Inhibrx announced that their optimized recombinant human AAT-Fc fusion protein, known as INBRX-101, has the potential to gain US Food and Drug Administration (FDA) accelerated approval for patients with emphysema due to alpha-1 antitrypsin deficiency (AATD).

The announcement, shared by news release, also noted that INBRX-101 was detected in the bronchoalveolar lavage fluid (BALF) of all patients included in its phase 1 trial.

In the first quarter of 2023, Inhibrx plans to launch a clinical trial employing functional AAT serum levels as a proxy endpoint. The aim is to submit INBRX-101 for regulatory approval as part of the FDA’s Accelerated Approval Program based on maintenance of the normal range of AAT trough levels as found in healthy individuals.

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The FDA has expressed support for this process, according to the news release, based on the phase 1 study of INBRX-101, which demonstrated that INBRX-101 dosing every 3 to 4 weeks led to functional AAT levels within the lower normal range of healthy individuals without AATD. In addition, the FDA has also requested evidence demonstrating that functional AAT levels correlate with clinical benefit for patients with AATD.

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Concurrently, Inhibrx reported on their analysis of BALF samples from 11 patients included in the phase 1 study that found that INBRX-101 was present in all of the patients and in all lung lobes sampled. The findings suggest evidence of a dose-dependent increase in lung exposure to INBRX-101.

INBRX-101 is an engineered recombinant protein designed to generate and maintain similar levels of AAT as found in healthy individuals, with the added benefit of a longer dosing interval compared with the weekly infusions of plasma-derived AAT treatments currently required.

In the phase 1 study, treatment with INBRX-101 was well tolerated, and no serious adverse events related to the study drug were recorded. INBRX-101 was granted orphan drug designation by the FDA in March 2022.


Inhibrx announces opportunity for accelerated approval pathway on functional AAT serum levels for INBRX-101 in AATD and announces bronchoalveolar lavage fluid detection results from the phase 1 study. News release. Inhibrx, Inc.; October 4, 2022.