FDA Grants Priority Review to Potential First-In-Class Treatment for Hairy Cell Leukemia

The Food and Drug Administration (FDA) granted priority review to moxetumomab pasudotox for the treatment of adult patients with hairy cell leukemia who received at least two prior lines of therapy, according to a press release from AstraZeneca and MedImmune, the drug’s developers.

Moxetumomab pasudotox (formerly known as CAT08015 or HA22) — which has the opportunity to be a first-in-class treatment for this patient population – is an investigational anti-CD22 recombinant immunotoxin. The drug works by binding to CD22 – a molecule on the surface of the cancer cell – and then goes into and kills the cancer cell.

The agent’s Biologics License Application included data from the ongoing phase 3 ‘1053’ trial, designed to evaluate the efficacy, safety, immunogenicity and pharmacokinetics of moxetumomab pasudotox in 80 patients with relapsed or refractory hairy cell leukemia — a rare form of blood cancer that leads to approximately 1,000 diagnoses in the US each year.

Patients on the trial received moxetumomab pasudotox intravenously on days one, three and five of each 28-day cycle for a maximum of six cycles or until disease progression, unacceptable toxicity, the start of an alternate therapy or a documented complete response.

The single-arm, multicenter trial met its primary endpoint of durable complete response, for which results will be presented at an upcoming medical meeting, the release said.

The study is estimated to be completed in May of 2018, and the FDA’s Prescription Drug User Fee Act (PDUFA) date is set for the third quarter of this year.

The potential approval offers hope to the rare blood cancer, which currently has no standard of care treatment protocol. While many patients respond to initial treatment, up to 40 percent will relapse. “With no established standard of care and very few treatments available, there remains significant unmet medical need for people with relapsed or refractory hairy cell leukemia,” the release said.