The results of this phase 1 study suggest that multiple ascending oral doses of the dopamine D1 receptor PAM ASP4345 (3–150 mg) may be safe and well tolerated in adult patients with schizophrenia, with respect to the AE profile, lack of clinically relevant changes on laboratory tests, vital signs, ECGs, and absence of worsening of movement disorders. The gene discussed is DRD1; the disease is schizophrenia.