The investigational drug, INBRX-101, has received Orphan Drug Designation from the US Food and Drug Administration (FDA) for the treatment of alpha-1 antitrypsin deficiency (AATD), according to Inhibrix, the manufacturers of the drug.

“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,” Mark Lappe, chief executive officer of Inhibrx said.

Inhibrix previously reported interim results of a phase 1 clinical trial in October 2021 that showed functional pharmacokinetic data for INBRX-101 collected from 21 patients with AATD with the ZZ mutation of the SERPINA1 gene. The pharmacokinetic data showed that dose-related increases to maximal and total INBRX-101 levels during the full range of single ascending dose levels from 10 mg/kg to 120 mg/kg.

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In the study, a multiple ascending dose cohort received 40 mg/kg every 3 weeks and displayed expected accumulation levels of functional alpha-1 antitrypsin (AAT) protein with trough levels exceeding the current levels achieved by the standard augmentation therapy using plasma-derived AAT.

“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,” Lappe said.

Inhibrix also reported interim safety data from 24 patients which showed no drug-related severe or serious adverse events for either the single ascending doses up to 120 mg/kg or for multiple ascending doses up to 80 mg/kg. Most drug-related adverse events were mild in nature with a few moderate events. All of the adverse events were transient and reversible.

“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,” the company concluded. They expect topline data from the study in quarter 2 of 2022 and an end of phase 1 meeting with FDA to follow.


Inhibrx receives FDA orphan-drug designation for INBRX-10 for the treatment of alpha-1 antitrypsin deficiency. News Release. Inhibrx; March 3, 2022.

INBRX-101 shows favorable safety profile in patients with alpha-1 antitrypsin deficiency and demonstrates the potential to achieve normal alpha-1 antitrypsin levels with monthly dosing. News Release. Inhibrx; October 12, 2021.