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A Phase 1/1b Study of PRT13722 in Participants With Advanced HR+/HER2- Breast Cancer
A Phase 1/1b, First-in-Human, Open-Label, Multicenter Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity of PRT13722, a KAT6A Protein Degrader, as Monotherapy and in Combination With Endocrine and Targeted Therapy in Adults With Locally Advanced or Metastatic HR-Positive, HER2-Negative Breast Cancer
Who can join
Ages 18 and older · All sexes
Full eligibility criteria
Inclusion Criteria: * Willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations (including contraception requirements), and other study procedures. * histological or cytological diagnosis of locally advanced or metastatic HR-positive/HER2-negative breast cancer * Disease progression following prior standard therapy and eligible for the assigned study cohort * Measurable or evaluable disease per RECIST v1.1 * Willingness to provide tumor tissue for biomarker analyses * Eastern Cooperative Oncology Group performance status of 0-1 * Negative serum or urine pregnancy test and agree to use highly effective contraception or maintain true abstinence. * Adequate organ function and bone marrow reserves (hematology, renal, and hepatic) Exclusion Criteria: * Untreated, symptomatic, or unstable brain metastases * Symptomatic visceral disease at risk of imminent life-threatening complications * Uncontrolled infection or significant concurrent medical conditions * Clinically significant cardiovascular disease or prolonged QT syndrome * Pregnancy or breastfeeding * Prior treatment with a KAT6-targeting agent * Recent anticancer therapy, radiotherapy, or major surgery * Use of prohibited concomitant medications, including strong CYP3A4 inhibitors or inducers, proton pump inhibitors, P-gp inhibitors or inducers, and breast cancer resistance protein inhibitors * Participation in another interventional clinical study * Any condition that would interfere with study participation or evaluation of study results
About the study
This first-in-human, open-label, multicenter study will evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of PRT13722, an oral KAT6A protein degrader, in adults with locally advanced or metastatic Hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer. PRT13722 will be evaluated as monotherapy and in combination with fulvestrant, abemaciclib plus fulvestrant, or imlunestrant to determine recommended dose(s) for expansion (RDE) and evaluate preliminary clinical activity.
What is being tested
- PRT13722 (drug)
- Fulvestrant (drug)
- Abemaciclib (drug)
- Imlunestrant (drug)
Sponsor: Prelude Therapeutics Incorporated · Participants: 242 · Started: Nov 16, 2026
Contact the study team
- Study Contact (Please Do Not Disclose Personal Information) · Phone: See Email
Official record on ClinicalTrials.gov — NCT07905001
Locations in the U.S.
| Florida | Florida Clinical Trials Group, Tamarac |
| Ohio | Taylor Cancer Research Center, Maumee |
| Virginia | NEXT Virginia, Fairfax |
Conditions
From ClinicalTrials.gov, data retrieved Nov 15, 2026. Each study sets its own eligibility; the study team decides who can join.