FDA Orphan Drug Designation Granted to INBRX-109 for Chondrosarcoma

The FDA has granted an orphan drug designation to INBRX-109 for the treatment of chondrosarcoma, according to a press release by Inhibrx, Inc.¹

INBRX-109 is a tetravalent death receptor 5 (DR5) agonist antibody that is meant to leverage tumor-biased cell death caused by DR5 activation. It was previously granted an FDA fast track designation for the treatment of patients with unresectable or metastatic conventional chondrosarcoma.

A phase 1 clinical trial of the INBRX-109 found that of the 12 patients evaluable for efficacy, disease control was observed in 11 patients. Tumor burden decrease was seen in 8 of 12 patients. As of October 2020, 2 patients achieved an active partial response with reduction in tumor size of 60% and 32%.²

At the 4-month follow-up, 67% of patients had observed disease control. Additionally, 7 of the 12 patients opted to continue on the study. The longest disease control duration observed for a patient in this cohort was approximately 8 months.

In terms of safety, INBRX-109 demonstrated to be safe and tolerable. Approximately 90% of patients experienced no signs of hepatotoxicity and no new serious or severe adverse events have been reported. 

An ongoing phase 2 study (NCT04950075) of the agent in patients with conventional chondrosarcoma is currently recruiting. The target enrollment of the randomized, quadruple masked study is 201 patients. The estimated completion date of June 2024. The study is investigation the primary end point is progression-free survival per RECIST v1.1 with INBRX-109 versus placebo. Secondary end points include overall survival, overall response rate per RECISTS v1.1, quality of life measured with a European Organization for Research and Treatment of Cancer questionnaire, incidence and grade of treatment-emergent adverse events determined by National Cancer Institute Common Terminology Criteria for Adverse Events criteria, immunogenicity of INBRX-109, area under the cure, peak serum concentration, trough serum concentration, and time to maximum concentration.³

During the study, patients will be randomized to receive either an intravenous infusion of INBRX-109 every 3 weeks, or a matching placebo every 3 weeks.

In order to participate, patients must have a diagnosis of unresectable or metastatic conventional chondrosarcoma, measurable disease, radiographic progression of disease, adequate hematologic, coagulation, hepatic, and renal function, an ECOG performance status of 0 or o1, an estimated life expectancy of at least 12 weeks, and have availability of archival tissue or fresh cancer biopsy.

Patients with any prior exposure to an DR5 agonist, allergy or sensitivity to INBRX-109, a diagnosis of non-conventional chondrosarcoma, prior or concurrent malignancies, or chronic liver disease are not eligible to participate. 

The study is currently recruiting or planning on recruiting in 29 study locations across Arizona, California, Colorado, Florida, Illinois, Iowa, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Tennessee, Texas, Virginia, and Washington.

_REFERENCES:

_{1.Inhibrx receives FDA orphan-drug designation for INBRX-109 in chondrosarcoma. News release. Inhibrx. December 1, 2021. Accessed December 2, 2021. https://bit.ly/3daZLhJ}

_{2.Inhibrx announces positive interim results from the phase 1 trial of INBRX-109 in chondrosarcoma patients. News release. Inhibrx. November 11, 2020. https://bit.ly/3ocPvf8}

_{3.Study of INBRX-109 in conventional chondrosarcoma. ClincialTrials.gov. Accessed December 2, 2021. https://bit.ly/3dt1TSd}