Rezatapopt Restores p53 Function & Shows Promise in Phase 1 Trial | Nature Medicine

A slight molecule, rezatapopt, has demonstrated the ability to bind to a unique pocket within a mutated form of the p53 protein – specifically the Y220C variant – and restore its function as a tumor suppressor, according to research published today in Nature Medicine.

The findings, detailed in a study released online March 24, 2026, offer a potential therapeutic approach for cancers driven by mutations in the TP53 gene, one of the most frequently mutated genes in human cancers. The research includes data from a Phase 1 clinical trial indicating proof of concept for this strategy.

The Y220C mutation, along with Y220N and Y220S, represents a common class of p53 mutations that disrupt the protein’s normal function. P53 is a critical tumor suppressor, responsible for regulating cell growth and preventing the development of cancer. When mutated, it often loses its ability to effectively control cell division, leading to uncontrolled growth.

Rezatapopt works by stabilizing the mutant p53 protein, allowing it to regain some of its tumor-suppressing capabilities. The study identifies a previously unknown binding pocket specific to these Y220-mutated forms of p53, offering a targeted approach to treatment.

Early clinical data from the Phase 1 trial, as well as ongoing Phase 2 trials, suggest that rezatapopt exhibits early activity in solid tumors harboring the TP53 Y220C mutation. The PYNNACLE Phase II clinical trial is currently evaluating rezatapopt monotherapy in patients with advanced or metastatic solid tumors carrying this specific mutation. Initial analysis of the PYNNACLE trial has been completed, with further data expected to be released in the coming months.

According to information released by Oncology Central, the PYNNACLE trial protocol focuses specifically on patients with advanced disease where other treatment options have been exhausted. The trial is designed to assess the efficacy and safety of rezatapopt as a single agent in this patient population.

Oncodaily reports that the observed activity of rezatapopt in early trials warrants further investigation, particularly given the limited treatment options currently available for cancers with this specific p53 mutation. The drug’s ability to selectively target the mutant protein, while sparing normal cells, is a key advantage of this therapeutic approach.