in which it met its primary endpoint of a durable complete response in adult patients with relapsed or refractory HCL. Results from the trial will be presented at a forthcoming medical meeting.

The study includes 80 participants who are experiencing relapsed or refractory HCL and who have received a minimum of 2 prior lines of therapy. Participants are being administered moxetumomab pasudotox IV on days 1, 3 and 5 of each 28-day cycle for a maximum of 6 cycles or until the disease progresses, unacceptable toxicity occurs, the subject begins alternate therapy, or documented CR occurs (for subjects who have no assessable minimal residual disease that did not exceed 6 cycles).²

The primary data being collected is the complete response rate in patients treated with the drug. Secondary outcomes include the overall response rate, the relapse free survival rate, the progression free survival rate, the time-to-response average, and safety. The study is anticipated to finish collecting data May 30, 2018.²

HCL is a slow-growing, incurable leukemia that is caused by the bone marrow’s overproduction of abnormal B cells or lymphocytes. Serious and life-threatening conditions, such as infections, anemia, and bleeding, can result from HCL. Approximately 1,000 people in the US are diagnosed with HCL annually.¹

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References:

1. “US FDA Accepts Biologics License Application for Moxetumomab Pasudotox in Hairy Cell Leukemia.” Business Wire. 3 Apr. 2018
2. “Moxetumomab Pasudotox for Advanced Hairy Cell Leukemia.” National Institute of Health 12 Feb. 2018