Inhibrx Announces Positive Interim Results from the Phase 1 Trial of INBRX-109 in Chondrosarcoma Patients

- Disease control observed in 92% of patients

SAN DIEGO, CA, USA I November 11, 2020 I Inhibrx, Inc. (Nasdaq: INBX), a biotechnology company with four clinical programs in development, announced updated interim results today from a Phase 1 clinical trial evaluating the efficacy and safety of INBRX-109 in patients with chondrosarcoma. This data will be presented to attendees of the Annual Connective Tissue Oncology Society ("CTOS") Conference on November 20, 2020 (Paper #16). Chondrosarcoma is an orphan disease and bone cancer with approximately 2,800 new patients diagnosed annually in the United States and the European Union. There are currently no therapeutics approved for the treatment of chondrosarcoma.

Inhibrx's most advanced program, INBRX-109, is a precision-engineered, tetravalent DR5 agonist antibody designed to exploit the tumor-biased cell death induced by DR5 activation.

  • Of the 12 patients evaluable for efficacy within the ongoing chondrosarcoma expansion cohort to date, disease control was observed in 11 of 12 patients (92%) and 8 of 12 patients (67%) had a decrease in their tumor burden by RECIST.
  • Two of the patients achieved partial responses with reductions in tumor size of 60% and 32% as of October 2020.
  • Based on these preliminary results, the observed disease control rate at the four-month follow-up was 8 of 12 subjects (67%) with 7 of 12 patients continuing on study. The longest disease control duration observed to date for a patient in this cohort was 33 weeks, or approximately eight months.
  • The safety and tolerability profile continued to be favorable with most patients, approximately 90%, experiencing no signs of hepatotoxicity. There have been no new serious or severe adverse events since Inhibrx's last safety update in July 2020.
  • The trial is ongoing and an additional 10 patient slots were added, per investigator requests, to the chondrosarcoma cohort.

"I am quite pleased to see prolonged progression free survival in a disease that has been unresponsive to conventional therapies," notes Dr. Sant P. Chawla, one of the principal investigators conducting the Phase 1 trial at the Sarcoma Oncology Center in Santa Monica, California.

"We believe the results in chondrosarcoma, a disease with a significant unmet need, are very promising. We are meeting with the Food and Drug Administration in the near future to discuss the design of a registration-enabling study that we anticipate initiating in the second quarter of next year," said Mark Lappe, CEO for Inhibrx. "Additionally, this month, we will initiate dosing in patients with synovial sarcoma, as well as our first chemotherapy combination cohorts with INBRX-109 in pancreatic adenocarcinoma and epithelioid subtype malignant pleural mesothelioma."

Conference Call Details
Inhibrx will hold a conference call to discuss these results today at 2:30 p.m. PT. Investors may join via the web: or may listen to the call by dialing (1-877-870-4263) from locations in the United States or (1-412-317-0790) from outside the United States. Please refer to Inhibrx, Inc. when calling in. Following the webcast, the presentation may be accessed through a link on the investors section of Inhibrx's website at The webcast will be available for 60 days following the event. Inhibrx has also updated its corporate presentation which is available on the "Investors" section of its website at

About INBRX-109
INBRX-109 is a precisely engineered tetravalent single domain antibody (sdAb) based therapeutic candidate that agonizes DR5 to induce tumor selective programmed cell death. A three-part, Phase 1 clinical trial was initiated in November 2018. Part 1, dose escalation, was completed in August 2019 with enrollment of 20 patients. INBRX-109 was well-tolerated, with no significant toxicities observed at doses up to and including the maximum administered dose of 30 mg/kg. No maximum tolerated dose was reached. Part 2, single agent dose expansion, commenced in September 2019, while Part 3, chemotherapy combination cohorts, initiated this month in epithelioid subtype malignant pleural mesothelioma and pancreatic adenocarcinoma.

About the Inhibrx sdAb Platform
Inhibrx utilizes diverse methods of protein engineering in the construction of therapeutic candidates that can address the specific requirements of complex target and disease biology. A key tool for this effort is the Inhibrx proprietary sdAb platform, which enables the development of therapeutic candidates with attributes superior to other monoclonal antibody and fusion protein approaches. This platform allows for the combination of multiple binding units in a single molecule, enabling therapeutic candidates with precisely defined valency or multiple specificities that can achieve enhanced cell signaling or conditional target activation. An additional benefit of this platform is that these optimized, multi-functional entities can be manufactured using established processes that are commonly used to produce therapeutic proteins.

About Inhibrx, Inc.
Inhibrx is a clinical-stage biotechnology company focused on developing a broad pipeline of novel biologic therapeutic candidates in oncology and orphan diseases. Inhibrx utilizes diverse methods of protein engineering to address the specific requirements of complex target and disease biology, including its proprietary sdAb platform. Inhibrx has collaborations with bluebird bio, Bristol-Myers Squibb and Chiesi. For more information, please visit

SOURCE: Inhibrx

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