A Study of ZEN003694 and Talazoparib in Patients With Triple Negative Breast Cancer (TNBC)

A Phase 2b Study of ZEN003694 in Combination With Talazoparib in Patients With Triple-Negative Breast Cancer

This is a two-part open label, non-randomized, Phase 2, study of ZEN003694 in combination with Talazoparib in patients with TNBC without germline mutations of BRCA1 or BRCA2. Part 1 is a dose escalation and Part 2 is a Simon 2-Stage design. There are 3 expansion cohorts: Expansion Cohort A (combination treatment in post-TROP2-ADC patients), Expansion Cohort B (ZEN003694 monotherapy), and Expansion Cohort C (combination treatment in TROP2-ADC-naive patients).

Study Overview

• Status: Terminated
• Conditions: Triple Negative Breast Cancer
• Intervention / Treatment: Drug: ZEN003694; Drug: Talazoparib

• Study Type: Interventional
• Enrollment (Actual): 115
• Phase: Phase 2

Contacts and Locations

Study Locations

• Belgium
  • Anderlecht, Belgium, 1070
    • Institut Jules Bordet
  • Leuven, Belgium, 3000
    • UZ Leuven
• China
  • Anhui
    • Bengbu, Anhui, China, 233000
      • The First Affiliated Hosptial of Bengbu Medical College
  • Guangdong
    • Guangzhou, Guangdong, China, 510060
      • Sun yat-sen University Cancer Center
    • Guangzhou, Guangdong, China, 510289
      • Sun Yat-sen Memorial Hospital, Sun Yat-sen University
  • Hunan
    • Changsha, Hunan, China, 410000
      • Hunan Cancer Hospital
  • Shandong
    • Jining, Shandong, China, 272000
      • Affliated Hospital of Jining Medical University
  • Sichuan
    • Neijiang, Sichuan, China, 641100
      • The Second People's Hospital of Neijiang
  • Tianjin Municipality
    • Tianjin, Tianjin Municipality, China, 300060
      • Tianjing Medical University Cancer Institute & Hospital
• Spain
  • Barcelona, Spain, 08035
    • Vall d'Hebron Institute of Oncology (VHIO)
  • Madrid, Spain, 28050
    • START Madrid
• United States
  • Arizona
    • Gilbert, Arizona, United States, 85234
      • Banner MD Anderson Cancer Center
  • Georgia
    • Atlanta, Georgia, United States, 30322
      • Emory University Winship Cancer Institute
  • Kansas
    • Westwood, Kansas, United States, 66203
      • University of Kansas Cancer Center
  • Massachusetts
    • Boston, Massachusetts, United States, 02115
      • Dana Farber Cancer Institute
  • New York
    • New York, New York, United States, 10065
      • Memorial Sloan Kettering Cancer Center
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104
      • University of Pennsylvania
  • Tennessee
    • Nashville, Tennessee, United States, 37203
      • Tennessee Oncology (Sarah Cannon)
  • Texas
    • Houston, Texas, United States, 77030
      • MD Anderson

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Females or males age ≥ 18 years (at time of signing informed consent)

2. Parts 1 and 2 only: Histologically confirmed metastatic or recurrent or locally advanced triple-negative breast cancer (estrogen receptor (ER) ≤10%; progesterone receptor (PR) ≤10%; and HER2 negative by immunohistochemistry (IHC) or fluorescent in situ hybridization (FISH)

   Expansion only: Histologically confirmed metastatic or recurrent, or locally advanced triple-negative breast cancer as defined by the most recent American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines.

3. Patient is not a candidate for endocrine based therapy, based on Investigator judgement
4. Have a history of progressive disease despite prior therapy

5. Part 1: Have had at least 1 prior cytotoxic chemotherapy.

   Part 2: Have had no more than 2 prior chemotherapy-inclusive regimens for locally advanced or metastatic disease, unless approved by the Sponsor (no limit on prior targeted anticancer therapies such as mechanistic target or rapamycin (mTOR) or CDK4/6 inhibitors, immune-oncology agents, tyrosine kinase inhibitors, or monoclonal antibodies against CTL4 or VEGF.)

   Expansion Cohort A (combination treatment in post-TROP2-ADC patients): Have received TROP2-ADC therapy for unresectable locally advanced or metastatic disease.

   Expansion Cohort B (ZEN003694 monotherapy): Have had at least 1 prior systemic therapy for locally advanced or metastatic disease which may or may not have included a TROP2-ADC.

   Expansion Cohort C (combination treatment in TROP2-ADC-naive patients): Have had at least 1 prior systemic therapy for locally advanced or metastatic disease and who have not received prior TROP2-ADC therapy.

6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
7. Part 2 and Expansion only: Measurable disease per RECIST version 1.1

Exclusion Criteria:

1. Documented germline mutations of BRCA1 or BRCA2
2. Parts 1 and 2 only: Evidence of disease progression during platinum treatment either in the neoadjuvant or in the metastatic setting. For patients receiving platinum in the neoadjuvant setting, at least 6 months must have elapsed between the last dose of platinum-based treatment and enrollment
3. Part 2 only: Patients with inflammatory breast cancer
4. Current or anticipated use of medications known to be strong inhibitors or inducers of CYP3A4 or substrates of CYP1A2 with narrow therapeutic windows. Strong inhibitors, inducers or substrates must be discontinued at least 7 days prior to the first administration of study drug.
5. Current or anticipated use within 7 days prior to the first administration of study drug, or during the study, of strong P-gp inhibitors.
6. Use of oral Factor Xa inhibitors (i.e., rivaroxaban, apixaban, betrixaban, edoxaban otamixaban, letaxaban, eribaxaban) and Factor IIa inhibitors (i.e., dabigatran). Low molecular weight heparin is allowed
7. Prior anticancer therapy (chemotherapy, radiation, hormone therapy, immunotherapy or investigational agent) within 3 weeks from the start of study drug (except for nitrosoureas and mitomycin C within 6 weeks from start of study drug)
8. Parts 1 and 2 only: Radiation to >25% of the bone marrow
9. Treatment with a bone-targeted radionuclide within 6 weeks of first dose of study drug
10. Have previously received an investigational BET inhibitor (including previous participation in studies with the Sponsor's drug, ZEN003694); except for patients in Expansion Cohort B who received ZEN003694 monotherapy and are eligible to cross-over to combination treatment
11. Prior treatment with a PARP inhibitor
12. QTcF interval > 470 msec
13. Insufficient recovery (i.e., has not recovered to at least Grade 1) from prior treatment-related toxicities except for alopecia, fatigue and Grade 2 neuropathy
14. Non-healing wound, ulcer or bone fracture (not including a pathological bone fracture caused by a pre-existing pathological bone lesion)

15. Parts 1 and 2 only: Brain metastases not adequately treated and clinically stable (at the discretion of the Investigator) for at least 3 months prior to the start of study treatment, unless a shorter interval is approved by the Sponsor's Medical Monitor

    Expansion only: Progressive, symptomatic, or untreated brain metastases. CNS metastases treated definitively with surgery and/or radiation must be radiographically stable based on imaging at least 3 months after definitive treatment. CNS metastases requiring steroid doses equivalent to prednisone doses >10 mg daily or an increase in steroid doses due to CNS disease prior to consent are not eligible

16. Expansion only: Disease initially diagnosed with expression of estrogen receptor (ER) or progesterone receptor (PR) as ≥5%
17. Expansion only: Patients treated with prior endocrine therapy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part 1 and Part 2; ZEN003694 will be administered PO QD with Talazoparib PO QD in 28-day cycles. Patients have histologically confirmed Triple Negative Breast Cancer and have no documented germline mutations of BRCA1 or BRCA2. Includes sites in the US and EU.	Drug: ZEN003694; PO QD; Other Names: ZEN-3694; Drug: Talazoparib; PO QD; Other Names: Talzenna
Experimental: Expansion Cohort A - Combination Treatment in post-TROP2-ADC patients; ZEN003694 will be administered PO QD with Talazoparib PO QD at the RP2D in 28-day cycles. Patients have histologically confirmed Triple Negative Breast Cancer and have no documented germline mutations of BRCA1 or BRCA2. Includes sites in the US and EU.	Drug: ZEN003694; PO QD; Other Names: ZEN-3694; Drug: Talazoparib; PO QD; Other Names: Talzenna
Experimental: Expansion Cohort B - ZEN003694 Monotherapy; ZEN003694 will be administered PO QD as monotherapy at the RP2D in 28-day cycles with the option to cross-over to combination treatment of ZEN003694 PO QD with Talazoparib PO QD at the time of disease progression (but no sooner than after 6 weeks of monotherapy). Patients have histologically confirmed Triple Negative Breast Cancer and have no documented germline mutations of BRCA1 or BRCA2. Includes sites in the US and EU.	Drug: ZEN003694; PO QD; Other Names: ZEN-3694
Experimental: Expansion Cohort C - Combination Treatment in TROP2-ADC-naïve patients; ZEN003694 will be administered PO QD with Talazoparib PO QD at the RP2D in 28-day cycles. Patients have histologically confirmed Triple Negative Breast Cancer and have no documented germline mutations of BRCA1 or BRCA2. Includes sites in China only.	Drug: ZEN003694; PO QD; Other Names: ZEN-3694; Drug: Talazoparib; PO QD; Other Names: Talzenna

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part 1 and Part 2: Number of Participants With Treatment-related Adverse Events (AE) and Treatment-related Serious Adverse Events (SAE)		Cycle 1 Day 1 to 30 days post last dose (each cycle is 28 days) up to 22 months
Part 1: Number of Participants With Dose-limiting Toxicities (DLT)	Determination of DLT will be made during the first 28 days of treatment (i.e., Cycle 1) in the dose escalation phase. A DLT is defined as a clinically significant AE or laboratory abnormality that is considered possibly, probably or definitely related to study drug.	Cycle 1, Up to 1 month
Part 2: Clinical Benefit Rate (CBR)	Percentage of patients with a best overall response of confirmed complete response (CR), partial response (PR), or stable disease (SD ≥ 4 cycles) by RECIST v1.1	From screening up to 18 months
Expansion Cohort A: Objective Response Rate (ORR) by RECIST v1.1 (CR or PR)	Percentage of participants with a confirmed complete response (CR) or partial response (PR) by RECIST 1.1	From screening up to 18 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part 2, Expansion Cohorts A and C: Change From Baseline in Global Health Status/Quality of Life (QoL) Measured by EORTC QLQ-C30 for Overall Duration	European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30): cancer-specific instrument with 30 questions to assess the participant QoL. First 28 questions used to evaluate 5 functional scales (physical, role, cognitive, emotional, social), 3 symptom scales (fatigue, nausea and vomiting, pain) and other single items (dyspnea, appetite loss, insomnia, constipation, diarrhea, financial difficulties). Each question assessed on 4-point scale (1= not at all, 2= a little, 3= quite a bit, 4= very much); functional scales: higher score = better level of functioning; symptom scale: higher score = more severe symptoms; for single items: higher score= more severe problem. Last 2 questions used to evaluate global health status (GHS)/QoL. Each question was assessed on 7-point scale (1= very poor to 7= excellent). Scores averaged, transformed to 0-100 scale; higher score=better quality of life/better level of functioning.	Screening and Day 1 of every 28-day Cycle, up to 18 months (Overall Duration)
Part 1, Expansion Cohorts A and C: Clinical Benefit Rate (CBR)	Percentage of participants with a confirmed complete response (CR), partial response (PR), or stable disease (SD ≥ 4 cycles) by RECIST 1.1	From screening up to 18 months
Part 1, Part 2, and Expansion Cohort C: Objective Response Rate (ORR)	Percentage of participants with a confirmed complete response (CR) or partial response (PR) by RECIST 1.1	From screening up to 18 months
Part 2, Expansion Cohorts A and C: Safety Profile of ZEN003694 in Combination With Talazoparib.	Incidence of Treatment-related Adverse Events (AE) and Treatment-related Serious Adverse Events (SAE) in Part 2, Expansion Cohorts A and C	From screening up to 18 months
Part 1, Part 2, Expansion Cohorts A & C: Evaluate Median Progression-free Survival	Median progression-free survival is the time from randomization to documented disease progression or death	From screening up to 18 months
Part 2, Expansion Cohorts A and C: Evaluate Duration of Response (DOR)	For subjects with a confirmed response of PR or CR, duration of response is measured from the date of the first response until the time that overall disease progression (radiographic progressive disease or clinical deterioration) or death is documented.	From screening up to 18 months
Part 1 and Part 2: Measure the Pharmacokinetic Parameter (PK) of Cmax of ZEN003694 and ZEN003791 (Active Metabolite)	Cmax is defined as the maximum or peak plasma concentration of drug (calculated from samples taken over a 4-hour or 8-hour time period). Cmax(0-8h) was calculated for Cycle 1, Day 1. Cmax(0-4h) was calculated for Cycle 2, Day 1. Pre-dose is time 0 for calculations.	Part 1: Cycle 1 Day 1: Pre-dose, 15 min, 30 min, 1 hour, 2 hour, 4 hour, 6 hour, and 8 hours post-dose. Parts 1 & 2: Cycle 2 Day 1: Pre-dose, 1 hour, 2 hour, and 4 hours post-dose. (cycles are 28 days)
Part 1 and Part 2: Measure the Pharmacokinetic (PK) Parameter of Combined AUC(0-4h or 0-8h) of ZEN003694 and ZEN003791 (Active Metabolite)	AUC(0-4h or 0-8h) is defined as the area under the curve (plasma concentration of drug calculated from samples taken over a 4-hour or 8-hour time period). AUC(0-8h) was calculated for Cycle 1, Day 1. AUC(0-4h) was calculated for Cycle 2, Day 1. Pre-dose is time 0 for calculations.	Part 1: Cycle 1 Day 1: Pre-dose, 15 min, 30 min, 1 hour, 2 hour, 4 hour, 6 hour, and 8 hours post-dose. Parts 1 & 2: Cycle 2 Day 1: Pre-dose, 1 hour, 2 hour, and 4 hours post-dose. (cycles are 28 days)
Part 1 & 2: Measure Plasma Concentrations of Talazoparib.	Plasma concentrations of talazoparib will be measured.	Part 1: Cycle 1 Day 15: Pre-dose; Parts 1& 2 Cycle 2 Day 1: Pre-dose; Cycle 2 Day 15: Pre-dose (each cycle is 28 days)
Expansion Cohorts A, B, and C: Measure Plasma Concentrations of ZEN003694 and the Active Metabolite ZEN003791.	Plasma concentrations of ZEN003694 and the active metabolite ZEN003791 will be measured.	Cycle 2 Day 1: Pre-dose, 1 hour, 2 hours, and 4 hours post-dose; Cycle 2 Day 15: Pre-dose (each cycle is 28 days)
Expansion Cohorts A and C: Measure Plasma Concentrations of Talazoparib.	Plasma concentrations of talazoparib will be measured.	Cycle 2 Day 1: Pre-dose, Cycle 2 Day 15: Pre-dose (each cycle is 28 days)
Part 2, Expansion Cohorts A and C: Change From Baseline in Breast Symptoms Scale as Assessed by the EORTC-QLQ-BR23	European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire Breast Cancer Module (EORTC-QLQ-BR23) is a disease-specific module for breast cancer developed as a supplement for the EORTC-QLQ-C30 to assess the quality of life of participants with breast cancer. EORTC-QLQ-BR23 symptoms subscale includes 4 items: systemic therapy side effects, breast symptoms, arm symptoms, upset by hair loss. Each item is rated by choosing 1 of 4 possible responses that record the level of intensity (1= not at all, 2= a little, 3= quite a bit, and 4= very much), higher scores=high level of symptom/problems.	Screening and Day 1 of every 28-day Cycle, up to 18 months (Overall Duration)

Collaborators and Investigators

• Sponsor: Zenith Epigenetics
• Collaborators: Pfizer; Newsoara Biopharma Co., Ltd.

Publications and helpful links

General Publications

• Kharenko OA, Patel RG, Calosing C, van der Horst EH. Combination of ZEN-3694 with CDK4/6 inhibitors reverses acquired resistance to CDK4/6 inhibitors in ER-positive breast cancer. Cancer Gene Ther. 2022 Jun;29(6):859-869. doi: 10.1038/s41417-021-00375-9. Epub 2021 Aug 12.

Study record dates

Study Major Dates

• Study Start (Actual): June 26, 2019
• Primary Completion (Actual): March 7, 2024
• Study Completion (Actual): March 7, 2024

Study Registration Dates

• First Submitted: March 22, 2019
• First Submitted That Met QC Criteria: April 1, 2019
• First Posted (Actual): April 3, 2019

Study Record Updates

• Last Update Posted (Estimated): October 7, 2025
• Last Update Submitted That Met QC Criteria: September 17, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Breast Cancer; TNBC; Talazoparib; ZEN003694; PARPi; ZEN-3694; poly ADP ribose polymerase; bromodomain; BETi
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Triple Negative Breast Neoplasms; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Antineoplastic Agents; Poly(ADP-ribose) Polymerase Inhibitors; talazoparib
• Other Study ID Numbers: ZEN003694-004; 2018-003906-26 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No