OATD-02 hydrochloride is the hydrochloride salt form of OATD-02. It is an orally effective, competitive, reversible, and non-covalent dual inhibitor of Arginase1 and Arginase2. OATD-02 hydrochloride serves as a sustained-release inhibitor that efficiently blocks the activity of intracellular arginases, with IC50 values of 20 nM (hARG1), 39 nM (hARG2), 39 nM (mARG1), and 28 nM (rARG1). It effectively eliminates tumor-induced immunosuppression caused by both types of arginases. This compound is utilized in research studies on melanoma.