Inhibrx has its chondrosarcoma program is back on track after the US Food and Drug Administration (FDA) lifted a partial clinical hold on two trials.

Inhibrx announced it would resume recruiting patients next month for a Phase II and Phase I trial evaluating INBRX-109 in rare bone cancers. The trials were paused due to concerns over liver toxicity, and Inhibrx subsequently amended study protocols to exclude at-risk patients.

During screening, both trials include the Hepatic Steatosis Index (HSI), which assesses the severity of fatty liver diseases, to exclude elderly individuals at high risk of severe liver toxicity. Inhibrx announced the enrollment pause in March 2023 as a result of pre-defined stopping rules, and the pause did not affect patients already receiving treatment.

The 201-patient Phase II trial of INBRX-109 (NCT04950075) is registration-enabling in unresectable or metastatic conventional chondrosarcoma. Chondrosarcoma describes a rare group of bone tumours caused by cells producing excessive cartilage. INBRX-109 is a death receptor 5 (DR5) agonist antibody. As a primary endpoint, the study evaluates progression-free survival over three years.

Meanwhile, the Phase I trial of INBRX-109 (NCT03715933) is testing the drug’s safety and tolerability in multiple oncology indications. These include malignant pleural mesothelioma, gastric adenocarcinoma, colorectal adenocarcinoma, and sarcoma.

Inhibrx expects data from the Phase II trial in H2 2024, and data from combination cohorts in the Phase I trial by the end of 2023. With the quick resumption of its INBRX-109 program, the company avoids a trial termination which has become increasingly common in the industry.

Inhibrx initiates registrational trial for emphysema

Inhibrx is also moving to the registration stage with a newly initiated trial of INBRX-101 in emphysema due to alpha-1 antitrypsin deficiency (AATD). The chronic, progressive lung disease can cause severe breathing complications such as shortness of breath.

The 90-patient study is a head-to-head superiority trial pitting INBRX-101 against plasma-derived alpha-1 antitrypsin (ATT) therapy at the FDA approved dose. INBRX-101 is a fusion protein designed to maintain ATT levels with less frequent dosing than the currently available weekly plasma-derived AAT therapy infusions.