Dong-A ST said Monday that it has received IND approval for a phase 1/2a clinical trial of its immuno-oncology drug, DA-4505, from the Ministry of Food and Drug Safety (MFDS), to treat solid tumors.

The study will evaluate the safety and efficacy of DA-4505 monotherapy or in combination with the PD-1 immune checkpoint inhibitor, pembrolizumab, in adult patients with locally advanced or metastatic solid tumors.

According to the company, DA-4505 is an aryl hydrocarbon receptor (AhR) antagonist. AhR is a regulator of the immune system, acting to suppress immune responses and prevent tumor cells from being attacked.

In preclinical studies, DA-4505 restored suppressed immune responses in the tumor microenvironment by inhibiting AhR. It also activated stimulatory immune cells such as dendritic cells and T cells, reducing the ability of cancer cells to suppress immunity, Dong-A ST said. 

In particular, the improved tumor suppression effect was shown in preclinical studies which compared DA-4505 with BAY2416964, AhR antagonists being developed by Bayer.

Also, the combo of DA-4505 and PD-1 immune checkpoint inhibitor, pembrolizumab, demonstrated tumor suppression in preclinical trials. 

The preclinical results showed the potential of DA-4505 to overcome the limitations of existing cancer immunotherapies, a Dong-A ST official said.