US-based clinical-stage biotechnology company Inhibrx has dosed the first patient in the Phase I dose-escalation study of INBRX-106.

The study seeks to determine the safety of INBRX-106 as a single agent and in combination with Keytruda for the treatment of solid tumours. It also aims to identify the recommended therapeutic dose level for future clinical development.

INBRX-106 is a hexavalent agonist of OX40, a co-stimulatory receptor expressed on immune cells. Its ligand, OX40L, is a trimeric protein that activates OX40 signalling through clustering.

INBRX-106, which is designed to bind six OX40 receptors, has outperformed bivalent antibodies in anti-tumour activity during pre-clinical trials.

As a single agent, it has shown strong activity in pre-clinical tumour models that do not respond to a PD-1/PD-L1 checkpoint inhibitor. The activity was found to increase when INBRX-106 is tested in combination with a PD-1 blocking antibody.

Inhibrx CEO Mark Lappe said: “The preclinical activity profile of INBRX-106 suggests that it has the potential to significantly increase the response rate and patient survival over those achieved with single-agent PD-1/PD-L1 blockade.

“INBRX-106 was designed to overcome the limitations of previously explored OX40 targeting approaches and we are excited to have achieved our first dose in a cancer patient.”

Inhibrx is engaged in the development of novel biologic therapeutic candidates in oncology and orphan diseases.

It uses different protein engineering methods to design therapeutic candidates. One such tool is its proprietary Inhibrx sdAb Platform.

The company also shares partnerships with bluebird bio, Bristol-Myers Squibb and Chiesi.