A phase 1 study of rezatapopt, a p53 reactivator, investigated the drug in patients with advanced solid tumors with the TP53 Y220C mutation.[1][3] Rezatapopt is the first small molecule that specifically binds the pocket created by this mutation, stabilizes the p53 protein structure and restores its tumor suppressor function.[2][3][6] In a phase 1 clinical trial (NCT04585750), rezatapopt demonstrated a favorable safety profile at all effective doses and achieved robust clinical efficacy as monotherapy in heavily pretreated patients with multiple types of solid tumors.[2][3] Among 97 patients in the efficacy population who received at least one dose of 2000 mg daily, the overall response rate (ORR) was 33% and in patients with ovarian cancer 43%, including one confirmed complete remission.[8] Patients had a median of 3 prior lines of systemic therapy (range 1-10).[8] The study was published in the New England Journal of Medicine on February 26, 2026.[title]