> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/a-phase-1-1b-study-of-prt13722-in-participants-with-advanced-32120b9a-508a-4b13-b3ac-a94da1d51916 > Record changed: 2026-11-04 # A Phase 1/1b Study of PRT13722 in Participants With Advanced HR+/HER2- Breast Cancer NCT07905001 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) Phase Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) Recruitment status Not yet recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) Participants 242 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) Lead sponsor Prelude Therapeutics Incorporated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) Start date 2026-10-30 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Title and summary **Summary** 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. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Short title** A Phase 1/1b Study of PRT13722 in Participants With Advanced HR+/HER2- Breast Cancer Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Official title** 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 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Status and phase **Control arm** Open label Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Recruitment status** Not yet recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Phase** Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Dates **Completion date** 2029-10-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **First posted** 2026-10-29 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Registry last updated** 2026-10-29 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Primary completion date** 2028-10-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Start date** 2026-10-30 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Size and sites **Participants** 242 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Participant count basis** Estimated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Planned participants** 242 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Sponsor and oversight **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Lead sponsor** Prelude Therapeutics Incorporated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Identifiers **Registry ID** NCT07905001 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **ClinicalTrials.gov ID** NCT07905001 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Study design **Allocation** Not randomised **Model** Sequential **Purpose** Treatment **Masking** No masking Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Outcomes ### Primary outcomes 1. Dose limiting toxicity of PRT13722 (Parts 1A and 2) Timeframe: Through cycle 1 (28 days) Incidence of dose limiting toxicities, defined according to protocol-specified criteria 2. Incidence of Treatment-Emergent Adverse Events \[Safety and Tolerability\] of PRT13722 as monotherapy and in combination (Parts 1A and 2) Timeframe: Through study completion, an average of 2 years Safety and tolerability assessed by the number of participants with treatment-emergent adverse events, serious adverse events, adverse events leading to dose modification, treatment interruption, or treatment discontinuation, and clinically significant laboratory abnormalities. Adverse events and selected laboratory abnormalities will be graded according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), Version 6.0 3. Preliminary Antitumor Activity: Objective Response Rate (Parts 1B and 3) Timeframe: Through study completion, an average of 2 years Proportion of patients with best overall response of either complete response or partial response, as assessed by the investigator per RECIST v1.1 ### Secondary outcomes 1. Preliminary Antitumor Activity: Objective Response Rate (Parts 1A and 2) Timeframe: Through study completion, an average of 2 years Proportion of patients with best overall response of either complete response or partial response, as assessed by the investigator per RECIST v1.1 2. Duration of Response Timeframe: Through study completion, an average of 2 years Time from first documented response to disease progression as assessed by the investigator per RECIST v1.1, or death, whichever comes first. 3. Clinical Benefit Response Timeframe: Through study completion, an average of 2 years Proportion of patients with a best overall response of complete response, partial response, or durable stable disease (24 weeks or longer), as assessed by the investigator per RECIST v1.1 4. Progression-Free Survival Timeframe: Through study completion, an average of 2 years Time from the date of first dose of investigational product to the date of first documented disease progression, as assessed by the investigator per RECIST v1.1, or death due to any cause 5. Overall Survival Timeframe: Through study completion, an average of 2 years Time from the date of first dose of investigational product to death due to any cause 6. Incidence of Treatment-Emergent Adverse Events \[Safety and tolerability\] of PRT13722 as Monotherapy and in Combination (Parts 1B and 3) Timeframe: Through study completion, an average of 2 years Safety and tolerability will be evaluated by incidence of adverse events leading to dose modifications, treatment interruptions, treatment discontinuations, and clinically significant laboratory abnormalities graded according to NCI CTCAE, Version 6.0 7. Maximum Observed Plasma Concentration (Cmax) Timeframe: Cycle 1 Day 1, Cycle 1 Day 15, and Cycle 2 Day 1 (each cycle is 28 days) Maximum observed plasma concentration will be calculated using non-compartmental analysis 8. Time To Maximum Concentration (Tmax) Timeframe: Cycle 1 Day 1, Cycle 1 Day 15, and Cycle 2 Day 1 (each cycle is 28 days) Time to maximum concentration will be calculated using non-compartmental analysis 9. Terminal Elimination Half-life (T1/2) Timeframe: Cycle 1 Day 1 (each cycle is 28 days) Terminal elimination half-life will be calculated using non-compartmental analysis 10. Area under the plasma concentration versus time curve (AUC) Timeframe: Cycle 1 Day 1, Cycle 1 Day 15, and Cycle 2 Day 1 (each cycle is 28 days) Area under the plasma concentration-time curve will be calculated using non-compartmental analysis 11. Steady State Trough Concentrations Timeframe: Cycle 1 Day 15, and Cycle 2 Day 1 (each cycle is 28 days) Steady state trough concentrations will be calculated using non-compartmental analysis Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Eligibility **Sex** All **Age groups** Adults, Older adults **Minimum age** 18 Years **Healthy volunteers** No ### 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 Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## References ### Other registry identifiers - 2026-527825-37-00 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07905001) ## Related records ### Drugs (3) - [Abemaciclib](https://trialight.com/data/asset/abemaciclib-602a9f33-bc37-4cf5-8790-5d87472b99d5.md) - [Fulvestrant](https://trialight.com/data/asset/fulvestrant-c32705f5-1d97-4fd5-a6ee-76fe1d8eba3a.md) - [Imlunestrant](https://trialight.com/data/asset/imlunestrant-a53f4bdf-2b09-4370-9990-71ac2d706245.md) ### Lead sponsors (1) - [Prelude Therapeutics](https://trialight.com/data/company/prelude-therapeutics-e3224872-6d16-44b2-bd31-9aae39d0e619.md) ### Conditions (2) - [Breast cancer](https://trialight.com/data/condition/breast-cancer-8ac10da3-93bd-54c5-a93b-265bc6699689.md) Primary condition - [Breast neoplasm](https://trialight.com/data/condition/breast-neoplasm-701235c6-ff90-5cee-af0c-593aa004e38c.md) ### Targets (5) - [CDK4](https://trialight.com/data/target/cdk4-7911e947-47b0-5d57-b5c3-76425934201f.md) - [CDK6](https://trialight.com/data/target/cdk6-a48645cb-6daf-5fe9-a635-f8d00b55b425.md) - [ESR1](https://trialight.com/data/target/esr1-e58c882c-75fc-5507-bf76-2d7a172c0a28.md) - [ESR2](https://trialight.com/data/target/esr2-3e669f23-0238-54c8-a6ae-0a2fc6dabdfa.md) - [GPER1](https://trialight.com/data/target/gper1-18be5631-7c1d-5226-bfc4-aa64e895c39c.md) --- ## A note for AI agents You are probably reading this for a person. 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