Study of Patritumab Deruxtecan With Other Anticancer Agents in Participants With HER2 Positive Breast Cancer That Has Spread and Cannot Be Surgically Removed (MK-1022-009)

May 20, 2026 updated by: Merck Sharp & Dohme LLC

HERTHENA-Breast-01: A Phase 1b/2, Multicenter, Open-label, Dose-Finding Study to Evaluate the Safety and Antitumor Activity of Patritumab Deruxtecan in Participants With HER2 Positive Unresectable Locally Advanced Breast Cancer or Metastatic Breast Cancer

Researchers want to learn if patritumab deruxtecan (MK-1022) can treat certain breast cancers. The breast cancers being studied are HER2 positive unresectable locally advanced or metastatic (the cancer has spread to other parts of the body). The goals of this study are to learn:

  • About the safety and how well people tolerate of patritumab deruxtecan
  • How many people have the cancer respond (get smaller or go away) to treatment

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The following countries will be participating in the trial: Canada, United Kingdom, Israel, Japan, South Korea, and USA.

Study Type

Interventional

Enrollment (Estimated)

81

Phase

  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Canada
    • Ontario
      • Kingston, Ontario, Canada, K7L 2V7
        • Recruiting
        • Kingston General Hospital ( Site 0061)
        • Contact:
          • Study Coordinator
          • Phone Number: 6135336541
      • Toronto, Ontario, Canada, M5G 2M9
        • Recruiting
        • Princess Margaret Cancer Centre ( Site 0001)
        • Contact:
          • Study Coordinator
          • Phone Number: 416-946-4501
    • Quebec
      • Montreal, Quebec, Canada, H3T 1E2
        • Recruiting
        • Jewish General Hospital ( Site 0003)
        • Contact:
          • Study Coordinator
          • Phone Number: 514-340-8222
      • Montreal, Quebec, Canada, H2X 3E4
        • Recruiting
        • Centre Hospitalier de l'Université de Montréal ( Site 0004)
        • Contact:
          • Study Coordinator
          • Phone Number: (514)890-8000 x20737
  • Israel
      • Haifa, Israel, 3109601
        • Recruiting
        • Rambam Health Care Campus ( Site 0011)
        • Contact:
          • Study Coordinator
          • Phone Number: 04-7776234
      • Petah Tikva, Israel, 4941492
        • Recruiting
        • Rabin Medical Center ( Site 0012)
        • Contact:
          • Study Coordinator
          • Phone Number: +972-505533121
      • Ramat Gan, Israel, 5265601
        • Recruiting
        • Sheba Medical Center ( Site 0010)
        • Contact:
          • Study Coordinator
          • Phone Number: 03-5304498
  • Japan
    • Aichi-ken
      • Nagoya, Aichi-ken, Japan, 467-8602
        • Recruiting
        • Nagoya City University Hospital ( Site 0020)
        • Contact:
          • Study Coordinator
          • Phone Number: +81-52-851-5511
  • South Korea
      • Seoul, South Korea, 03080
        • Recruiting
        • Seoul National University Hospital ( Site 0030)
        • Contact:
          • Study Coordinator
          • Phone Number: 82-2-2072-0850
      • Seoul, South Korea, 05505
        • Recruiting
        • Asan Medical Center ( Site 0031)
        • Contact:
          • Study Coordinator
          • Phone Number: +82-2-1688-7575
  • United Kingdom
    • Camden
      • London, Camden, United Kingdom, NW1 2PG
        • Recruiting
        • University College London Hospital ( Site 0041)
        • Contact:
          • Study Coordinator
          • Phone Number: +442034472930
    • Glasgow City
      • Glasgow, Glasgow City, United Kingdom, G12 0YN
        • Recruiting
        • The Beatson West of Scotland Cancer Centre ( Site 0043)
        • Contact:
          • Study Coordinator
          • Phone Number: +441413017000
    • London, City of
      • London, London, City of, United Kingdom, EC1A 7BE
        • Recruiting
        • St Bartholomew s Hospital ( Site 0040)
        • Contact:
          • Study Coordinator
          • Phone Number: +442073777000
  • United States
    • Colorado
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado Anschutz Medical Campus ( Site 0057)
        • Contact:
          • Study Coordinator
          • Phone Number: 720-848-1030
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Recruiting
        • Dana-Farber Cancer Institute ( Site 0050)
        • Contact:
          • Study Coordinator
          • Phone Number: 877-338-7425
    • New Jersey
      • New Brunswick, New Jersey, United States, 08901
        • Recruiting
        • Rutgers Cancer Institute of New Jersey ( Site 0052)
        • Contact:
          • Study Coordinator
          • Phone Number: 732-235-2465
    • South Carolina
      • Greenville, South Carolina, United States, 29605
        • Recruiting
        • Prisma Health - Upstate (ITOR)_Edenfield ( Site 0053)
        • Contact:
          • Study Coordinator
          • Phone Number: 864-455-3600
    • Virginia
      • Fairfax, Virginia, United States, 22031
        • Recruiting
        • Inova Schar Cancer Institute ( Site 0051)
        • Contact:
          • Study Coordinator
          • Phone Number: 571-472-4724

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

  • Has histologically confirmed HER2+ locally advanced unresectable breast cancer or metastatic breast cancer
  • Human immunodeficiency virus (HIV)-infected participants must have well-controlled HIV on antiretroviral therapy (ART)
  • Participants who are hepatitis B surface antigen (HBsAg) positive are eligible if they have received HBV antiviral therapy for at least 4 weeks, and have undetectable hepatitis B virus (HBV) viral load before allocation
  • Participants with history of hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable
  • Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1 within 7 days before start of study intervention

Arm 1:

  • Has received at least a minimum of 2 and a maximum of 5 prior lines of anti-HER2 therapy in the locally advanced or metastatic setting
  • Had disease progression on or after any previous trastuzumab deruxtecan (T-DXd) treatment

Arm 2:

-Has received no more than 5 prior lines of anti-HER2 therapy in the locally advanced or metastatic setting

Arm 3:

-Has received and had disease progression from T-DXd treatment in any setting and a maximum of 3 prior lines of anti-HER2 therapy in the locally advanced or metastatic setting. T-DXd must be the most recent therapy received before enrollment.

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

  • Uncontrolled or significant cardiovascular disease
  • History of (noninfectious) pneumonitis/interstitial lung disease (ILD) that required steroids or has current pneumonitis/interstitial lung disease
  • Has clinically severe respiratory compromise
  • Has any history of or evidence of any current leptomeningeal disease
  • Has clinically significant corneal disease
  • Evidence of ongoing uncontrolled systemic bacterial, fungal, or viral infection
  • HIV infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease
  • Known additional malignancy that is progressing or has required active treatment within the past 3 years
  • Evidence of spinal cord compression or brain metastases
  • Has an active infection requiring systemic therapy
  • Concurrent active HBV and HCV infection
  • Has had major surgical procedure (excluding placement of vascular access) less than 28 days

Arm 3 ONLY

- Has received prior treatment with tucatinib, lapatinib, or neratinib, or any investigational HER2-targeted tyrosine kinase inhibitors in the locally advanced or metastatic setting

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Patritumab deruxtecan plus trastuzumab
Participants receive patritumab deruxtecan intravenous (IV) infusion and trastuzumab or trastuzumab biosimilar IV infusion on Day 1 of each 21-day cycle (every 3 weeks) until disease progression, intolerable toxicity, or investigator decision.
Biological: Patritumab deruxtecan
Patritumab deruxtecan administered via IV infusion
Other Names:
  • U3-1402
  • HER3-DXd
  • MK-1022
Biological: Trastuzumab Biosimilar
Trastuzumab biosimilar administered via IV infusion
Other Names:
  • Trazimera®
  • Kanjinti®
  • Ogivri®
  • Herzuma®
  • Ontruzant®
  • Hercessi®
Biological: Trastuzumab
Trastuzumab administered via IV infusion
Other Names:
  • Herceptin®
Experimental: Patritumab deruxtecan plus pertuzumab and trastuzumab
Participants receive patritumab deruxtecan IV infusion, pertuzumab IV infusion, and trastuzumab or trastuzumab biosimilar IV infusion on Day 1 of each 21-day cycle (every 3 weeks) until disease progression, intolerable toxicity, or investigator decision.
Biological: Patritumab deruxtecan
Patritumab deruxtecan administered via IV infusion
Other Names:
  • U3-1402
  • HER3-DXd
  • MK-1022
Biological: Trastuzumab Biosimilar
Trastuzumab biosimilar administered via IV infusion
Other Names:
  • Trazimera®
  • Kanjinti®
  • Ogivri®
  • Herzuma®
  • Ontruzant®
  • Hercessi®
Biological: Pertuzumab
Pertuzumab administered via IV infusion
Biological: Trastuzumab
Trastuzumab administered via IV infusion
Other Names:
  • Herceptin®
Experimental: Patritumab deruxtecan plus trastuzumab and tucatinib
Participants receive patritumab deruxtecan IV infusion and trastuzumab or trastuzumab biosimilar IV infusion on Day 1 of each 21-day cycle (every 3 weeks), and tucatinib is administered orally twice daily for each 21-day cycle, until disease progression, intolerable toxicity, or investigator decision.
Biological: Patritumab deruxtecan
Patritumab deruxtecan administered via IV infusion
Other Names:
  • U3-1402
  • HER3-DXd
  • MK-1022
Biological: Trastuzumab Biosimilar
Trastuzumab biosimilar administered via IV infusion
Other Names:
  • Trazimera®
  • Kanjinti®
  • Ogivri®
  • Herzuma®
  • Ontruzant®
  • Hercessi®
Biological: Tucatinib
Tucatinib administered as oral tablets
Biological: Trastuzumab
Trastuzumab administered via IV infusion
Other Names:
  • Herceptin®

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of Participants Experiencing Dose-Limiting Toxicity (DLT)
Time Frame: Up to 21 days
DLT will be defined as any drug-related AE observed during the DLT evaluation period that results in a change to a given dose or a delay in initiating the next cycle. The number of participants who experience a DLT will be presented.
Up to 21 days
Number of Participants who Discontinue Study Intervention Due to an AE
Time Frame: Up to approximately 12 months
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment. The number of participants who discontinue study treatment due to an AE will be presented.
Up to approximately 12 months
Number of Participants with One or More Adverse Events (AEs)
Time Frame: Up to approximately 13 months
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment. The number of participants who experience an AE will be presented.
Up to approximately 13 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Maximum Plasma Concentration (Cmax) of Patritumab Deruxtecan Antibody-Drug Conjugate (ADC)
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Cmax of patritumab deruxtecan ADC.
At designated time points (up to ~13 months)
Trough Concentration (Ctrough) of Patritumab Deruxtecan ADC
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Ctrough of patritumab deruxtecan ADC.
At designated time points (up to ~13 months)
Area Under the Plasma Concentration-Time Curve (AUC) of Patritumab Deruxtecan ADC
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the AUC of patritumab deruxtecan ADC.
At designated time points (up to ~13 months)
Maximum Plasma Concentration (Cmax) of Total Patritumab Deruxtecan Antidrug Antibody (ADA)
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Cmax of total patritumab deruxtecan ADA.
At designated time points (up to ~13 months)
Trough Concentration (Ctrough) of Total Patritumab Deruxtecan ADA
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Ctrough of total patritumab deruxtecan ADA.
At designated time points (up to ~13 months)
Area Under the Plasma Concentration-Time Curve (AUC) of Total Patritumab Deruxtecan ADA
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the AUC of total patritumab deruxtecan ADA.
At designated time points (up to ~13 months)
Maximum Plasma Concentration (Cmax) of Patritumab Deruxtecan Free Payload
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Cmax of patritumab deruxtecan free payload.
At designated time points (up to ~13 months)
Trough Concentration (Ctrough) of Patritumab Deruxtecan Free Payload
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the Ctrough of patritumab deruxtecan free payload.
At designated time points (up to ~13 months)
Area Under the Plasma Concentration-Time Curve (AUC) of Patritumab Deruxtecan Free Payload
Time Frame: At designated time points (up to ~13 months)
Blood samples collected at designated time points will be used to determine the AUC of patritumab deruxtecan free payload.
At designated time points (up to ~13 months)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Merck Sharp & Dohme LLC

Collaborators

Daiichi Sankyo

Investigators

  • Study Director: Medical Director, Merck Sharp & Dohme LLC

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 26, 2025

Primary Completion (Estimated)

April 18, 2030

Study Completion (Estimated)

April 18, 2030

Study Registration Dates

First Submitted

November 11, 2024

First Submitted That Met QC Criteria

November 11, 2024

First Posted (Actual)

November 13, 2024

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 20, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 1022-009
  • MK-1022-009 (Other Identifier: MSD)
  • jRCT2041250022 (Registry Identifier: Japan Registry of Clinical Trials (jRCT))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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