Inhibrx, Inc., a biotechnology company with four clinical programs in development and a strong emerging pipeline, today announced that the U.S. Food and Drug Administration, or FDA, has granted orphan-drug designation for INBRX-101 for the treatment of alpha-1 antitrypsin deficiency, or AATD.

"We believe this designation from the FDA acknowledges the significant unmet need for novel therapeutic options in a patient community where the standard of care has not seen an improvement in many decades," said Inhibrx Chief Executive Officer, Mark Lappe. "We believe INBRX-101 can greatly improve the quality of life for AAT patients and look forward to working closely with regulators, key opinion leaders, patients and their families to achieve this."

The FDA's Office of Orphan Products Development grants orphan designation status to drugs and biologics that are intended for the safe and effective treatment, diagnosis or prevention of rare diseases, or conditions that affect fewer than 200,000 people in the U.S. Orphan-drug designation provides certain benefits, including financial incentives to support clinical development and the potential for up to seven years of market exclusivity in the U.S. upon regulatory approval.

About AATD and INBRX-101

Alpha-1 antitrypsin deficiency, or AATD, is an inherited orphan disease affecting an estimated 100,000 patients in the United States. AATD is characterized by deficient levels of the AAT protein, which causes loss of lung tissue and function and decreased life expectancy.  Plasma-derived AAT is the current standard of care but does not maintain patients in the normal AAT range, and requires frequent and inconvenient once-weekly IV dosing, while relying on plasma collection practices that might not be sustainable.

INBRX-101 is a precisely engineered recombinant human AAT-Fc fusion protein designed to safely achieve and maintain levels of AAT found in healthy individuals with a favorable safety profile and the potential for once-monthly dosing.

In October 2021, the Company announced interim functional PK data from 21 AATD patients  in the Phase 1 study. Dose related increases in maximal and total INBRX-101 exposure occurred across the entirety of the tested single ascending dose range of 10 to 120 mg/kg. Data from the first multiple ascending dose cohort of INBRX-101 at 40 mg/kg IV every three weeks showed the expected accumulation of functional AAT levels with observed trough levels exceeding the goal of the current standard augmentation therapy with plasma-derived AAT.

Interim safety data from 24 patients with AATD showed no drug-related severe or serious adverse events at doses up to and including 120 mg/kg single dose and 80 mg/kg multiple dose. Drug-related adverse events were predominantly mild with a few moderate events, and all were transient and reversible. No signs of neutralizing anti-drug antibodies have been observed.