A phase I dose-escalation clinical study on ribociclib for single-agent therapy, enrolling 132 Rb-positive solid tumors including 20 breast cancer cases, demonstrated that one breast cancer patient with positive status of CCND1 and ER achieved partial responses (PR) at the dose of 600 mg daily during continuous ribociclib treatment [85]. The gene discussed is CCND1; the disease is breast carcinoma.