Acquired On-Target Alterations Drive Clinical Resistance to p53-Y220C Reactivators
The tumor suppressor TP53 is the most frequently altered gene in cancer, and the Y220C hotspot, found in 1.8% of TP53-mutant tumors, creates a druggable cavity that destabilizes p53. Rezatapopt, a first-in-class, orally bioavailable reactivator of Y220C-mutant p53, has demonstrated promising initial efficacy in the phase 1/2 PYNNACLE trial. We report the first clinical mechanisms of resistance to this therapeutic class. Profiling of circulating tumor DNA, tumor biopsies, and rapid autopsy specimens upon rezatapopt progression revealed multiple heterogenous secondary TP53 alterations in cis with Y220C, including: (1) DNA-binding domain mutations or frameshift/nonsense mutations that abolish transcriptional activity, and (2) mutations within the Y220C binding surface predicted to hinder drug binding. Functional modeling confirmed these double mutants eliminate p53 reactivation and target gene induction by rezatapopt. These findings establish a molecular framework for resistance to p53 Y220C reactivators and inform strategies to overcome resistance with next-generation agents.
Authors
- Jakob M. Riedl (ORCID: https://orcid.org/0000-0002-5144-4715)
- L. J. Wirth
- Hitomi Sumiyoshi Okuma (ORCID: https://orcid.org/0000-0001-9639-7361)
- Nicholas Chevalier (ORCID: https://orcid.org/0009-0009-0116-8108)
- Clara Kim
- Bryanna L. Norden (ORCID: https://orcid.org/0000-0003-2084-473X)
- Parasvi S. Patel (ORCID: https://orcid.org/0000-0002-0326-7902)
- Ryan Bruce Corcoran (ORCID: https://orcid.org/0000-0001-8173-5778)
- Aparna R. Parikh (ORCID: https://orcid.org/0000-0002-5245-7841)
- Andreas Varkaris (ORCID: https://orcid.org/0000-0001-5776-8844)
- Manisha J. Patel
- Keelan Z. Guiley (ORCID: https://orcid.org/0000-0002-8149-4262)
- Jessica Hopkins
- D. Gulhan (ORCID: https://orcid.org/0000-0001-5419-0549)
- Jacquelyn Curtis
- Sara Ehnstrom
- S W Lee
- Allison M. Kehlmann (ORCID: https://orcid.org/0009-0001-0246-4023)
- Alvin A. Morales-Giron (ORCID: https://orcid.org/0009-0006-0534-2634)
- Ankit Singh (ORCID: https://orcid.org/0000-0002-2049-9887)
- F. Warren Nugent
- Haley Barnes
- Elijah W. Kushner
- Brendan Connell
- Ferran Fece de la Cruz
- Kevan M. Shokat
- Kayao Lau
- Leontios Pappas
Institutions
- Broad Institute (US)
- Lahey Hospital and Medical Center (US)
- Howard Hughes Medical Institute (US)
- Harvard University (US)
- Medical University of Graz (AT)
- National Cancer Centre Japan (JP)
- Massachusetts General Hospital (US)
- National Cancer Center (US)
- Lahey Medical Center (US)
- National Cancer Center Hospital East (JP)
- Tokyo National Hospital (JP)
Publication Details
- Journal
- Cancer Discovery
- Published
- 2026-01-08
- DOI
- https://doi.org/10.1158/2159-8290.cd-25-1761
- Primary Topic
- Cancer-related Molecular Pathways
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Bristol-Myers Squibb
- Eli Lilly and Company
- BeiGene
- Syndax Pharmaceuticals
- Revolution Medicines
- Relay Therapeutics
- Moderna
- Astellas Pharma
- National Institutes of Health
- Genentech
- National Cancer Institute
- Moonshot Research and Development Program
- Daiichi Sankyo Europe